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FXUS21 KWNC 291921
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST NOVEMBER 29 2024
SYNOPSIS: A REINFORCING SHOT OF COLD AIR IS LIKELY TO MOVE INTO THE EASTERN
CONTIGUOUS U.S. (CONUS) NEAR THE START OF THE WEEK-2 PERIOD WITH DEEPENING
MID-LEVEL LOW PRESSURE. THE ADDITIONAL COLD AIR ADVECTION INTO THE NORTHEASTERN
CONUS MAY CONTINUE TO PROMOTE LAKE EFFECT SNOW OFF THE GREAT LAKES. MEANWHILE
IN SOUTHEASTERN ALASKA, REPEATED CHANCES FOR HEAVY PRECIPITATION ARE POSSIBLE
THROUGHOUT WEEK-2.
HAZARDS
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR INTERIOR NEW ENGLAND,
SAT-TUE, DEC 7-10.
SLIGHT RISK OF EPISODIC HEAVY SNOW FOR FAVORED LAKE EFFECT SNOW BELTS AND ALONG
THE ALLEGHENY FRONT, SAT-TUE, DEC 7-10.
SLIGHT RISK OF PERIODIC HEAVY PRECIPITATION FOR PORTIONS OF SOUTH-CENTRAL AND
SOUTHEAST MAINLAND ALASKA AND SOUTHEAST ALASKA, FRI-THU, DEC 7-13.
DETAILED SUMMARY
FOR MONDAY DECEMBER 02 - FRIDAY DECEMBER 06:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR SATURDAY DECEMBER 07 - FRIDAY DECEMBER 13: NEGATIVE 500-HPA HEIGHT
ANOMALIES AND TROUGHING CONTINUE TO BE FORECAST FOR THE EASTERN CONUS DURING
MUCH OF THE WEEK-1 AND 2 PERIOD. THIS TROUGH WILL BE REINFORCED WITH ANOTHER
ROUND OF NEGATIVE HEIGHT ANOMALIES MOVING SOUTH FROM THE ARCTIC AT THE START OF
WEEK-2 AND BRING ENHANCED CHANCES FOR MUCH BELOW-NORMAL TEMPERATURES TO
PORTIONS OF THE NORTHEAST. MINIMUM TEMPERATURES FROM THE RAW ECENS ARE FORECAST
TO BE NEAR 0 DEG F. SIMILARLY, THE GEFS PROBABILISTIC EXTREMES TOOL (PET)
INDICATES 20-40% CHANCES FOR TEMPERATURES FALLING BELOW 10 DEG F AND BELOW THE
15TH CLIMATOLOGICAL PERCENTILE. THEREFORE, A SLIGHT RISK OF MUCH BELOW-NORMAL
TEMPERATURES IS POSTED FOR DEC 7-10 ACROSS THE INTERIOR PORTIONS OF NEW ENGLAND.
THE BROAD MID-LEVEL TROUGH ACROSS THE NORTHEASTERN CONUS CONTINUES TO BRING
CHANCES FOR LAKE EFFECT SNOW OFF THE GREAT LAKES. WHILE THE ENVIRONMENT DOES
NOT APPEAR TO BE AS FAVORABLE FOR HEAVY LAKE EFFECT INTO WEEK-2 AS IN THE
COMING WEEK, THERE CONTINUES TO BE SOME SIGNALS FOR SHORTWAVE TROUGHS TO MOVE
THROUGH THE REGION THAT MAY PROMOTE ADDITIONAL SNOW CHANCES. A SLIGHT RISK OF
EPISODIC HEAVY SNOW IS POSTED FOR DOWNWIND OF THE GREAT LAKES AND ACROSS THE
ALLEGHENY FRONT FOR DEC 7-10.
IN THE SOUTH-CENTRAL CONUS SOME TOOLS SHOW ENHANCED CHANCES FOR HEAVY
PRECIPITATION DURING WEEK-2. AT THIS TIME THERE IS CONSIDERABLE UNCERTAINTY
ABOUT THIS POTENTIAL, AND EVEN THE MOST AGGRESSIVE TOOLS ARE NOT REMARKABLY
WETTER THAN HAZARDS THRESHOLDS, SO FOR NOW, NO ASSOCIATED HAZARD IS POSTED.
MODEL GUIDANCE REMAINS FAIRLY ROBUST WITH THE POTENTIAL FOR A SERIES OF STRONG
LOW PRESSURE SYSTEMS TO TRACK ACROSS OR NEAR THE GULF OF ALASKA. THE TIMING,
STRENGTH, AND TRACK OF INDIVIDUAL STORM SYSTEMS IS HIGHLY UNCERTAIN, BUT A
LARGE-SCALE PATTERN FAVORABLE FOR PERIODS OF STORMY WEATHER IS EXPECTED ALONG
PARTS OF THE SOUTHERN TIER OF ALASKA THROUGHOUT WEEK-2. FOR THIS REASON, A
SLIGHT RISK OF PERIODIC HEAVY PRECIPITATION IS POSTED FOR SOUTH-CENTRAL AND
SOUTHEASTERN ALASKA FOR THE ENTIRETY OF THE PERIOD. ABOVE-NORMAL TEMPERATURES
ARE FAVORED IN MUCH OF SOUTHERN ALASKA, THEREFORE, SNOW LEVELS MAY BE AT HIGHER
ELEVATIONS THAN NORMAL LEADING TO THE POTENTIAL FOR RAIN ON SNOW, INCREASING
HAZARDOUS RISKS. IN ADDITION, HIGH WINDS WILL BE POSSIBLE AT TIMES ACROSS THE
ENTIRE SOUTHERN TIER OF THE STATE, INCLUDING PARTS OF THE ALEUTIANS. RIGHT NOW,
HOWEVER, IT APPEARS THAT HIGH WINDS WILL PRIMARILY AFFECT OFFSHORE AREAS, SO NO
HIGH WIND HAZARD IS POSTED, BUT THIS SITUATION WILL NEED TO BE CLOSELY
MONITORED FOR INCREASING SIGNALS OF HIGHER WINDS OCCURRING INLAND.
FORECASTER: RYAN BOLT
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