512
FXUS21 KWNC 162011
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST NOVEMBER 16 2023
SYNOPSIS: LOW PRESSURE IS FORECAST TO MOVE AWAY FROM THE EASTERN CONTIGUOUS
U.S. (CONUS) EARLY IN THE FORECAST PERIOD. IN ITS WAKE, STRONG WINDS ARE
POSSIBLE OVER THE NORTHEASTERN CONUS, AND A LONG FETCH OF COLD AIR ACROSS LAKES
ERIE AND ONTARIO MAY GENERATE HEAVY LAKE-EFFECT SNOW DOWNWIND IN PARTS OF
WESTERN PENNSYLVANIA AND UPSTATE NEW YORK. THE COLD AIR WILL ENCAPSULATE THE
CENTRAL AND EASTERN CONUS FOR MOST OF THE PERIOD, POTENTIALLY BRINGING THE
FIRST HARD FREEZE OF THE YEAR TO SOME AREAS ALONG THE CENTRAL GULF COAST.
FARTHER WEST, UPSLOPE FLOW PAIRED WITH REASONABLE ACCESS TO MOISTURE FROM LOWER
LATITUDES AND COLDER AIR MOVING IN FROM CANADA BRINGS A CHANCE FOR HEAVY SNOW
FOR PORTIONS OF THE ROCKIES AND HIGH PLAINS WHICH COULD PUSH EASTWARD INTO
PORTIONS OF THE NATION’S MIDSECTION BEFORE DISSIPATING AROUND THE MIDDLE OF THE
PERIOD.
HAZARDS
SLIGHT RISK FOR HIGH WINDS FOR PORTIONS OF THE OHIO VALLEY, CENTRAL
APPALACHIANS, MID-ATLANTIC, AND NORTHEAST U.S., FRI, NOV 24.
SLIGHT RISK FOR HEAVY SNOW DOWNWIND FROM LAKES ERIE AND ONTARIO, FRI-SAT, NOV
24-25.
SLIGHT RISK FOR MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE CENTRAL GULF
COAST REGION, FRI-SAT, NOV 24-25.
SLIGHT RISK FOR HEAVY SNOW FOR PORTIONS OF THE ROCKIES, HIGH PLAINS, AND
CENTRAL AND SOUTHERN GREAT PLAINS, FRI-SUN, NOV 24-26.
DETAILED SUMMARY
FOR SUNDAY NOVEMBER 19 - THURSDAY NOVEMBER 23:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR FRIDAY NOVEMBER 24 - THURSDAY NOVEMBER 30: ALL GUIDANCE SHOWS SURFACE LOW
PRESSURE NORTHEAST OF THE CONUS MOVING AWAY FROM THE NATION WHILE COLD HIGH
PRESSURE ORIGINATING FROM NORTHERN CANADA PUSHES SOUTHEASTWARD INTO THE CENTRAL
AND EASTERN CONUS. THE PRESSURE GRADIENT BETWEEN THESE TWO SYSTEMS CREATES A
SLIGHT RISK FOR HIGH WINDS OVER THE NORTHEASTERN CONUS ON THE FIRST DAY OF THE
PERIOD. WHETHER OR NOT THEY REACH HAZARDS THRESHOLDS, THESE WINDS WILL BE
CARRYING COLD AIR THAT ORIGINATED NEAR THE ARCTIC, AND WILL HAVE A LONG FETCH
ACROSS LAKES ERIE AND ONTARIO, WHICH ARE SLIGHTLY WARMER THAN NORMAL. THIS IS A
FAVORABLE PATTERN FOR HEAVY LAKE-EFFECT SNOWFALL DOWNWIND FROM LAKES ERIE AND
ONTARIO, AND A SLIGHT RISK FOR HEAVY SNOW IS POSTED THERE FOR THE FRIDAY AND
SATURDAY AFTER THANKSGIVING.
THE COLD HIGH PRESSURE ORIGINATING IN CANADA IS EXPECTED TO PREVAIL ACROSS THE
CENTRAL AND EASTERN CONUS UNTIL LATE IN THE PERIOD. UNUSUALLY COLD WEATHER IS
EXPECTED OVER MOST OF THIS BROAD AREA THROUGH AT LEAST THE THANKSGIVING HOLIDAY
WEEKEND, BUT AT THIS TIME, HAZARDOUSLY COLD CONDITIONS ARE EXPECTED TO BE
LIMITED TO SOME LOCATIONS NEAR THE CENTRAL GULF COAST, WHICH COULD SEE THEIR
FIRST HARD FREEZE OF THE SEASON THE FRIDAY OR SATURDAY AFTER THANKSGIVING.
SURFACE LOW PRESSURE FORECAST NEAR THE FOUR CORNERS REGION COUPLED WITH COLD
HIGH PRESSURE MOVING INTO THE GREAT PLAINS SETS UP EASTERLY TO SOUTHEASTERLY
FLOW ALONG THE EASTERN SLOPE OF THE ROCKIES, WHICH IS FAVORABLE FOR ENHANCING
POTENTIAL SNOWFALL. THE SURFACE STORM IS EXPECTED TO TRACK INTO THE
SOUTH-CENTRAL CONUS OVER THE THANKSGIVING HOLIDAY WEEKEND, TAPPING A LIMITED
AMOUNT OF GULF MOISTURE WHICH MAY ALLOW SIGNIFICANT SNOWFALL TO EXTEND EASTWARD
INTO THE CENTRAL GREAT PLAINS BEFORE DISSIPATING. A SLIGHT RISK FOR HEAVY SNOW
IS POSTED ACROSS PORTIONS OF THE EASTERN ROCKIES, ADJACENT HIGH PLAINS, AND
CENTRAL GREAT PLAINS FOR NOV 24-26 WHERE THE GEFS SNOW WATER EQUIVALENT (SWE)
PET INDICATES AT LEAST A 20 PERCENT CHANCE OF SWE EXCEEDING THE 85TH
CLIMATOLOGICAL PERCENTILE. IN ADDITION, THE 6Z AND 12Z DETERMINISTIC GFS RUNS
BOTH DROP OVER 6 INCHES OF SNOW ON THE LOWER ELEVATIONS OF THE CENTRAL GREAT
PLAINS BEFORE THE SYSTEM WEAKENS.
STRONG RIDGING OVER ALASKA FAVORS ANOMALOUSLY WARM TEMPERATURES ACROSS THE
STATE. DURING THE EARLY AND MIDDLE PART OF WEEK-2, THE EUROPEAN, CANADIAN, AND
GEFS ENSEMBLE MEANS ALL SHOW TEMPERATURES AVERAGING 8 TO 14 DEG. F ABOVE NORMAL
ACROSS THE NORTH SLOPE, AND 6 TO 12 DEG. F ABOVE NORMAL ACROSS INTERIOR
SECTIONS OF SOUTH-CENTRAL AND SOUTHWESTERN MAINLAND ALASKA. THIS COULD RESULT
IN POOR ICE CONDITIONS IN PORTIONS OF INTERIOR SOUTH-CENTRAL AND SOUTHWESTERN
ALASKA WHERE TEMPERATURES COULD REACH ABOVE FREEZING FOR SEVERAL DAYS ON END.
IN ADDITION, AT LEAST ONE SURFACE STORM SYSTEM IS EXPECTED TO PASS NEAR
SOUTHWESTERN AND SOUTH-CENTRAL ALASKA, WHICH COULD BRING SOME LIQUID RAIN OR
RAIN-ON-SNOW INTO PARTS OF THESE AREAS. NO HAZARD IS POSTED FOR NOW, BUT THE
SITUATION WILL CONTINUE TO BE CLOSELY MONITORED.
FORECASTER: RICH TINKER
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