944
FXUS02 KWBC 071957
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
257 PM EST Fri Nov 7 2025

Valid 12Z Mon Nov 10 2025 - 12Z Fri Nov 14 2025

***First winter-like chill and lake effect snow event of the season
 for much of the central and eastern U.S. into early next week***

20Z Update: The overall forecast remains very similar to the
previous overnight issuance, with good overall agreement noted in
the latest model guidance through Wednesday. The CMC becomes much
more amplified with the upper trough across the Western U.S. by the
end of the period late Friday. The NBM appeared to be too light
with both lake effect and upslope flow snowfall for the first half
of the week, so the QPF values for these regions were more aligned
with a CMC/ECMWF/GFS blend and then increased by about 30%, while
the NBM looked more reasonable for the West Coast region. There was
also an upward adjustment to POPs for these same areas given
confidence in the overall synoptic pattern. The fronts/pressures
forecast was primarily derived from a multi-model consensus, with a
gradual increasing of the ensemble means to about 40% by next
Friday, whilst using a little of previous WPC continuity in the
blends. The previous overnight discussion is appended below for
reference. /Hamrick
-----------------------

...Overview...

An anomalously deep upper trough will be in place atop the east-
central U.S. at the start of the medium range period Monday, which
along with surface cold fronts will allow for winter-like
temperatures in the eastern half of the lower 48 with freezing
temperatures as far south as the Gulf Coast. The depth of the
trough should ease as the week progresses, but some troughing will
persist in the Great Lakes to Northeast and lead to rounds of lake
effect precipitation, including snow. Upper ridging in the West is
forecast to slowly move toward the central U.S. and bring warmer
than average temperatures. By mid to late next week, upper
troughing will edge toward the West and could direct an atmospheric
river toward California in particular.


...Guidance/Predictability Assessment...

Model guidance begins the period in rather good agreement with the
synoptic scale pattern, including the deep trough with its axis
over the east-central U.S. to begin the period. There is some
typical spread with embedded energies within the trough, but a
multi-model blend handled the differences fine. At the surface, low
pressure over Massachusetts or vicinity early Monday shows a bit
of spread as it pivots north and westward by Tuesday, but is
outside the lower 48 by that time in eastern Canada. The trough is
forecast to lift as it moves east, but a shortwave moving over top
the ridge in south-central Canada should reach the Great Lakes by
midweek and maintain troughing aloft that lasts through late week,
with good model agreement.

Model consensus is also good with an upper ridge over the West
early next week, getting suppressed on its northeast side due to
the shortwave and slowly getting pushed east by eastern Pacific
troughing from combining northern and southern stream energies. The
trough and potentially an embedded upper low has the most forecast
uncertainty by later week. Through the 12/18Z model cycle, the CMC
suite, especially several of its ensemble members, were farther
east/faster with the trough than the slower EC and especially GFS
model suites. The incoming 00Z models show a generally slower/more
offshore trend, though the 00Z GFS may be a western extreme. This
also affects the surface low(s) and timing and amounts of
precipitation, so continue to monitor forecasts.

The WPC forecast was based on a blend of the deterministic models
early in the period, and then increasing proportions of the GEFS
and EC ensemble means into the later period given the increasing
spread particularly in the West. Compared to the NBM, slowed the
precipitation arrival in the West mid to late week.


...Weather/Hazards Highlights...

A low pressure system will quickly move through the Northeast on
Monday, with precipitation associated with it. The westerly flow
behind this system and under the upper trough will bring rounds of
wintry precipitation chances to the Great Lakes continuing through
the workweek as additional cold fronts move through to provide
added forcing. On Monday, some accumulating snow is also expected
across higher elevations of the central/southern Appalachians, with
some light wintry precipitation also possible for the Ohio and
Tennessee Valleys. There will also be chances for isolated showers
in the Mid-Atlantic and along the Southeast Coast as a trailing
cold front pushes across the region, and a few flurries cannot be
ruled out for the Mid-Atlantic Monday.

Most other areas of the lower 48 will see dry conditions next
week, until precipitation chances increase along the West Coast mid
to late week as a Pacific system approaches. There is some
uncertainty in the timing of this system (which would affect the
onset time of precipitation) and the orientation (which would
affect how much precipitation reaches the Pacific Northwest versus
California). But generally the current forecast shows a potential
atmospheric river could reach northern California on Wednesday and
spread inland by Thursday, with potentially heavy precipitation
especially in the favored terrain along the coast and in the Sierra
Nevada.

On the backside of the early week clipper system, a series of
successive cold fronts will push south across the central and
eastern U.S., ushering in a cold and dry Arctic air mass bringing
the first winter-like chill of the season. Temperatures are
forecast to drop to 10-25 degrees below average, with highs only in
the 40s and 50s across the Southeast and even into north Florida
by Monday. Sub-freezing lows are forecast as far south as the Gulf
Coast by Monday night into Tuesday morning, with a hard freeze for
the interior Southeast. Numerous daily record tying/breaking lows
are possible. The coldest temperatures will be in the north-central
U.S. where lows are expected to be in the teens Monday morning.
Meanwhile in the West, strong upper ridging will dominate the
weather pattern through early next week, which will result in dry
weather with above average temperatures generally by around 10-15
degrees. These warmer than average temperatures are forecast to
spread east into the Plains and eventually the Mississippi Valley
as the week progresses as the ridge shifts east. Temperatures
should also moderate in the East by Wednesday and beyond, for near
to just slightly below average temperatures.


Tate


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



$$