482
FXUS21 KWNC 111927
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST NOVEMBER 11 2024
SYNOPSIS: MODEL ENSEMBLES DEPICT LOW PRESSURE AT THE SURFACE AND ALOFT OVER THE
WESTERN CONTIGUOUS U.S. (CONUS) AT THE OUTSET OF WEEK-2, WHICH HAS THE
POTENTIAL TO BRING HEAVY SNOW AND STRONG WINDS TO PORTIONS OF THE CENTRAL CONUS
AS WELL AS A SHOT OF COLD AIR TO PORTIONS OF THE WESTERN AND CENTRAL CONUS.
HAZARDS
SLIGHT RISK OF HEAVY SNOW FOR PORTIONS OF THE CENTRAL ROCKIES, CENTRAL AND
NORTHERN PLAINS, AND UPPER MISSISSIPPI VALLEY, TUE-THU, NOV 19-21.
SLIGHT RISK OF HIGH WINDS FOR PORTIONS OF THE GREAT PLAINS, MIDDLE AND UPPER
MISSISSIPPI VALLEY, AND GREAT LAKES, TUE-THU, NOV 19-21.
SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR PORTIONS OF THE GREAT BASIN,
SOUTHWEST, ROCKY MOUNTAINS, AND GREAT PLAINS, TUE-THU, NOV 19-21.
DETAILED SUMMARY
FOR THURSDAY NOVEMBER 14 - MONDAY NOVEMBER 18:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR TUESDAY NOVEMBER 19 - MONDAY NOVEMBER 25: ENSEMBLE SOLUTIONS FROM THE GEFS
AND ECENS BOTH DEPICT A FAIRLY AMPLIFIED HIGH FREQUENCY WAVETRAIN EXTENDING
FROM THE BERING SEA ACROSS THE NORTH PACIFIC AND NORTH
AMERICA AND INTO THE NORTH ATLANTIC, WITH ONE OF THE TROUGHS LOCATED OVER THE
WESTERN CONUS AT THE OUTSET OF WEEK-2. GIVEN THE HIGH WAVE NUMBER THIS FEATURE
IS FAVORED TO MOVE EASTWARD QUICKLY AND DEAMPLIFY, SETTLING OVER THE GREAT
LAKES AS THE JET STREAM REORGANIZES INTO A LOWER WAVE NUMBER. WHILE THE GEFS
AND ECENS DIFFER WITH REGARD TO THE LOCATION OF THE TROUGH AT THE BEGINNING OF
THE FORECAST PERIOD, THEY BOTH INDICATE A SIMILAR POTENTIAL FOR IMPACTFUL
WEATHER AS A RESULT OF THIS STORM SYSTEM.
SEVERAL RECENT DETERMINISTIC GFS RUNS DEPICT A SURFACE LOW FORMING IN THE LEE
OF THE ROCKIES ROUGHLY ON NOV 19, GENERATING PERIODS OF POTENTIALLY HEAVY SNOW
ACROSS THE CENTRAL ROCKIES AND INTO THE CENTRAL AND NORTHERN PLAINS.
ADDITIONALLY, THE UNCALIBRATED ECENS INDICATES WIDESPREAD PROBABILITIES OF AT
LEAST 20% FOR EXCEEDING 4 INCHES OF SNOW ACCUMULATION OVER PORTIONS OF THE
NORTHERN PLAINS, WITH THE POTENTIAL FOR 6 INCHES OR GREATER FOR PORTIONS OF THE
CENTRAL ROCKIES AND ADJACENT PLAINS FOR NOV 19-21. THEREFORE A SLIGHT RISK FOR
HEAVY SNOW IS POSTED FOR THE REGIONS LISTED ABOVE FOR NOV 19-21.
THE GFS DETERMINISTIC RUNS DESCRIBED ABOVE ALSO DEPICT STRONG SURFACE PRESSURE
GRADIENTS OVER MUCH OF THE GREAT PLAINS AND INTO THE GREAT LAKES EARLY IN THE
FORECAST PERIOD. THIS IS ALSO SUPPORTED BY THE PROBABILISTIC EXTREMES TOOLS
(PETS) FOR THE ECMWF AND GEFS, WHICH BOTH INDICATE THE POTENTIAL FOR MAXIMUM
WIND SPEED TO EXCEED THE 85TH PERCENTILE AND AT LEAST 20 MPH OVER PORTIONS OF
THE GREAT PLAINS AND POINTS EASTWARD THROUGH THE MIDDLE OF THE WEEK-2 PERIOD.
MODEL AGREEMENT DECLINES FURTHER INTO THE FORECAST PERIOD, SO A SLIGHT RISK FOR
HIGH WINDS IS POSTED FOR MUCH OF THE GREAT PLAINS, THE MIDDLE AND UPPER
MISSISSIPPI VALLEY, AND GREAT LAKES REGIONS FOR NOV 19-21.
ANOMALOUSLY COLD AIR IS FAVORED TO BE ASSOCIATED WITH THE UPPER LEVEL TROUGH
OVER THE WESTERN CONUS, BRINGING POTENTIALLY IMPACTFUL MINIMUM TEMPERATURES FOR
PORTIONS OF THE WESTERN AND CENTRAL CONUS. THE GEFS AND ECENS PETS BOTH
INDICATE AT LEAST 20% PROBABILITIES OF MINIMUM TEMPERATURES FALLING BELOW THE
15TH PERCENTILE OVER MUCH OF THE WEST, WITH WIDESPREAD POTENTIAL FOR
TEMPERATURES BELOW 20 DEG F CENTERED OVER THE ROCKIES AND EXTENDING WEST INTO
THE GREAT BASIN, WHILE THE POTENTIAL FOR SUB-FREEZING TEMPERATURES EXTENDS
SOUTHEASTWARD INTO THE GREAT PLAINS TO INCLUDE PORTIONS OF NORTH TEXAS.
THEREFORE A SLIGHT RISK FOR MUCH BELOW-NORMAL TEMPERATURES IS POSTED FOR
PORTIONS OF THE GREAT BASIN, ROCKIES, AND CENTRAL AND SOUTHERN PLAINS FOR NOV
19-21.
THE NATIONAL HURRICANE CENTER (NHC) IS CURRENTLY MONITORING THE WESTERN
CARIBBEAN FOR THE POTENTIAL OF TROPICAL CYCLONE FORMATION DURING THE NEXT 7
DAYS.THERE IS STILL A GREAT DEAL OF UNCERTAINTY AS TO WHETHER A STORM ACTUALLY
FORMS AND WHERE SUCH A STORM WOULD TRACK SO NO ASSOCIATED HAZARDS ARE POSTED AT
THIS TIME, BUT INTERESTS ALONG THE GULF COAST SHOULD MONITOR THIS SITUATION.
FORECASTER: DANNY BARANDIARAN
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