040
FXUS21 KWNC 131953
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EST November 13 2025

SYNOPSIS: Throughout week-2, dynamical models continue to favor an active
pattern during the period. One or more impulses of mid-level low pressure are
expected to bring an increased risk for periods of high winds and
high-elevation snow across many parts of the Interior West. Meanwhile, surface
low formation in the lee of the Rockies is expected to tap ample Gulf moisture,
supporting elevated chances for heavy precipitation and high winds over parts
of the interior eastern Conterminous U.S. (CONUS) early week-2. Late week-2,
amplifying mid-level flow in western North America could begin the delivery of
cold Arctic air into the interior West.

HAZARDS

Slight risk of heavy precipitation for much of the southeastern Great Plains,
the Mississippi, Tennessee and Ohio Valleys, and adjacent Southeast, Fri-Sun,
Nov 21-23.

Slight risk of high winds for much of the Mississippi, Tennessee, and Ohio
Valleys, portions of the Great Lakes region, much of the Appalachians, and the
adjacent Southeast, Fri-Sat, Nov 21-22.

Slight risk of heavy snow over much of the Rockies, Great Basin, and adjacent
High Plains, Fri-Thu, Nov 21-27.

Slight risk of high winds for many parts of the western and central CONUS,
Fri-Thu, Nov 21-27.

Slight risk of much below normal temperatures for much of the central and
northern Interior West, Wed-Thu, Nov 26-27.

DETAILED SUMMARY

FOR SUNDAY NOVEMBER 16 - THURSDAY NOVEMBER 20:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR FRIDAY NOVEMBER 21 - THURSDAY NOVEMBER 27: The European ensemble (ECENS),
Canadian ensemble (CNENS), and GEFS means are in decent agreement on the
evolution of the 500-hPa height pattern influencing North America during
week-2. Early in the period, a fairly potent mid-level low is expected to
weaken as it is ejected northeastward from the southwestern or south-central
CONUS, bringing a surface low pressure and frontal system from the lee of the
Rockies into the eastern CONUS. Meanwhile, at higher latitudes, the period
begins with an amplified mid-level high centered west of Greenland. Over the
course of the period, troughing farther west near Alaska dissipates in
deference to a building mid-level ridge that becomes established over or near
the state during the latter half of week-2. Positive 500-hPa anomalies should
predominate across the higher latitudes around North America through the
period, with the largest positive height anomalies shifting from the weakening
ridge centered west of Greenland to the mid-level ridge amplifying near Alaska.
This building ridge will likely reload the downstream mid-level troughing
established over the western CONUS. Toward the end of the period, the ensemble
means diverge on the evolution of the re-intensifying mid-level trough in the
western CONUS, with the CNENS is most progressive, tracking this feature
eastward into the mid-latitudes of central and eastern North America by the end
of week-2 while the GEFS extends subnormal heights eastward into east-central
North America while also keeping below-normal mid-level heights lingering into
the interior western CONUS. The ECENS is in the middle, moving the mid-level
trough slowly eastward into the central CONUS. The differences in these
solutions result in a lot of forecast uncertainty toward the end of week-2, but
one scenario they all generally favor is the delivery of cold Arctic air into
part of the western half of the CONUS in association with cold surface high
pressure sliding southward downstream from the Alaskan mid-level ridge and near
or in the wake of the re-loaded mid-level trough moving toward or into the
central CONUS. This could be the beginning of a mid-level pattern change that
delivers cold air into at least parts of the CONUS after Thanksgiving.



Early week-2, the weakening mid-level shortwave ejecting toward the eastern
CONUS is expected to induce surface low development in the lee of the Southern
Rockies, where there continues to be good model support for enhanced and
potentially heavy precipitation over much of the east-central and interior
eastern CONUS. Raw precipitation output from the ensemble means and the
dynamical models show moderate to heavy precipitation there for the first three
days of the period. Most of the raw guidance drops 1 to 2 inches of
precipitation on areas from the southeastern Great Plains through a large part
of the Mississippi, Ohio, and Tennessee Valleys, with some showing locally
higher totals. The Probabilistic Extreme Tools (PETs) from all the ensembles
highlight 20 percent odds or better for precipitation totals in the top 15
percent of the historical envelope and over an inch total in this area for the
first 3 days of week-2. On the other hand, while all of the PETs show somewhat
elevated odds for heavy precipitation, none of them is particularly robust. The
ECENS PET has the highest chances for the aforementioned heavy amounts, but
still keeps odds for such totals below 40 percent. For these reasons, a slight
risk for heavy precipitation is posted for the first 3 days of week-2 in this
region, which will be a continuation of the heavy precipitation threat at the
end of week-1. In addition, later week-2, when a shortwave trough may be
ejected eastward from the western CONUS, there is some potential for renewed
heavy precipitation, although there is a lot of uncertainty with this
late-period development and no hazard is posted at this time. With several
rounds of heavy precipitation possible in this region over the next 2 weeks,
however, the threat for flooding will increase. Right now the National Water
Model highlights the Ozarks and Tennessee Valley as locations potentially at
risk for week-2 flooding, but heavy rain could focus almost anywhere in the
slight risk region, and maybe in a different locale later week-2. Given the
uncertainties, no flood risk is posted at this time, but the situation will be
monitored over the next few days.



This surface low pressure and associated frontal system tracking through the
interior eastern CONUS also has the potential to generate a period of high
winds early week-2. This is highlighted by the ECENS PET, which shows a better
than 30 percent chance for wind speeds over 20 mph and in the top 15th
percentile of the historic distribution. The GEFS PET is not as strong,
however, and the CNENS PET roughly splits the difference. The dynamical
European model (ECMWF) depicts wind gusts briefly reaching 30 to 45 mph early
week-2 near the Mississippi/Ohio Rivers` Confluence, but other models show
weaker solutions. All things considered, a slight risk of high winds is
justified in areas identified by the ECENS PET, the ECMWF, and scattered other
guidance for Nov 21-22 before any surface storm/frontal complex weakens and
shifts eastward or northeastward.



Mean mid-level troughing is expected over the western CONUS during week-2.
There will be some ebb-and-flow with the strength and location of the mid-level
trough, which is expected to move eastward and weaken while the subnormal
500-hPa heights in the West get reinforced downstream from a mid-level ridge
over or near Alaska. The precise timing and evolution of individual features is
uncertain, but the persistent mid-level troughing and cyclonically-curved
mid-level flow is enough to post a slight risk for periods of high winds over
much of the interior West and Pacific Northwest along with a slight risk for
heavy snow across the higher elevations of the interior West, both for the
entirety of week-2. These hazards are consistent with the snow water equivalent
PET from GEFS and the high winds PET from the ECENS. The latter shows odds
topping 40 percent for high winds in the top 15 percent of the historic
distribution over the Northwest for the first few days of week-2, with odds
backing off thereafter but remaining elevated through all 7 days of the period.



There is a lot of model variability late week-2, but one signal becoming more
consistent is the potential delivery of cold Arctic air into part of the
western half of the CONUS near the end of the period. This would be driven by
cold surface high pressure which would be forced southward into the CONUS in
the wake of a mid-level shortwave trough and downstream from a building or
somewhat entrenched mid-level ridge expected to develop near or over Alaska and
potentially extending southward into the eastern North Pacific. The PETs are
beginning to favor this scenario toward Thanksgiving, and there are some
indications in longer-range tools that this could be the start of a significant
pattern change which would feature continued delivery of Arctic air into parts
of the CONUS beyond the end of week-2.



Over Alaska, today`s forecast mid-level pattern forecast no longer favors deep
low pressure near the western or southern reaches of Alaska early week-2,
instead beginning to build in higher surface pressure. This has reduced the
high wind threat over southern Alaska, so yesterday`s posted hazard is removed.

FORECASTER: Rich Tinker

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