Weather Prediction Center

National Oceanic and Atmospheric Administration

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
221 AM EDT Sun Aug 30 2026

Valid 12Z Sun Aug 30 2026 - 12Z Tue Sep 01 2026

...There is a Slight Risk (level 2/4) of excessive rainfall over
parts of the Southwest, Great Basin, and Central Rockies through
Monday...

Monsoonal moisture will produce showers and thunderstorms with
heavy rain over parts of the Southwest, Great Basin, and Central
Rockies through Monday. Therefore, the WPC has issued a Slight
Risk (level 2/4) of excessive rainfall over parts of the
Southwest, Great Basin, and Central Rockies on Sunday and Monday. 
The associated heavy rain will create mainly localized areas of
flash flooding, with urban areas, roads, small streams, narrow
canyons/gullies, and burn scars the most vulnerable.

A quasi-stationary front from the North Carolina Coast
southwestward to the Lower Mississippi Valley will slowly
dissipate from west to east to the North Carolina Coast by late
Sunday morning. Near and south of the front, showers and
thunderstorms will develop over the Southern Mid-Atlantic to the
Southeast and Central/Eastern Gulf Coast through Sunday evening.
From Sunday night to Tuesday morning, showers and thunderstorms
will develop over the Central/Eastern Gulf Coast and into parts of
the Western Gulf Coast.

Showers and thunderstorms will also develop over the Northern High
Plains and into the Northern Plains through early Monday morning. 
Additionally, showers and thunderstorms will develop along and
near a warm front extending from the Great Lakes into parts of the
Northeast and Mid-Atlantic from Monday through Tuesday.  Lastly,
scattered rain will develop over parts of the Northwest Coast on
early Tuesday morning.


Ziegenfelder


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

Extreme Heat Key Messages available at:
https://www.wpc.ncep.noaa.gov/key_messages/LatestKeyMessage_1.png

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
303 AM EDT Sun Aug 30 2026

Valid 12Z Wed Sep 02 2026 - 12Z Sun Sep 06 2026


...Dangerous heat continues from the central and southern Plains
eastward to the Midwest, Mid-Atlantic, and Southeast through late
week...

...Pattern Overview...

A late summer heat wave will continue to bring scorching hot
temperatures to much of the south-central and southeastern U.S.
through mid to late week before a cold front brings some relief
next weekend. Meanwhile, a strong Pacific storm coupled with a
potential atmospheric river will bring notable rainfall to parts of
the Pacific Northwest Wednesday into Thursday. Downstream, heavy
rainfall and severe weather will be possible from the northern
Plains and the Upper Midwest to the Great Lakes, Mid-Atlantic, and
Northeast.


...Guidance/Predictability Assessment...

A fairly stable mid/upper level height pattern remains entrenched
across the CONUS through the medium range period, featuring
persistent and deep troughing across the West Coast, stout ridging
over the central and southeastern U.S., and increasing troughing
across the northeastern U.S. Overall, the latest available models
have a decent handle on the large scale pattern, but spatial and
temporal differences of individual waves (several impulses ejecting
eastward out of the western U.S. and over top the central U.S.
ridge) become more notable beyond Days 5 and 6. As a result, the
WPC forecast utilized a blend of deterministic dynamical and
machine learning guidance with a lean towards the ECMWF suite
through Day 5, then incorporated more weighting towards the
ensemble means of the EPS and GEFS (up to 50% of the blend) for
Days 6 and 7. This approach preserved the dominant large scale
pattern while mitigating the spread of smaller scale features.


...Weather/Hazards Highlights...

Intense late-summer heat with high temperatures well into the 90s
and 100s will persist from the central and southern Plains to the
Midwest, Mid-Atlantic, and Southeast through mid to late week as a
large and sprawling mid/upper ridge dominates the region. Some
relief is possible by next weekend as a cold front presses in from
the north (especially parts of the Ohio Valley and Mid-Atlantic),
but the core of the heat will likely continue from the
central/southern Plains to the Mid/Lower Mississippi Valley into
the second week of September. Well above normal temperatures
combined with high humidity and very warm overnight lows in the 70s
to near 80 will result in widespread areas of Major to Extreme
HeatRisk and a concern for heat-related illnesses. Please see WPC's
Key Messages for more details.

A Pacific storm descending out of the Gulf of Alaska coupled with
a weak to moderate atmospheric river will bring heavy rainfall to
parts of the Pacific Northwest Wednesday through Thursday with
lighter showers likely lingering into Friday. The heaviest rain
will mostly fall on Wednesday and be confined to coastal areas of
Washington and Oregon, along with the Cascades. The rainy, cloudy,
and generally unsettled weather associated with the storm itself
and persistent troughing along the West Coast will help to keep
temperatures on the cooler side of normal through the end of the
week and into next weekend.

Farther downstream, a frontal system and a series of mid-level
impulses tracking eastward along the northern periphery of the
elongated mid/upper ridge will interact with anomalous moisture and
instability to produce episodes of heavy rainfall and possible
severe weather from the northern Plains, Upper Midwest, Great
Lakes, and Northeast mid to late week. On Wednesday in particular,
there is a growing signal for severe thunderstorms and notable
rainfall across portions of the Interior Northeast and New England.
The rain could be heavy enough to produce isolated to scattered
instances of flash flooding, especially in urban, low-lying, and
poor drainage areas.

Elsewhere, after a brief reprieve, another surge of monsoonal
moisture is likely to bring a return to more numerous showers and
thunderstorms across parts of the Southwest and Intermountain West
by Thursday or Friday and possibly lasting through next weekend.
Meanwhile, underneath the strong ridge to the north, small scale
disturbances interacting with plenty of moisture will result in
daily chances for scattered to numerous thunderstorms across the
Deep South, Gulf Coast, and Florida through next weekend. Many of
these storms will contain heavy rainfall rates, leading to the
potential for localized flash flooding.


Miller


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, excessive rainfall outlook,
winter weather outlook probabilities, heat indices and Key Messages
are at:

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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1157 AM EDT Sun Aug 30 2026
Day 1
Valid 16Z Sun Aug 30 2026 - 12Z Mon Aug 31 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
SOUTHWEST AND FOUR CORNERS...

...The West...
An active monsoon day is still expected today as the region becomes
increasingly pinched between an anomalous mid-level ridge centered
over the MS VLY (500mb heights above the 97th percentile) and an
amplifying trough over the Eastern Pacific. The pinched flow
between these two features will manifest as intensifying 850-500mb
SW winds, which will draw impressive thermodynamics northward from
Baja, Mexico through the Central and Northern Rockies. The
accompanying IVT plume is progged to exceed the 99.5th percentile
according to NAEFS, driving PWs to above 1 inch as far north as the
Four Corners, overlapping MUCAPE of more than 1000 J/kg, with 500+
MUCAPE arcing all the way into southern WY. Additionally, embedded
shortwaves within this flow will help focus ascent which will
already be robust through the RRQ of a developing downstream jet
streak.

Together, this all suggests widespread thunderstorm activity today
from Arizona/New Mexico northward into Utah/Colorado, with some
lingering activity this morning even stretching into Wyoming
(although that region should wane by the aftn as drier air advects
eastward). Sufficient shear of 30-40 kts combined with widespread
cells will likely lead to clusters of storms either through
organization or mergers/collisions, through which rainfall rates
could top 1"/hr. Although 0-6km mean winds are likely to remain
progressive at 15-25 kts, parallel propagation vectors suggests
repeating storms to offset the rapid motions, suggesting the
inherited SLGT risk remains needed as FFG exceedance reaches
20-30%. The greatest risk will be across vulnerable soils and
terrain features, as well as urban areas this aftn/eve.

Tonight, the guidance indicates a stronger vort max may lift within
the flow and result in an impressive cluster of storms moving
northward through Arizona. This may produce a more widespread
excessive rainfall risk tonight that could impact areas that are
generally less vulnerable, but that development is uncertain enough
that no changes to the ERO are needed.

...Northern Plains into the Northeast...
An elongated frontal boundary aligned generally west to east from
North Dakota, through the Great Lakes, and into the northern Mid-
Atlantic will serve as a boundary for convective development today.
While convection will likely be scattered, and generally focused
where shortwaves tracking within the flow overlap the low-level
convergence, sufficient 0-6km bulk shear of 25-40 kts will help
organize storms into clusters, through which rainfall rates could
reach 1-2"/hr. While there is considerable uncertainty into the
placement of clusters today (as well as the overall coverage), any
storms that due develop will occur within favorable thermodynamics
to support heavy rain, with some training likely through aligned
Corfidi vectors/mean winds. For this reason the inherited MRGL risk
was modified only slightly account for new guidance.

...Southeast/Gulf Coast...
Slow moving and weak upper low drifting westward along the Central
Gulf Coast combined with a weakening TUTT positioned east of
Florida will combine to produce another active day of slow moving
thunderstorms from the Gulf Coast through the Southeast Coastal
Plain. A plume of impressive PWs exceeding 2 inches will remain
entrenched across this region, which when combined with ample
MUCAPE of 750-1500 J/kg and 14,000+ ft of warm cloud depth will
support 2+"/hr rain rates (20-40% chance). Although shear will be
minimal, suggesting primarily pulse type storms, very slow movement
(0-6km mean winds just 5 kts) and weak/anti-parallel Corfidi
vectors indicate a likelihood for some training or mergers to
enhance the rainfall potential. Although this region continues to
have high FFG, 0-40cm soil moisture has increased due to recent
heavy rain, making portions of the area slightly more vulnerable to
impacts. While the inherited MRGL risk remains, some adjustments
were made, mostly to expand it north along the eastern Carolinas,
along with other small cosmetic changes to account for the latest
HREF guidance.

Weiss


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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1157 AM EDT Sun Aug 30 2026
Day 2
Valid 12Z Mon Aug 31 2026 - 12Z Tue Sep 01 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE INTERMOUNTAIN WEST...

...Intermountain West...

A broad Slight Risk for excessive rainfall and elevated threat for
flash flooding remains in effect from Arizona northward to Utah
and Colorado. During this period a series of upper level
disturbances will be traveling through the deep longwave trough
over the Pacific Northwest. Meanwhile Pacific moisture will be
pooled over the region along a steady influx leading to anomalous
moisture of 2-3 sigma above normal. This environment will be
supportive of scattered showers and thunderstorms developing with
the monsoon. Much of this area is very prone to flash flooding
should heavy enough rains occur, which is likely given the history
of afternoon showers and storms in this same region under the same
pattern. The degree of moisture expected could lead to hourly rain
amounts to 2" wherever cells sit, merge, or train especially near
favored terrain, urbanized areas, box/slot canyons, arroyos/dry
washes, and burn scars being the most prone to flooding.

...Upper Midwest/Lower Great Lakes/Northeast...

Organized showers and thunderstorms expected thanks to upper-level
forcing for ascent supporting local enhancement. PW values above
the 90th climatological percentile will revolve around the northern
flank of the ridge and reach the Northeast by evening. The
environment will be supportive for at least localized areas of
excessive rainfall across much of New York, northern Pennsylvania,
and as far east as the I-95 corridor from northern New Jersey to
southern New England. A Marginal Risk remains in effect from the
Minnesota Arrowhead to portions of the Northeast.

...Eastern Gulf Coast...

The Marginal Risk for excessive rainfall remains in effect. Shortwave
energy moving westward underneath the closed 500 mb High will be
the focus for potentially more numerous (organized) convective
clusters during peak diurnal heating, especially when interacting
with the Atlantic and Gulf sea breezes.

Campbell/Mullinax/Wegman


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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1157 AM EDT Sun Aug 30 2026
Day 3
Valid 12Z Tue Sep 01 2026 - 12Z Wed Sep 02 2026

...A MARGINAL RISK OF EXCESSIVE RAINFALL EXISTS ACROSS PARTS OF THE
SOUTHWEST & NORTHERN TIER OF THE COUNTRY...

...Southwest...

Above average PW values expected to return to portions of Arizona
as the upper level trough strengthens over the West during this
period. Hourly rain amounts up to 2" are possible given the
moisture and instability expected, which would be most problematic
in burn scars, slot/box canyons, dry washes/arroyos, and urban
areas. Therefore a Marginal Risk was maintained for portions of
Arizona, New Mexico, West Texas and southeast Colorado.

...Northern Plains, Southern New England and northern Mid-
Atlantic...

A shortwave passing within the flow will trigger scattered
convection across the northern tier states capable of producing
hourly rates up to 2 inches/hour should cell training and mergers
occur. Through this period PW values will be near 1.25-1.75 inches
as Gulf moisture advects northward within the low-level flow.

A moist west to west-northwest low-level flow imports precipitable
water values of 1.5-2" across the region on the northeast side of a
warm core ridge as upper level disturbances near a front lead to
heavy rainfall concerns. Hourly rain amounts to 2.5" with local
totals to 5" are possible given the ingredients expected. A
Marginal Risk spans from eastern Montana/Wyoming to southern New
England. There may be a need for an upgrade in the future particularly
across portions of the Megalopolis between Philadelphia and New
York City should guidance trend higher.

Campbell/Roth

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

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
154 PM EDT Wed May 6 2026

Valid 00Z Thu May 07 2026 - 00Z Sun May 10 2026

...WPC Winter Weather Desk no longer routinely staffed until
late September, 2026...

Pending any significant winter weather, the WPC Winter Weather Desk
will not be staffed through the summer. The desk will resume
continuous staffing starting in the fall.

The WPC winter products will continue to be produced, however, and
all products except the heavy snow discussion (HSD) will be
available. This includes the Winter Storm Outlook (WSO), Winter
Storm Severity Index (WSSI), and Probabilistic Winter Precipitation
Forecasts (PWPF).


WPC

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
303 AM EDT Sun Aug 30 2026

Valid 12Z Wed Sep 02 2026 - 12Z Sun Sep 06 2026


...Dangerous heat continues from the central and southern Plains
eastward to the Midwest, Mid-Atlantic, and Southeast through late
week...

...Pattern Overview...

A late summer heat wave will continue to bring scorching hot
temperatures to much of the south-central and southeastern U.S.
through mid to late week before a cold front brings some relief
next weekend. Meanwhile, a strong Pacific storm coupled with a
potential atmospheric river will bring notable rainfall to parts of
the Pacific Northwest Wednesday into Thursday. Downstream, heavy
rainfall and severe weather will be possible from the northern
Plains and the Upper Midwest to the Great Lakes, Mid-Atlantic, and
Northeast.


...Guidance/Predictability Assessment...

A fairly stable mid/upper level height pattern remains entrenched
across the CONUS through the medium range period, featuring
persistent and deep troughing across the West Coast, stout ridging
over the central and southeastern U.S., and increasing troughing
across the northeastern U.S. Overall, the latest available models
have a decent handle on the large scale pattern, but spatial and
temporal differences of individual waves (several impulses ejecting
eastward out of the western U.S. and over top the central U.S.
ridge) become more notable beyond Days 5 and 6. As a result, the
WPC forecast utilized a blend of deterministic dynamical and
machine learning guidance with a lean towards the ECMWF suite
through Day 5, then incorporated more weighting towards the
ensemble means of the EPS and GEFS (up to 50% of the blend) for
Days 6 and 7. This approach preserved the dominant large scale
pattern while mitigating the spread of smaller scale features.


...Weather/Hazards Highlights...

Intense late-summer heat with high temperatures well into the 90s
and 100s will persist from the central and southern Plains to the
Midwest, Mid-Atlantic, and Southeast through mid to late week as a
large and sprawling mid/upper ridge dominates the region. Some
relief is possible by next weekend as a cold front presses in from
the north (especially parts of the Ohio Valley and Mid-Atlantic),
but the core of the heat will likely continue from the
central/southern Plains to the Mid/Lower Mississippi Valley into
the second week of September. Well above normal temperatures
combined with high humidity and very warm overnight lows in the 70s
to near 80 will result in widespread areas of Major to Extreme
HeatRisk and a concern for heat-related illnesses. Please see WPC's
Key Messages for more details.

A Pacific storm descending out of the Gulf of Alaska coupled with
a weak to moderate atmospheric river will bring heavy rainfall to
parts of the Pacific Northwest Wednesday through Thursday with
lighter showers likely lingering into Friday. The heaviest rain
will mostly fall on Wednesday and be confined to coastal areas of
Washington and Oregon, along with the Cascades. The rainy, cloudy,
and generally unsettled weather associated with the storm itself
and persistent troughing along the West Coast will help to keep
temperatures on the cooler side of normal through the end of the
week and into next weekend.

Farther downstream, a frontal system and a series of mid-level
impulses tracking eastward along the northern periphery of the
elongated mid/upper ridge will interact with anomalous moisture and
instability to produce episodes of heavy rainfall and possible
severe weather from the northern Plains, Upper Midwest, Great
Lakes, and Northeast mid to late week. On Wednesday in particular,
there is a growing signal for severe thunderstorms and notable
rainfall across portions of the Interior Northeast and New England.
The rain could be heavy enough to produce isolated to scattered
instances of flash flooding, especially in urban, low-lying, and
poor drainage areas.

Elsewhere, after a brief reprieve, another surge of monsoonal
moisture is likely to bring a return to more numerous showers and
thunderstorms across parts of the Southwest and Intermountain West
by Thursday or Friday and possibly lasting through next weekend.
Meanwhile, underneath the strong ridge to the north, small scale
disturbances interacting with plenty of moisture will result in
daily chances for scattered to numerous thunderstorms across the
Deep South, Gulf Coast, and Florida through next weekend. Many of
these storms will contain heavy rainfall rates, leading to the
potential for localized flash flooding.


Miller


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, excessive rainfall outlook,
winter weather outlook probabilities, heat indices and Key Messages
are at:

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