Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
352 PM EDT Tue Oct 21 2025

Valid 12Z Fri Oct 24 2025 - 12Z Tue Oct 28 2025

...Heavy rain could cause flash flooding in the south-central U.S.
Friday-Saturday...

...Atmospheric river could cause heavy rain, mountain snow, and
gusty winds in the Pacific Northwest/northern California...

...Overview...

Late this week, a southern stream shortwave crossing from the Four
Corners to the central/southern Plains will support a surface low
and frontal system with plenty of moisture across the south-central
Plains and Lower Mississippi Valley, with numerous showers and
storms that could lead to flash flooding. Meanwhile out West, a
pattern change will take place going into the weekend as an upper
trough amplifies over the region and leads to colder weather. An
atmospheric river of moderate strength should yield coastal/low
elevation rain with isolated flooding concerns, as well as
widespread mountain snow. This same trough is expected to spur
surface cyclogenesis over the central/northern Plains by early next
week with additional showers and storms expected.


...Guidance/Predictability Assessment...

Model guidance is in reasonably good agreement through the early-
mid part of the forecast period. The southern stream upper and
surface lows traversing the Four Corners region into the south-
central U.S. by this weekend could be handled by a multi-model
blend. The same was true for eastern Pacific/West troughing and an
initial trough lifting out of the East. The WPC forecast used a
blend of the 06Z GFS and 00Z ECMWF/UKMET/CMC through Days 3-4. The
newer 12Z model guidance seems consistent as well.

By early next week, there are increasing model differences with
the details of the pattern. In the Great Lakes to East, another
shortwave may come through and dig another round of troughing,
especially per non-NCEP guidance. The GFS runs are farther east
with trough development. Likely even more impactful to sensible
weather is the evolution of the western trough and energies within
it. The bulk of guidance has troughing shifting into the north-
central U.S. early next week. But by Tuesday, the 00Z ECMWF split
energy well south into the southern Plains rather than consensus of
an easterly/southeasterly track of troughing. With other dynamical
and AI/ML models (even EC-based ones) not showing anything like
the 00Z EC, considered this an outlier and leaned away from it.
Fortunately the 12Z ECMWF came in closer to consensus. It remains
uncertain if a closed upper low will develop within this pattern by
around Tuesday. The WPC forecast quickly ramped up the proportion
of ensemble means in the forecast as the medium range period
progressed, while eliminating the 00Z ECMWF. In terms of QPF, like
the previous forecast, decreased the coverage of high QPF over the
Ark-La-Tex compared to the NBM.


...Weather/Hazards Highlights...

The surface low pressure system that is forecast to evolve over
the southern Plains later this week, along with strong warm air
advection and increasing instability, will fuel the development of
widespread showers and thunderstorms. On Friday, much of Oklahoma
into the Ozarks could see ample rain that may be long lasting.
Farther south into Texas, convection is likely to spark into Friday
night, with potentially extreme rainfall rates over 2-3 inches per
hour. Thus have both areas blanketed with a Slight Risk of
excessive rainfall for scattered instances of flash flooding. MCSs
continue into Saturday and push east across southeast Texas and
southwest Louisiana. Global models show 4-8 inches of QPF
accumulating Saturday and Saturday night, so a Slight Risk of
excessive rainfall has been introduced for this region for the Day
5 ERO. The Storm Prediction Center will continue to monitor the
possible severe threat with this system. Some rain and storms
should move across the central Gulf Coast and Southeast into
Sunday.

In the West, upper troughing will direct an atmospheric river at
coastal areas and inland late this week into the weekend. Rain
along the coast and in lower elevations could lead to isolated
flooding in the Pacific Northwest Friday and extending south into
northern California on Saturday as the AR moves south, so Marginal
Risks are in place in the Days 4/5 EROs. Gusty winds and
significant waves could also be impactful in the Pacific Northwest
with this system. Snow levels come down Friday night and through
the weekend, yielding widespread snow through the Cascades and
higher terrain of the Intermountain West and the central/northern
Rockies as multiple shortwaves pass through the amplifying upper
trough. Accumulation looks to be well over a foot in the higher
terrain, likely over 2 feet in at least the Cascades. Then, a new
surface low is likely to develop by Monday across the
central/northern Plains as a potent shortwave ejects eastward from
the Rockies, supporting an increase in showers/storms and gusty
winds from the Dakotas to Missouri. Elsewhere across the nation,
lake enhanced showers from Michigan to Upstate New Year will be
prevalent as colder air aloft moves across the warmer lake waters
late this week, but likely too warm for any snow this time.

Much above normal temperatures by 10 to 20 degrees are likely for
highs in the north-central U.S. through the weekend, with actual
values well into the 60s and 70s. Periods of warmer than average
temperatures into the 80s are also likely across the southern
Plains, though with periodic cold fronts moving across much of the
region cooling most areas at times, other than southern Texas that
could remain in the 90s. Meanwhile much colder weather makes its
arrival for the West Coast and into the Intermountain West by the
weekend as the upper trough builds in along with widespread cloud
cover. Temperatures should be near to slightly below average for
the East, with a frost/freeze threat in the Ohio Valley into Friday
morning.


Tate/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