263
FXUS02 KWBC 291957
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
357 PM EDT Thu Oct 29 2026

Valid 12Z Sun Nov 1 2026 - 12Z Thu Nov 5 2026


...Developing storm system will bring precipitation across the
West through Monday and into the central U.S. mid-week...

20Z Update: The 12Z model guidance suite has come into better
agreement on the synoptic scale pattern across the country,
including the evolution of the storm system across the Plains
through Wednesday morning. Differences become evident near
Minnesota with the GFS portraying a much stronger low near the
Canadian border, and the CMC is considerably faster to bring the
next Pacific trough inland across the Western U.S. The pattern
becomes more uncertain across the West to end the period Thursday
as additional shortwave energy reaches the Coast. For fronts and
pressures, a general blend of the GFS/ECMWF/UKMET/AIFS worked well
as a starting point through Monday, and then mainly a
ECMWF/ECENS/AIFS approach beyond that with increasing weighting of
the ensemble means through the middle to end of the week. The
forecast overall is fairly similar to previous continuity, except
by Thursday the main surface low has trended farther north across
the Ohio Valley and Great Lakes region. The previous forecast
discussion is appended below for reference. /Hamrick
--------------------

...Overview...

An amplifying trough progressing from the western U.S. into the
central U.S. will produce cyclogenesis over the Plains and an
expansive areas of precipitation spreading eastward. Meanwhile, a
series of shortwaves embedded within mid-level ridging will
support additional rounds of showers and thunderstorms from the
Mississippi Valley into the Southeast and Ohio Valley. By early
next week, the frontal system moving eastward across central U.S.
will provide a focus for widespread rainfall and gusty winds.


...Guidance/Predictability Assessment...

Models continue to show reasonable agreement on the broad evolution
of the troughing moving eastward into western U.S. and gradually
pushing into central U.S. through the week. The challenge remains
with the timing and degree of phasing of the northern stream
energy dropping southeastward into the West, while the southern-
stream progresses into the Southwest. Furthermore, there is
uncertainty with the timing and speed of the trough and cold front
progression eastward. A slower or more amplified solution would
favor a longer period of rainfall across portions of the central
U.S., while a faster progression would shift the main precipitation
axis east. Additionally, there are differences amongst the models
regarding the shortwave moving across eastern U.S. at the
beginning of the period that will effect sensible weather. The GFS
continues to show a more northward and faster track.

The forecast reflected greater weight on a multi-model blend with
the CMC/ECMWF/GFS and AI-based model solutions, with less weight on
the GFS, for the first portion of the period. Heavier weighting
towards the ensemble means were used for the latter portion of the
period.


...Weather/Hazards Highlights...

Across the central and eastern U.S., shortwave disturbances moving
around the ridge may support additional rounds of showers and
thunderstorms from the lower Mississippi Valley into the Southeast
and portions of the Midwest/Ohio Valley on Sunday. A moist low-
level flow from the Gulf combined with increasing mid-level
forcing may favor periods of organized convection and heavy
rainfall. The WPC Excessive Rainfall Outlook features a Marginal
Risk that is in place for portions of the eastern Florida Coast
for Sunday and Monday.

The combination of the upper trough extending across the western
U.S. with embedded shortwave energy and increasing Pacific
moisture will lead to widespread precipitation across portions of
California and the Intermountain West. Heavy rainfall will be
possible in favored terrain enhancement areas, particularly where
moisture transport becomes strongest. The WPC Excessive Rainfall
Outlook has Marginal and embedded Slight Risk areas in place for
the Southwest and central Plains/Midwest for Sunday. Furthermore,
snow is likely across higher elevations of the Rockies into Monday,
with snow levels dependent on the depth of the incoming cold air.
The trough will continue to progress eastward into the Plains, with
increasing potential for a closed low developing. Strengthening
cyclonic flow aloft will draw Gulf moisture northward into the
Plains and will pool along the eastward moving frontal boundary,
leading to showers and thunderstorms across much of the central
U.S. on Monday. Locally heavy rainfall may be possible along parts
of the Mississippi Valley, where deep moisture overlaps with mid-
level forcing. WPC has expanded a Marginal Risk for Excessive
Rainfall for portions of the Mississippi Valley and Plains for
Monday. Additionally, strong pressure gradients around the
deepening surface low may bring gusty winds across portions of the
Plains on Monday. Widespread showers and thunderstorms will push
eastward as the system moves towards the eastern U.S. through
Wednesday.

Behind the system, cooler and drier air should begin to spread into
portions of the central U.S. Temperatures will trend towards
seasonal values across the Plains, while the eastern states may
remain relatively mild ahead of the advancing front.

Oudit/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, excessive rainfall outlook,
winter weather outlook probabilities, heat indices and Key Messages
are at:

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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