373
FXUS02 KWBC 151758
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
1258 PM EST Sat Nov 15 2025

Valid 12Z Tue Nov 18 2025 - 12Z Sat Nov 22 2025


...Guidance/Predictability Assessment...

Latest 00/06Z deterministic guidance is well clustered for the
start of the medium range period mid-next week despite a generally
progressive split-stream pattern with multiple upper-waves of
various scales. Larger scale features include an upper-low
progressing slowly to the northeast over southeastern Canada/the
Northeast U.S., an upper-trough/low dropping southward along the
West Coast and another upper-trough upstream over the northeastern
Pacific. The pattern trends more zonal over the central to eastern
U.S. as the eastern upper-low lifts northward, with the upper-
trough/low along the West Coast progressing eastward into the
central U.S. as an open wave bringing the potential for moderate to
heavy rainfall along a lingering wavy frontal boundary. Despite
similarities on the larger scale, embedded shortwaves do lead to
varying precipitation chances across the Interior West.

Both the deterministic and mean guidance begin to diverge with
respect to the upper-trough upstream over the northeastern Pacific
as it reaches and begins to drop southward along the West Coast
later next week. The ECMWF is trending on the faster side bringing
it eastward across the Southwest U.S. while the GFS and CMC are not
only slower but depict a cutoff low developing along the coast.
The suite of AI guidance from the EC shows similarly varying
solutions accentuating the uncertainty, with the means tending to
favor their deterministic counter parts but to a lesser degree.
This results in significant differences in precipitation potential
from southern California east through the Southwest U.S. into the
south- central U.S., with the faster ECMWF naturally favoring
precipitation moving through the Southwest U.S. and into the south-
central U.S. late next week/early next weekend, while the GFS
would favor greater precipitation chances lingering over southern
California and into the Desert Southwest. The means/NBM tend to
lean more towards this latter scenario but with lower amounts.
There are also growing differences for the eastern U.S., with the
ECMWF and CMC both faster with the upper- wave over the central to
eastern U.S. and the GFS slower.

The updated WPC forecast used a composite blend of the 00Z
ECMWF/CMC and 06Z GFS given the relatively good agreement on the
overall pattern through the middle portion of the period. A large
contribution from the ECens/GEFS means is added for the latter part
of the period, compromising 70% of the blend by day 7, as the
deterministic guidance diverges in varying degrees across the CONUS
and with the means offering a compromise solution for the noted
features.


...Weather/Hazards Highlights...

In the wake of early next week cooling/unsettling Northeast upper
trough exit, shearing trough energy with an associated progressive
surface system will bring some moderate rainfall eastward Tuesday
into Wednesday from the Mid-Mississippi and Ohio Valleys to the
Mid- Atlantic. Well upstream, digging upper troughing will
meanwhile reach the West Coast to promote another round of enhanced
precipitation. Moisture feed across portions of the West/Southwest
to snowy Rockies elevations will be much weaker than the system
during the short range period. However, into mid- later next week
downstream system progression and lead moisture and instability
return flow genesis into wavy fronts over the central to eastern
U.S. and meso-scale features should lead to emergence of a growing
area of moderate to heavy rains and some strong thunderstorms from
the South-central U.S. eastward. Accordingly, there is a WPC Day
5/Wednesday Excessive Rainfall Outlook Marginal threat area for the
south-central U.S. with the start of an expanding mid-late week
east- central U.S. heavy rainfall pattern.

Back West, yet another east Pacific system may offer enhanced
precipitation to the West Coast into Thursday/Friday with
associated closed low potential into the Southwest next Saturday.
Precipitation could be moderate or heavy at times to monitor.

Pre-frontal temperatures will be much warmer than average for much
of the south-central/southern U.S. next week to include some
record temperatures upwards to 10-20 degrees above normal. This
translates to highs commonly into the 80s, with some warming
shifting to the East late next week/weekend. Meanwhile, rounds of
troughing in California to the Southwest will lead to below average
highs hovering next week about 5-10+ degrees below climatology.

Putnam/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 (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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