126
FXUS21 KWNC 281901
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EST November 28 2025

SYNOPSIS: A broad area of mid-level low pressure is expected to persist over
the higher latitudes of eastern North America which favors below-normal
temperatures across the Midwest and Northeast. The wet fall pattern for
southern California may continue into early December. A rapid transition from
above to below-normal temperatures remains likely for Alaska prior to the start
of week-2, December 6.

HAZARDS

Slight risk of much below normal temperatures for parts of the Upper
Mississippi Valley, Great Lakes, and Northeast, Sat-Sun, Dec 6-7.

Slight risk of heavy snow for parts of the eastern Great Lakes, Central
Appalachians, and Northeast, Sat, Dec 6.

Slight risk of heavy precipitation for southern California, Sat-Sun, Dec 6-7.

Slight risk of heavy snow across the Northern to Central Rockies, Sat-Mon, Dec
6-8.

DETAILED SUMMARY

FOR MONDAY DECEMBER 01 - FRIDAY DECEMBER 05:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR SATURDAY DECEMBER 06 - FRIDAY DECEMBER 12: The GEFS, ECENS, and CMCE are in
reasonably good agreement through the beginning of week-2 with anomalous
500-hPa troughing depicted over eastern North America. The ECENS indicates the
most amplified trough with negative 500-hpa height anomalies extending south to
the Gulf Coast and Florida. Early in week-2, the multi-model ensemble means
diverge, with the ECENS and CMCE maintaining the anomalous 500-hPa trough over
eastern North America but the GEFS depicting this trough weakening. Based on
better agreement and continuity, the ECENS and CMCE model solutions and their
temperature guidance was preferred today.  A slight risk of much below-normal
temperatures (valid December 6 and 7) is posted for parts of the Great Lakes,
northern New York, and New England where the ECENS Probabilistic Extremes Tool
(PET) has more than a 20 percent chance of minimum temperatures falling below
the 10th percentile and 0 degrees F. Gusty winds, associated with the predicted
cold air advection, elevates chances of apparent temperatures reaching  NWS
Cold Advisory criteria for these designated areas. Strong cold air advection is
expected to promote lake-effect snow later next week with a slight risk of
heavy snow posted for areas downwind of Lakes Erie and Ontario along with parts
of the Central Appalachians on December 6. The slight risk of heavy snow
extends east to include parts of New England due to several ECENS ensemble
members depicting coastal low formation in this region. The amplified and
full-latitude 500-hPa trough, predicted by the ECENS, would lead to subfreezing
temperatures across the Southeast. Since this region already had their first
widespread freeze of the season earlier in November, no cold hazard is
warranted.



As is typical with shortwave troughs forecast to separate from the mid-latitude
westerlies and dig into the Southwest or offshore of southern California, the
precipitation outlook is uncertain for those areas late next week. The ECENS
depicts a 500-hPa trough or even cut-off low near southern California which
increases the chance of heavy precipitation for this area. Based on the ECENS
PET and its uncalibrated model output, a slight risk of heavy precipitation is
posted for southern California on December 6 and 7. A longwave 500-hPa trough
along with support from the GEFS snow water equivalent (SWE) PET and the
uncalibrated ECENS results in a slight risk of heavy snow for parts of the
Northern to Central Rockies from December 6 to 8. Beyond the early part of
week-2, the heavy snow signal diminishes in the GEFS SWE PET. For the Pacific
Northwest and northern California, poor model agreement and continuity preclude
the designation on any precipitation or snow hazards at this time.



A quick transition from above to below-normal temperatures remains likely for
Mainland Alaska later next week after 500-hPa heights decrease and an upstream
mid-level ridge develops near the Bering Strait.  Despite this pattern change,
temperatures are not expected to reach NWS cold advisory criteria.

FORECASTER: Brad Pugh

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