202
FXUS21 KWNC 241928
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EST November 24 2025

SYNOPSIS: Mid-level low pressure extending from northern Canada into the
southwestern Contiguous U.S. (CONUS) is favored to usher Arctic air deep into
the Great Plains, potentially resulting in the first freeze of the season for
portions of the Southern Plains. A secondary round of strong cold air advection
may bring Arctic cold back into portions of the Plains and Upper Midwest later
in week-2. Persistent mid-level low pressure across the West increases the
likelihood of heavy snow for high elevations across the Interior West, with the
heavy snow risk persisting later in week across the Great Lakes and
northeastern CONUS.  Predicted strong frontal forcing elevates the risk of
heavy precipitation, with possible flooding across portions of the Ohio and
Tennessee Valleys early in the period.

HAZARDS

Moderate risk of heavy precipitation for parts of the Tennessee and Ohio
Valleys, Tue, Dec 2.

Slight risk of much below-normal temperatures for portions of the Southern
Plains, Tue-Wed, Dec 2-3.

Slight risk of much below normal temperatures for many parts of the Northern
and Central Plains, Middle and Upper Mississippi Valley, and the western Great
Lakes, Wed-Sat, Dec 3-6.

Slight risk of heavy snow for much of the Northern Plains, Great Lakes, and
northern New England, Tue-Sun, Dec 2-7.

Slight risk of heavy snow across the Rockies, Great Basin and the Northern
Intermountain, Tue-Sat, Dec 2-6.

Slight risk of heavy precipitation for portions of the Lower and Middle
Mississippi Valley, the Tennessee and Ohio Valleys, eastern Southern Plains,
Appalachians, and Southeast, Tue-Thu, Dec 2-4.

Flooding possible for the Tennessee and Ohio Valleys.

DETAILED SUMMARY

FOR THURSDAY NOVEMBER 27 - MONDAY DECEMBER 01:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR TUESDAY DECEMBER 02 - MONDAY DECEMBER 08: Towards the end of week-1, there
is good agreement in the dynamical models featuring a highly amplified 500-hPa
ridge overspreading the northeastern Pacific and extending northward into the
Bering Sea. In conjunction with a strongly negative mean height anomaly center
over southeastern Canada, a deep trough is favored to dig pretty far south into
the southwestern CONUS and northern Mexico and shift eastward into the Great
Plains. As a result, a strong frontal system remains favored at the surface,
serving as the main focus for multiple weather related hazards heading into the
week-2 period. Ensembles show the pattern gradually becoming more deamplified,
however there is the potential for additional shortwave energy to propagate
along the mean longwave trough axis throughout the Interior West, which looks
to bring a renewed hazards threat later in week-2.



On days 6 and 7 ( Nov 30 and Dec 1), surface prognosis analysis charts from the
Weather Prediction Center (WPC) depict strong surface high pressure descending
southward from the Canadian Prairies, with the southern extent of the frontal
boundary reaching the Southern Plains and the Lower Mississippi Valley. Based
on raw temperature tools, the peak of the coldest temperatures is expected on
days 7 and 8 where there remains a risk for the first subfreezing temperatures
for parts of the south-central for the season. A slight risk of much below
normal temperatures remains issued across portions of central and southern
Texas for Dec 2-3, before temperatures are expected to moderate. However, there
looks to be a short reprieve following the first wave of cold air east of the
Rockies, as guidance is advertising a second round of potentially strong cold
air advection into the Plains and Upper Midwest tied to a reloading trough
upstream. Compared to the GEFS, the ECMWF and Canadian ensemble are more
bullish with this potential, which is reflected in the Probabilistic Extreme
Tools (PETs) depicting renewed signals in percentile space, upwards of 40-60%
chances for minimum temperatures falling below the 15th percentile. Apparent
temperatures from the 0z ECMWF deterministic solution even shows colder minimum
temperatures (dipping into the negative 20 degrees F) compared to the cold snap
favored initially in late week-1 and into early week-2. Due to the potential
for these temperatures reaching winter hazards criteria, an additional slight
risk area for much below normal temperatures is posted over portions of the
Northern and Central Plains, the Middle and Upper Mississippi Valley, and the
western Great Lakes for Dec 3-6.



With mean troughing favored to persist throughout the Interior West, a slight
risk of heavy snow remains posted over the higher elevations of the Rockies,
Great Basin and Northern Intermountain and is extended through Dec 6, which is
supported in both the raw snow tools and the GEFS Snow Water Equivalent (SWE)
PET.  Periods of high winds are possible at the base and along the mean
troughing axis across the West, however tools are not quite supportive of a
corresponding wind hazard at this time. Snow guidance also shows an increased
heavy snow potential further east associated with much of the anomalously cold
air shifting eastward with time and mixing with enhanced tropospheric moisture.
Perhaps of greater concern is the potential for locally heavy Lake Effect snow
given stronger signals in/around the Great Lakes region, as Lake temperatures
remain well in the 40s (degrees F).  A moderate risk of heavy snow is being
considered for inclusion, though lesser support from the GEFS precludes this
hazard designation at this time. Therefore, a slight risk of heavy snow remains
posted for much of the northeastern CONUS and is also extended through Dec 7
given the aforementioned potential for renewed cold air advection over the part
of the country.



The anomalous cold air behind the mean low pressure system late in week-1 looks
to bring a good deal of frontal forcing to promote enhanced and possibly heavy
precipitation across the southcentral CONUS, with the risk shifting eastward
early in week-2. Although both the GEFS and ECMWF PETs remain supportive of
continuing a slight risk designation, there is good model agreement in the raw
tools indicating 30-50% chances for 3-day amounts exceeding an inch on days
8-10 mainly focused over the Ohio and Tennessee Valleys. Due to better forecast
skill of the raw model tools compared to the calibrated guidance over the past
month or so for this part of the country, a moderate risk of heavy
precipitation is posted for Dec 3.  Within the moderate risk area, a possible
flooding hazard is posted from northeastern Mississippi through the Tennessee
and parts of the Ohio valley where antecedent ground conditions are favorable
for flood responses, with flash, urban flooding, and isolated river flooding
cannot be ruled out at this time.  A broader slight risk area remains issued
and is expanded in coverage where PETs show at least 20% chances for 3-day
amounts exceeding the 85th percentile and one inch.



No hazards are issued over Alaska. Mean surface low pressure favored in the
Gulf of Alaska is expected to bring above-normal precipitation and periods of
elevated wind speeds for parts of the Mainland and the Southeast, though totals
are not expected to reach hazard thresholds.

FORECASTER: Nick Novella

$$