362
FXUS02 KWBC 241943
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
243 PM EST Mon Nov 24 2025

Valid 12Z Thu Nov 27 2025 - 12Z Mon Dec 01 2025

...Overview...

A strong low pressure system crossing Quebec will have a trailing
cold front that will exit the East Coast by Thanksgiving morning.
Much colder conditions will arrive for the eastern U.S. by the end
of the week, with a sprawling Canadian surface high enveloping
areas from the northern Plains to the Southeast states, and heavy
lake effect snows from Michigan to New York state. Then, an upper
level trough will amplify across the western U.S. going into the
weekend, which should spur surface cyclogenesis across the western
High Plains and bring potentially heavy rainfall ahead of it
especially over the Lower Mississippi Valley. This trough should
also cause very cold temperatures in the northern/central High
Plains.


...Guidance/Predictability Assessment...

There is good overall synoptic scale agreement across the
contiguous U.S. to begin the forecast period Thursday, with a
general model blend used for fronts and pressures. Similar to the
past few days, the QPF for the Great Lakes region was raised
slightly above NBM, since the NBM is probably underdone with lake
effect snow amounts Thursday through late Friday.

However, model differences increase quickly across the western
half of the nation late week into the weekend. Initial shortwave
energy moving through the Pacific Northwest Thursday is reasonably
agreeable, but how strong it remains as it tracks east along the
northern tier will lead to sensible weather differences like the
potential for snow. Then another round of energy spilling south
from Alaska Friday-Saturday is particularly strong in GFS (and AI-
GFS) runs compared to the non-NCEP guidance. This results in a
stronger/farther west upper low separating into the southern stream
atop California/Nevada by Sunday compared to a phased solution in
other guidance. The 00Z ECMWF being phased was a marked change from
its previous couple of runs that showed a southern stream closed
low, but the new 12Z EC (available after forecast generation time)
is pretty similar to its 00Z run (though does end up with a weak
closed low by next Monday). The 00Z CMC was somewhat of a middle
ground, and liked the EC-AIFS. Overall for forecast blending
purposes, moved quickly toward an ensemble-mean heavy blend for the
latter half of the period.


...Weather/Hazards Highlights...

Moderate to heavy lake effect snow is likely to persist
Thanksgiving Day into late Friday from Michigan to western New
York, with some areas potentially getting 6-12+ inches of snow
accumulation. Meanwhile a weakening atmospheric river will lead to
lingering rain and snow across the Pacific Northwest and northern
Rockies going into Thanksgiving. Rain totals should be below
thresholds for any excessive rainfall areas, while heavy snow
should be generally limited to the higher peaks. Into Friday, rain
could begin to emerge over eastern portions of the Plains into the
Mississippi Valley, but mainly light to moderate in intensity
initially, so continue to hold off on excessive rainfall areas for
Day 5/Friday as well. Looking ahead to the weekend, depending on
the level of moisture return ahead of the developing storm system
over the Plains, showers and thunderstorms are expected to increase
in coverage and intensity from eastern Texas across the Lower
Mississippi Valley into to the Mid-South. In addition, moisture
over-running the arctic airmass over the northern Plains could lead
to more widespread snowfall chances across the north-central
Plains into the Midwest Friday into Saturday, possibly spreading
into the Interior Northeast Sunday. Another round of snow is
possible in the northern/central High Plains on Saturday and
spreading east once again on Sunday. Meanwhile higher elevation
areas like the central Rockies could receive heavy snow. The
details are all highly dependent on uncertain model guidance
though, so continue to check updated forecasts.

In terms of temperatures, a strong cold front heralds the arrival
of a December-like airmass to the eastern U.S. for the end of the
week, dropping temperatures about 20 degrees for many areas by
Friday compared to the mild weather midweek. Temperatures in the
East will gradually raise closer to average into early next week.
But meanwhile a much colder arctic airmass then oozes southward
across Montana and much of the Dakotas by the weekend, with some
subzero overnight lows within the realm of possibility near the
Canadian border, along with highs in the teens.


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


$$