847
FXUS02 KWBC 301900
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
300 PM EDT Wed Jul 30 2025

Valid 12Z Sat Aug 02 2025 - 12Z Wed Aug 06 2025

...Heavy rain and flash flooding potential for the Southeast into
the weekend especially for areas closer to the coast...

...Overview...

A rather broad and deep upper trough is forecast to settle into the
eastern U.S. by this weekend as the western U.S. upper ridge
attempts to edge east toward the High Plains by the middle of next
week. Disturbances rounding the eastern edge of the ridge should
trigger rounds of thunderstorms and possibly heavy rain across
portions of the central/southern Plains this weekend and across the
northern Plains this weekend and toward the middle of next week.
Meanwhile, heavy rain threat across portions of the Southeast this
weekend should gradually spread northward up the eastern U.S.
toward the middle of next week with a more localized heavy rain
threat.


...Guidance/Predictability Assessment...

Model guidance remains in relatively good agreement through the
medium-range period. The WPC medium-range forecasts lean toward the
ECMWF cluster, with QPF farther south into the southern Plains for
this weekend.


...Weather/Hazards Highlights...

A rather strong cold front for early August is forecast to push
into the Southeast with the arrival of a positively-tilted upper
trough into the East Coast this weekend. High moisture content and
instability along and ahead of the front interacting with the right
entrance region of the upper jet will promote heavy to excessive
rainfall in thunderstorms that could cause localized flash
flooding. High rain rates in widespread thunderstorms should lead
to a flash flooding risk -- a Slight Risk remains in place in the
Day 4/Saturday ERO for southern Georgia into southern South
Carolina. The front stretching west across the Gulf Coast states in
a moist and unstable environment could promote scattered diurnal
thunderstorms into Saturday, and a Marginal Risk is in place in the
Day 4 ERO due to high rain rates that may overcome the high Flash
Flood Guidance and/or fall atop urban areas. By Sunday, the front
will push south a bit more and clear the central Gulf Coast from
seeing much rain, but thunderstorm chances linger from the Florida
Panhandle northward across parts of the Southeast. A Marginal Risk
is delineated for the Day 5/Sunday ERO for this activity. The front
is forecast to become nearly stationary from along the Gulf Coast
to just off the Southeast U.S. by early next week, which should
maintain scattered convection across the Southeast.

Farther west, shortwaves rounding the eastern edge of the upper
ridge in the western U.S. is forecast to interact with the same
front that bends back across the Great Plains, where rounds of
rain and thunderstorms are likely with possibly multiple MCSs. Above
normal moisture and instability should support high rain rates at
times, with some areas possibly seeing repeated rounds of storms
as the front begins to lift as a warm front. Broad Marginal Risks
cover much of the Plains on Day 4/Saturday, as well as back into
the northern Rockies/High Plains near the back end of the front as
much higher than average instability (per the Extreme Forecast
Index) lingers before lessening early next week. No Slight Risk
areas are noted at this time due to uncertainties in rainfall
placement and the localized/isolated nature of the thunderstorm
complexes. Also looped the Marginal Risk around southeastern New
Mexico where some monsoonal moisture could linger Saturday and
create isolated flooding issues over sensitive burn scars. By
Sunday the elongated front is forecast to move a bit east, with the
thunderstorm chances moving with it. A Marginal Risk encompasses
the Plains into parts of the Mississippi Valley for the Day
5/Sunday ERO for likely additional rounds of MCSs. The details are
uncertain at this point, but there is a general trend for the
Ohio/Tennessee Valley into the East to see increasing rain and
thunderstorms by Monday-Tuesday as the front continues moving east.
Meanwhile the Southwest should dry out around Sunday, but there
may be a bit of a monsoonal moisture return by Monday-Tuesday over
Arizona/New Mexico amid the relatively dry monsoon season
especially across Utah/Arizona.

The cold front pushing through the Southeast will continue to
lessen the scope of dangerous heat into Saturday. Florida can
expect some heat to linger though, where HeatRisk remains in the
Major (level 3/4) and Extreme (level 4/4) categories, as
temperatures reach well into the 90s with higher heat indices
(nearing 110F), while morning lows well into the 70s and nearing 80
will not provide much relief. But thunderstorms are forecast to
increase in Florida early next week and limit extreme heat. Behind
the front, cooler than average temperatures (especially highs) are
likely. Into the weekend, highs of 5-10 degrees below normal are
forecast in the East, while much of the Plains can expect highs of
10-15 degrees below average, with highs in the 70s as far south as
parts of Kansas and Missouri. Temperatures should gradually warm
across those areas into early next week. Meanwhile the Northwest
can expect below normal temperatures as rounds of troughing move
through. But farther south, the Southwest can expect seasonable
heat (near to slightly above average), with the lower desert areas
seeing temperatures 105-110+ degrees.


Kong/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





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