932
FXUS02 KWBC 300754
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
254 AM EST Sun Nov 30 2025

Valid 12Z Wed Dec 03 2025 - 12Z Sun Dec 07 2025

...Heavy rain potential returns late week for parts of the central
Gulf Coast...


...Overview...

Next week remains cold and active over much of the CONUS because
of a sprawling deep and cold low that remains more or less settled
over Hudson Bay through much of the period. Some ridging gets into
the Pacific Northwest later in the week, but otherwise cyclonic
flow around this vortex rules the pattern. A shortwave, responsible
for a winter storm across the Northeast during the end of the
short range period, will be exiting the East Coast by Wednesday.
The next system will be dropping through the West at this time,
eventually progressing eastward through the Southern Plains by next
weekend. Heavy rain chances are likely downstream along the Gulf
Coast and Southeast through this latter half of this week. There is
some signal, but a lot of uncertainty, for wintry precipitation on
the northern side of the precipitation shield. Weak northern
stream shortwaves will maintain lake effect snows across the Great
Lakes most days.


...Guidance/Predictability Assessment...

The main forecast concern this period remains with the Western to
Southern U.S. shortwave. Models continue to trend faster and more
progressive with this system, but still some uncertainty in how
much southern stream energy separates from this system over the
Southwest and northern Mexico. The ECMWF for a few days now had
been an outlier in showing a deep cutoff upper low off the
California coast, but the past two runs (the 12z run yesterday, and
tonight`s 00z run) have trended more towards the consensus. In
general now, much of the guidance shows good agreement on the large
scale evolution of this system, but plenty of uncertainty in the
details which are crucial to sensible weather and heavy rainfall
impacts downstream across the Gulf Coast and Southeast. Some energy
should progress into the Southeast/East with signal for a weak
area of low pressure developing along the Gulf Coast and eventually
off the East Coast. The impacts of this system remain wildly
uncertain.

Otherwise, a couple of northern stream shortwaves will progress
across the Northern Tier and Great Lakes through the period, with
increasing uncertainty mid to late period on the depth and timing
of these systems.

The WPC forecast tonight used a general model compromise of the
deterministic solutions for Days 3-5. Increased weighting of the
ensemble means to 60 percent of the blend by Day 7 to account for
the increasing uncertainty.


...Weather/Hazards Highlights...

With the departing Nor`Easter by early Wednesday, much of the
country should be generally quiet on Wednesday with the exception
of some light lake effect snows across the Great Lakes. Rain and
mountain snows should start to develop across parts of the
Southwest by Wednesday with the next system, with some light
rainfall emerging downstream over the western and central Gulf
Coast. As southerly flow ahead of this system strengthens into
Thursday, heavy rainfall chances increase along the Gulf Coast. Did
introduce a marginal risk in the Day 5/Thursday ERO given a signal
for high QPF amounts, but much of this area has been relatively
dry and instability outside of the immediate coasts will be
lacking. Heavy Rain will spread into the Southeast by Friday and
Saturday along a slow moving frontal boundary. There are wintry
weather chances on the north side of a possible area of low
pressure from the Appalachians into the Mid-Atlantic, but a lot of
uncertainty in what sort of impacts this may bring.

Elsewhere, impulses and shortwave trough crossings should continue
to bring at least periodic lake effect snows to typical snow belts
off the Great Lakes Wednesday through the weekend. A couple weak
shortwaves into the Pacific Northwest will also increase
precipitation chances by later in the week.

Widespread and persistent below average temperatures can be
expected to sweep across the Lower 48 next week under the sprawling
low vortex centered over Hudson Bay. Expect high temperatures of
15 to 20 degrees below normal to spread from the Rockies and
northern Plains Wednesday through the Midwest to southern Plains
Thursday, and the Northeast on Friday. Wind chills look to bottom
out around -20F in the Upper Midwest Thursday morning. Temperature
relief comes in the form of an upper ridge extending into the
Northwest Thursday, though the progression of the low over the
Southwest should determine how far inland the warmer air pushes. As
of now the western U.S. should return to above normal temperatures
by this weekend, with another push of well below normal
temperatures into the Northern Plains next Sunday.


Santorelli


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










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