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Surface Fronts and Sea-Level Pressures Legacy Page:
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+ Short Range Forecast Discussion (Day ½-2½)
+ Medium Range Forecast Discussion (Day 3-7)
+ Hawaii Forecast Discussion (Day 1-7)
Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
259 AM EDT Thu Apr 3 2025
Valid 00Z Fri 04 Apr 2025 - 00Z Fri 11 Apr 2025
An upper low well to the north of Hawaii will lift out of the
region by this weekend. The cold front for this system may briefly
stall over northern islands allowing for some increased
precipitation chances, primarily for Kauai. By this weekend and
into next week, a surface high will build to the north of Hawaii
allowing for a return of more typical and breezy trades. Winds may
relax briefly mid next week as a weak shortwave trough moves in
east of the state. The guidance shows excellent agreement on this
fairly quiet pattern over the next week for Hawaii.
Santorelli
+ Additional Links
Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
400 AM EDT Thu Apr 03 2025
Valid 12Z Thu Apr 03 2025 - 12Z Sat Apr 05 2025
...Life-threatening, catastrophic, and potentially historic flash flood
event continues across the Lower Ohio Valley and Mid-South...
...A couple rounds of significant severe weather expected from the
Mid-South west through the Ozarks and ArkLaTex with very large hail and
strong tornadoes possible...
...Moderate to locally heavy snow showers expected for the Rockies, with
some snow showers spreading eastward into the High and Northern/Central
Plains...
...Well above average, very warm Spring temperatures to end the week
across the Southeast with numerous record-tying/breaking highs possible...
A powerful Spring storm system will continue to bring the threat of
life-threatening flash flooding and significant severe weather focused on
the Ohio Valley west-southwest through the Middle Mississippi Valley,
Mid-South, and ArkLaTex. A leading upper-level shortwave within a broader
large-scale trough over the western/central U.S. and accompanying surface
low pressure/frontal system will continue eastward over the Great Lakes
and Northeast today, with a trailing cold front stretching southwestward
through the Mid-Atlantic, Ohio Valley, Mid-South, and into the Southern
Plains. A building upper-level ridge over the Southeast has brought the
progress of this frontal boundary to a halt overnight, with the boundary
expected to remain quasi-stationary through the region over the next few
days. The blocking pattern has also focused southerly flow of deep
boundary layer moisture from the Gulf along the front which will help to
fuel continued rounds of intense downpour-producing thunderstorms
throughout the region, but with a particular focus centered on the Lower
Ohio Valley into the Mid-South. Storm initiation and movement roughly
parallel to the boundary will lead to repeated rounds of rainfall over the
same areas, including those already hard hit on Wednesday, leading to
significant to extreme rainfall totals over increasingly saturated soils.
A High Risk of Excessive Rainfall (level 4/4) is in effect Thursday from
southwestern Kentucky into western Tennessee and northeastern Arkansas
where the greatest threat for numerous instances of life-threatening flash
flooding exists following heavy rainfall over the same areas Wednesday. A
broader Moderate Risk (level 3/4) stretches from the Lower Ohio Valley
southwest through the Mid-South with a Slight Risk (level 2/4) across the
broader Ohio Valley southwest to the ArkLaTex where additional scattered
to numerous instances of flash flooding are possible. Another Moderate
Risk is in effect on Friday with the focus shifting a bit northwestward
over the Middle Mississippi Valley southwest through the ArkLaTex, areas
that have not been as hard hit compared to the Lower Ohio
Valley/Mid-South, but are still expected to see significant heavy rainfall
totals and scattered to numerous instances of flash flooding. A Slight
Risk extends further northeast towards the Great Lakes as well as
southwest into portions of the southern Plains where additional scattered
instances of flash flooding will be possible. Then, on Saturday, another
High Risk is in effect as the focus shifts back towards the hard hit Lower
Ohio Valley/Mid-South. This is a catastrophic, potentially historic heavy
rainfall and flash flood event, with some locations potentially seeing
rainfall amounts as high as 10-15"+ through the weekend. The additional
rounds of heavy rainfall each day will also raise the risk of catastrophic
river flooding from western Kentucky into northwest Tennessee, and
widespread significant river flooding from the Ozarks/ArkLaTex through the
Lower Ohio Valley. Communities in the region should prepare for possible
long duration and severe disruptions to daily life.
In addition to the flash flood threat, significant severe weather will
also remain a concern for many of the same locations over the next couple
of days. Embeded shortwaves within the broader trough will help to bring
upper-level dynamic support amidst intense low-level southerly flow and
sufficient instability to support supercells. The Storm Prediction Center
has issued an Enhanced Risk of severe weather (level 3/5) from the
Mid-South west through the ArkLaTex Thursday for the threat of a few
tornadoes, some of which could be strong, very large hail, and damaging
winds. A broader Slight Risk (level 2/5) extends along the boundary from
the Mid-Atlantic southwest though the Tennessee Valley/Mid-South and into
northern Texas for the threat of large hail, damaging winds, and a few
tornadoes. An Enhanced Risk is also in place Friday across the
Ozarks/ArkLaTex as another round of storms will bring yet another threat
for a few tornadoes, including strong tornadoes, very large hail, and
damaging winds. A Slight Risk extends from the Middle/Lower Mississippi
Valley southwest through northern and central Texas mainly for the threat
of large hail and damaging winds.
A pair of upper waves and a passing cold front will help support snow
showers over the Rockies as well as bring the chance for some wintry
precipitation to the High and northern/central Plains the next couple of
days. To the north, a northern stream upper wave dropping south from
Canada and accompanying surface cold front will bring moderate to heavy
snows Thursday to the northern Rockies, as well as a wintry mix of rain
and snow spreading eastward into portions of the northern/central Plains
Thursday into Friday. Accumulations are expected to remain light with any
snows over the Plains. To the south, an upper-level shortwave in the
broader western/central U.S. trough will pass over the Four Corners region
and central/southern Rockies as an area of low pressure in the lee of the
Rockies helps to focus upslope flow along the mountains. Moderate to
locally heavy snows are expected Thursday into Friday for the regional
mountain ranges, with the potential for some snow for portions of the High
Plains along the Front Range. The cold front to the north will also pass
southward by late Friday and into the day Saturday, bringing renewed
post-frontal upslope flow and additional heavy snow for the mountains of
the Front Range. There is also an increasing potential for accumulating
snow spreading further east across the Raton Mesa on Friday and across
portions of the southern High Plains on Saturday. Elsewhere, some showers
and thunderstorms are expected across the Northeast Thursday as the lead
system passes through the region. Wintry precipitation will remain
possible further north into northern Maine, with some light snow and ice
accumulations possible. Some lingering snow showers are expected Thursday
over portions of the western Great Basin and into the Sierra Nevada, with
rain showers for southern California.
The amplifying pattern will lead to expanding well above average, warm
Spring temperatures over portions of the eastern U.S. as the upper-level
ridge builds northward, while temperatures will remain much cooler and
below average under the upper-level trough over most of the
western/central U.S. Forecast highs the the next couple days from southern
Texas east through the Lower Mississippi Valley and into the Southeast
will be in the 80s to low 90s, with numerous record-tying/breaking highs
possible. Well above average temperatures are also forecast from the Lower
Great Lakes east into the Mid-Atlantic/Northeast Thursday as highs rise
into the 60s, 70s, and low 80s before a cold front brings more seasonable
temperature mainly in the 60s Friday. Forecast highs from the
Northern/Central Plains into the Interior West will be mostly well below
average, with 30s and 40s expected. Areas of the Southern Plains outside
of south Texas will cool from the 60s Thursday to the 50s on Friday, while
the Desert Southwest will see highs mainly in the 60s to low 70s. The West
Coast will see warmer, above average temperatures compared to the rest of
the West as a ridge builds northward over the region, with highs in the
60s.
Putnam
Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php
NWS Weather Prediction Center College Park MD
400 AM EDT Thu Apr 03 2025
Valid 12Z Thu Apr 03 2025 - 12Z Sat Apr 05 2025
...Life-threatening, catastrophic, and potentially historic flash flood
event continues across the Lower Ohio Valley and Mid-South...
...A couple rounds of significant severe weather expected from the
Mid-South west through the Ozarks and ArkLaTex with very large hail and
strong tornadoes possible...
...Moderate to locally heavy snow showers expected for the Rockies, with
some snow showers spreading eastward into the High and Northern/Central
Plains...
...Well above average, very warm Spring temperatures to end the week
across the Southeast with numerous record-tying/breaking highs possible...
A powerful Spring storm system will continue to bring the threat of
life-threatening flash flooding and significant severe weather focused on
the Ohio Valley west-southwest through the Middle Mississippi Valley,
Mid-South, and ArkLaTex. A leading upper-level shortwave within a broader
large-scale trough over the western/central U.S. and accompanying surface
low pressure/frontal system will continue eastward over the Great Lakes
and Northeast today, with a trailing cold front stretching southwestward
through the Mid-Atlantic, Ohio Valley, Mid-South, and into the Southern
Plains. A building upper-level ridge over the Southeast has brought the
progress of this frontal boundary to a halt overnight, with the boundary
expected to remain quasi-stationary through the region over the next few
days. The blocking pattern has also focused southerly flow of deep
boundary layer moisture from the Gulf along the front which will help to
fuel continued rounds of intense downpour-producing thunderstorms
throughout the region, but with a particular focus centered on the Lower
Ohio Valley into the Mid-South. Storm initiation and movement roughly
parallel to the boundary will lead to repeated rounds of rainfall over the
same areas, including those already hard hit on Wednesday, leading to
significant to extreme rainfall totals over increasingly saturated soils.
A High Risk of Excessive Rainfall (level 4/4) is in effect Thursday from
southwestern Kentucky into western Tennessee and northeastern Arkansas
where the greatest threat for numerous instances of life-threatening flash
flooding exists following heavy rainfall over the same areas Wednesday. A
broader Moderate Risk (level 3/4) stretches from the Lower Ohio Valley
southwest through the Mid-South with a Slight Risk (level 2/4) across the
broader Ohio Valley southwest to the ArkLaTex where additional scattered
to numerous instances of flash flooding are possible. Another Moderate
Risk is in effect on Friday with the focus shifting a bit northwestward
over the Middle Mississippi Valley southwest through the ArkLaTex, areas
that have not been as hard hit compared to the Lower Ohio
Valley/Mid-South, but are still expected to see significant heavy rainfall
totals and scattered to numerous instances of flash flooding. A Slight
Risk extends further northeast towards the Great Lakes as well as
southwest into portions of the southern Plains where additional scattered
instances of flash flooding will be possible. Then, on Saturday, another
High Risk is in effect as the focus shifts back towards the hard hit Lower
Ohio Valley/Mid-South. This is a catastrophic, potentially historic heavy
rainfall and flash flood event, with some locations potentially seeing
rainfall amounts as high as 10-15"+ through the weekend. The additional
rounds of heavy rainfall each day will also raise the risk of catastrophic
river flooding from western Kentucky into northwest Tennessee, and
widespread significant river flooding from the Ozarks/ArkLaTex through the
Lower Ohio Valley. Communities in the region should prepare for possible
long duration and severe disruptions to daily life.
In addition to the flash flood threat, significant severe weather will
also remain a concern for many of the same locations over the next couple
of days. Embeded shortwaves within the broader trough will help to bring
upper-level dynamic support amidst intense low-level southerly flow and
sufficient instability to support supercells. The Storm Prediction Center
has issued an Enhanced Risk of severe weather (level 3/5) from the
Mid-South west through the ArkLaTex Thursday for the threat of a few
tornadoes, some of which could be strong, very large hail, and damaging
winds. A broader Slight Risk (level 2/5) extends along the boundary from
the Mid-Atlantic southwest though the Tennessee Valley/Mid-South and into
northern Texas for the threat of large hail, damaging winds, and a few
tornadoes. An Enhanced Risk is also in place Friday across the
Ozarks/ArkLaTex as another round of storms will bring yet another threat
for a few tornadoes, including strong tornadoes, very large hail, and
damaging winds. A Slight Risk extends from the Middle/Lower Mississippi
Valley southwest through northern and central Texas mainly for the threat
of large hail and damaging winds.
A pair of upper waves and a passing cold front will help support snow
showers over the Rockies as well as bring the chance for some wintry
precipitation to the High and northern/central Plains the next couple of
days. To the north, a northern stream upper wave dropping south from
Canada and accompanying surface cold front will bring moderate to heavy
snows Thursday to the northern Rockies, as well as a wintry mix of rain
and snow spreading eastward into portions of the northern/central Plains
Thursday into Friday. Accumulations are expected to remain light with any
snows over the Plains. To the south, an upper-level shortwave in the
broader western/central U.S. trough will pass over the Four Corners region
and central/southern Rockies as an area of low pressure in the lee of the
Rockies helps to focus upslope flow along the mountains. Moderate to
locally heavy snows are expected Thursday into Friday for the regional
mountain ranges, with the potential for some snow for portions of the High
Plains along the Front Range. The cold front to the north will also pass
southward by late Friday and into the day Saturday, bringing renewed
post-frontal upslope flow and additional heavy snow for the mountains of
the Front Range. There is also an increasing potential for accumulating
snow spreading further east across the Raton Mesa on Friday and across
portions of the southern High Plains on Saturday. Elsewhere, some showers
and thunderstorms are expected across the Northeast Thursday as the lead
system passes through the region. Wintry precipitation will remain
possible further north into northern Maine, with some light snow and ice
accumulations possible. Some lingering snow showers are expected Thursday
over portions of the western Great Basin and into the Sierra Nevada, with
rain showers for southern California.
The amplifying pattern will lead to expanding well above average, warm
Spring temperatures over portions of the eastern U.S. as the upper-level
ridge builds northward, while temperatures will remain much cooler and
below average under the upper-level trough over most of the
western/central U.S. Forecast highs the the next couple days from southern
Texas east through the Lower Mississippi Valley and into the Southeast
will be in the 80s to low 90s, with numerous record-tying/breaking highs
possible. Well above average temperatures are also forecast from the Lower
Great Lakes east into the Mid-Atlantic/Northeast Thursday as highs rise
into the 60s, 70s, and low 80s before a cold front brings more seasonable
temperature mainly in the 60s Friday. Forecast highs from the
Northern/Central Plains into the Interior West will be mostly well below
average, with 30s and 40s expected. Areas of the Southern Plains outside
of south Texas will cool from the 60s Thursday to the 50s on Friday, while
the Desert Southwest will see highs mainly in the 60s to low 70s. The West
Coast will see warmer, above average temperatures compared to the rest of
the West as a ridge builds northward over the region, with highs in the
60s.
Putnam
Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php
Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
234 AM EDT Thu Apr 3 2025
Valid 12Z Sun Apr 06 2025 - 12Z Thu Apr 10 2025
...Overview...
The frontal boundary responsible for significant and potentially
historic flooding and flash flooding during the short range period
should finally push east by Sunday. This happens from a gradually
amplifying Great Lakes to Northeast trough and eventual ejection of
southern stream energy. Some moderate to heavy rainfall potential
along the central Gulf Coast and parts of the Southeast with this
front. A shortwave reaching the West on Sunday-Monday could bring
mostly light precipitation to parts of the Northwest. After Monday,
the medium range period should trend much drier across the country
as the overall pattern briefly becomes flatter and more
progressive on the way toward a western ridge/eastern trough
configuration.
...Guidance/Predictability Assessment...
Overall, the latest guidance shows good agreement on the larger
scale pattern, but plenty of uncertainty still in the details of
smaller scale systems/energies. There are still some initial
questions on how fast southern stream energy ejects eastward on
Sunday-Monday, with the GFS still on the slightly faster side of
consensus. Elsewhere, latest GFS runs remain most aggressive with
the degree to which the digging Great Lakes trough closes off an
upper low by Tuesday, leading to a stronger/more wrapped surface
system. The CMC also shows this to some extent as well, but the
better consensus of models would favor more of an open trough, with
some potential for a neutral or negative tilt at times. Mean
troughing over the northeast Pacific should send a couple of
shortwaves into the West, which could eventually reach the Plains
by midweek. Both the GFS and ECMWF show a modest reflection of a
stronger system with a defined surface low, but the CMC is much
weaker. Ensemble means are also weak/flat which indicates there is
still a lot of uncertainty with this.
The WPC forecast for tonight favored a deterministic model blend
for the first half of the period, increasing the ensemble means to
half the blend by Day 7 to mitigate differences in the guidance.
This maintains good continuity with the previous WPC forecast, at
least through Day 6.
...Weather/Hazards Highlights...
By the start of the period on Sunday, the front responsible for
significant rainfall over the Lower Mississippi Valley to Ohio
Valley region should finally begin to shift eastward. Moderate to
heavy rain and strong storms are possible along the front from the
Gulf Coast states into the Tennessee Valley/Southeast, and farther
north into the Mid-Atlantic and Northeast near the front. The
Sunday ERO shows a Marginal Risk for this region with an embedded
Slight Risk farther south across parts of southern Alabama and
Mississippi where recent heavy rainfall has primed soils and the
greatest instability should be located. Guidance shows potential
for a band of somewhat heavy QPF to extend farther northeast across
northern Georgia into or near the far southern Appalachians, but
latest first-guess fields plus neutral ground moisture (and likely
drier by then given no rain forecast in the shorter term) favor
keeping this region in Marginal Risk for the time being. The front
may slow for a period across parts of the Southeast into Monday,
and anomalous moisture and instability favor just a marginal risk
for the Day 5 ERO at this point since current QPF signals are
modest at best.
Elsewhere by Monday, a cold upper trough reaching the Great Lakes
should lead to unsettled weather over the region with rain or snow.
This precipitation should extend into the Northeast as well.
Latest guidance shows significant differences for surface/upper
evolution over the Northeast early- mid week, with the more extreme
side of the spread producing some significant snowfall over parts
of New England in contrast to much lighter and scattered snow in
the greater proportion of solutions. Probabilities of 0.25 inch
liquid in the form of snow reach no higher than 10-15 percent or so
during the Tuesday-Tuesday night period, reflecting the guidance
majority.
Meanwhile upstream, the upper shortwave/front expected to reach
the West Coast into early next week will be accompanied by a brief
increase in moisture but the system will be fairly progressive.
Thus expect mostly light precipitation but with some terrain-
enhanced moderate activity over western Washington/Oregon and
northwestern California, with decreasing amounts inland over the
Northwest.
Above normal temperatures will linger along the East Coast into
Sunday with daytime highs 10 to 20 degrees above normal.Meanwhile,
well below normal temperatures will be in place across parts of the
southern Rockies and Plains where daytime highs 10 to 20 degrees
below normal may linger into Sunday. Moderated below normal
temperatures will also shift into the central U.S. and Midwest
Monday and the East by Tuesday-Wednesday. Highs over and near the
Ohio Valley could be up to 15 to 20 degrees below normal on
Tuesday. Warmer than average temperatures initially over the
Northwest this weekend should expand into the remainder of the West
and the northern/central Plains by next week. A strengthening
upper ridge will likely expand coverage of plus 10 to 20 degree
anomalies over the West on Wednesday and Thursday.
Santorelli
Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation forecast (QPF), excessive rainfall
outlook (ERO), winter weather outlook (WWO) probabilities, heat
indices, and Key Messages can be accessed from:
https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/#page=ero
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml
https://www.wpc.ncep.noaa.gov/#page=ovw
NWS Weather Prediction Center College Park MD
234 AM EDT Thu Apr 3 2025
Valid 12Z Sun Apr 06 2025 - 12Z Thu Apr 10 2025
...Overview...
The frontal boundary responsible for significant and potentially
historic flooding and flash flooding during the short range period
should finally push east by Sunday. This happens from a gradually
amplifying Great Lakes to Northeast trough and eventual ejection of
southern stream energy. Some moderate to heavy rainfall potential
along the central Gulf Coast and parts of the Southeast with this
front. A shortwave reaching the West on Sunday-Monday could bring
mostly light precipitation to parts of the Northwest. After Monday,
the medium range period should trend much drier across the country
as the overall pattern briefly becomes flatter and more
progressive on the way toward a western ridge/eastern trough
configuration.
...Guidance/Predictability Assessment...
Overall, the latest guidance shows good agreement on the larger
scale pattern, but plenty of uncertainty still in the details of
smaller scale systems/energies. There are still some initial
questions on how fast southern stream energy ejects eastward on
Sunday-Monday, with the GFS still on the slightly faster side of
consensus. Elsewhere, latest GFS runs remain most aggressive with
the degree to which the digging Great Lakes trough closes off an
upper low by Tuesday, leading to a stronger/more wrapped surface
system. The CMC also shows this to some extent as well, but the
better consensus of models would favor more of an open trough, with
some potential for a neutral or negative tilt at times. Mean
troughing over the northeast Pacific should send a couple of
shortwaves into the West, which could eventually reach the Plains
by midweek. Both the GFS and ECMWF show a modest reflection of a
stronger system with a defined surface low, but the CMC is much
weaker. Ensemble means are also weak/flat which indicates there is
still a lot of uncertainty with this.
The WPC forecast for tonight favored a deterministic model blend
for the first half of the period, increasing the ensemble means to
half the blend by Day 7 to mitigate differences in the guidance.
This maintains good continuity with the previous WPC forecast, at
least through Day 6.
...Weather/Hazards Highlights...
By the start of the period on Sunday, the front responsible for
significant rainfall over the Lower Mississippi Valley to Ohio
Valley region should finally begin to shift eastward. Moderate to
heavy rain and strong storms are possible along the front from the
Gulf Coast states into the Tennessee Valley/Southeast, and farther
north into the Mid-Atlantic and Northeast near the front. The
Sunday ERO shows a Marginal Risk for this region with an embedded
Slight Risk farther south across parts of southern Alabama and
Mississippi where recent heavy rainfall has primed soils and the
greatest instability should be located. Guidance shows potential
for a band of somewhat heavy QPF to extend farther northeast across
northern Georgia into or near the far southern Appalachians, but
latest first-guess fields plus neutral ground moisture (and likely
drier by then given no rain forecast in the shorter term) favor
keeping this region in Marginal Risk for the time being. The front
may slow for a period across parts of the Southeast into Monday,
and anomalous moisture and instability favor just a marginal risk
for the Day 5 ERO at this point since current QPF signals are
modest at best.
Elsewhere by Monday, a cold upper trough reaching the Great Lakes
should lead to unsettled weather over the region with rain or snow.
This precipitation should extend into the Northeast as well.
Latest guidance shows significant differences for surface/upper
evolution over the Northeast early- mid week, with the more extreme
side of the spread producing some significant snowfall over parts
of New England in contrast to much lighter and scattered snow in
the greater proportion of solutions. Probabilities of 0.25 inch
liquid in the form of snow reach no higher than 10-15 percent or so
during the Tuesday-Tuesday night period, reflecting the guidance
majority.
Meanwhile upstream, the upper shortwave/front expected to reach
the West Coast into early next week will be accompanied by a brief
increase in moisture but the system will be fairly progressive.
Thus expect mostly light precipitation but with some terrain-
enhanced moderate activity over western Washington/Oregon and
northwestern California, with decreasing amounts inland over the
Northwest.
Above normal temperatures will linger along the East Coast into
Sunday with daytime highs 10 to 20 degrees above normal.Meanwhile,
well below normal temperatures will be in place across parts of the
southern Rockies and Plains where daytime highs 10 to 20 degrees
below normal may linger into Sunday. Moderated below normal
temperatures will also shift into the central U.S. and Midwest
Monday and the East by Tuesday-Wednesday. Highs over and near the
Ohio Valley could be up to 15 to 20 degrees below normal on
Tuesday. Warmer than average temperatures initially over the
Northwest this weekend should expand into the remainder of the West
and the northern/central Plains by next week. A strengthening
upper ridge will likely expand coverage of plus 10 to 20 degree
anomalies over the West on Wednesday and Thursday.
Santorelli
Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation forecast (QPF), excessive rainfall
outlook (ERO), winter weather outlook (WWO) probabilities, heat
indices, and Key Messages can be accessed from:
https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/#page=ero
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml
https://www.wpc.ncep.noaa.gov/#page=ovw
Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
259 AM EDT Thu Apr 3 2025
Valid 00Z Fri 04 Apr 2025 - 00Z Fri 11 Apr 2025
An upper low well to the north of Hawaii will lift out of the
region by this weekend. The cold front for this system may briefly
stall over northern islands allowing for some increased
precipitation chances, primarily for Kauai. By this weekend and
into next week, a surface high will build to the north of Hawaii
allowing for a return of more typical and breezy trades. Winds may
relax briefly mid next week as a weak shortwave trough moves in
east of the state. The guidance shows excellent agreement on this
fairly quiet pattern over the next week for Hawaii.
Santorelli
Quantitative Precipitation Forecasts Legacy Page:
Valid 12Z 04/06/2025 - 12Z 04/07/2025
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Excessive Rainfall Forecasts Interactive Page:
Valid Thu Apr 03 2025 - 12Z Thu Apr 03 2025
Valid Thu Apr 03 2025 - 12Z Fri Apr 04 2025
Valid Fri Apr 04 2025 - 12Z Sat Apr 05 2025
Valid Sat Apr 05 2025 - 12Z Sun Apr 06 2025
Valid 12Z Sun Apr 6 2025 - 12Z Mon Apr 7 2025
Valid 12Z Mon Apr 7 2025 - 12Z Tue Apr 8 2025
Interactive Page
+ Forecast Discussion
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
857 PM EDT Wed Apr 2 2025
Day 1
Valid 01Z Thu Apr 03 2025 - 12Z Thu Apr 03 2025
...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FROM EASTERN
ARKANSAS TO CENTRAL KENTUCKY...
..A PROLONGED LIFE-THREATENING FLASH FLOOD EVENT WILL BEGIN TODAY
WITH SEVERAL DAYS OF HEAVY RAINFALL IMPACTING A LARGE PORTION OF
THE LOWER MISSISSIPPI AND OHIO VALLEYS..
...01Z Update...
Updates to the Day 1 ERO were mainly focused on peeling away the
back (western) side of the Slight and Marginal Risk areas across
parts of the Midwest, based on the latest observational trends and
more recent high-res guidance (current HRRR trends and 18Z HREF
deterministic and probabilistic data). Notable changes to the
remainder of the ERO include confining the northeastern portion of
the Slight (eastern edge now across eastern OH instead of western
NY-northwest PA), while pulling the eastern edges of the Slight
and Moderate Risk areas ever so slightly E-SE, again based on the
latest guidance trends.
Hurley
...16Z Update...
Generally minor updates were made to the ongoing ERO risk areas,
but they were numerous. Most of the changes were based on changes
among the latest CAMs regarding where the heaviest precipitation is
expected through tonight. In summary though, little has changed
with the prior forecast reasoning across the Moderate Risk area.
A High Risk upgrade was precluded for this update for a few
reasons: First, generally the least coverage of expected rainfall
of 2 inches or more compared with subsequent days, second, dry
antecedent soil conditions and relatively low river levels prior to
the start of this event, and third, a good portion of the event
occurs into the Day 2/Thursday period, so the time for heavy rain
to cause flooding will be limited as the storms associated with the
front are progressive/fast-moving for the first half of today as
they're moving into place. There is little doubt that portions of
the moderate risk area will see training storms resulting in flash
flooding, but the coverage of flash flooding are not expected to rise
to High Risk levels today and tonight.
A squall line and attendant cold front moving across Missouri and
northwestern Arkansas will stall along the southern portion of the
line (where the Moderate Risk remains and been expanded), whereas
the northern portion of the line should continue moving eastward
with the upper level energy, which should limit the training
potential. It's important to note that some of the guidance in
southern Indiana suggests a second round of storms develops and
follows closely behind the initial line. However, this second round
of storms is also rather fast moving. Thus, think there should only
be a few hours of heavy rain potential, which suggests the Slight
would be the more appropriate category for that area.
Elsewhere, the Moderate Risk was expanded east to include metro
Nashville due to the slowing of the line and much greater potential
for training than areas further north. For similar reasons, the
Moderate risk was also expanded east to include much of south-
central Kentucky.
The CAMs guidance is in very good agreement that the line will
stall over the northwest corner of Mississippi and is unlikely to
progress much further south and east in northern Mississippi
through 12Z (but likely will after 12Z and into the Day 2 period).
Thus, the risk areas were both trimmed back about a row of counties
and intentionally left with a really tight gradient between the
Moderate risk to the northwest and nothing. This reflects the high
likelihood that the forward progress of the storms stops, resulting
in towns getting little or no rainfall close to others that get
flooding rains only a short distance away.
The warm front of the developing Plains low causing all of this
rainfall appears more likely to get hung up across western New York
tonight. This could result in multiple hours of moderate rainfall
in the Buffalo area and along the Lake Ontario shoreline. Thus, the
Slight Risk area was expanded east. For northern New York into
Vermont, temperatures should remain cold enough that a significant
portion of the precipitation falls as snow or a wintry mix, which
should prevent flooding concerns at least until after 12Z, so the
Marginal Risk area was trimmed.
The broad synoptic setup described in the previous discussion below
remains valid and has been included for reference.
Wegman
Day 1 threat area: www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
411 AM EDT Thu Apr 3 2025
Day 1
Valid 12Z Thu Apr 03 2025 - 12Z Fri Apr 04 2025
...THERE IS A HIGH RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
LOWER TO MID-MISSISSIPPI VALLEYS WITH MAJOR FLOODING EXPECTED...
..A PROLONGED LIFE-THREATENING FLASH FLOOD EVENT WILL CONTINUE
TODAY WITH HEAVY RAINFALL IMPACTING A LARGE PORTION OF THE LOWER
MISSISSIPPI AND OHIO VALLEY'S ONCE AGAIN...
Significant rainfall over the past 12-24 hrs will only add to the
favor of widespread flash flooding later this afternoon and evening
as the next round of heavy rainfall occurs as the next surface wave
rides up the quasi-stationary boundary in place across the Lower to
Mid-Mississippi and Ohio Valleys. Widespread 2-4" of rain with
maxima between 5-6" has fallen this evening across a zone spanning
from southern Arkansas up through western Tennessee and Kentucky
leading to several flash flood warnings as the first surface wave
lifts north. Some overturning of the atmosphere is anticipated by
morning with areal theta_e's decreasing across areas north of the
Ohio River and a tightening instability gradient positioned along
and south of the quasi-stationary front nestled from southwest to
northeast over the Mississippi Valley. Despite some limiting
factors early on, small mid-level perturbations embedded within the
mean flow will still cause some scattered light to moderate
convective development through the morning and afternoon leading to
a continuation of priming from the prior evening.
The nocturnal period will once again become the main period of
interest as the nocturnal LLJ kicks back in across the Deep South
and banks into the stationary front bisecting the Mississippi and
southern Ohio Valley. The same areas that saw the significant rain
and flash flooding this evening will be hit once again with another
wave of convection that will initiate across the ArklaTex and
southern Arkansas and eventually move northeast as the flow aligns
parallel to the stationary front. Additional precip totals of 2-4"
with local to 6" will once again be in the cards for much of
Arkansas, western Tennessee, and southwestern Kentucky which will
ultimately put 48-hr totals between 4-8" with locally up to 10"
during the time frame. Local FFG's are already very low after
today's precip with much of the corridor spanning eastern AR up
through north-central KY exhibiting 1 and 3-hr FFG intervals
running below 1/1.5" respectively. 00z HREF is very much indicating
that rainfall rates during the peak of diurnal convection will
reside within that 1-2"/hr marker with FFG exceedance probabilities
above 50% for the 1/3/6-hr intervals in place. Neighborhood
probabilities for >3" total are between 40-60% across eastern AR
with as high as 60-80% over northwest TN and southwestern KY. >5"
neighborhood probs are running between 25-40% within the same
corridor, backed up by EAS probs >2" sufficiently above 50% along
the Mississippi north of Memphis to points northeast.
Despite the overall output being slightly lower than what occurred
this evening, the prescience has been set for significant flood
potential given the already saturated soils, expected rates, and
regional rivers running high from the previous period of rainfall.
The previous High Risk inherited was generally maintained with
small adjustments accounting for recent rainfall trends, updated
FFG's, and encompassing elevated probabilities from both the hi-res
and national ensemble blends. A Moderate Risk still in effect for
a large area surrounding the High Risk in place across the Lower to
Mid-Mississippi Valley with a span that covers areas of southwest
Arkansas up to as far northeast as Cincinnati.
This is quickly becoming a high-end flash flood scenario with
another day or two of rainfall expected on top of what has occurred
and what will occur. If you lie within a flood plane or any area
that is prone to flash flooding across Arkansas, western Tennessee,
and western Kentucky, you will want to pay close attention and
have a plan to seek higher ground, if possible.
Kleebauer
Day 1 threat area: www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
411 AM EDT Thu Apr 3 2025
Day 2
Valid 12Z Fri Apr 04 2025 - 12Z Sat Apr 05 2025
...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR A LARGE
PORTION OF THE LOWER AND MID-MISSISSIPPI VALLEYS...
The previous synoptic scale forecast was relatively unchanged
within the run to run assessment over the course of Friday into
Saturday morning. The final surface wave within the atmospheric
parade across the Southern Plains to Mississippi Valley will show
itself by late- Friday morning through the remainder of the period.
This wave will likely be the strongest of the 3 allowing a much
more amplified surface evolution that will shift the focus of
heavier precip further northwest while also providing some vigor in
the overall QPF distribution. The trend the past 48 hrs is for a
zone of significant (3-6+") totals to be recognized across portions
of the Southern Plains up through the Ozarks and Mid-Mississippi
Valley of Missouri, spanning as far north as south- central
Illinois. When assessing the theta_e environment, there is a
noticeable push north of more modestly unstable air with the most
pertinent area of available instability situated across southern MO
down through AR, southeastern OK, and even northeastern TX. A
sharp uptick in regional PWATs with deviations between +3 to +4 anomaly-
wise are forecast within that zone correlating with a substantial
rise in area convection blossoming late Friday afternoon, onward.
This setup is fortunately further west compared to the previous
periods, so the overlap of the heaviest rainfall is not anticipated
to be as problematic as the previous period.
Having said that, the pattern will yield high precip totals due to
widespread convective activity, falling over some areas that will
have seen appreciable rain, and over other areas that are more
prone to flooding due to complex terrain situated over the Ozarks.
The pattern is such that several areas from east of DFW up through
IL will see rainfall amounts of 3-6" with locally higher beginning
Friday afternoon with the heaviest rainfall likely to occur by the
evening with the implementation of yet another LLJ structure
thanks to the surface wave mentioned previously. Further to the
west, another closed upper reflection across the Southwest U.S.
will only entice greater upper forcing within a broad axis of
difluence situated over the Plains. This setup is more privy to
convection forming as far west as the Western Rolling Plains of TX
to points east and northeast. Even there, modest 1-2" with locally
higher totals are forecast in-of those zones. The heaviest
precipitation axis based off the latest NBM probabilities still has
a significant footprint of at least 3" located near the Dallas
metro and points just east (40-60%) to as high as 60-80% in a large
area spanning the Red River of northeast TX up through much of
western and northern AR, through the Ozarks of MO, finally reaching
the Mississippi River south of St.Louis. Ensemble mean QPF output
signals a massive area of at least 2" with urban centers like
Dallas, Little Rock, St. Louis, and Springfield, MO all within a
core of the heavy precip footprint.
Considering the probabilistic output of the NBM, the consistency
within guidance for a significant corridor of very heavy rainfall,
and a well-defined axis of training precip potential, a broad
Moderate Risk was maintained and even expanded to account for the
expanse of likely flash flooding. A high-end Moderate is a likely
tag for places within southeast OK up through western and northern
AR through the Ozarks of Missouri as these areas will have the
greatest threat of enhanced rates over top of either complex
terrain or primed soils. An upgrade is plausible in future updates
pending additional convective probability details.
Kleebauer
Day 2 threat area: www.wpc.ncep.noaa.gov/qpf/98epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
411 AM EDT Thu Apr 3 2025
Day 3
Valid 12Z Sat Apr 05 2025 - 12Z Sun Apr 06 2025
...THERE IS A HIGH RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
LOWER TO MID-MISSISSIPPI VALLEYS WITH MAJOR FLOODING EXPECTED...
..LIFE-THREATENING FLASH FLOODING IS EXPECTED ON SATURDAY AFTERNOON
THROUGH SUNDAY MORNING..
The combination of intense right-entrance region jet dynamics,
highly anomalous atmospheric moisture, and very saturated
antecedent soil moisture will lead to another high impact flash
flood forecast for Saturday afternoon through Sunday morning across
the Lower to Mid-Mississippi Valley. This threat will extend
further east as a cold front helps finally sweep the stagnant
pattern out of the region, but not before another round of heavy
rainfall inundates areas that will be sensitive to any appreciable
rainfall.
A stout 190-200kt upper jet located over the Great Lakes will lend
to a pronounced upper ascent pattern situated over the Mississippi
Valley during the period. At the surface, our quasi-stationary
front that will linger through the course of several days will
still be confined to similar areas that have been impacted by its
presence in the days prior. Upper low located over the Southwest
U.S. will begin to open up and eject eastward, becoming sheared on
the northern edge due to an amplifying trough digging out of
Canada. To the east, our Western Atlantic ridge that has provided a
stalemate to any frontal progression moving east of the Mississippi
will provide one last period of favorable low to mid-level
convergence as the pattern evolves with the large trough to the
west countering the ridge across the Southeast. In the middle of
the atmospheric squeeze-play, elevated moisture presence and
favorable instability will remain present to be activated with the
addition of diurnal destabilization and increasingly favorable
ascent to match. The combination will allow for a rapid development
of widespread convection across the Missouri Valley with slow
advancement eastward towards the Low to Mid-Mississippi Valley
convergence point.
This setup has trended prolific in the QPF realm of the forecast
with very little deviation in all major deterministic at this
juncture. An expanse of 3-6" with locally up to 8" of rainfall is
forecast across a large portion of Arkansas extending east-
northeast through far southeastern Missouri, all of western and
central Tennessee and Kentucky, to as far north as the
Ohio/Kentucky border along the Ohio River. Northwest Mississippi
will also lie within the axis of heaviest precipitation leading to
quite a large area of not only heavy precip, but significant
overlap of areas that will have super saturated grounds that will
struggle to maintain the ability to absorb more rainfall. This
setup will yield a very dangerous scenario where widespread flash
flooding with considerable and potentially catastrophic impacts
would be favored. The agreement among all major NWP for substantial
rainfall totals and projected hourly rates >1-2"/hr is a testament
to the overall gravity of what is to come.
In coordination with the local WFO's across Arkansas, Tennessee,
and Kentucky...a High Risk area for excessive rainfall has been
added over central and eastern AR, all of western TN and KY, far
southeastern MO, and the southern edge of IN. Additional storm
totals will bring multi-day amounts between 8-12" with some areas
potentially reaching as high as 14" over the span of 5 days. A
broad Moderate Risk spans the outer perimeter of the High Risk
leading to several more areas prone to significant flash flood
concerns due to the setup. This is becoming an increasingly
life-threatening situation for areas of the Lower and Mid-
Mississippi Valley region.
Kleebauer
Day 3 threat area: www.wpc.ncep.noaa.gov/qpf/99epoints.txt
+ Additional Links
+ Forecast Discussion
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
857 PM EDT Wed Apr 2 2025
Day 1
Valid 01Z Thu Apr 03 2025 - 12Z Thu Apr 03 2025
...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FROM EASTERN
ARKANSAS TO CENTRAL KENTUCKY...
..A PROLONGED LIFE-THREATENING FLASH FLOOD EVENT WILL BEGIN TODAY
WITH SEVERAL DAYS OF HEAVY RAINFALL IMPACTING A LARGE PORTION OF
THE LOWER MISSISSIPPI AND OHIO VALLEYS..
...01Z Update...
Updates to the Day 1 ERO were mainly focused on peeling away the
back (western) side of the Slight and Marginal Risk areas across
parts of the Midwest, based on the latest observational trends and
more recent high-res guidance (current HRRR trends and 18Z HREF
deterministic and probabilistic data). Notable changes to the
remainder of the ERO include confining the northeastern portion of
the Slight (eastern edge now across eastern OH instead of western
NY-northwest PA), while pulling the eastern edges of the Slight
and Moderate Risk areas ever so slightly E-SE, again based on the
latest guidance trends.
Hurley
...16Z Update...
Generally minor updates were made to the ongoing ERO risk areas,
but they were numerous. Most of the changes were based on changes
among the latest CAMs regarding where the heaviest precipitation is
expected through tonight. In summary though, little has changed
with the prior forecast reasoning across the Moderate Risk area.
A High Risk upgrade was precluded for this update for a few
reasons: First, generally the least coverage of expected rainfall
of 2 inches or more compared with subsequent days, second, dry
antecedent soil conditions and relatively low river levels prior to
the start of this event, and third, a good portion of the event
occurs into the Day 2/Thursday period, so the time for heavy rain
to cause flooding will be limited as the storms associated with the
front are progressive/fast-moving for the first half of today as
they're moving into place. There is little doubt that portions of
the moderate risk area will see training storms resulting in flash
flooding, but the coverage of flash flooding are not expected to rise
to High Risk levels today and tonight.
A squall line and attendant cold front moving across Missouri and
northwestern Arkansas will stall along the southern portion of the
line (where the Moderate Risk remains and been expanded), whereas
the northern portion of the line should continue moving eastward
with the upper level energy, which should limit the training
potential. It's important to note that some of the guidance in
southern Indiana suggests a second round of storms develops and
follows closely behind the initial line. However, this second round
of storms is also rather fast moving. Thus, think there should only
be a few hours of heavy rain potential, which suggests the Slight
would be the more appropriate category for that area.
Elsewhere, the Moderate Risk was expanded east to include metro
Nashville due to the slowing of the line and much greater potential
for training than areas further north. For similar reasons, the
Moderate risk was also expanded east to include much of south-
central Kentucky.
The CAMs guidance is in very good agreement that the line will
stall over the northwest corner of Mississippi and is unlikely to
progress much further south and east in northern Mississippi
through 12Z (but likely will after 12Z and into the Day 2 period).
Thus, the risk areas were both trimmed back about a row of counties
and intentionally left with a really tight gradient between the
Moderate risk to the northwest and nothing. This reflects the high
likelihood that the forward progress of the storms stops, resulting
in towns getting little or no rainfall close to others that get
flooding rains only a short distance away.
The warm front of the developing Plains low causing all of this
rainfall appears more likely to get hung up across western New York
tonight. This could result in multiple hours of moderate rainfall
in the Buffalo area and along the Lake Ontario shoreline. Thus, the
Slight Risk area was expanded east. For northern New York into
Vermont, temperatures should remain cold enough that a significant
portion of the precipitation falls as snow or a wintry mix, which
should prevent flooding concerns at least until after 12Z, so the
Marginal Risk area was trimmed.
The broad synoptic setup described in the previous discussion below
remains valid and has been included for reference.
Wegman
Day 1 threat area: www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
411 AM EDT Thu Apr 3 2025
Day 1
Valid 12Z Thu Apr 03 2025 - 12Z Fri Apr 04 2025
...THERE IS A HIGH RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
LOWER TO MID-MISSISSIPPI VALLEYS WITH MAJOR FLOODING EXPECTED...
..A PROLONGED LIFE-THREATENING FLASH FLOOD EVENT WILL CONTINUE
TODAY WITH HEAVY RAINFALL IMPACTING A LARGE PORTION OF THE LOWER
MISSISSIPPI AND OHIO VALLEY'S ONCE AGAIN...
Significant rainfall over the past 12-24 hrs will only add to the
favor of widespread flash flooding later this afternoon and evening
as the next round of heavy rainfall occurs as the next surface wave
rides up the quasi-stationary boundary in place across the Lower to
Mid-Mississippi and Ohio Valleys. Widespread 2-4" of rain with
maxima between 5-6" has fallen this evening across a zone spanning
from southern Arkansas up through western Tennessee and Kentucky
leading to several flash flood warnings as the first surface wave
lifts north. Some overturning of the atmosphere is anticipated by
morning with areal theta_e's decreasing across areas north of the
Ohio River and a tightening instability gradient positioned along
and south of the quasi-stationary front nestled from southwest to
northeast over the Mississippi Valley. Despite some limiting
factors early on, small mid-level perturbations embedded within the
mean flow will still cause some scattered light to moderate
convective development through the morning and afternoon leading to
a continuation of priming from the prior evening.
The nocturnal period will once again become the main period of
interest as the nocturnal LLJ kicks back in across the Deep South
and banks into the stationary front bisecting the Mississippi and
southern Ohio Valley. The same areas that saw the significant rain
and flash flooding this evening will be hit once again with another
wave of convection that will initiate across the ArklaTex and
southern Arkansas and eventually move northeast as the flow aligns
parallel to the stationary front. Additional precip totals of 2-4"
with local to 6" will once again be in the cards for much of
Arkansas, western Tennessee, and southwestern Kentucky which will
ultimately put 48-hr totals between 4-8" with locally up to 10"
during the time frame. Local FFG's are already very low after
today's precip with much of the corridor spanning eastern AR up
through north-central KY exhibiting 1 and 3-hr FFG intervals
running below 1/1.5" respectively. 00z HREF is very much indicating
that rainfall rates during the peak of diurnal convection will
reside within that 1-2"/hr marker with FFG exceedance probabilities
above 50% for the 1/3/6-hr intervals in place. Neighborhood
probabilities for >3" total are between 40-60% across eastern AR
with as high as 60-80% over northwest TN and southwestern KY. >5"
neighborhood probs are running between 25-40% within the same
corridor, backed up by EAS probs >2" sufficiently above 50% along
the Mississippi north of Memphis to points northeast.
Despite the overall output being slightly lower than what occurred
this evening, the prescience has been set for significant flood
potential given the already saturated soils, expected rates, and
regional rivers running high from the previous period of rainfall.
The previous High Risk inherited was generally maintained with
small adjustments accounting for recent rainfall trends, updated
FFG's, and encompassing elevated probabilities from both the hi-res
and national ensemble blends. A Moderate Risk still in effect for
a large area surrounding the High Risk in place across the Lower to
Mid-Mississippi Valley with a span that covers areas of southwest
Arkansas up to as far northeast as Cincinnati.
This is quickly becoming a high-end flash flood scenario with
another day or two of rainfall expected on top of what has occurred
and what will occur. If you lie within a flood plane or any area
that is prone to flash flooding across Arkansas, western Tennessee,
and western Kentucky, you will want to pay close attention and
have a plan to seek higher ground, if possible.
Kleebauer
Day 1 threat area: www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
411 AM EDT Thu Apr 3 2025
Day 2
Valid 12Z Fri Apr 04 2025 - 12Z Sat Apr 05 2025
...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR A LARGE
PORTION OF THE LOWER AND MID-MISSISSIPPI VALLEYS...
The previous synoptic scale forecast was relatively unchanged
within the run to run assessment over the course of Friday into
Saturday morning. The final surface wave within the atmospheric
parade across the Southern Plains to Mississippi Valley will show
itself by late- Friday morning through the remainder of the period.
This wave will likely be the strongest of the 3 allowing a much
more amplified surface evolution that will shift the focus of
heavier precip further northwest while also providing some vigor in
the overall QPF distribution. The trend the past 48 hrs is for a
zone of significant (3-6+") totals to be recognized across portions
of the Southern Plains up through the Ozarks and Mid-Mississippi
Valley of Missouri, spanning as far north as south- central
Illinois. When assessing the theta_e environment, there is a
noticeable push north of more modestly unstable air with the most
pertinent area of available instability situated across southern MO
down through AR, southeastern OK, and even northeastern TX. A
sharp uptick in regional PWATs with deviations between +3 to +4 anomaly-
wise are forecast within that zone correlating with a substantial
rise in area convection blossoming late Friday afternoon, onward.
This setup is fortunately further west compared to the previous
periods, so the overlap of the heaviest rainfall is not anticipated
to be as problematic as the previous period.
Having said that, the pattern will yield high precip totals due to
widespread convective activity, falling over some areas that will
have seen appreciable rain, and over other areas that are more
prone to flooding due to complex terrain situated over the Ozarks.
The pattern is such that several areas from east of DFW up through
IL will see rainfall amounts of 3-6" with locally higher beginning
Friday afternoon with the heaviest rainfall likely to occur by the
evening with the implementation of yet another LLJ structure
thanks to the surface wave mentioned previously. Further to the
west, another closed upper reflection across the Southwest U.S.
will only entice greater upper forcing within a broad axis of
difluence situated over the Plains. This setup is more privy to
convection forming as far west as the Western Rolling Plains of TX
to points east and northeast. Even there, modest 1-2" with locally
higher totals are forecast in-of those zones. The heaviest
precipitation axis based off the latest NBM probabilities still has
a significant footprint of at least 3" located near the Dallas
metro and points just east (40-60%) to as high as 60-80% in a large
area spanning the Red River of northeast TX up through much of
western and northern AR, through the Ozarks of MO, finally reaching
the Mississippi River south of St.Louis. Ensemble mean QPF output
signals a massive area of at least 2" with urban centers like
Dallas, Little Rock, St. Louis, and Springfield, MO all within a
core of the heavy precip footprint.
Considering the probabilistic output of the NBM, the consistency
within guidance for a significant corridor of very heavy rainfall,
and a well-defined axis of training precip potential, a broad
Moderate Risk was maintained and even expanded to account for the
expanse of likely flash flooding. A high-end Moderate is a likely
tag for places within southeast OK up through western and northern
AR through the Ozarks of Missouri as these areas will have the
greatest threat of enhanced rates over top of either complex
terrain or primed soils. An upgrade is plausible in future updates
pending additional convective probability details.
Kleebauer
Day 2 threat area: www.wpc.ncep.noaa.gov/qpf/98epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
411 AM EDT Thu Apr 3 2025
Day 3
Valid 12Z Sat Apr 05 2025 - 12Z Sun Apr 06 2025
...THERE IS A HIGH RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
LOWER TO MID-MISSISSIPPI VALLEYS WITH MAJOR FLOODING EXPECTED...
..LIFE-THREATENING FLASH FLOODING IS EXPECTED ON SATURDAY AFTERNOON
THROUGH SUNDAY MORNING..
The combination of intense right-entrance region jet dynamics,
highly anomalous atmospheric moisture, and very saturated
antecedent soil moisture will lead to another high impact flash
flood forecast for Saturday afternoon through Sunday morning across
the Lower to Mid-Mississippi Valley. This threat will extend
further east as a cold front helps finally sweep the stagnant
pattern out of the region, but not before another round of heavy
rainfall inundates areas that will be sensitive to any appreciable
rainfall.
A stout 190-200kt upper jet located over the Great Lakes will lend
to a pronounced upper ascent pattern situated over the Mississippi
Valley during the period. At the surface, our quasi-stationary
front that will linger through the course of several days will
still be confined to similar areas that have been impacted by its
presence in the days prior. Upper low located over the Southwest
U.S. will begin to open up and eject eastward, becoming sheared on
the northern edge due to an amplifying trough digging out of
Canada. To the east, our Western Atlantic ridge that has provided a
stalemate to any frontal progression moving east of the Mississippi
will provide one last period of favorable low to mid-level
convergence as the pattern evolves with the large trough to the
west countering the ridge across the Southeast. In the middle of
the atmospheric squeeze-play, elevated moisture presence and
favorable instability will remain present to be activated with the
addition of diurnal destabilization and increasingly favorable
ascent to match. The combination will allow for a rapid development
of widespread convection across the Missouri Valley with slow
advancement eastward towards the Low to Mid-Mississippi Valley
convergence point.
This setup has trended prolific in the QPF realm of the forecast
with very little deviation in all major deterministic at this
juncture. An expanse of 3-6" with locally up to 8" of rainfall is
forecast across a large portion of Arkansas extending east-
northeast through far southeastern Missouri, all of western and
central Tennessee and Kentucky, to as far north as the
Ohio/Kentucky border along the Ohio River. Northwest Mississippi
will also lie within the axis of heaviest precipitation leading to
quite a large area of not only heavy precip, but significant
overlap of areas that will have super saturated grounds that will
struggle to maintain the ability to absorb more rainfall. This
setup will yield a very dangerous scenario where widespread flash
flooding with considerable and potentially catastrophic impacts
would be favored. The agreement among all major NWP for substantial
rainfall totals and projected hourly rates >1-2"/hr is a testament
to the overall gravity of what is to come.
In coordination with the local WFO's across Arkansas, Tennessee,
and Kentucky...a High Risk area for excessive rainfall has been
added over central and eastern AR, all of western TN and KY, far
southeastern MO, and the southern edge of IN. Additional storm
totals will bring multi-day amounts between 8-12" with some areas
potentially reaching as high as 14" over the span of 5 days. A
broad Moderate Risk spans the outer perimeter of the High Risk
leading to several more areas prone to significant flash flood
concerns due to the setup. This is becoming an increasingly
life-threatening situation for areas of the Lower and Mid-
Mississippi Valley region.
Kleebauer
Day 3 threat area: www.wpc.ncep.noaa.gov/qpf/99epoints.txt
Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
234 AM EDT Thu Apr 3 2025
By the start of the period on Sunday, the front responsible for
significant rainfall over the Lower Mississippi Valley to Ohio
Valley region should finally begin to shift eastward. Moderate to
heavy rain and strong storms are possible along the front from the
Gulf Coast states into the Tennessee Valley/Southeast, and farther
north into the Mid-Atlantic and Northeast near the front. The
Sunday ERO shows a Marginal Risk for this region with an embedded
Slight Risk farther south across parts of southern Alabama and
Mississippi where recent heavy rainfall has primed soils and the
greatest instability should be located. Guidance shows potential
for a band of somewhat heavy QPF to extend farther northeast across
northern Georgia into or near the far southern Appalachians, but
latest first-guess fields plus neutral ground moisture (and likely
drier by then given no rain forecast in the shorter term) favor
keeping this region in Marginal Risk for the time being. The front
may slow for a period across parts of the Southeast into Monday,
and anomalous moisture and instability favor just a marginal risk
for the Day 5 ERO at this point since current QPF signals are
modest at best.
Elsewhere by Monday, a cold upper trough reaching the Great Lakes
should lead to unsettled weather over the region with rain or snow.
This precipitation should extend into the Northeast as well.
Latest guidance shows significant differences for surface/upper
evolution over the Northeast early- mid week, with the more extreme
side of the spread producing some significant snowfall over parts
of New England in contrast to much lighter and scattered snow in
the greater proportion of solutions. Probabilities of 0.25 inch
liquid in the form of snow reach no higher than 10-15 percent or so
during the Tuesday-Tuesday night period, reflecting the guidance
majority.
Meanwhile upstream, the upper shortwave/front expected to reach
the West Coast into early next week will be accompanied by a brief
increase in moisture but the system will be fairly progressive.
Thus expect mostly light precipitation but with some terrain-
enhanced moderate activity over western Washington/Oregon and
northwestern California, with decreasing amounts inland over the
Northwest.
Above normal temperatures will linger along the East Coast into
Sunday with daytime highs 10 to 20 degrees above normal.Meanwhile,
well below normal temperatures will be in place across parts of the
southern Rockies and Plains where daytime highs 10 to 20 degrees
below normal may linger into Sunday. Moderated below normal
temperatures will also shift into the central U.S. and Midwest
Monday and the East by Tuesday-Wednesday. Highs over and near the
Ohio Valley could be up to 15 to 20 degrees below normal on
Tuesday. Warmer than average temperatures initially over the
Northwest this weekend should expand into the remainder of the West
and the northern/central Plains by next week. A strengthening
upper ridge will likely expand coverage of plus 10 to 20 degree
anomalies over the West on Wednesday and Thursday.
Santorelli
NWS Weather Prediction Center College Park MD
234 AM EDT Thu Apr 3 2025
By the start of the period on Sunday, the front responsible for
significant rainfall over the Lower Mississippi Valley to Ohio
Valley region should finally begin to shift eastward. Moderate to
heavy rain and strong storms are possible along the front from the
Gulf Coast states into the Tennessee Valley/Southeast, and farther
north into the Mid-Atlantic and Northeast near the front. The
Sunday ERO shows a Marginal Risk for this region with an embedded
Slight Risk farther south across parts of southern Alabama and
Mississippi where recent heavy rainfall has primed soils and the
greatest instability should be located. Guidance shows potential
for a band of somewhat heavy QPF to extend farther northeast across
northern Georgia into or near the far southern Appalachians, but
latest first-guess fields plus neutral ground moisture (and likely
drier by then given no rain forecast in the shorter term) favor
keeping this region in Marginal Risk for the time being. The front
may slow for a period across parts of the Southeast into Monday,
and anomalous moisture and instability favor just a marginal risk
for the Day 5 ERO at this point since current QPF signals are
modest at best.
Elsewhere by Monday, a cold upper trough reaching the Great Lakes
should lead to unsettled weather over the region with rain or snow.
This precipitation should extend into the Northeast as well.
Latest guidance shows significant differences for surface/upper
evolution over the Northeast early- mid week, with the more extreme
side of the spread producing some significant snowfall over parts
of New England in contrast to much lighter and scattered snow in
the greater proportion of solutions. Probabilities of 0.25 inch
liquid in the form of snow reach no higher than 10-15 percent or so
during the Tuesday-Tuesday night period, reflecting the guidance
majority.
Meanwhile upstream, the upper shortwave/front expected to reach
the West Coast into early next week will be accompanied by a brief
increase in moisture but the system will be fairly progressive.
Thus expect mostly light precipitation but with some terrain-
enhanced moderate activity over western Washington/Oregon and
northwestern California, with decreasing amounts inland over the
Northwest.
Above normal temperatures will linger along the East Coast into
Sunday with daytime highs 10 to 20 degrees above normal.Meanwhile,
well below normal temperatures will be in place across parts of the
southern Rockies and Plains where daytime highs 10 to 20 degrees
below normal may linger into Sunday. Moderated below normal
temperatures will also shift into the central U.S. and Midwest
Monday and the East by Tuesday-Wednesday. Highs over and near the
Ohio Valley could be up to 15 to 20 degrees below normal on
Tuesday. Warmer than average temperatures initially over the
Northwest this weekend should expand into the remainder of the West
and the northern/central Plains by next week. A strengthening
upper ridge will likely expand coverage of plus 10 to 20 degree
anomalies over the West on Wednesday and Thursday.
Santorelli
Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
234 AM EDT Thu Apr 3 2025
By the start of the period on Sunday, the front responsible for
significant rainfall over the Lower Mississippi Valley to Ohio
Valley region should finally begin to shift eastward. Moderate to
heavy rain and strong storms are possible along the front from the
Gulf Coast states into the Tennessee Valley/Southeast, and farther
north into the Mid-Atlantic and Northeast near the front. The
Sunday ERO shows a Marginal Risk for this region with an embedded
Slight Risk farther south across parts of southern Alabama and
Mississippi where recent heavy rainfall has primed soils and the
greatest instability should be located. Guidance shows potential
for a band of somewhat heavy QPF to extend farther northeast across
northern Georgia into or near the far southern Appalachians, but
latest first-guess fields plus neutral ground moisture (and likely
drier by then given no rain forecast in the shorter term) favor
keeping this region in Marginal Risk for the time being. The front
may slow for a period across parts of the Southeast into Monday,
and anomalous moisture and instability favor just a marginal risk
for the Day 5 ERO at this point since current QPF signals are
modest at best.
Elsewhere by Monday, a cold upper trough reaching the Great Lakes
should lead to unsettled weather over the region with rain or snow.
This precipitation should extend into the Northeast as well.
Latest guidance shows significant differences for surface/upper
evolution over the Northeast early- mid week, with the more extreme
side of the spread producing some significant snowfall over parts
of New England in contrast to much lighter and scattered snow in
the greater proportion of solutions. Probabilities of 0.25 inch
liquid in the form of snow reach no higher than 10-15 percent or so
during the Tuesday-Tuesday night period, reflecting the guidance
majority.
Meanwhile upstream, the upper shortwave/front expected to reach
the West Coast into early next week will be accompanied by a brief
increase in moisture but the system will be fairly progressive.
Thus expect mostly light precipitation but with some terrain-
enhanced moderate activity over western Washington/Oregon and
northwestern California, with decreasing amounts inland over the
Northwest.
Above normal temperatures will linger along the East Coast into
Sunday with daytime highs 10 to 20 degrees above normal.Meanwhile,
well below normal temperatures will be in place across parts of the
southern Rockies and Plains where daytime highs 10 to 20 degrees
below normal may linger into Sunday. Moderated below normal
temperatures will also shift into the central U.S. and Midwest
Monday and the East by Tuesday-Wednesday. Highs over and near the
Ohio Valley could be up to 15 to 20 degrees below normal on
Tuesday. Warmer than average temperatures initially over the
Northwest this weekend should expand into the remainder of the West
and the northern/central Plains by next week. A strengthening
upper ridge will likely expand coverage of plus 10 to 20 degree
anomalies over the West on Wednesday and Thursday.
Santorelli
NWS Weather Prediction Center College Park MD
234 AM EDT Thu Apr 3 2025
By the start of the period on Sunday, the front responsible for
significant rainfall over the Lower Mississippi Valley to Ohio
Valley region should finally begin to shift eastward. Moderate to
heavy rain and strong storms are possible along the front from the
Gulf Coast states into the Tennessee Valley/Southeast, and farther
north into the Mid-Atlantic and Northeast near the front. The
Sunday ERO shows a Marginal Risk for this region with an embedded
Slight Risk farther south across parts of southern Alabama and
Mississippi where recent heavy rainfall has primed soils and the
greatest instability should be located. Guidance shows potential
for a band of somewhat heavy QPF to extend farther northeast across
northern Georgia into or near the far southern Appalachians, but
latest first-guess fields plus neutral ground moisture (and likely
drier by then given no rain forecast in the shorter term) favor
keeping this region in Marginal Risk for the time being. The front
may slow for a period across parts of the Southeast into Monday,
and anomalous moisture and instability favor just a marginal risk
for the Day 5 ERO at this point since current QPF signals are
modest at best.
Elsewhere by Monday, a cold upper trough reaching the Great Lakes
should lead to unsettled weather over the region with rain or snow.
This precipitation should extend into the Northeast as well.
Latest guidance shows significant differences for surface/upper
evolution over the Northeast early- mid week, with the more extreme
side of the spread producing some significant snowfall over parts
of New England in contrast to much lighter and scattered snow in
the greater proportion of solutions. Probabilities of 0.25 inch
liquid in the form of snow reach no higher than 10-15 percent or so
during the Tuesday-Tuesday night period, reflecting the guidance
majority.
Meanwhile upstream, the upper shortwave/front expected to reach
the West Coast into early next week will be accompanied by a brief
increase in moisture but the system will be fairly progressive.
Thus expect mostly light precipitation but with some terrain-
enhanced moderate activity over western Washington/Oregon and
northwestern California, with decreasing amounts inland over the
Northwest.
Above normal temperatures will linger along the East Coast into
Sunday with daytime highs 10 to 20 degrees above normal.Meanwhile,
well below normal temperatures will be in place across parts of the
southern Rockies and Plains where daytime highs 10 to 20 degrees
below normal may linger into Sunday. Moderated below normal
temperatures will also shift into the central U.S. and Midwest
Monday and the East by Tuesday-Wednesday. Highs over and near the
Ohio Valley could be up to 15 to 20 degrees below normal on
Tuesday. Warmer than average temperatures initially over the
Northwest this weekend should expand into the remainder of the West
and the northern/central Plains by next week. A strengthening
upper ridge will likely expand coverage of plus 10 to 20 degree
anomalies over the West on Wednesday and Thursday.
Santorelli
Winter Weather Forecasts Legacy Page:
» Interactive Winter Weather Map (Day 1-3)
» Interactive Winter Weather Map (Day 4-7)
» Winter Storm Severity Index
» Experimental Probabilistic Precipitation Portal
+ Forecast Discussion (Day 1-3)
Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
340 AM EDT Thu Apr 3 2025
Valid 12Z Thu Apr 03 2025 - 12Z Sun Apr 06 2025
...Northeast...
Days 1 & 3...
An icy wintry mix will continue from the White Mountains and
through much of interior Maine this morning as ongoing WAA and
intense 850mb FGEN sustains an icy setup over northern New England.
The lingering sub-freezing boundary layer will gradually erode as
the warm front advances northward with only northern Maine holding
on to any notable wintry mix through midday. WPC probabilities
depict low chances (10-30%) for additional ice accumulations >0.1"
in the White Mountains and western Maine through this morning.
Following a break in the action Thursday night through Saturday
morning, the next round of wintry mix arrives Saturday afternoon
as moisture from the Mississippi Valley streams northward into New
England. Similar to the Day 1 setup, low-mid level WAA and 850mb
FGEN are the primary mechanisms of lift that will promote
precipitation. The antecedent air-mass is not nearly as cold as the
Wed-Thurs air-mass. However, the modestly cold air-mass will be
tough to erode in the higher terrain, thus making the White
Mountains and western Maine the most likely areas to see a mix of
snow and freezing rain through Saturday night. WPC probabilities
show moderate- to- high chances (50-70%) for >0.1" of ice, with low
chances (10-30%) for ice accumulations >0.25".
...Intermountain West & Southern High Plains...
Days 1-3...
The weather pattern over the western third of the Lower 48 is
primarily driven by a pair of upper level disturbances; one
tracking across Montana today and early Friday, and the other is a
closed upper low over the Southwest. Starting in Montana, a cold
front at the leading edge of the 500mb shortwave trough will act as
a trigger for snow showers, some of which could have snow squall-
like impacts with bursts of snow and gusty winds Thursday
afternoon. With high pressure building in from Alberta, easterly
upslope flow into the Lewis Range and Absaroka through Thursday
evening. Snow associated with this upper trough is also expected as
far south as the Big Horns and even as far east as western North
Dakota Thursday night. By Friday morning, the cold front makes its
way south through the Central Plains and Central Rockies with
NErly upslope flow aiding in minor snow accumulations along the
Front Range of the WY/CO Rockies through Friday morning.
Farther south, the closed upper low will make its way toward New
Mexico with 200-500-700mb heights along the AZ/NM and Mexico
borders below the 10th climatological percentile. As the 700mb low
reaches western New Mexico Friday afternoon, winds over southeast
CO and northeast NM will turn easterly at the same time the
aforementioned cold front to the north plunges south. Southern CO
and northern NM will also be co-located beneath the divergent left-
exit region of a 500mb jet streak located over northern Mexico. The
heaviest snowfall looks to ensue Friday afternoon and into Friday
night across the Front Range, Palmer Divide, San Juans, and Sangre
De Cristo (including Raton Pass). By Saturday morning, snow is
forecast for most of the Southern Rockies and even parts of the
southern High Plains as the cold front continues to dive south and
the deformation zone on the northern and western periphery of the
700mb low moves in overhead. Note that with the time of year, it
will have to snow exceptionally hard (>1"/hr) for snow to
accumulate outside of the mountain ranges given the higher sun
angle and warmer soil temperatures. Still, periods of moderate snow
combined with 30-40 kt 850mb winds will cause poor visibilities
through Saturday afternoon before the snow finally tapers off
Saturday evenings.
WPC probabilities depict moderate-to-high chances (50-70%) for
snowfall >8" along the >9,000ft peaks of the Sangre De Cristo and
San Juans between Friday afternoon and Saturday afternoon. Along
the I-25 corridor, the most concerning area for heavy snowfall is
along Raton Pass where up to 12" of snow in the forecast. WSSI
depicts Moderate impact potential in the Sangre De Cristo, Raton
Mesa, and San Juans. Note that there are some Moderate Impacts in
the plains of eastern NM and the TX Panhandle with Blowing Snow the
primary impact in these areas.
Mullinax
+ Additional Links
» Interactive Winter Weather Map (Day 4-7)
» Winter Storm Severity Index
» Experimental Probabilistic Precipitation Portal
+ Forecast Discussion (Day 1-3)
Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
340 AM EDT Thu Apr 3 2025
Valid 12Z Thu Apr 03 2025 - 12Z Sun Apr 06 2025
...Northeast...
Days 1 & 3...
An icy wintry mix will continue from the White Mountains and
through much of interior Maine this morning as ongoing WAA and
intense 850mb FGEN sustains an icy setup over northern New England.
The lingering sub-freezing boundary layer will gradually erode as
the warm front advances northward with only northern Maine holding
on to any notable wintry mix through midday. WPC probabilities
depict low chances (10-30%) for additional ice accumulations >0.1"
in the White Mountains and western Maine through this morning.
Following a break in the action Thursday night through Saturday
morning, the next round of wintry mix arrives Saturday afternoon
as moisture from the Mississippi Valley streams northward into New
England. Similar to the Day 1 setup, low-mid level WAA and 850mb
FGEN are the primary mechanisms of lift that will promote
precipitation. The antecedent air-mass is not nearly as cold as the
Wed-Thurs air-mass. However, the modestly cold air-mass will be
tough to erode in the higher terrain, thus making the White
Mountains and western Maine the most likely areas to see a mix of
snow and freezing rain through Saturday night. WPC probabilities
show moderate- to- high chances (50-70%) for >0.1" of ice, with low
chances (10-30%) for ice accumulations >0.25".
...Intermountain West & Southern High Plains...
Days 1-3...
The weather pattern over the western third of the Lower 48 is
primarily driven by a pair of upper level disturbances; one
tracking across Montana today and early Friday, and the other is a
closed upper low over the Southwest. Starting in Montana, a cold
front at the leading edge of the 500mb shortwave trough will act as
a trigger for snow showers, some of which could have snow squall-
like impacts with bursts of snow and gusty winds Thursday
afternoon. With high pressure building in from Alberta, easterly
upslope flow into the Lewis Range and Absaroka through Thursday
evening. Snow associated with this upper trough is also expected as
far south as the Big Horns and even as far east as western North
Dakota Thursday night. By Friday morning, the cold front makes its
way south through the Central Plains and Central Rockies with
NErly upslope flow aiding in minor snow accumulations along the
Front Range of the WY/CO Rockies through Friday morning.
Farther south, the closed upper low will make its way toward New
Mexico with 200-500-700mb heights along the AZ/NM and Mexico
borders below the 10th climatological percentile. As the 700mb low
reaches western New Mexico Friday afternoon, winds over southeast
CO and northeast NM will turn easterly at the same time the
aforementioned cold front to the north plunges south. Southern CO
and northern NM will also be co-located beneath the divergent left-
exit region of a 500mb jet streak located over northern Mexico. The
heaviest snowfall looks to ensue Friday afternoon and into Friday
night across the Front Range, Palmer Divide, San Juans, and Sangre
De Cristo (including Raton Pass). By Saturday morning, snow is
forecast for most of the Southern Rockies and even parts of the
southern High Plains as the cold front continues to dive south and
the deformation zone on the northern and western periphery of the
700mb low moves in overhead. Note that with the time of year, it
will have to snow exceptionally hard (>1"/hr) for snow to
accumulate outside of the mountain ranges given the higher sun
angle and warmer soil temperatures. Still, periods of moderate snow
combined with 30-40 kt 850mb winds will cause poor visibilities
through Saturday afternoon before the snow finally tapers off
Saturday evenings.
WPC probabilities depict moderate-to-high chances (50-70%) for
snowfall >8" along the >9,000ft peaks of the Sangre De Cristo and
San Juans between Friday afternoon and Saturday afternoon. Along
the I-25 corridor, the most concerning area for heavy snowfall is
along Raton Pass where up to 12" of snow in the forecast. WSSI
depicts Moderate impact potential in the Sangre De Cristo, Raton
Mesa, and San Juans. Note that there are some Moderate Impacts in
the plains of eastern NM and the TX Panhandle with Blowing Snow the
primary impact in these areas.
Mullinax
Medium Range Forecasts Legacy Page:
Valid 12Z Sun Apr 06, 2025
Valid 12Z Mon Apr 07, 2025
Valid 12Z Tue Apr 08, 2025
Valid 12Z Wed Apr 09, 2025
Valid 12Z Thu Apr 10, 2025
Image Options:
+ Forecast Discussion
+ Additional Links
Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
234 AM EDT Thu Apr 3 2025
Valid 12Z Sun Apr 06 2025 - 12Z Thu Apr 10 2025
...Overview...
The frontal boundary responsible for significant and potentially
historic flooding and flash flooding during the short range period
should finally push east by Sunday. This happens from a gradually
amplifying Great Lakes to Northeast trough and eventual ejection of
southern stream energy. Some moderate to heavy rainfall potential
along the central Gulf Coast and parts of the Southeast with this
front. A shortwave reaching the West on Sunday-Monday could bring
mostly light precipitation to parts of the Northwest. After Monday,
the medium range period should trend much drier across the country
as the overall pattern briefly becomes flatter and more
progressive on the way toward a western ridge/eastern trough
configuration.
...Guidance/Predictability Assessment...
Overall, the latest guidance shows good agreement on the larger
scale pattern, but plenty of uncertainty still in the details of
smaller scale systems/energies. There are still some initial
questions on how fast southern stream energy ejects eastward on
Sunday-Monday, with the GFS still on the slightly faster side of
consensus. Elsewhere, latest GFS runs remain most aggressive with
the degree to which the digging Great Lakes trough closes off an
upper low by Tuesday, leading to a stronger/more wrapped surface
system. The CMC also shows this to some extent as well, but the
better consensus of models would favor more of an open trough, with
some potential for a neutral or negative tilt at times. Mean
troughing over the northeast Pacific should send a couple of
shortwaves into the West, which could eventually reach the Plains
by midweek. Both the GFS and ECMWF show a modest reflection of a
stronger system with a defined surface low, but the CMC is much
weaker. Ensemble means are also weak/flat which indicates there is
still a lot of uncertainty with this.
The WPC forecast for tonight favored a deterministic model blend
for the first half of the period, increasing the ensemble means to
half the blend by Day 7 to mitigate differences in the guidance.
This maintains good continuity with the previous WPC forecast, at
least through Day 6.
...Weather/Hazards Highlights...
By the start of the period on Sunday, the front responsible for
significant rainfall over the Lower Mississippi Valley to Ohio
Valley region should finally begin to shift eastward. Moderate to
heavy rain and strong storms are possible along the front from the
Gulf Coast states into the Tennessee Valley/Southeast, and farther
north into the Mid-Atlantic and Northeast near the front. The
Sunday ERO shows a Marginal Risk for this region with an embedded
Slight Risk farther south across parts of southern Alabama and
Mississippi where recent heavy rainfall has primed soils and the
greatest instability should be located. Guidance shows potential
for a band of somewhat heavy QPF to extend farther northeast across
northern Georgia into or near the far southern Appalachians, but
latest first-guess fields plus neutral ground moisture (and likely
drier by then given no rain forecast in the shorter term) favor
keeping this region in Marginal Risk for the time being. The front
may slow for a period across parts of the Southeast into Monday,
and anomalous moisture and instability favor just a marginal risk
for the Day 5 ERO at this point since current QPF signals are
modest at best.
Elsewhere by Monday, a cold upper trough reaching the Great Lakes
should lead to unsettled weather over the region with rain or snow.
This precipitation should extend into the Northeast as well.
Latest guidance shows significant differences for surface/upper
evolution over the Northeast early- mid week, with the more extreme
side of the spread producing some significant snowfall over parts
of New England in contrast to much lighter and scattered snow in
the greater proportion of solutions. Probabilities of 0.25 inch
liquid in the form of snow reach no higher than 10-15 percent or so
during the Tuesday-Tuesday night period, reflecting the guidance
majority.
Meanwhile upstream, the upper shortwave/front expected to reach
the West Coast into early next week will be accompanied by a brief
increase in moisture but the system will be fairly progressive.
Thus expect mostly light precipitation but with some terrain-
enhanced moderate activity over western Washington/Oregon and
northwestern California, with decreasing amounts inland over the
Northwest.
Above normal temperatures will linger along the East Coast into
Sunday with daytime highs 10 to 20 degrees above normal.Meanwhile,
well below normal temperatures will be in place across parts of the
southern Rockies and Plains where daytime highs 10 to 20 degrees
below normal may linger into Sunday. Moderated below normal
temperatures will also shift into the central U.S. and Midwest
Monday and the East by Tuesday-Wednesday. Highs over and near the
Ohio Valley could be up to 15 to 20 degrees below normal on
Tuesday. Warmer than average temperatures initially over the
Northwest this weekend should expand into the remainder of the West
and the northern/central Plains by next week. A strengthening
upper ridge will likely expand coverage of plus 10 to 20 degree
anomalies over the West on Wednesday and Thursday.
Santorelli
Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation forecast (QPF), excessive rainfall
outlook (ERO), winter weather outlook (WWO) probabilities, heat
indices, and Key Messages can be accessed from:
https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/#page=ero
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml
https://www.wpc.ncep.noaa.gov/#page=ovw
NWS Weather Prediction Center College Park MD
234 AM EDT Thu Apr 3 2025
Valid 12Z Sun Apr 06 2025 - 12Z Thu Apr 10 2025
...Overview...
The frontal boundary responsible for significant and potentially
historic flooding and flash flooding during the short range period
should finally push east by Sunday. This happens from a gradually
amplifying Great Lakes to Northeast trough and eventual ejection of
southern stream energy. Some moderate to heavy rainfall potential
along the central Gulf Coast and parts of the Southeast with this
front. A shortwave reaching the West on Sunday-Monday could bring
mostly light precipitation to parts of the Northwest. After Monday,
the medium range period should trend much drier across the country
as the overall pattern briefly becomes flatter and more
progressive on the way toward a western ridge/eastern trough
configuration.
...Guidance/Predictability Assessment...
Overall, the latest guidance shows good agreement on the larger
scale pattern, but plenty of uncertainty still in the details of
smaller scale systems/energies. There are still some initial
questions on how fast southern stream energy ejects eastward on
Sunday-Monday, with the GFS still on the slightly faster side of
consensus. Elsewhere, latest GFS runs remain most aggressive with
the degree to which the digging Great Lakes trough closes off an
upper low by Tuesday, leading to a stronger/more wrapped surface
system. The CMC also shows this to some extent as well, but the
better consensus of models would favor more of an open trough, with
some potential for a neutral or negative tilt at times. Mean
troughing over the northeast Pacific should send a couple of
shortwaves into the West, which could eventually reach the Plains
by midweek. Both the GFS and ECMWF show a modest reflection of a
stronger system with a defined surface low, but the CMC is much
weaker. Ensemble means are also weak/flat which indicates there is
still a lot of uncertainty with this.
The WPC forecast for tonight favored a deterministic model blend
for the first half of the period, increasing the ensemble means to
half the blend by Day 7 to mitigate differences in the guidance.
This maintains good continuity with the previous WPC forecast, at
least through Day 6.
...Weather/Hazards Highlights...
By the start of the period on Sunday, the front responsible for
significant rainfall over the Lower Mississippi Valley to Ohio
Valley region should finally begin to shift eastward. Moderate to
heavy rain and strong storms are possible along the front from the
Gulf Coast states into the Tennessee Valley/Southeast, and farther
north into the Mid-Atlantic and Northeast near the front. The
Sunday ERO shows a Marginal Risk for this region with an embedded
Slight Risk farther south across parts of southern Alabama and
Mississippi where recent heavy rainfall has primed soils and the
greatest instability should be located. Guidance shows potential
for a band of somewhat heavy QPF to extend farther northeast across
northern Georgia into or near the far southern Appalachians, but
latest first-guess fields plus neutral ground moisture (and likely
drier by then given no rain forecast in the shorter term) favor
keeping this region in Marginal Risk for the time being. The front
may slow for a period across parts of the Southeast into Monday,
and anomalous moisture and instability favor just a marginal risk
for the Day 5 ERO at this point since current QPF signals are
modest at best.
Elsewhere by Monday, a cold upper trough reaching the Great Lakes
should lead to unsettled weather over the region with rain or snow.
This precipitation should extend into the Northeast as well.
Latest guidance shows significant differences for surface/upper
evolution over the Northeast early- mid week, with the more extreme
side of the spread producing some significant snowfall over parts
of New England in contrast to much lighter and scattered snow in
the greater proportion of solutions. Probabilities of 0.25 inch
liquid in the form of snow reach no higher than 10-15 percent or so
during the Tuesday-Tuesday night period, reflecting the guidance
majority.
Meanwhile upstream, the upper shortwave/front expected to reach
the West Coast into early next week will be accompanied by a brief
increase in moisture but the system will be fairly progressive.
Thus expect mostly light precipitation but with some terrain-
enhanced moderate activity over western Washington/Oregon and
northwestern California, with decreasing amounts inland over the
Northwest.
Above normal temperatures will linger along the East Coast into
Sunday with daytime highs 10 to 20 degrees above normal.Meanwhile,
well below normal temperatures will be in place across parts of the
southern Rockies and Plains where daytime highs 10 to 20 degrees
below normal may linger into Sunday. Moderated below normal
temperatures will also shift into the central U.S. and Midwest
Monday and the East by Tuesday-Wednesday. Highs over and near the
Ohio Valley could be up to 15 to 20 degrees below normal on
Tuesday. Warmer than average temperatures initially over the
Northwest this weekend should expand into the remainder of the West
and the northern/central Plains by next week. A strengthening
upper ridge will likely expand coverage of plus 10 to 20 degree
anomalies over the West on Wednesday and Thursday.
Santorelli
Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation forecast (QPF), excessive rainfall
outlook (ERO), winter weather outlook (WWO) probabilities, heat
indices, and Key Messages can be accessed from:
https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/#page=ero
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml
https://www.wpc.ncep.noaa.gov/#page=ovw
Forecaster's Toolbox (Prototype)
Tools Generated at WPC
These tools are NOT operationally supported. Data may not update regularly due to workstation failure and/or data unavailability.
Intense Rainfall and Flash Flood Reports
Displays flood and flash flood reports as well as intense rainfall observations for user-selectable time ranges and customizable geographic regions. Includes ability to download reports and associated metadata in csv format.
GEFS Probabilities
Plots of GEFS probabilistic forecast of precipitation, temperature, and sea-level pressure exceeding various thresholds.
Local Storm Reports
Custom plots of Local Storm Reports across the Contiguous United States. Reports include rain, snow, ice, and severe weather, as well as other significant information from storm spotters.
Extreme Precipitation Monitor
Displays the climatological significance of precipitation forecast by WPC. The climatological significance is represented by Average Recurrence Intervals (ARIs) of precipitation estimates from NOAA Atlas-14 and Atlas2.
Ensemble Situational Awareness Table
An interactive situational awareness table that displays anomalies, percentiles, and return intervals from the GEFS, NAEFS, and ECMWF Ensembles (login required to view ECMWF data).
*Please note that there is currently an issue where only users on a NOAA network can access this page. We are actively working to resolve this problem.
NDFD Forecast Temperature Records
Interactive display of where temperatures could approach or exceed records within the contiguous U.S. (based on NDFD temperature forecasts)
NWS NDFD Max/Min Temperatures and Departure from Normal
Displays Days 1-7 NDFD maximum and minimum temperatures, along with their respective departures from climatology.
Prototype Snowband Probability Forecasts
An interactive tool that depicts areas of heavy snowfall from individual members of high-resolution short range ensemble forecasts.
Weather in Context Prototype
Displays forecast information and its climatological context to quickly alert a forecaster when a record or neear-record breaking event is possible. This tool is available for both CONUS and Alaska.
Automated Forecast Low Clusters
Displays 0-72 hour cyclone forecast positions from global ensemble and deterministic model guidance.
1/3/6/24-hr Changes
Change in weather parameters (temperature, dewpoint, surface pressure, etc) over the last 1/3/6/24 hours. Data is provided from the Real-Time Mesoscale Analysis (RTMA) or the Rapid Refresh (RAP).
Experimental HeatRisk
The experimental National Weather Service (NWS) HeatRisk is a color-numeric-based index that provides a forecast of the potential level of risk for heat-related impacts to occur over a 24-hour period, with forecasts available out through 7 days.
Other Favorite Forecast Tools
CIPS Guidance
Analog guidance that uses an objective approach to find historical events that are similar to the upcoming forecast.
National Blend of Models
Nationally consistent and skillful suite of calibrated forecast guidance based on a blend of both NWS and non-NWS numerical weather prediction model data and post-processed model guidance.
