677
FXUS02 KWBC 161935
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
235 PM EST Sun Nov 16 2025

Valid 12Z Wed Nov 19 2025 - 12Z Sun Nov 23 2025


...South-central U.S. Heavy Rain/Runoff Threat mid-late week...



...Guidance/Predictability Assessment...

Updated 00/06Z guidance remains well clustered on the larger-scale
at the start of the medium range period mid-week. A deep upper-
low forecast to be lifting away from the northeast U.S./southeast
Canada will allow for a more zonal flow pattern over the central to
eastern U.S. with progressive upper-waves in split
northern/southern streams. Details diverge with the phasing of a
paired northern stream upper-wave and upper-low over the southwest
U.S. expected to lift northeastward over the south-central U.S. as
an open wave mid- to late this week which increases uncertainty on
precipitation coverage especially across the central/northern
Plains to Midwest. Coverage/potential for heavy rain across the
south-central U.S. has better agreement. Uncertainty continues to
remain higher late this week and into the weekend as guidance
diverges in handling an upper-trough/low expected to drop southward
along the West Coast. The ECMWF has remained on the more
progressive side of the guidance bringing the upper-trough/low
eastward across the southwest U.S., with the latest 00Z CMC also
now trending this way as well. The GFS is now the outlier in terms
of the deterministic guidance depicting a cutoff low developing off
the coast. The ECens, GEFS, and CMC ensemble means generally lean
more progressive overall to varying degrees, showing at least some
eastward progression of upper-energy. This leads to a great deal of
uncertainty with respect to precipitation chances from southern
California eastward through the southwestern and then south-central
U.S., with the potential for more heavy rainfall over the south-
central U.S. later next weekend depending on this upper-energy
timing over a lingering frontal boundary. Precipitation across the
track remains lighter in the NBM and favor the Canadian as a
compromise in showing timing/coverage/amounts.

The updated WPC forecast begins with a composite blend of the
ECMWF/GFS/CMC given good initial agreement. A contribution from the
ECens mean is added into the middle of the period given noted
detail differences across the central U.S. The GEFS mean is added
to replace the GFS and the mean contribution is brought up to 55%
of the total blend by the end of the period as the guidance begins
to diverge more over the western U.S. and the GFS depicts more of
an outlier solution.


...Weather/Hazards Highlights...

Ample upper trough energy and organized precipitation set to dig
through the West Coast within an emerging southern stream flow over
the next few days will spread across the Great basin/Southwest
midweek to include some enhanced mountain snows. Mid-later week
downstream system progression and lead moisture and instability
return flow genesis into wavy fronts over the south-central to
eastern U.S. and meso-scale features should lead to emergence of a
growing area of moderate to heavy rains and strong thunderstorms
over the south-central U.S., along with eastward progression later
week into the weekend. Accordingly, there is a WPC Day 4/Wednesday
Excessive Rainfall Outlook Marginal Risk area for the south-
central U.S. and a Day 5/Thursday Slight Risk area there given
cumulative heavy convective/repeat rain potential.

Another digging east Pacific system may offer some enhanced
precipitation chances to the West Coast states Thursday/Friday
along with closed low potential offshore and to the Southwest next
weekend along with uncertain organized precipitation to monitor.

Pre-frontal temperatures will be much warmer than average for much
of the south-central/southern U.S. into this period 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 week/weekend. Meanwhile, rounds of
troughing in California to the West/Southwest will lead to below
average highs this 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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