Weather Prediction Center

National Oceanic and Atmospheric Administration

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
356 PM EDT Sat Jul 26 2025

Valid 00Z Sun Jul 27 2025 - 00Z Tue Jul 29 2025

...There is a Slight Risk of excessive rainfall over parts of the Middle
Mississippi/Ohio Valleys, northern Mid-Atlantic/Lower Great Lakes, and
Northeast on Saturday...

...There is a Slight Risk of excessive rainfall over parts of the Upper
Mississippi Valley/Upper Great Lakes, Ohio Valley/Central Appalachians,
northern Mid-Atlantic, and Northeast on Sunday...

...There is a Slight Risk of severe thunderstorms over parts of the
Northern Plains/Upper Mississippi Valley and Mid-Atlantic on Saturday and
parts of the Upper Mississippi Valley/Upper Great Lakes on Sunday...

On Saturday, a front extending from the Northern Plains to the Northern
Rockies will move eastward to the Great Lakes and southward to the Central
Plains and Northern Rockies by Monday evening. In addition, on Saturday, a
second front extending from the Mid-Atlantic to the Great Lakes will
slowly move eastward to off the Mid-Atlantic Coast by Monday. The northern
front will trigger showers and severe thunderstorms over parts of the
Northern Plains/Upper Mississippi Valley. Therefore, the SPC has issued a
Slight Risk (level 2/5) of severe thunderstorms over parts of the Northern
Plains/Upper Mississippi Valley through Sunday morning. The hazards
associated with these thunderstorms are frequent lightning, severe
thunderstorm wind gusts, hail, and a few tornadoes.

The eastern front will produce showers and severe thunderstorms over parts
of the Mid-Atlantic. Therefore, the SPC has issued a Slight Risk (level
2/5) of severe thunderstorms over parts of the Northern Plains/Upper
Mississippi Valley through Sunday morning. The hazards associated with
these thunderstorms are frequent lightning, severe thunderstorm wind
gusts, and a minimal threat of hail and tornadoes.

Moreover, tropical moisture pooling along the Mid-Atlantic to Middle
Mississippi/Ohio Valleys front will produce multiple areas of heavy rain
over parts of the Middle Mississippi/Ohio Valleys, northern
Mid-Atlantic/Lower Great Lakes, and Northeast. Therefore, the WPC has
issued a Slight Risk (level 2/4) of excessive rainfall over parts of the
Middle Mississippi/Ohio Valleys, northern Mid-Atlantic/Lower Great Lakes,
and Northeast through Sunday 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.

Furthermore, showers and thunderstorms are expected to develop over parts
of the Southern Plains, the Tennessee Valley, and the Southeast on
Saturday.

On Sunday, showers and severe thunderstorms will develop over parts of the
Upper Mississippi Valley and Upper Great Lakes near the front. Therefore,
the SPC has issued a Slight Risk (level 2/5) of severe thunderstorms over
parts of the Upper Mississippi Valley and Upper Great Lakes from Sunday
through Monday morning. The hazards associated with these thunderstorms
are frequent lightning, severe thunderstorm wind gusts, hail, and a few
tornadoes.

Additionally, on Sunday, increasing moisture over the Upper Midwest will
produce showers and thunderstorms, accompanied by heavy rain, over parts
of the Upper Mississippi Valley/Upper Great Lakes. Therefore, the WPC has
issued a Slight Risk (level 2/4) of excessive rainfall with these
thunderstorms over parts of the Upper Mississippi Valley/Upper Great Lakes
from Sunday 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.

Furthermore, on Sunday, showers and thunderstorms will develop over parts
of the Ohio Valley, extending eastward to the Mid-Atlantic and Northeast,
due to tropical moisture pooling along the associated front. Multiple
areas of heavy rain will develop with these thunderstorms over parts of
the Ohio Valley/Central Appalachians, northern Mid-Atlantic, and
Northeast. Therefore, the WPC has issued a Slight Risk (level 2/4) of
excessive rainfall with these thunderstorms over parts of the Ohio
Valley/Central Appalachians, northern Mid-Atlantic, and Northeast from
Sunday 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 thunderstorms are expected to develop
over parts of the Southern Rockies, Southern Plains, and most of the Gulf
Coast.

Moreover, an upper-level high over the Southeast will aid in producing
dangerous high temperatures, accompanied by high humidity from the
Northern Plains and Upper Mississippi/Ohio Valleys to the Southern Plains,
Lower Mississippi Valley, Tennessee Valley, as well as the Mid-Atlantic
and Southeast. Extreme Heat Warnings, Heat Advisories, and Extreme Heat
Watches are over these regions through Monday. An extended period of
extreme heat and minimal nighttime relief can lead to cumulative heat
stress on the body. As temperatures rise, plan to limit outdoor
activities, stay hydrated, and ensure access to air conditioning and other
cooling areas. Additionally, be sure to check on vulnerable family
members, friends, and neighbors.


Ziegenfelder


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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
235 PM EDT Sat Jul 26 2025

...Dangerous heat wave persists in the Southeast through midweek
with gradual relief later week...

...Overview...

A large and strong upper high meandering over the central/southern
Plains into the Mid-South will cause a persistent and major heat
wave for those areas and especially into the Southeast through
midweek. Dangerous heat is forecast to extend north through the
Ohio Valley and Mid-Atlantic/Northeast Tuesday-Wednesday but
gradually get pressed southward behind a cold front as the week
progresses. Complexes of showers and storms are likely along the
northern periphery of the ridge -- across the northern/central High
Plains eastward into the Midwest. Scattered thunderstorms are
possible farther east at times, especially near the front as it
pushes southward and along a retrograding trough/low near the Gulf
Coast. Additionally, southerly flow will bring monsoonal moisture
into the Southwest states with possibly heavy rain.


...Guidance/Predictability Assessment...

Model agreement is excellent for the overall pattern through much
of next week. Models are unified in showing an expansive upper high
of 2+ standard deviations above normal, with widespread 594+ dm
500mb heights but with low chances of reaching 600 dm. Guidance
shows the high at its greatest expanse into Tuesday as it
encompasses the south-central Rockies eastward across the
Mississippi and Ohio Valleys and Southeast, before shrinking in
scope and being centered over the southern Plains by later next
week. Meanwhile the ridge axis will shift westward and build north
across the northern Rockies into western Canada starting Tuesday,
coincident with the upper trough edging into the north-central to
northeastern U.S. anchored by a large Hudson Bay to eastern Canada
upper low. Model differences were mostly negligible through the
period, considering the forecast horizon, and a general model blend
sufficed with only a minority weighting of the GEFS/ECMWF
ensembles by next Fri/Sat. This maintained very good continuity.

Regardless of the large scale agreement, shortwaves riding around
the ridge will cause more differences in sensible weather like
frontal placement, and convection will have further uncertainties
due to small boundaries like outflows interacting. These tend not
to become clearer until the short range or near term, so the
details of QPF remain uncertain, but at least the overall pattern
seems set.


...Weather/Hazards Highlights...

The persistent and strong upper ridge will lead to continued
dangerous heat that will be longest lasting across the Tennessee
Valley/Mid-South and Southeast into the Carolinas next week.
HeatRisk is in the Major (level 3/4) to Extreme (level 4/4)
categories for these areas through Wednesday or Thursday. High
temperatures will be in the upper 90s and 100s with heat indices
potentially exceeding 110 to 115 degrees, while morning lows well
into the 70s and nearing 80 will not provide much relief. This is
likely to set scattered daily records for maximum temperatures and
perhaps more widespread records for minimum temperatures. Farther
north, the Ohio Valley into the Mid-Atlantic and Northeast can
expect hotter than normal temperatures into the 90s with Major
HeatRisk into Tuesday, but these areas are likely to cool by
Wednesday or Thursday behind a cold front. This cold front
eventually making its way southward should finally lead to heat
relief in much of the Southeast later in the week, though Florida
could still be hot.

Rain and thunderstorms are forecast to focus on the periphery of
the ridge. Some upper jet and shortwave forcing combined with
sufficient moisture and high to extreme instability just ahead of a
front or two should lead to convection across the northern Rockies
into the north-central Plains and Mississippi Valley on Tuesday
and Wednesday. These ingredients will likely lead to heavy rain
rates, but model spread remains high with the axis of storms and
placement of heaviest rain. Another complicating factor for
potential flash flooding is the possibility of the maximum rain
amounts falling over the Nebraska Sandhills which is not a
sensitive area for heavy rain. For those reasons, held off on any
Slight Risk areas in the Day 4/Tuesday and Day 5/Wednesday EROs at
this point, but broad Marginal Risks cover these areas and
eventually Slight Risks may need to be added. Did expand the
Wednesday (D5) Marginal Risk to the East Coast to account for
potentially heavier rain in a moisture-laden pre-frontal
environment coincident with areas that have seen well above normal
rainfall the past several weeks.

Meanwhile to the west of the ridge, monsoonal moisture (with
precipitable water values generally in the 75th-90th percentile)
will be present over the Southwest with some instability. Marginal
Risks are in place in the Days 4 and 5 EROs for the Southwest and
reaching into the central Rockies/High Plains as the monsoonal
moisture meets the frontal system to the north. The central Rockies
and Plains look to be areas of focus for heavy rain into Thursday
and Friday as well.

Elsewhere, moisture and instability could lead to scattered
thunderstorms in parts of the eastern half of the U.S. from day to
day. There may be some focus for storms over northern
Florida/southern Georgia Tuesday and near the central Gulf Coast
Wednesday as a surface/low level trough/weak low retrogrades.
Marginal Risks of flash flooding are in place for those areas due
to high rain rates that may overcome the high Flash Flood Guidance
and/or fall atop urban areas. Farther north, moisture pooling along
the front pushing southward could enhance rainfall from the Mid-
Atlantic southward into the Carolinas Thursday into Friday.


Fracasso/Tate


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
341 AM EDT Sat Jul 26 2025

Valid 00Z Sun 27 Jul 2025 - 00Z Sun 03 Aug 2025

Light to moderate trade winds are likely over the next couple of
days. For Saturday, mostly dry weather is likely aside from some
Big Island showers, but shower potential could increase Saturday
night into early next week as moisture increases near a surface
trough and under a weak trough aloft.

Into next week, a tropical disturbance is forecast to pass south
of the state around Tuesday-Wednesday. Recent model guidance has
become more agreeable that this possible tropical low should stay
well south of the islands. But what this feature will do is
increase the pressure gradient and strengthen winds to breezy
levels that should last through much of the week. Drier air is
also likely as the moisture stays south of the state, though yet
another tropical low moving westward south of Hawaii has a chance
of bringing moisture to the Big Island, but with high uncertainty
at this point.


Tate

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
857 PM EDT Sat Jul 26 2025
Day 1
Valid 01Z Sun Jul 27 2025 - 12Z Sun Jul 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PARTS OF
THE MID MISSISSIPPI AND OHIO VALLEYS AND THE NORTHEAST...

01Z Update...Maintained all of the previous outlook areas, with
some modifications based on recent runs of the HRRR, the latest
HREF, and radar trends. The biggest adjustment to any of the Slight
Risk areas was to adjust the Mid Mississippi to Ohio valleys area
a little farther south. Recent guidance and observation trends
suggest heavy amounts, producing isolated to scattered instances
of flash flooding will continue along a corridor extending east
from northern Missouri into the Ohio Valley.

Pereira

16Z... In coordination with the New York offices an upgrade to a
Slight Risk was made for the rest of the period. The PW values will
be near a daily max and certainly could fuel locally enhanced rain
rates leading to isolated flash flooding, especially over
sensitive terrain. The Slight spans across central/eastern New
York. The Slight over much of Pennsylvania was broadened a little
in a NW to SE fashion. The latest guidance depicts higher rainfall
rates for far northeast Ohio/northwest Pennsylvania than previous
forecast and for western portions of Ohio.

Campbell

Heavy to excessive rainfall is possible along a corridor associated
with vort energy embedded within mid-level flow which was interacting
with a quasi- stationary front and a modestly unstable, but very
moist airmass pooled along it.The continuous influx of high PW
values over this boundary will aid in locally enhanced rainfall.
In addition...the winds aloft will be favorable for training and
backbuilding of storms over recently wet soils. This will elevate
the risk for localized flash flooding, especially for the flash
prone areas within the terrain of Pennsylvania and surrounding
locations. Given the amount of rain that fell in parts of Illinois
on Friday and in the overnight period from Friday night into early
this morning prior to the start of the Day 1 period...introduced a
Slight risk area in addition to the one that was already issued.

...Gulf Coast...

The disorganized area of showers and thunderstorms associated with
a trough of low pressure situated across the western half of the
Gulf will make its way inland over southeast Texas today. Deep
moisture/high precipitable water values and mid- and upper level
forcing continue producing downpours across the central and
western Gulf coast with an emphasis on the immediate coastal plain.

...Northern Plains...

16Z update... Current observations show organized convection
tracking across Minnesota with a renewal of thunderstorm
development this afternoon and evening for the Dakotas and
Minnesota. Guidance is depicting the line of storms to progress
further east which is outside of the morning issuance of the
Marginal Risk. The eastern boundary was adjusted eastward to
account for this trend.

Campbell

The next in a series of potent shortwaves will eject eastward
across the northern tier of states of the Northern
Plains...resulting in another round of heavy precip potential with
more organized convective clusters migrating through the Dakotas.
Isolated 2 to 3 inch rainfall maxima are possible and embedded
within broader areas of lesser rainfall amounts. The pattern is
fairly progressive so see little reason to move from the Marginal
risk category...although minor nudges were made based on the latest
guidance.

...Northeastern California and Northwest Nevada...

Almost a carbon copy of the prior period for convective impacts
lingering across the Northern Sierra up through northeastern
California and northwest Oregon. The upper pattern is pretty slow
to breakdown with the diffluent area in the longwave setup still
situated over northern California into Nevada. Instability is
expected to be modest and slightly above normal moisture in the
terrain will offer the capability for some isolated flash flood
concerns within any complex terrain and burn scar remnants in the
above area.

Bann

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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
857 PM EDT Sat Jul 26 2025
Day 2
Valid 12Z Sun Jul 27 2025 - 12Z Mon Jul 28 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE UPPER MIDWEST, NORTHERN APPALACHIANS AND PARTS OF THE NORTHEAST...

...The eastern Dakotas and Upper Midwest...

21Z update... Very minor reshaping of the southern boundary near
the Minnesota/Wisconsin border to account for the latest guidance
and WPC QPF.

Campbell

The effects of a shortwave trough interacting with a surface front
across the Upper Midwest will continue into Sunday as does
uncertainty with placement and timing of any convection capable of
supporting heavy rainfall. Convection early in the period looks to
be progressive enough to preclude much thereat of excessive
rainfall. However...there should be a weak boundary to the
southwest of the initial convection track with stronger
instability to the south. The instability and the shear set up a
scenario where additional convection will be more capable of
producing heavy to potentially excessive rainfall. Opted to
maintain a the previously issued Slight risk area after shifting
the area eastward.

...The Ohio Valley and Mid Atlantic to southern New England...

21Z update... In coordination with the local forecast offices 2
Slight Risks were raised for this period. The first one covers much
of eastern Ohio, West Virginia, western Maryland and southwest
Pennsylvania. The second one spans from the Chesapeake bay area
northward to southern New England. These new areas overlap some of
same the sensitive areas highlighted for the D1 period. Locally
enhanced rainfall will persist in the very moist environment near
the west-east frontal boundary.

Campbell

Mid-level flow flattens over the Great Lakes and Ohio
Valley...allowing embedded shortwave energy to start propagating
eastward. With the center of the upper high expected to shift just
far enough eastward...some weak height falls will allow shortwave
energy to dig over parts of the Mid-Atlantic. With an anomalously
moist air mass in place...convection with localized downpours have
a low-end threat to result in localized flooding.

...Southwest US...

Deeper moisture that made its way across parts of the Gulf and
inland across Mexico should start to be drawn northwest into parts
of the Southwest United States...resulting in scattered late day
and evening convection across parts of New Mexico and a small
portion of Arizona.

Bann

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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
857 PM EDT Sat Jul 26 2025
Day 3
Valid 12Z Mon Jul 28 2025 - 12Z Tue Jul 29 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE NORTHERN
HIGH PLAINS INTO THE UPPER MIDWEST AND ACROSS PARTS OF THE
SOUTHWEST UNITED STATES...

...Plains of Eastern Montana to parts of the Upper Midwest...

21Z update... The latest guidance is signaling for some of the
highest QPF to focus over South Dakota, southern Minnesota and
western Wisconsin and noted and uptick in areal coverage over this
part of the country. A minor expansion of the northern boundary was
made across central Minnesota ans western Wisconsin.

Campbell

Showers and thunderstorms capable of producing excessive rainfall
are possible on Monday and Monday night from the plains of Montana
southeastward into parts of the Upper Midwest as surface/low level
flow accelerates between low pressure to the south and high
pressure strengthening over southern Canada. Development of surface
low pressure over southwest South Dakota/northwest Nebraska
results in moisture transport up and over the boundary...leading to
a better chance for enhanced rainfall rates from the Dakotas into
Minnesota or Iowa. Farther west...there should be a feed of
moisture and some instability in the easterly flow into eastern
Montana. Given considerable uncertainty...not incline for more than
a Marginal risk area.


...Southwest US...

A continuation of deeper moisture transport into the Southwest US
will linger into Monday...with a continued chance for scattered
late day and evening convection across parts of New Mexico and a
small portion of Arizona that extends northward along the southern
and central Colorado front range.

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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
235 PM EDT Sat Jul 26 2025


The persistent and strong upper ridge will lead to continued
dangerous heat that will be longest lasting across the Tennessee
Valley/Mid-South and Southeast into the Carolinas next week.
HeatRisk is in the Major (level 3/4) to Extreme (level 4/4)
categories for these areas through Wednesday or Thursday. High
temperatures will be in the upper 90s and 100s with heat indices
potentially exceeding 110 to 115 degrees, while morning lows well
into the 70s and nearing 80 will not provide much relief. This is
likely to set scattered daily records for maximum temperatures and
perhaps more widespread records for minimum temperatures. Farther
north, the Ohio Valley into the Mid-Atlantic and Northeast can
expect hotter than normal temperatures into the 90s with Major
HeatRisk into Tuesday, but these areas are likely to cool by
Wednesday or Thursday behind a cold front. This cold front
eventually making its way southward should finally lead to heat
relief in much of the Southeast later in the week, though Florida
could still be hot.

Rain and thunderstorms are forecast to focus on the periphery of
the ridge. Some upper jet and shortwave forcing combined with
sufficient moisture and high to extreme instability just ahead of a
front or two should lead to convection across the northern Rockies
into the north-central Plains and Mississippi Valley on Tuesday
and Wednesday. These ingredients will likely lead to heavy rain
rates, but model spread remains high with the axis of storms and
placement of heaviest rain. Another complicating factor for
potential flash flooding is the possibility of the maximum rain
amounts falling over the Nebraska Sandhills which is not a
sensitive area for heavy rain. For those reasons, held off on any
Slight Risk areas in the Day 4/Tuesday and Day 5/Wednesday EROs at
this point, but broad Marginal Risks cover these areas and
eventually Slight Risks may need to be added. Did expand the
Wednesday (D5) Marginal Risk to the East Coast to account for
potentially heavier rain in a moisture-laden pre-frontal
environment coincident with areas that have seen well above normal
rainfall the past several weeks.

Meanwhile to the west of the ridge, monsoonal moisture (with
precipitable water values generally in the 75th-90th percentile)
will be present over the Southwest with some instability. Marginal
Risks are in place in the Days 4 and 5 EROs for the Southwest and
reaching into the central Rockies/High Plains as the monsoonal
moisture meets the frontal system to the north. The central Rockies
and Plains look to be areas of focus for heavy rain into Thursday
and Friday as well.

Elsewhere, moisture and instability could lead to scattered
thunderstorms in parts of the eastern half of the U.S. from day to
day. There may be some focus for storms over northern
Florida/southern Georgia Tuesday and near the central Gulf Coast
Wednesday as a surface/low level trough/weak low retrogrades.
Marginal Risks of flash flooding are in place for those areas due
to high rain rates that may overcome the high Flash Flood Guidance
and/or fall atop urban areas. Farther north, moisture pooling along
the front pushing southward could enhance rainfall from the Mid-
Atlantic southward into the Carolinas Thursday into Friday.


Fracasso/Tate

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
235 PM EDT Sat Jul 26 2025


The persistent and strong upper ridge will lead to continued
dangerous heat that will be longest lasting across the Tennessee
Valley/Mid-South and Southeast into the Carolinas next week.
HeatRisk is in the Major (level 3/4) to Extreme (level 4/4)
categories for these areas through Wednesday or Thursday. High
temperatures will be in the upper 90s and 100s with heat indices
potentially exceeding 110 to 115 degrees, while morning lows well
into the 70s and nearing 80 will not provide much relief. This is
likely to set scattered daily records for maximum temperatures and
perhaps more widespread records for minimum temperatures. Farther
north, the Ohio Valley into the Mid-Atlantic and Northeast can
expect hotter than normal temperatures into the 90s with Major
HeatRisk into Tuesday, but these areas are likely to cool by
Wednesday or Thursday behind a cold front. This cold front
eventually making its way southward should finally lead to heat
relief in much of the Southeast later in the week, though Florida
could still be hot.

Rain and thunderstorms are forecast to focus on the periphery of
the ridge. Some upper jet and shortwave forcing combined with
sufficient moisture and high to extreme instability just ahead of a
front or two should lead to convection across the northern Rockies
into the north-central Plains and Mississippi Valley on Tuesday
and Wednesday. These ingredients will likely lead to heavy rain
rates, but model spread remains high with the axis of storms and
placement of heaviest rain. Another complicating factor for
potential flash flooding is the possibility of the maximum rain
amounts falling over the Nebraska Sandhills which is not a
sensitive area for heavy rain. For those reasons, held off on any
Slight Risk areas in the Day 4/Tuesday and Day 5/Wednesday EROs at
this point, but broad Marginal Risks cover these areas and
eventually Slight Risks may need to be added. Did expand the
Wednesday (D5) Marginal Risk to the East Coast to account for
potentially heavier rain in a moisture-laden pre-frontal
environment coincident with areas that have seen well above normal
rainfall the past several weeks.

Meanwhile to the west of the ridge, monsoonal moisture (with
precipitable water values generally in the 75th-90th percentile)
will be present over the Southwest with some instability. Marginal
Risks are in place in the Days 4 and 5 EROs for the Southwest and
reaching into the central Rockies/High Plains as the monsoonal
moisture meets the frontal system to the north. The central Rockies
and Plains look to be areas of focus for heavy rain into Thursday
and Friday as well.

Elsewhere, moisture and instability could lead to scattered
thunderstorms in parts of the eastern half of the U.S. from day to
day. There may be some focus for storms over northern
Florida/southern Georgia Tuesday and near the central Gulf Coast
Wednesday as a surface/low level trough/weak low retrogrades.
Marginal Risks of flash flooding are in place for those areas due
to high rain rates that may overcome the high Flash Flood Guidance
and/or fall atop urban areas. Farther north, moisture pooling along
the front pushing southward could enhance rainfall from the Mid-
Atlantic southward into the Carolinas Thursday into Friday.


Fracasso/Tate

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
235 PM EDT Sat Jul 26 2025

...Dangerous heat wave persists in the Southeast through midweek
with gradual relief later week...

...Overview...

A large and strong upper high meandering over the central/southern
Plains into the Mid-South will cause a persistent and major heat
wave for those areas and especially into the Southeast through
midweek. Dangerous heat is forecast to extend north through the
Ohio Valley and Mid-Atlantic/Northeast Tuesday-Wednesday but
gradually get pressed southward behind a cold front as the week
progresses. Complexes of showers and storms are likely along the
northern periphery of the ridge -- across the northern/central High
Plains eastward into the Midwest. Scattered thunderstorms are
possible farther east at times, especially near the front as it
pushes southward and along a retrograding trough/low near the Gulf
Coast. Additionally, southerly flow will bring monsoonal moisture
into the Southwest states with possibly heavy rain.


...Guidance/Predictability Assessment...

Model agreement is excellent for the overall pattern through much
of next week. Models are unified in showing an expansive upper high
of 2+ standard deviations above normal, with widespread 594+ dm
500mb heights but with low chances of reaching 600 dm. Guidance
shows the high at its greatest expanse into Tuesday as it
encompasses the south-central Rockies eastward across the
Mississippi and Ohio Valleys and Southeast, before shrinking in
scope and being centered over the southern Plains by later next
week. Meanwhile the ridge axis will shift westward and build north
across the northern Rockies into western Canada starting Tuesday,
coincident with the upper trough edging into the north-central to
northeastern U.S. anchored by a large Hudson Bay to eastern Canada
upper low. Model differences were mostly negligible through the
period, considering the forecast horizon, and a general model blend
sufficed with only a minority weighting of the GEFS/ECMWF
ensembles by next Fri/Sat. This maintained very good continuity.

Regardless of the large scale agreement, shortwaves riding around
the ridge will cause more differences in sensible weather like
frontal placement, and convection will have further uncertainties
due to small boundaries like outflows interacting. These tend not
to become clearer until the short range or near term, so the
details of QPF remain uncertain, but at least the overall pattern
seems set.


...Weather/Hazards Highlights...

The persistent and strong upper ridge will lead to continued
dangerous heat that will be longest lasting across the Tennessee
Valley/Mid-South and Southeast into the Carolinas next week.
HeatRisk is in the Major (level 3/4) to Extreme (level 4/4)
categories for these areas through Wednesday or Thursday. High
temperatures will be in the upper 90s and 100s with heat indices
potentially exceeding 110 to 115 degrees, while morning lows well
into the 70s and nearing 80 will not provide much relief. This is
likely to set scattered daily records for maximum temperatures and
perhaps more widespread records for minimum temperatures. Farther
north, the Ohio Valley into the Mid-Atlantic and Northeast can
expect hotter than normal temperatures into the 90s with Major
HeatRisk into Tuesday, but these areas are likely to cool by
Wednesday or Thursday behind a cold front. This cold front
eventually making its way southward should finally lead to heat
relief in much of the Southeast later in the week, though Florida
could still be hot.

Rain and thunderstorms are forecast to focus on the periphery of
the ridge. Some upper jet and shortwave forcing combined with
sufficient moisture and high to extreme instability just ahead of a
front or two should lead to convection across the northern Rockies
into the north-central Plains and Mississippi Valley on Tuesday
and Wednesday. These ingredients will likely lead to heavy rain
rates, but model spread remains high with the axis of storms and
placement of heaviest rain. Another complicating factor for
potential flash flooding is the possibility of the maximum rain
amounts falling over the Nebraska Sandhills which is not a
sensitive area for heavy rain. For those reasons, held off on any
Slight Risk areas in the Day 4/Tuesday and Day 5/Wednesday EROs at
this point, but broad Marginal Risks cover these areas and
eventually Slight Risks may need to be added. Did expand the
Wednesday (D5) Marginal Risk to the East Coast to account for
potentially heavier rain in a moisture-laden pre-frontal
environment coincident with areas that have seen well above normal
rainfall the past several weeks.

Meanwhile to the west of the ridge, monsoonal moisture (with
precipitable water values generally in the 75th-90th percentile)
will be present over the Southwest with some instability. Marginal
Risks are in place in the Days 4 and 5 EROs for the Southwest and
reaching into the central Rockies/High Plains as the monsoonal
moisture meets the frontal system to the north. The central Rockies
and Plains look to be areas of focus for heavy rain into Thursday
and Friday as well.

Elsewhere, moisture and instability could lead to scattered
thunderstorms in parts of the eastern half of the U.S. from day to
day. There may be some focus for storms over northern
Florida/southern Georgia Tuesday and near the central Gulf Coast
Wednesday as a surface/low level trough/weak low retrogrades.
Marginal Risks of flash flooding are in place for those areas due
to high rain rates that may overcome the high Flash Flood Guidance
and/or fall atop urban areas. Farther north, moisture pooling along
the front pushing southward could enhance rainfall from the Mid-
Atlantic southward into the Carolinas Thursday into Friday.


Fracasso/Tate


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