808
FXUS21 KWNC 231925
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST DECEMBER 23 2024
SYNOPSIS: A COASTAL STORM AND ASSOCIATED COLD FRONT IS FORECAST TO RING IN THE
NEW YEAR ACROSS THE EAST COAST WITH SLIGHT CHANCES OF HEAVY PRECIPITATION ALONG
THE NORTHEAST CORRIDOR, WITH HEAVY SNOW POSSIBLE FOR THE INTERIOR NORTHEAST,
AND POTENTIAL HIGH WINDS FOR MUCH OF THE EAST. QUIETER AND COOLER CONDITIONS
ARE FAVORED ACROSS MUCH OF THE REMAINDER OF THE COUNTRY RELATIVE TO THE WEEK-1
PERIOD.
HAZARDS
SLIGHT RISK OF HEAVY PRECIPITATION FOR PORTIONS OF COASTAL NORTHEAST AND
MID-ATLANTIC, TUE-THU, DEC 31-JAN 2.
SLIGHT RISK OF HEAVY HEAVY SNOW FOR THE INTERIOR NORTHEAST AND DOWNWIND OF
LAKES ERIE AND ONTARIO, TUE-THU, DEC 31-JAN 2.
SLIGHT RISK OF HIGH WINDS FOR MUCH OF THE EAST, TUE-THU, DEC 31-JAN 2.
DETAILED SUMMARY
FOR THURSDAY DECEMBER 26 - MONDAY DECEMBER 30:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR TUESDAY DECEMBER 31 - MONDAY JANUARY 06: THE FORECAST MID-LEVEL HEIGHT
PATTERN ACROSS MUCH OF THE COUNTRY IS FAVORED TO BECOME MORE PROGRESSIVE DURING
THE WEEK-2 PERIOD. WEAK MID-LEVEL RIDGING DEVELOPS ACROSS THE WEST EARLY IN THE
PERIOD, WITH MID-LEVEL TROUGHING BECOMING MORE ESTABLISHED ACROSS THE EAST.
HOWEVER, THERE REMAINS CONSIDERABLE UNCERTAINTY IN THE EVOLUTION OF THE
PATTERN.
MID-LEVEL SHORTWAVE TROUGHING IS FORECAST TO UNDERCUT A STRONG POSITIVE 500-HPA
HEIGHT ANOMALIES CENTER ACROSS EASTERN CANADA LATE IN WEEK-1 AND INTO EARLY
WEEK-2 ACROSS THE SOUTHEASTERN CONTIGUOUS U.S. (CONUS). THIS MAY INTRODUCE
COOLER TEMPERATURES TO THE SOUTHEASTERN CONUS RELATIVE TO THE WEEK-1 PERIOD.
FOLLOWING THE PASSAGE OF THE SHORTWAVE, WIND SPEEDS MAY INCREASE ACROSS
PORTIONS OF THE SOUTHEAST AS COOLER AIR IS ADVECTED INTO THE REGION. AS THE
SHORTWAVE TROUGH PROGRESSES OFFSHORE, SOME MODEL GUIDANCE INDICATES POTENTIAL
FORMATION OF A POTENT COASTAL STORM MOVING ALONG THE EASTERN SEABOARD. ECENS
AND GEFS PROBABILISTIC EXTREMES TOOLS (PETS) INDICATE A 20-40% CHANCE OF 3-DAY
ACCUMULATED PRECIPITATION EXCEEDING THE 85TH PERCENTILE, CLIMATOLOGICALLY, AND
.75 INCHES ALONG MUCH OF THE NORTHEAST CORRIDOR. ACROSS THE INTERIOR NORTHEAST,
BACK TO THE EASTERN GREAT LAKES, PRECIPITATION MAY FALL AS SNOW, DESPITE
ABOVE-NORMAL TEMPERATURES FORECAST FOR THE REGION. IF THE STORM DEEPENS AS SOME
ENSEMBLE GUIDANCE SUGGESTS, HIGH WINDS WOULD ALSO BE OF CONCERN INTO THE
NORTHEAST. THEREFORE, A SLIGHT RISK OF HEAVY PRECIPITATION IS FORECAST FOR
TUE-THU, DEC 31-JAN 2 FOR COASTAL PORTIONS OF THE NORTHEAST AND MID-ATLANTIC. A
SLIGHT RISK OF HEAVY SNOW IS POSTED FOR INTERIOR NEW ENGLAND AND DOWNWIND OF
THE EASTERN GREAT LAKES FOR THE SAME PERIOD. A SLIGHT RISK OF HIGH WINDS IS
HIGHLIGHTED ACROSS MUCH OF THE EAST FOR THIS PERIOD AS WELL.
ACROSS THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY, THE GEFS PET SHOWS AT
LEAST A 20% CHANCE OF MINIMUM TEMPERATURES FALLING BELOW THE 15TH PERCENTILE
AND 0 DEGF. HOWEVER, ADVISORY LEVEL COLD HAZARDS REQUIRE APPARENT TEMPERATURES
NEAR -30 DEGF IN THESE REGIONS AND APPARENT TEMPERATURES SEEM UNLIKELY TO REACH
THESE THRESHOLDS. THEREFORE, NO CORRESPONDING HAZARD IS POSTED BUT THIS AREA
WILL CONTINUE TO BE MONITORED.
IN SOUTHERN CALIFORNIA, THERE IS SOME SUGGESTION OF AN INVERTED TROUGH NEAR THE
COAST IN SOME OF THE ENSEMBLE GUIDANCE. HOWEVER, MOST OF THE MODEL GUIDANCE
DOES NOT INDICATE STRONG HIGH PRESSURE FORMING OVER THE GREAT BASIN AT THIS
TIME WHICH WOULD LIMIT THE POTENTIAL OF ANY SANTA ANA WIND THREAT AT THIS TIME.
IN ALASKA, ABOVE-NORMAL PRECIPITATION IS FORECAST ACROSS THE SOUTHERN MAINLAND.
HOWEVER, PETS DO NOT INDICATE ELEVATED CHANCES FOR PRECIPITATION TO EXCEED 2
INCHES DURING ANY 3 DAY PERIOD DURING WEEK-2. THUS, NO CORRESPONDING HAZARD IS
FORECAST AT THIS TIME. SIMILARLY, THE ECENS PET SHOWS SIGNALS FOR WINDS TO
EXCEED THE 85TH PERCENTILE IN SOUTHERN MAINLAND ALASKA, BUT THE HIGHEST WIND
SPEEDS ARE LIKELY TO REMAIN OFFSHORE RESULTING IN NO ASSOCIATED HAZARD BEING
POSTED.
FORECASTER: RYAN BOLT
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