562
FXUS02 KWBC 250742
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
342 AM EDT Sun Oct 25 2026

Valid 12Z Wed Oct 28 2026 - 12Z Sun Nov 01 2026


...Overview...

An upper low will meander atop British Columbia and the
northwestern U.S. mid to late week, while shortwaves farther south
serve to deepen the trough across the West. Precipitation looks to
focus across the Northwest Wednesday-Thursday, and meanwhile
tropical moisture will spread into south-central Texas for
potentially heavy rainfall. Downstream upper ridging will allow for
warmer than average temperatures to spread across much of the
eastern half of the U.S. through the week. Rounds of light to
moderate rain are possible in the Midwest to Northeast as
shortwaves traverse north of the ridge. Then by late week,
combining systems and the deepening Western trough should bring
more widespread precipitation to the Intermountain West and
broadening in the central U.S. into next weekend.


...Guidance/Predictability Assessment...

Model agreement is very good through around Friday with the
overall pattern, including the upper low slowly drifting from
British Columbia into the Northwest, deepening troughing overall in
the West, and downstream mean ridging. A multi-model blend of the
dynamical and AI individual guidance worked well to depict the
pattern.

By next weekend, more dramatic model differences start to arise as
models start to diverge with the evolution of the trough in the
West. Some guidance like the GFS and AIGFS runs pull some energy
southwest to form an upper low in the eastern Pacific, with some
energy tracking eastward in southern Canada. Meanwhile the recent
00Z ECMWF and AIFS maintain a consolidated upper low in the
Northwest drifting a bit south. Ensemble members vary considerably,
but the ensemble means generally end up as a middle ground
solution. Quickly ramped up the proportion of ensemble means in the
forecast blend by the latter part of the medium range period due
to the increasing spread.


...Weather/Hazards Highlights...

Rain and higher elevation snow are forecast for the Pacific
Northwest across the northern Great Basin and Rockies Wednesday-
Thursday with the persistent upper trough. Shortwaves in the
northern tier will also support rounds of rain and possible
thunderstorms in the Midwest. Farther south, rain and thunderstorms
are forecast for the southern Plains, ramping up by Thursday as
moisture from current Hurricane Vance streams in and produces
potentially heavy rain in the Edwards Plateau/south-central Texas.
Into late week, deepening upper troughing across the West with
Pacific and Gulf moisture inflow will lead to broadening
precipitation coverage for much of the West and increasing for the
central to east-central U.S. by next weekend. The details of where
precipitation occurs and could be moderate/heavy are dependent on
the uncertain upper-level flow, so expect changing forecast
details. Additionally, persistent easterly flow across Florida will
bring scattered showers and thunderstorms to at least its east
coast.

Well above average temperatures are expected for portions of the
central and eastern U.S. from day to day under mean upper ridging.
Highs in the 70s are forecast as far north as the Upper Great Lakes
region, with 80s reaching the Mid-Mississippi Valley, broadly
around 15-20 degrees above normal. Temperatures should be slightly
below average in the western U.S., especially for highs.


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, 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


$$