224
FXUS21 KWNC 131929
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST FEBRUARY 13 2024
SYNOPSIS: MID-LEVEL LOW PRESSURE IS FORECAST TO PERSIST OVER THE NORTH PACIFIC,
RESULTING IN CONTINUED STORMINESS FOR PORTIONS OF THE WEST COAST DURING THE
FORECAST PERIOD. MOISTURE IS FAVORED TO MOVE INLAND, BRINGING THE POTENTIAL FOR
HEAVY SNOW TO THE NORTHERN AND CENTRAL RANGES OF THE ROCKIES AND GREAT BASIN.
DISTURBANCES EJECTING OFF THE MOUNTAINS AND INTO THE GREAT PLAINS INCREASE THE
POTENTIAL FOR HIGH WINDS OVER PORTIONS OF THE HIGH PLAINS, THEN OVER PORTIONS
OF THE MIDWEST AND NORTHEASTERN CONTIGUOUS U.S. (CONUS) AS THESE SYSTEMS MOVE
EASTWARD. A SERIES OF LOW PRESSURE SYSTEMS OVER THE BERING SEA AND GULF OF
ALASKA INCREASES THE RISK FOR HIGH WINDS FOR PORTIONS OF THE SOUTHERN COAST OF
ALASKA.
HAZARDS
SLIGHT RISK FOR HEAVY PRECIPITATION FOR CENTRAL AND SOUTHERN CALIFORNIA,
SOUTHERN NEVADA, AND MUCH OF ARIZONA, WED, FEB 21.
SLIGHT RISK FOR HEAVY PRECIPITATION FOR NORTHERN CALIFORNIA ,NORTHWESTERN
NEVADA, AND THE PACIFIC NORTHWEST, FRI-TUE, FEB 23-27.
SLIGHT RISK FOR HEAVY SNOW FOR THE SIERRA NEVADA, KLAMATH, AND CASCADE
MOUNTAINS, FRI-TUE, FEB 23-27.
SLIGHT RISK FOR HEAVY SNOW FOR THE HIGHER ELEVATIONS OF THE NORTHERN AND
CENTRAL ROCKIES AND THE WASATCH MOUNTAINS, WED-SUN, FEB 21-25.
SLIGHT RISK FOR HIGH WINDS FOR MUCH OF CALIFORNIA, WED, FEB 21.
SLIGHT RISK FOR HIGH WINDS FOR COASTAL PORTIONS OF NORTHERN CALIFORNIA AND THE
PACIFIC NORTHWEST, FRI-TUE, FEB 23-27.
SLIGHT RISK FOR PERIODS OF HIGH WINDS FOR PORTIONS OF THE HIGH PLAINS, WED-SUN,
FEB 21-25.
SLIGHT RISK FOR PERIODS OF HIGH WINDS ACROSS PORTIONS OF THE OHIO, TENNESSEE,
AND MIDDLE MISSISSIPPI VALLEYS, NORTHERN APPALACHIANS, MID-ATLANTIC, AND
NORTHEAST U.S., THU-SUN, FEB 22-25.
SLIGHT RISK FOR PERIODS OF HIGH WINDS FOR THE SOUTHERN COAST OF ALASKA FROM THE
ALASKA PENINSULA EAST TO YAKUTAT, WED-SAT, FEB 21-24.
FLOODING POSSIBLE FOR MUCH OF CALIFORNIA.
DETAILED SUMMARY
FOR FRIDAY FEBRUARY 16 - TUESDAY FEBRUARY 20:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR WEDNESDAY FEBRUARY 21 - TUESDAY FEBRUARY 27: TODAY’S MODEL ENSEMBLE
SOLUTIONS PORTRAY DIMINISHING RISKS FOR HAZARDOUS PRECIPITATION ALONG THE WEST
COAST FOR WEEK-2 AS THE HEAVIEST ATMOSPHERIC RIVER (AR) ACTIVITY HAS MOSTLY
SHIFTED TO THE WEEK-1 PERIOD. BOTH THE GEFS AND ECMWF DEPICTIONS OF INTEGRATED
VAPOR TRANSPORT (IVT) INTO THE WEST COAST INDICATE THAT THE LARGEST MOISTURE
FLUXES ARE MOSTLY CONFINED TO THE WEEK-1 PERIOD, WITH WEAKER IVT VALUES OVERALL
DURING THE WEEK-2 PERIOD. THERE IS ALSO A PROMINENT NORTHWARD SHIFT IN HIGHEST
IVT TOTALS, MOVING FROM SOUTHERN CALIFORNIA ON DAY-8 (FEB 21) TO THE PACIFIC
NORTHWEST BY DAY-11 (FEB 24). A SLIGHT RISK FOR HEAVY PRECIPITATION REMAINS IN
PLACE FOR SOUTHERN CALIFORNIA, SOUTHERN NEVADA, AND MUCH OF ARIZONA FOR FEB 21,
CONSISTENT WITH GUIDANCE FROM THE IVT TOOL. AFTER A SLIGHT BREAK, THE LARGEST
MOISTURE FLUXES ARE FAVORED NORTH OF THE BAY AREA. THE ECMWF AND GEFS
PROBABILISTIC EXTREMES TOOLS (PETS) ALSO INDICATE THIS SHIFT OF ENHANCED
MOISTURE FLUX, WITH AT LEAST A 20% PROBABILITY OF 3-DAY PRECIPITATION TOTALS
EXCEEDING THE 85TH PERCENTILE AND 1 INCH FOR NORTHERN CALIFORNIA AND THE
PACIFIC NORTHWEST FOR FEB 23-27. A SLIGHT RISK FOR HEAVY SNOW IS ALSO POSTED
FOR THE SIERRA NEVADA, KLAMATH, AND CASCADE MOUNTAINS FOR FEB 23-27, CONSISTENT
WITH THE PORTRAYED ENHANCED MOISTURE FLUX. FURTHER INLAND, THE GEFS SNOW WATER
EQUIVALENT (SWE) PET SHOWS A DIMINISHED SIGNAL RELATIVE TO YESTERDAY’S MODEL
SOLUTIONS, BUT STILL SUPPORTS A SLIGHT RISK FOR HEAVY SNOW FOR THE HIGHER
ELEVATIONS OF THE NORTHERN AND CENTRAL ROCKIES, AND THE WASATCH MOUNTAINS. THE
PETS ALSO INDICATE AT LEAST A 20% PROBABILITY FOR WIND SPEEDS EXCEEDING THE
85TH PERCENTILE AND 25 MPH FOR MUCH OF THE WEST COAST AT SOME POINT DURING
WEEK-2. LIKE THE HEAVY SNOW HAZARDS NEAR THE WEST COAST, NORTH/SOUTH SPLITTING
OF A SLIGHT RISK FOR HIGH WINDS IS INDICATED ALONG THE WEST COAST WITH POINTS
SOUTH OF CAPE MENDOCINO HIGHLIGHTED FOR FEB 21 AND NORTH OF CAPE MENDOCINO FOR
FEB 23-27. FINALLY, GIVEN THE LARGE PRECIPITATION TOTALS ANTICIPATED DURING THE
WEEK-1 PERIOD AND A WET PATTERN PERSISTING THROUGHOUT WEEK-2, A RISK FOR
FLOODING REMAINS FOR MUCH OF CALIFORNIA DURING THE FORECAST PERIOD.
DOWNSTREAM OF THE ROCKIES BOTH THE GEFS AND ECMWF PORTRAY EPISODES OF LEE
CYCLOGENESIS OVER THE GREAT PLAINS DURING WEEK-2, RESULTING IN THE POTENTIAL
FOR HIGH WINDS FOR PORTIONS OF THE CENTRAL PLAINS AND DOWNSTREAM FOR PARTS OF
THE EASTERN CONUS LATER IN THE FORECAST PERIOD. THE ECMWF AND CMCE PETS BOTH
INDICATE AT LEAST A 20% CHANCE FOR WIND SPEEDS EXCEEDING THE 85TH PERCENTILE
AND 20 MPH FOR MUCH OF THE CENTRAL PLAINS FOR FEB 21-25, AS WELL AS A SWATH
THROUGH THE CENTRAL AND EASTERN CONUS EXTENDING FROM ROUGHLY MISSOURI THROUGH
THE OHIO AND TENNESSEE VALLEYS AND INTO PORTIONS OF THE NORTHEAST U.S. FOR FEB
22-25, WARRANTING A SLIGHT RISK FOR HIGH WINDS FOR THESE REGIONS. THESE PASSING
DISTURBANCES ARE LIKELY TO PRODUCE PERIODS OF POTENTIALLY HEAVY PRECIPITATION,
AS WELL AS SNOW FOR NORTHERN LOCALES, BUT WITH CONSIDERABLE MODEL SPREAD AND A
LACK OF DEFINITIVE EVIDENCE FOR HAZARDOUS THRESHOLDS BEING MET, NO ASSOCIATED
HAZARDS ARE POSTED AT THIS TIME.
A SERIES OF STRONG LOW PRESSURE SYSTEMS ARE DEPICTED TRACKING FROM THE BERING
SEA INTO THE GULF OF ALASKA, BRINGING PERIODS OF STORMY WEATHER INTO THE
SOUTHERN COASTAL PORTIONS OF THE STATE. THE PETS INDICATE AT LEAST A 20% CHANCE
OF WIND SPEEDS EXCEEDING THE 85TH PERCENTILE AND 40 MPH THROUGH AT LEAST FEB
21-24 FROM THE ALASKAN PENINSULA EASTWARD TO YAKUTAT, THEREFORE A SLIGHT RISK
FOR PERIODS OF HIGH WINDS IS POSTED FOR THIS PORTION OF THE SOUTHERN ALASKA
COAST. HEAVY PRECIPITATION IS ALSO INDICATED BY THE PETS, BUT 3-DAY
PRECIPITATION TOTALS ARE NOT EXPECTED TO EXCEED HAZARDOUS THRESHOLDS.
FORECASTER: DANNY BARANDIARAN
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