384
FXUS02 KWBC 271958
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
258 PM EST Thu Nov 27 2025

Valid 12Z Sun Nov 30 2025 - 12Z Thu Dec 04 2025


...Storm system brings enhanced rainfall to the Southeast Monday-
Tuesday with possible wintry weather to its north, especially into
the Interior Northeast...


...Overview...

A few impactful shortwaves are forecast over the lower 48 into next
week as they round the base of a deep upper low/trough anchored
over the Hudson Bay. First, a shortwave lifting out of the Great
Lakes region along with a surface low could provide lingering snow
there into Sunday. The next shortwave is forecast to dive through
the Four Corners and cause some central Rockies to Kansas snow into
early next week. Then it should track through the southern tier and
spread enhanced rain across the Gulf Coast and Southeast Monday-
Tuesday, along with possible snow and ice on the northern side of
the precipitation shield, near the Middle Mississippi to Ohio
Valley. As the trough axis and possible surface low tracks into the
western Atlantic, snow chances could increase for the Appalachians
to Northeast Tuesday and Tuesday night, while plenty of uncertainty
remains in the details. Then additional energy aloft is forecast to
dive through the West and cause some precipitation there. The
rounds of shortwaves will also keep temperatures chilly in the
central U.S. in particular.


...Guidance/Predictability Assessment...

Model guidance shows reasonable agreement on the larger scale
pattern described above, but there are a few smaller scale model
differences that nevertheless could impact sensible weather. First,
ECMWF and the EC ensemble members were pretty uniformly slower
than the GFS/CMC suites with the low track into the Great Lakes
early Sunday. There was a minor convergence in the 12Z models
showing the EC slightly faster and the GFS/GEFS mean slightly
slower.

Then the trough upstream shows general agreement in its depth
going into the first half of next week, but with minor spread in
its timing and width. At the surface, low pressure is likely to
reform along a stalled Gulf front that tracks east then northward,
but its exact track of being more suppressed or less suppressed
will affect precipitation amounts and types. No particular outliers
are seen at this time, so tried to reach a middle ground solution
with a multi-model/ensemble blend.

The next trough coming into the West does show somewhat more
synoptic scale model differences, with uncertainty of how much
energy could pull off into the southern stream and potentially form
a closed low over southern California or so. The 00Z GFS was
particularly slow and deep with a closed low, but the 06Z and 12Z
GFS look more in line with other guidance. Showing some stream
separation seemed reasonable, but without completely separating
from the broader trough, which is also consistent with the EC-AIFS.

The WPC forecast was composed of a multi-model blend early, with
increasing proportions of the GEFS and EC ensemble means, reaching
just under half before the end of the period.


...Weather/Hazards Highlights...

The main weather headlines during the medium range period will
likely come from two low pressure systems. A deepening low pressure
system will likely track across the Great Lakes on Sunday, causing
lingering snow that could continue to impact Thanksgiving weekend
travel, so see WPC`s Key Messages for further information. Snow is
forecast to spread into the Interior Northeast by Sunday, but will
generally result in less snow as the low track moves quickly across
southeastern Canada.

An area of snow associated with the next shortwave digging across
the western U.S. should be reaching the Great Basin on Sunday
followed by the central Rockies on Monday. How much this shortwave
interacts with the tail end of the previous front extending
near/along the Gulf Coast could determine how far north a low
pressure wave will eventually track and how much Gulf moisture will
be drawn into the eastern U.S. through midweek next week. It
appears that the central Gulf Coast region will be the prime
location of seeing heavy rain from this developing system, although
the speed of motion of this system will probably limit the total
rainfall amounts. With this in mind, will maintain a Marginal Risk
in the Day 5/Monday ERO across the central Gulf Coast into portions
of the Southeast for isolated flash flooding. Meanwhile, the
northern extent of this developing system will likely have wintry
weather concerns. Generally, some light snow is possible across
Kansas early in the week, possibly spreading across the Middle
Mississippi Valley into much of the Ohio Valley, with high
uncertainty in the details. Light freezing rain is also a concern,
with areas of Arkansas and then into the southern/central
Appalachians showing the highest possibility for that. Then as the
low tracks into the western Atlantic by Tuesday, snow could occur
across the Appalachians to Mid-Atlantic and Northeast. In the
current forecasts, the highest snow probabilities are in interior
areas of the Northeast west of I-95, with potential for rain closer
to the coast (possible initial snow changing to rain). But all of
this is rather uncertain as small changes to the low track could
yield large differences in precipitation amounts and type.

Following a round of snow on Sunday in the central Rockies,
additional energy moving across the Northwest should support lower
elevation rain and higher elevation snow in the Pacific Northwest
to Intermountain West and Rockies by Tuesday-Wednesday.

Widespread and persistent below average temperatures for this time
of year can be expected for the central U.S. in particular through
most of the forecast period as arctic air spills south. The
coldest anomalies for both highs and lows (around 15-25 degrees
below normal) are forecast over the Plains and Mississippi Valley
Sunday, and into the Midwest Monday-Tuesday given the snow cover
there. Lows are likely to be below 0F in the northern Plains to
Minnesota Sunday-Monday, with highs in the teens. Rounds of cooler
than average temperatures are likely in the East as well, but with
anomalies closer to 5-15 degrees below normal, aside from Florida
that should be warmer than average by a few degrees. The Rockies
westward should be with a few degrees of normal for most of the
period.


Tate/Kong


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



$$