116
FXUS02 KWBC 040756
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
356 AM EDT Sat Oct 4 2025

Valid 12Z Tue Oct 07 2025 - 12Z Sat Oct 11 2025


...General Overview...

Upper ridging over the Southeast Tuesday will drift west over the
Gulf Coast to Texas through the rest of next week. Meanwhile a
more transient upper pattern continues to the north with a deep
trough swinging through Ontario and Quebec Tuesday and Wednesday.
A cold front and Canadian surface high pressure follows this trough
with cooler than normal temperatures tracking from the northern
Plains Tuesday to the Northeast by Thursday. Finally, deep upper
troughing looks to develop into a low along/off the Pacific
Northwest coast for middle to late portions of the week.


...Guidance/Predictability Assessment...

The main feature to track in the forecast period is a digging
trough over BC Tuesday that closes into an upper low off the
Pacific Northwest coast on Wednesday and then persists/drifts
off/along the coast into the weekend as a cutoff. There is decent
agreement among global deterministics and the EC-AIFS for this
feature with the ECMWF still forming the low closer/over the PacNW
coast and then drifting farther south than consensus (off northern
CA). The UKMET (which is back in our software system) was in
agreement at 12Z, but the 00Z is farther inland/tracking farther
south, so it is now an outlier. Also of note is a tropical feature
in from the east-Pac that the ECMWF remains the only global
deterministic that brings it to the Desert SW which is by Friday.
This will continue to be monitored, but was used for both forecast
maps and QPF.

An even global model blend trended toward the GEFS and ECENS means
beyond Day 5 given agreement with the EC-AIFS. WPCQPF for Days 4-7
was mainly from the 01Z NBM, the 12Z ECMWF, and the 18Z EC-AIFS
with some inclusion of the 18Z GFS and 12Z UKMET in the footprint
of the initial three-source blend.


...Weather/Hazards Highlights...

A cold front ahead of a powerful trough shifts from the Midwest
through the central Appalachians Tuesday/Tuesday night. Despite the
generally progressive nature of this pre-frontal activity,
sufficient moisture (PW two sigma above normal) warrants a Day 4
Marginal Risk over the middle/upper Ohio Valley to the crest of the
central Appalachians.

Moisture anomalies increase over New Mexico Tuesday from continued
surges of moisture from the western Gulf onto a frontal wave that
is stalled over northern NM. Maintain the Marginal Risk now for Day
4 with some further expansion over NM.
An influx of tropical moisture from the eastern Pacific into the
Desert Southwest looks to still occur, but possible not until
Friday. An upper-low lingering off the West Coast through this time
would allow the tropical moisture to surge over much of the western
U.S. by next weekend.

Cool conditions shift east with a cold front from the Northern
Plains Tuesday, the Midwest Wednesday, and the Eastern Seaboard for
Thursday/Friday. Meanwhile, ridging drifting over the Gulf Coast
through Texas will maintain above normal temperatures over The
South through next week.


Jackson


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



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