333
FXUS02 KWNH 210751
PREEPD

Preliminary Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
250 AM EST Fri Nov 21 2025

Valid 12Z Mon Nov 24 2025 - 12Z Fri Nov 28 2025


***Heavy Rain Threat from the ArkLaTex to the Midsouth on Monday***

...Overview...

A potent shortwave crossing the southern Plains Monday will
sustain a surface low, with plenty of deep moisture surging north
to support widespread heavy showers and thunderstorms. This
shortwave should weaken through Tuesday as the storm system over
the northern Plains and Upper Midwest becomes the dominant weather
feature by the middle of the week. This will usher in a much colder
Canadian surface high behind a cold front tracking towards the East
Coast around Thanksgiving. Meanwhile, periods of rain and mountain
snow are likely for the Pacific Northwest with an active storm
track over the northeast Pacific.

...Guidance/Predictability Assessment...

The latest 00Z model guidance suite features decent overall
synoptic scale agreement for the beginning of the work week, with a
general deterministic model blend working out well as a starting
point. Going into the middle of the week, recent runs of the GFS
have been slower with the progression of the main cold front across
the east-central U.S. when compared to the model consensus and
AIFS guidance, so less GFS was used for Wednesday and beyond to
account for this. The GEFS is closer to the consensus, but still
slower than the CMC/ECMWF/ECENS guidance. The CMC is to the north
of the consensus with the main occluded low over Quebec, but the
placement of the cold front is close to the WPC blend preference.
By the end of the forecast period Friday, there is good overall
agreement for an expansive surface high to settle in across the
east-central U.S. with broad cyclonic flow aloft, and more
mesoscale differences across the western U.S.

In terms of changes, the surface low across the north-central U.S.
has trended southeast compared to the previous forecast for early
in the week, and the trailing cold front is trending faster over
the southern Plains and the Midwest states, and QPF is a little
higher over the Pacific Northwest over the Day 4-7 period. The
ensemble means were increased to about half by next Friday.

...Weather/Hazards Highlights...

Widespread moderate to heavy rainfall, mainly in the form of
repeating rounds of thunderstorms, is likely from northeastern
Texas to the greater Memphis metro area. This region will be in the
warm and humid sector of a developing storm system. In terms of
the excessive rainfall outlooks, the Day 4/Monday period will be
quite similar to the previous Day 5 outlook, thus maintaining the
Slight Risk area. For the new Day 5/Tuesday outlook, a Marginal
Risk will be valid from Mississippi to the southern Appalachians
where the best model signal exists for organized showers and
storms, albeit some weakening is expected compared to Sunday and
Monday. Although no risk areas are currently depicted for western
Oregon and Washington, there is a good chance a Marginal Risk could
eventually be needed for the middle of the week as a potential
atmospheric river sets up and advects copious moisture towards the
coast. Cold air advection combined with the deformation zone on the
western side of the Upper Midwest storm system will likely result
in moderate snow from the Dakotas to northern Minnesota.

Temperatures are expected to be mild for this time of year from the
Gulf Coast to the Great Lakes region ahead of the cold front, with
highs running 5-15+ degrees above late November averages through
Tuesday. This mild airmass then reaches the East Coast by
Wednesday with highs well into the 50s and 60s for many areas,
followed by a return to slightly below average conditions to close
out the week. There will be enough cold air advection across the
Great Lakes to support lake effect snows across northern Michigan,
and also from northeast Ohio to central New York for Thanksgiving
and into early Friday. A modest warm-up is likely for the
northwestern U.S. towards Thanksgiving as the early colder airmass
modifies and flow from the Pacific moves into the region.

Hamrick


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







$$