676
FXUS02 KWBC 251942
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
342 PM EDT Tue Aug 25 2026

Valid 12Z Fri Aug 28 2026 - 12Z Tue Sep 01 2026


...Hazardous Heat from the Desert Southwest and far south Texas to
reposition across the South-Central U.S. and Mid-South this
weekend into next week...


...Overview...

Dangerous late summer heat will persist across the Desert
Southwest and far south Texas before shifting back into the
central/southern Plains and Mid-South this weekend into next week.
Surges of monsoonal moisture will support daily showers and
thunderstorms over portions of the Southwest and Intermountain
West/Rockies with localized flash flooding possible. Meanwhile,
several frontal systems will push across the northern tier of the
CONUS, bringing several chances for organized thunderstorms and
possible severe weather. Lingering frontal boundaries across the
southern Mid- Atlantic and Southeast will also lead to additional
risks for heavy rain producing storms.

...Guidance/Predictability Assessment...

Guidance remains in overall good agreement on the synoptic weather
pattern, though uncertainty with the timing of systems working
through the Northwest to the U.S. northern tier remains. Given
continued larger scale agreement, favor a composite model/ensemble
mean/machine learning guidance solution that seems to provide a
good general forecast and threat messaging baseline in line with
continuity. The blend process tends to mute/mitigate embedded
smaller scale system differences as consistent with individual
predictability, but maintains main focusing features.

...Weather/Hazards Highlights...

Under the influence of the upper high/ridge this week, daily
maximum temperatures across the far southern Plains / southern
Texas will continue to rise into the 90s and 100s with oppressive
heat indices. Record-breaking warm overnight temperatures across
the southern tier will further limit recovery from the heat,
resulting in widespread Major to Extreme HeatRisk that may cause
heat related illnesses. As the upper ridge flattens into this
weekend and shifts eastward into early next week, hazardous heat
will refocus over the southern Plains and steadily expand north
across the south-central U.S and Mid-Lower Mississippi Valley/Mid-
South along with the main closed high. For the Desert Southwest,
daily max temperatures are forecast to soar into the 110s, which
will keep heat concerns in place. Please see WPC`s Key Messages for
more extreme heat details.

Monsoonal moisture streaming northward on the western periphery of
the upper ridge and ahead of Northwest U.S. upper troughing will
continue to fuel scattered, diurnally driven convection from the
Southwest and Intermountain West to the Rockies. Individual cells
may lead to isolated instances of flash flooding for sensitive
locations such as burn scars, favored terrain like slot canyons,
and urban areas. Marginal Risk areas cover portions of these broad
areas on the WPC Day 4/Friday and Day 5/Saturday Excessive Rainfall
Outlooks (EROs).

Shortwaves rounding the top of the ridge and pivoting into the
downstream mean upper trough while interacting with wavy frontal
systems will periodically trigger episodes of heavy rain and strong
to severe thunderstorms from the Plains to the Upper Midwest late
week into the weekend. Marginal Risk ERO areas were maintained for
Friday and Saturday. Meanwhile downstream, Marginal Risk ERO areas
also highlight a protracted threat for repeated rounds of locally
heavy rainfall across the southern Mid-Atlantic and especially the
coastal Southeast as wavy frontal boundaries approach and
ultimately stall over these moist regions.


Miller/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, 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

$$