Weather Prediction Center

National Oceanic and Atmospheric Administration

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
338 PM EDT Sun Jul 20 2025

Valid 00Z Mon Jul 21 2025 - 00Z Wed Jul 23 2025

...There is a Moderate Risk of excessive rainfall over parts of the Middle
Valley on Sunday...

...There is a Slight Risk of excessive rainfall over parts of the Northern
Plains on Sunday and the Ohio Valleys on Monday...

...There is a Slight Risk of severe thunderstorms over parts of the
Northeast/New England, Ohio Valley/Central Appalachians, and
Northern/Central High Plains on Sunday and parts of the Northern Plains on
Monday...

A quasi-stationary front extending from the Great Basin to the Northern
Plains and Middle Mississippi Valley remains quasi-stationary through
Tuesday evening. The eastern half of the front, extending from the
Mid-Atlantic to the Middle Mississippi Valley on Sunday, will move
southward to the Southeast and then extend northwestward to the Middle
Mississippi Valley by Tuesday evening. Moisture pooling along the front
over the Ohio Valley will produce showers and thunderstorms, accompanied
by heavy rain. Therefore, the WPC has issued a Moderate Risk (level 3/4)
of excessive rainfall over parts of the Ohio Valley through Monday
morning. Numerous flash flooding events are possible. Additionally, many
streams may flood, potentially impacting larger rivers.

Additionally, on Sunday, moisture just north of the front will produce
showers and thunderstorms, accompanied by heavy rain, over parts of the
Northern Plains. Therefore, the WPC has issued a Slight Risk (level 2/4)
of excessive rainfall with these thunderstorms over parts of the Northern
Plains through Monday morning. The associated heavy rain will primarily
create localized areas of flash flooding, with urban areas, roads, small
streams, and low-lying areas being the most vulnerable.

Additionally, on Sunday, showers and severe thunderstorms are expected to
develop over parts of the Northern/Central High Plains, along and north of
the front. Therefore, the SPC has issued a Slight Risk (level 2/5) of
severe thunderstorms over parts of the Northern/Central High Plains
through Monday morning. The hazards associated with these thunderstorms
are frequent lightning, severe thunderstorm wind gusts, hail, and a few
tornadoes. Moreover, there is an increased threat of hail two inches or
greater over the area. Additionally, Air Quality Alerts are in effect over
northern Minnesota due to wildfires in Canada from Sunday into Monday.

Furthermore, the cold front over the Northeast to the Central
Appalachians/Ohio Valley will produce two areas of showers and severe
thunderstorms. Therefore, the SPC has issued a Slight Risk (level 2/5) of
severe thunderstorms over parts of the Northeast and Central
Appalachians/Ohio Valley through Monday morning. The hazards associated
with these thunderstorms are frequent lightning, severe thunderstorm wind
gusts, hail, and a few tornadoes. The severe thunderstorms over the
Central Appalachians/Ohio Valley will have a minimal threat for hail. In
addition, showers and thunderstorms will develop over parts of the
Central/Southern Rockies, Central/Southern High Plains, and Southwest on
Sunday.

Moreover, on Monday, moisture will continue to pool along the front over
the Ohio/Tennessee Valleys, creating showers and thunderstorms. Heavy
rain will develop with the showers and thunderstorms over parts of the
Ohio/Tennessee Valleys, as well as the Central/Southern Appalachians.
Therefore, the WPC has issued a Slight Risk (level 2/4) of excessive
rainfall associated with these thunderstorms over parts of the
Ohio/Tennessee Valleys, as well as the Central/Southern Appalachians, from
Monday into Tuesday morning. The associated heavy rain will primarily
create localized areas of flash flooding, with urban areas, roads, small
streams, and low-lying areas being the most vulnerable.

Additionally, on Monday, the western end of the front will trigger showers
and severe thunderstorms over parts of the Northern High Plains.
Therefore, the SPC has issued a Slight Risk (level 2/5) of severe
thunderstorms over parts of the Northern High Plains from Monday into
Tuesday morning. The hazards associated with these thunderstorms are
frequent lightning, severe thunderstorm wind gusts, hail, and a few
tornadoes.

On Monday, showers and thunderstorms are expected to develop south of the
front, from the southern Mid-Atlantic to the Gulf Coast. Moreover, showers
and thunderstorms will develop near and along the front from the Northern
Plains/Upper Mississippi Valley. More showers and thunderstorms develop
along and near the front over the Southern High Plains, Central/Southern
Rockies, and Great Basin/Southwest. Showers and thunderstorms will also
develop in the moisture-rich air over the Southeast to the Central Gulf
Coast.

On Tuesday, strong to severe thunderstorms will develop near the front
over the Northern/Central Plains into the Upper Mississippi Valley.
Further, showers and thunderstorms with heavy rain will develop over parts
of the Upper Midwest. Therefore, the WPC has issued a Slight Risk (level
2/4) of excessive rainfall with these thunderstorms over parts of the
Upper Mississippi Valley and Upper Great Lakes on Tuesday. The associated
heavy rain will primarily create localized areas of flash flooding, with
urban areas, roads, small streams, and low-lying areas being the most
vulnerable.

Also on Tuesday, showers and thunderstorms will develop over parts of the
Southeast, the Central Gulf Coast, the Central/Southern High Plains, the
Central/Southern Rockies, and the Southwest.


Ziegenfelder



Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
300 PM EDT Sun Jul 20 2025

Valid 12Z Wed Jul 23 2025 - 12Z Sun Jul 27 2025

...Major heat wave building from the Southeast into parts of the
Central U.S. next week and beyond...

...Overview...

A hot upper ridge will center over the Mississippi Valley midweek
and expand/split to the East and the Plains later week into next
weekend, with a mean troughing over the Great Lakes/Northeast. An
active flow pattern aloft will continue across the northern tier
states and southern Canada, with several cold frontal passages.
Elsewhere, an upper trough with potential closed low is likely
near northern California with some monsoonal flow channeled into
the Rockies on the western periphery of the main ridge. There will
also be a moist stationary front over the northern Gulf with a
surface low set to work westward just offshore from the eastern to
central Gulf Coast.

...Guidance/Predictability Assessment...

Guidance solutions remain clustered much better than normal valid
in a pattern with above normal predictability. A favored model
composite has good ensemble support and provides a solid forecast
basis for mid-later this week. Switched to a very reasonable
composite of compatible models and ensemble means along with WPC
continuity by next weekend amid slowly increasing forecast spread.

...Weather/Hazards Highlights...

A cold front is progged to slowly drop southward across the Dakotas
and the Upper Midwest for the middle of the week, with a weak wave
of low pressure developing along it. This boundary will be
intersecting a warm and very humid airmass, and this is expected to
fuel the development of multiple thunderstorm complexes from
Nebraska to near Lake Superior Wednesday into Thursday. A Marginal
Risk area is valid for both Day 4 and Day 5 across much of this
region since some of the storms may have convective training, and
thus increasing the risk of localized flooding where this happens.
Improving conditions return to this region by Friday into next
weekend as a drier airmass settles in.

Another area of unsettled weather is expected to reside across
northern Florida and extending westward to the central Gulf Coast
mid to late week. A surface low is likely to form along a lingering
stationary front, and this should gradually track west through the
end of the week. There has been a modest increase in QPF associated
with this compared to the previous forecast issuance, but still
within the Marginal Risk category for Wednesday and Thursday with
the heaviest rainfall staying offshore during this time. The
rainfall potential continues into Friday as well, and this will
continue to be closely monitored in the days ahead. The potential
exists for several inches of rainfall in localized cases from
southern Louisiana to the Florida Panhandle, and a Slight Risk may
eventually be needed as the forecast guidance comes into better
focus in future model runs.

Elsewhere across the nation, moisture associated with the Southwest
U.S. monsoon will likely be reduced compared to recent days, with
some lingering showers/storms across New Mexico and into southern
Colorado, and affecting less of Arizona. However, there may be a
few convective cells that are slow moving across burnscar and other
sensitive areas, and therefore Marginal Risks remain prudent in the
excessive rainfall outlooks. Across New England, there will likely
be an axis of showers and thunderstorms moving in on Thursday, but
it currently does not look to cause much in the way of flooding
concerns.

The other big story will be the building heat across a large
portion of the east-central U.S. for the second half of the week
and into next weekend, courtesy of a large upper high becoming
anchored over the Mid-South. Heat Risk in the major category will
be prevalent from the Deep South to the Midwest and extending
eastward to include Tennessee and Ohio River Valleys to close out
the work week. Some of this heat will likely reach the East Coast
by Friday and next weekend following the pleasant stretch of
cooler weather for the first half of the week. Highs well into the
90s and even some low 100s will be commonplace from the Central
Plains to the East Coast, with the hottest readings across
Oklahoma, Texas, and Arkansas. It will also be uncomfortably warm
and humid at night, providing only limited relief from the heat.

Hamrick/Schichtel


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
255 AM EDT Sun Jul 20 2025

Valid 00Z Mon 21 Jul 2025 - 00Z Mon 28 Jul 2025

The main subtropical surface high over the eastern Pacific will be
positioned well north of the Islands going into next week,
generally between 40 and 45 degrees north. The state will be on
the far southern periphery of this high, and this will keep a
general easterly low level flow in place, with some backing to the
northeast at times through the next 7 days. The models agree that
the overall pressure gradient will weaken some going into the
middle to end of the week, and a lighter trade wind flow as a
result. The ensemble means are in good synoptic scale agreement
on the overall pattern.

In terms of rainfall prospects, there may be a slight increase in
showers across the Islands through Monday morning owing to a weak
upper level trough over the region, but otherwise the normal
trade wind induced showers can be expected through the remainder
of the week with no major rainfall events expected.


Hamrick

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
424 PM EDT Sun Jul 20 2025
Day 1
Valid 16Z Sun Jul 20 2025 - 12Z Mon Jul 21 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL IN AND NEAR
CENTRAL ILLINOIS...

16Z Excessive Rainfall Discussion...
Based on the 12Z HREF QPF and neighborhood ensemble
probabilities...nudged the western boundaries of the outlook areas
in the Mississippi Valley and Northern Plain a bit eastward. Also expanded
the Marginal and Slight boundaries a bit southward in Missouri to
provide a somewhat larger apron for heavy rainfall before
temperatures aloft start to cap activity. Remainder of the outlook
in decent shape.

Bann


0830Z Excessive Rainfall Discussion...

...Midwest, Ohio Valley, & Southern Appalachians...
High moisture persists into Sunday -- precipitable water values
eclipsing 2.25" -- with the core of the instability pool more
significant across portions of the Ohio Valley on Sunday as warming
at 700 hPa occurs across the Central Plains, slowly strengthening
a mid-level capping inversion. Effective bulk shear remains
sufficient for convective organization, including mesocyclone
formation. Two rounds of convection are expected -- a morning round
dropping out of IA into the Midwest and Ohio Valley with a second
round forming in the vicinity of northeast KS during the afternoon
and evening hours. Of some concern is the backing of the low-level
winds during the 18-00z time frame, which could act to anchor any
existing convection in place/limit forward propagation. Any complex
that forms in northeast KS and northern MO is expected to spill
into portions of IL during the evening and overnight hours late
this day (into early Monday morning). Considering the degree of
moisture, instability, and effective bulk shear, there is the
potential for 3-4" amounts in an hour and local 8" totals. The
guidance has increased its signal for higher amounts with a few
pieces of guidance advertising 8-11" of rain in the 00z model suite,
so in coordination with LSX/St Louis MO, ILX/Central IL, and
IND/Indianapolis IN forecast offices, added a Moderate Risk area
in and near central IL. Localized High Risk impacts cannot be
ruled out should any training bands or cell backbuilding persists
for 3+ hours.

To the southeast of the Moderate Risk area, a higher end Slight
Risk appears to exist for much of the rest of the Ohio Valley and
western slopes of the Southern Appalachians, with some guidance
showing a secondary maximum between eastern KY and the KY/OH/WV
border junction. Lingering model uncertainty kept us from upgrading
to a Moderate Risk for the possible secondary maximum. With the
same rainfall potential -- hourly amounts to 3-4" with local 8"
totals possible -- localized Moderate Risk impacts cannot be ruled
out.


...Northern Plains...
The Dakotas/MN will be at the nose of a modest low level jet. A
shortwave moving by the area may be all it takes to initiate a
line of storms across the region, though there may be two separate
rounds: one in the morning and a second Sunday night. The guidance
has been slowly shifting east and southeast with time, and the
area of potential Slight Risk continues to shrink. Believe this is
a lower end Slight Risk.


Southwest/Southern Rockies...
Enough moisture is available for scattered monsoon convection on
Sunday, with the most noted across south-central AZ. Hourly
amounts to 2" are possible due to diurnal heating, which would be
most problematic in urban areas, dry washes/arroyos, or burn scars.


New England/Northern Mid-Atlantic states...
A cold front is expected to sweep through the region, which could
lead to locally heavy pockets of rainfall. Available moisture and
instability supports hourly rain amounts to 2" where cells can
manage to train or merge. Both the 00z HREF and 18z RRFS have a
heavy rain signal from 12z onward this morning from the eastern tip
of Long Island near Block Island, Martha's Vineyard, and Nantucket.
Recent radar imagery (as of this writing) shows a vorticity maximum
in this general neighborhood which could be the responsible party.
If so, it appears to be running ahead of the model guidance and
shouldn't be the threat advertised. Radar estimates are quite low
in its vicinity as is.


Roth



Day 1 threat area: www.wpc.ncep.noaa.gov/qpf/94epoints.txt

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
424 PM EDT Sun Jul 20 2025
Day 2
Valid 12Z Mon Jul 21 2025 - 12Z Tue Jul 22 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
KENTUCKY, TENNESSEE, SOUTHWEST WEST VIRGINIA, & WESTERNMOST
VIRGINIA...

2030Z Excessive Rainfall Discussion Update...

Introduced a targeted Marginal risk area in/near the Washington
Cascades over concerns of fairly modest rainfall over burn scars
and regions of steep terrain from slow-moving late day storms. The
numerical guidance does generate some instability to support rainfall
rates that are problematic in hydrologically sensitive area. Some
minor expansion was made to the Marginal risk boundary in the
Southeast US and over the Ohio Valley area.

Bann


0830Z Excessive Rainfall Discussion...

In and near KY & TN...
An axis of moisture and instability pivots between a convective
frontal wave offshore the Southeast and a strengthening warm
advection pattern across the Plains. Declining low-level inflow
is noted with time, but the GFS forecasts enough effective bulk
shear for some level of convective organization during the period
of daytime heating, which doesn't drop off significantly until
around sunset. Consideration the degree of saturation area soils
have now and the expectation for further saturation on Sunday and
Sunday night, adding a Slight Risk area here makes sense. Hourly
amounts to 3" with local totals to 5" are possible where cells
train or merge which would be most problematic in urban areas and
over saturated soils. This appears more likely within the defined
Slight Risk than the surrounding Marginal Risk area. There was
some consideration for a Slight Risk for coastal sections of NC,
but with coastal marsh in some of those areas, decided against it.


Plains/Southern Rockies...
Surface boundaries/low pressure areas/upper level disturbances are
on this move this period, which along with warming temperatures at
700 hPa/increased mid- level capping across portions of the
Central Plains and IA should limit QPF and flash flood potential
elsewhere. Hourly amounts up to 2" and local totals to 4" are
considered possible in this region. At the moment, it appears any
flash flooding would be on an isolated to widely scattered basis.
In the Southwest and Southern Rockies, burn scars and dry
washes/arroyos would be most at risk. Anywhere within these
regions, urban areas would be of most concern.

Roth


Day 2 threat area: www.wpc.ncep.noaa.gov/qpf/98epoints.txt

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
424 PM EDT Sun Jul 20 2025
Day 3
Valid 12Z Tue Jul 22 2025 - 12Z Wed Jul 23 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
MINNESOTA, NORTHERN WISCONSIN, & NORTHWESTERN MICHIGAN...

2030Z Excessive Rainfall Discussion...

Primary focus for excessive rainfall remains in the Upper
Midwest/Western Great Lakes where increasing low level moisture
transport interacts with sfc low pressure and mid-level height
falls coming out of the Dakotas. The potentially convective low
over the Southeast also remains a possible focus for locally heavy
to excessive rainfall. The numerical guidance continued to show run
to run consistency in the big picture but had less agreement on the
finer details. Either way...changes to the Excessive Rainfall
Outlook were minor.

Bann

0830Z Excessive Rainfall Discussion...

In and near the Western Great Lakes...
A strengthening low-level jet out of the southwest is expected
downwind of an amplified Western trough and under the base of a
cold low moving across central Canada. Precipitable water values
rise to 2"+ and a broad reservoir of CAPE up to 5000 J/kg builds
near southeast SD due to significant warming at 700 hPa/a
strengthening mid-level capping inversion across portions of the
Plains to the east of the Western trough. Effective bulk shear
should be more than sufficient for organized thunderstorms,
including mesocyclone formation. Weekly rainfall anomalies show
that portions of the Arrowhead Peninsula and Upper Peninsula of
MI have had 300%+ of their average rainfall, leading to some degree
of saturation. Hourly rain amounts to 2.5" with local amounts to
5" could lead to flash flooding, with urban areas most prone to
issues. The Slight Risk was shifted somewhat north of continuity
per the latest guidance.


Southeast...
A potentially convective low retrogrades through portions of
northern FL this period. Precipitable water values rise to 2-2.25".
CAPE should rise to 3000 J/kg due to either daytime heating where
present or due to onshore flow from the warm western Atlantic,
Gulf, and FL Straits. There does appear to be enough effective bulk
shear present for at least some loose convective organization.
Hourly amounts to 3" and local totals to 6" are possible here.
Considered a Slight Risk as some portions of northern FL saw above
average precipitation with the previous retrograding convective low
on July 16-17, but the heavy rain signal at the moment shows
minimal overlap with the the previous convective low's rainfall
footprint.



Southern Rockies...
Enough moisture and instability is expected to hourly amounts up
to 2" and local totals to 4", with a distinct diurnal cycle
expected. At the moment, it appears any flash flooding would be on
an isolated to widely scattered basis. Burn scars and dry
washes/arroyos, and urban areas would be most at risk.


Roth

Day 3 threat area: www.wpc.ncep.noaa.gov/qpf/99epoints.txt

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
300 PM EDT Sun Jul 20 2025


A cold front is progged to slowly drop southward across the Dakotas
and the Upper Midwest for the middle of the week, with a weak wave
of low pressure developing along it. This boundary will be
intersecting a warm and very humid airmass, and this is expected to
fuel the development of multiple thunderstorm complexes from
Nebraska to near Lake Superior Wednesday into Thursday. A Marginal
Risk area is valid for both Day 4 and Day 5 across much of this
region since some of the storms may have convective training, and
thus increasing the risk of localized flooding where this happens.
Improving conditions return to this region by Friday into next
weekend as a drier airmass settles in.

Another area of unsettled weather is expected to reside across
northern Florida and extending westward to the central Gulf Coast
mid to late week. A surface low is likely to form along a lingering
stationary front, and this should gradually track west through the
end of the week. There has been a modest increase in QPF associated
with this compared to the previous forecast issuance, but still
within the Marginal Risk category for Wednesday and Thursday with
the heaviest rainfall staying offshore during this time. The
rainfall potential continues into Friday as well, and this will
continue to be closely monitored in the days ahead. The potential
exists for several inches of rainfall in localized cases from
southern Louisiana to the Florida Panhandle, and a Slight Risk may
eventually be needed as the forecast guidance comes into better
focus in future model runs.

Elsewhere across the nation, moisture associated with the Southwest
U.S. monsoon will likely be reduced compared to recent days, with
some lingering showers/storms across New Mexico and into southern
Colorado, and affecting less of Arizona. However, there may be a
few convective cells that are slow moving across burnscar and other
sensitive areas, and therefore Marginal Risks remain prudent in the
excessive rainfall outlooks. Across New England, there will likely
be an axis of showers and thunderstorms moving in on Thursday, but
it currently does not look to cause much in the way of flooding
concerns.

The other big story will be the building heat across a large
portion of the east-central U.S. for the second half of the week
and into next weekend, courtesy of a large upper high becoming
anchored over the Mid-South. Heat Risk in the major category will
be prevalent from the Deep South to the Midwest and extending
eastward to include Tennessee and Ohio River Valleys to close out
the work week. Some of this heat will likely reach the East Coast
by Friday and next weekend following the pleasant stretch of
cooler weather for the first half of the week. Highs well into the
90s and even some low 100s will be commonplace from the Central
Plains to the East Coast, with the hottest readings across
Oklahoma, Texas, and Arkansas. It will also be uncomfortably warm
and humid at night, providing only limited relief from the heat.

Hamrick/Schichtel

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
300 PM EDT Sun Jul 20 2025


A cold front is progged to slowly drop southward across the Dakotas
and the Upper Midwest for the middle of the week, with a weak wave
of low pressure developing along it. This boundary will be
intersecting a warm and very humid airmass, and this is expected to
fuel the development of multiple thunderstorm complexes from
Nebraska to near Lake Superior Wednesday into Thursday. A Marginal
Risk area is valid for both Day 4 and Day 5 across much of this
region since some of the storms may have convective training, and
thus increasing the risk of localized flooding where this happens.
Improving conditions return to this region by Friday into next
weekend as a drier airmass settles in.

Another area of unsettled weather is expected to reside across
northern Florida and extending westward to the central Gulf Coast
mid to late week. A surface low is likely to form along a lingering
stationary front, and this should gradually track west through the
end of the week. There has been a modest increase in QPF associated
with this compared to the previous forecast issuance, but still
within the Marginal Risk category for Wednesday and Thursday with
the heaviest rainfall staying offshore during this time. The
rainfall potential continues into Friday as well, and this will
continue to be closely monitored in the days ahead. The potential
exists for several inches of rainfall in localized cases from
southern Louisiana to the Florida Panhandle, and a Slight Risk may
eventually be needed as the forecast guidance comes into better
focus in future model runs.

Elsewhere across the nation, moisture associated with the Southwest
U.S. monsoon will likely be reduced compared to recent days, with
some lingering showers/storms across New Mexico and into southern
Colorado, and affecting less of Arizona. However, there may be a
few convective cells that are slow moving across burnscar and other
sensitive areas, and therefore Marginal Risks remain prudent in the
excessive rainfall outlooks. Across New England, there will likely
be an axis of showers and thunderstorms moving in on Thursday, but
it currently does not look to cause much in the way of flooding
concerns.

The other big story will be the building heat across a large
portion of the east-central U.S. for the second half of the week
and into next weekend, courtesy of a large upper high becoming
anchored over the Mid-South. Heat Risk in the major category will
be prevalent from the Deep South to the Midwest and extending
eastward to include Tennessee and Ohio River Valleys to close out
the work week. Some of this heat will likely reach the East Coast
by Friday and next weekend following the pleasant stretch of
cooler weather for the first half of the week. Highs well into the
90s and even some low 100s will be commonplace from the Central
Plains to the East Coast, with the hottest readings across
Oklahoma, Texas, and Arkansas. It will also be uncomfortably warm
and humid at night, providing only limited relief from the heat.

Hamrick/Schichtel

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
214 PM EDT Wed May 7 2025

Valid 00Z Thu May 08 2025 - 00Z Sun May 11 2025


...Colorado...
Day 1...

Lingering vorticity on the western side of the departing upper low
will still trigger some light snow over the San Juans this evening
before tapering off tonight/early Thursday. WPC probabilities for
at least an additional 4 inches of snow after 00Z are low (10-40%)
above 11,000ft.

For days 2-3, the probability of at least 4 inches of snow is less
than 10%.

The probability of significant freezing rain across the CONUS is
less than 10%.

Note - this is the last regularly scheduled discussion (QPFHSD)
for the 2024-2025 winter season. Unless a significant winter
weather threat emerges, this discussion will next be updated on or
about September 25, 2025.


Fracasso

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
300 PM EDT Sun Jul 20 2025

Valid 12Z Wed Jul 23 2025 - 12Z Sun Jul 27 2025

...Major heat wave building from the Southeast into parts of the
Central U.S. next week and beyond...

...Overview...

A hot upper ridge will center over the Mississippi Valley midweek
and expand/split to the East and the Plains later week into next
weekend, with a mean troughing over the Great Lakes/Northeast. An
active flow pattern aloft will continue across the northern tier
states and southern Canada, with several cold frontal passages.
Elsewhere, an upper trough with potential closed low is likely
near northern California with some monsoonal flow channeled into
the Rockies on the western periphery of the main ridge. There will
also be a moist stationary front over the northern Gulf with a
surface low set to work westward just offshore from the eastern to
central Gulf Coast.

...Guidance/Predictability Assessment...

Guidance solutions remain clustered much better than normal valid
in a pattern with above normal predictability. A favored model
composite has good ensemble support and provides a solid forecast
basis for mid-later this week. Switched to a very reasonable
composite of compatible models and ensemble means along with WPC
continuity by next weekend amid slowly increasing forecast spread.

...Weather/Hazards Highlights...

A cold front is progged to slowly drop southward across the Dakotas
and the Upper Midwest for the middle of the week, with a weak wave
of low pressure developing along it. This boundary will be
intersecting a warm and very humid airmass, and this is expected to
fuel the development of multiple thunderstorm complexes from
Nebraska to near Lake Superior Wednesday into Thursday. A Marginal
Risk area is valid for both Day 4 and Day 5 across much of this
region since some of the storms may have convective training, and
thus increasing the risk of localized flooding where this happens.
Improving conditions return to this region by Friday into next
weekend as a drier airmass settles in.

Another area of unsettled weather is expected to reside across
northern Florida and extending westward to the central Gulf Coast
mid to late week. A surface low is likely to form along a lingering
stationary front, and this should gradually track west through the
end of the week. There has been a modest increase in QPF associated
with this compared to the previous forecast issuance, but still
within the Marginal Risk category for Wednesday and Thursday with
the heaviest rainfall staying offshore during this time. The
rainfall potential continues into Friday as well, and this will
continue to be closely monitored in the days ahead. The potential
exists for several inches of rainfall in localized cases from
southern Louisiana to the Florida Panhandle, and a Slight Risk may
eventually be needed as the forecast guidance comes into better
focus in future model runs.

Elsewhere across the nation, moisture associated with the Southwest
U.S. monsoon will likely be reduced compared to recent days, with
some lingering showers/storms across New Mexico and into southern
Colorado, and affecting less of Arizona. However, there may be a
few convective cells that are slow moving across burnscar and other
sensitive areas, and therefore Marginal Risks remain prudent in the
excessive rainfall outlooks. Across New England, there will likely
be an axis of showers and thunderstorms moving in on Thursday, but
it currently does not look to cause much in the way of flooding
concerns.

The other big story will be the building heat across a large
portion of the east-central U.S. for the second half of the week
and into next weekend, courtesy of a large upper high becoming
anchored over the Mid-South. Heat Risk in the major category will
be prevalent from the Deep South to the Midwest and extending
eastward to include Tennessee and Ohio River Valleys to close out
the work week. Some of this heat will likely reach the East Coast
by Friday and next weekend following the pleasant stretch of
cooler weather for the first half of the week. Highs well into the
90s and even some low 100s will be commonplace from the Central
Plains to the East Coast, with the hottest readings across
Oklahoma, Texas, and Arkansas. It will also be uncomfortably warm
and humid at night, providing only limited relief from the heat.

Hamrick/Schichtel


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