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FXUS02 KWBC 281959
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
259 PM EST Fri Nov 28 2025

Valid 12Z Mon Dec 01 2025 - 12Z Fri Dec 05 2025


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


...Overview...

The medium range period looks fairly active over the lower 48 next
week with a couple of impactful shortwaves rounding the base of an
upper low anchored over the Hudson Bay. By Monday, a shortwave
will be coming through the Four Corners region into the southern
tier, as a surface low deepens along a front near the Gulf Coast.
This shortwave and surface low will lift up the East Coast
spreading possibly heavy precipitation from the South into the East
early to mid next week, with some snow and ice possible on the
northern side of the precipitation shield. The best chance of snow
will be across interior New England. The next shortwave will dive
into the West Tuesday-Wednesday, with plenty of uncertainty on its
evolution later in the week.


...Guidance/Predictability Assessment...

The models continue to have a good handle on the larger scale
pattern for early-mid next week, but plenty of uncertainty in the
details that could have impacts on sensible weather. Models
continue to show some spread with the timing and track of the first
shortwave in the South and East and the resultant surface low. The
00Z GFS seemed to be a fast outlier with this system while the 00Z
UKMET was slower than consensus. The 06Z GFS and 00Z ECMWF and CMC
seemed like a good compromise at forecast generation time, and the
newer 12Z models seem generally in line. While model differences
are relatively minor, it is the smaller scale details in the low
track (and surface high to the north) that make for a tricky
forecast in terms of precipitation types on the northern side of
the precipitation shield, so continue to monitor for forecast
changes along the Eastern Seaboard.

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 or near southern California during the latter
half of next week. Regarding the 00/06Z model guidance, the ECMWF
was alone in pulling a closed low well offshore into the eastern
Pacific. While a lot of guidance shows some stream separation, the
ECMWF track seemed like a western outlier, especially considering
EC-based AI models were farther east. Preferred the EC ensemble
mean over the deterministic EC by the late period. The 12Z ECMWF
does stand pat on pulling energy well southwest, and the 12Z CMC
was more aggressive with stream separation than its 00Z run, though
not as far west as the ECMWF.

The WPC forecast tonight was able to use a multi-model blend
early, with increasing weighting from the ensemble means to about
half of the blend Day 6 and more Day 7 as spread continued to
increase. Generally maintained good agreement with WPC continuity
as well.


...Weather/Hazards Highlights...

An area of snow associated with a shortwave digging across the
western U.S. should eventually spin up a wave of low pressure along
the Gulf Coast and lift up the East Coast as well. It appears that
the central Gulf Coast into the Southeast and East Coast may be
the prime location of seeing heavy rain from this developing
system, as strong dynamical support will be in place with the jet
aloft and moisture will likely be above the 90th percentile for
this time of year. A limiting factor will be the fast speed of the
low pressure system though. For Monday/Day 4 ERO, continue to show
a Marginal Risk from the central Gulf Coast into the Southeast for
isolated flooding concerns. Plan to maintain a Marginal Risk across
parts of the Carolinas toward Cape Cod for Day 5/Tuesday as the
system tracks northeast. For areas north of the Carolinas,
instability may be limited onshore dependent on the low track,
which could yield lower rain rates and thus limiting flooding
concerns, but maintained continuity for now. 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, moderate to heavy
snow could occur across the Appalachians to interior Mid-Atlantic
and Northeast. All of this is still rather uncertain as small
changes to the low track could yield large differences in
precipitation amounts and type.

A northern stream shortwave through the Upper Midwest and Great
Lakes behind this main system will bring additional light snows to
parts of this region with some likely lake enhancement in downwind
favorable locations.

The next shot of energy moving into the West next week should
support low elevation rain and mountain snow in the Pacific
Northwest to the Intermountain West and Rockies Tuesday and
Wednesday. Depending on the eventual evolution of the shortwave,
precipitation looks to increase in the Southwest midweek.
Additional precipitation is possible in the Northwest again into
later week. Meanwhile another Gulf low pressure/frontal system
could lead to another round of rainfall across the Gulf Coast
Wednesday-Thursday.

Widespread and persistent below average temperatures for this time
of year can be expected for the central U.S. in particular for at
least the first half of the week as arctic air spills south. The
coldest anomalies for both highs and lows (around 15-25 degrees
below normal) are forecast in the Midwest Monday-Tuesday given the
snow cover there, and then again on Thursday behind another front.
Lows are likely to be below 0F in the northern Plains to Minnesota
into Monday, with highs in the teens. Much of the central U.S.
should finally see temperatures moderate by next Friday. 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 on
Monday and Tuesday. The Rockies westward should be more near or
slightly above normal for most of the period.


Tate/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


$$