687
FXUS02 KWBC 281947
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
347 PM EDT Wed Oct 28 2026

Valid 12Z Sat Oct 31 2026 - 12Z Wed Nov 04 2026


...Storm system will bring precipitation across the West this
weekend and into the central U.S. Monday-Tuesday...


...Overview...

Over the weekend, a shortwave or two will push through a warm mean
upper ridge in the eastern half of the U.S., combining with
Pacific tropical and Gulf moisture. This will spread rain and
thunderstorms across the Mississippi Valley and East, with moderate
to heavy rain totals possible in the southern tier. Meanwhile, a
large upper trough is forecast to move through the West and bring
widespread precipitation to include heavy rain/runoff and elevation
heavy snow threats there over the weekend. Forecast models
indicate the upper trough should make its way east and likely
become a closed low when it reaches the Plains by Monday-Tuesday.
This should carry a surface low/frontal system and bring widespread
rain to the central U.S. early next week.


...Guidance/Predictability Assessment...

Model guidance is generally agreeable with the large scale pattern
described above, though with differences in the details that will
affect sensible weather. There is typical model spread with the
shortwaves moving through the central and eastern U.S. this
weekend. Recent GFS and to a lesser degree GEFS runs track the
resulting QPF faster across the Southeast and more northeastward up
the East Coast in contrast to non-NCEP guidance and even the AI-
GFS, so this was not favored by WPC after collaboration with
selected Southeast U.S. WFOs. The lastest 12 UTC GFS has trended
toward the favored concensus, bolstering forecast confidence.

Farther west, it remains questionable how exactly northern and
southern streams interact and combine within the eastern
Pacific/West trough over the weekend. However, guidance remains
overall agreeable that the trough should track east across the
Intermountain West Monday and develop a closed low later Monday
into Tuesday as it reaches the Plains. There is some model spread
in the exact position in this upper low position and deepening
surface low Monday-Tuesday, but clustering is better than normal.

The WPC forecast favored a multi-model, ensemble mean and
dynamical/AI blend through the medium range period, albeit
accordingly discounting recent runs of the GFS/GEFS.


...Weather/Hazards Highlights...

Rain and thunderstorms are likely across the Lower Mississippi
Valley to Southeast over the weekend, and locally heavy rainfall is
possible as ample moisture combines with the shortwave aloft.A WPC
Excessive Rainfall Outlook Marginal Risk threat area shows focus
over the central Gulf Coast states with system genesis and slow
passage. Rain could also spread across the Midwest to Ohio Valley
and eventually into the dammed high pressure cooled East, with
generally modest amounts.

Ample moisture will spread into California/Southwest and the
Intermountain West ahead of the upper trough over the weekend. This
system offers quite anomalous fueling moisture. Accordingly, heavy
rain is possible especially across the Southwest, while heavy snow
is possible in the higher elevations, particularly the San Juans
and central Rockies in Colorado. WPC Excessive Rainfall Outlook
Marginal and embedded Slight Risk areas are in place over the
weekend. However, the details of precipitation timing and
placement, type (including snow levels), and amounts are all
somewhat uncertain dependent on upper-level and surface flow model
differences, so continue to monitor future forecasts as the details
could change. Some rain should overspread much of the central U.S.
later on Sunday and especially Monday as the low strengthens,
including possibly heavy convective amounts. Some northern/central
High Plains snow or rain/snow mix cannot be ruled out on the
backside of the low. Additionally, gusty winds may be possible in
the Plains behind the reasonably strong surface low. Moderate to
heavy rain may persist into Tuesday with some shift east, with
continued uncertainty in the details.

Above average temperatures are expected for much of the central
and eastern U.S. under mean upper ridging (albeit with occasional
shortwaves) over the weekend into early next week. Highs in the 70s
are forecast as far north as the Ohio Valley at times, as broad
areas reach around 10-20 degrees above normal. Temperatures should
be somewhat below average in the western U.S. underneath the upper
trough, especially for highs. By Tuesday-Wednesday, the Plains
should moderate to near normal temperatures as that upper
trough/low moves eastward.


Tate/Schichtel


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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