338
FXUS21 KWNC 122043
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST FEBRUARY 12 2024
SYNOPSIS: MID-LEVEL LOW PRESSURE IS FORECAST TO PERSIST OVER THE NORTH PACIFIC,
RESULTING IN CONTINUED STORMINESS FOR THE WEST COAST FOR MUCH OF 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. A
FAST-MOVING DISTURBANCE EJECTING OFF THE MOUNTAINS AND INTO THE GREAT PLAINS
INCREASES THE POTENTIAL FOR HIGH WINDS OVER PORTIONS OF THE HIGH PLAINS, THEN
OVER PORTIONS OF THE MIDWEST AND NORTHEASTERN CONTIGUOUS U.S. (CONUS) AS THE
SYSTEM MOVES EASTWARD. A SERIES OF LOW PRESSURE SYSTEMS OVER THE BERING SEA AND
GULF OF ALASKA BRING A RISK FOR HIGH WINDS FOR PORTIONS OF THE SOUTHERN COAST
OF ALASKA.
HAZARDS
MODERATE RISK FOR HEAVY PRECIPITATION FOR MUCH OF CALIFORNIA AND ARIZONA AS
WELL AS PORTIONS OF SOUTHERN NEVADA, TUE-WED, FEB 20-21.
SLIGHT RISK FOR HEAVY PRECIPITATION FOR MUCH OF CALIFORNIA AND ARIZONA AS WELL
AS PORTIONS OF SOUTHERN NEVADA, AND WESTERN OREGON AND WASHINGTON, TUE-SUN, FEB
20-25.
MODERATE RISK FOR HEAVY SNOW FOR THE SIERRA NEVADA MOUNTAINS, TUE-WED, FEB
20-21.
SLIGHT RISK FOR HEAVY SNOW FOR THE SIERRA NEVADA AND KLAMATH MOUNTAINS,
TUE-SUN, FEB 20-25.
SLIGHT RISK FOR HEAVY SNOW FOR THE CASCADE RANGE, FRI-SUN, FEB 23-25.
SLIGHT RISK FOR HEAVY SNOW FOR THE CENTRAL AND NORTHERN ROCKIES, AND HIGHER
ELEVATIONS OF THE NORTHERN GREAT BASIN, TUE-SUN, FEB 20-25.
SLIGHT RISK FOR HIGH WINDS FOR MUCH OF CALIFORNIA SOUTH OF CAPE MENDOCINO,
TUE-WED, FEB 20-21.
SLIGHT RISK FOR HIGH WINDS FOR PORTIONS OF NORTHERN CALIFORNIA NORTH OF CAPE
MENDOCINO, AS WELL AS WESTERN OREGON AND WASHINGTON, FRI-SUN, FEB 23-25.
SLIGHT RISK FOR HIGH WINDS FOR PORTIONS OF THE CENTRAL PLAINS, TUE-SAT, FEB
20-24.
SLIGHT RISK FOR HIGH WINDS FOR PORTIONS OF THE OHIO, TENNESSEE, AND MIDDLE
MISSISSIPPI VALLEYS, NORTHERN APPALACHIANS, MID-ATLANTIC, AND NORTHEAST U.S.,
THU-SAT, FEB 22-24.
SLIGHT RISK FOR HIGH WINDS FOR THE SOUTHERN COAST OF ALASKA FROM THE ALASKAN
PENINSULA EASTWARD TO YAKUTAT, TUE-SUN, FEB 20-23.
FLOODING POSSIBLE FOR MUCH OF CALIFORNIA.
DETAILED SUMMARY
FOR THURSDAY FEBRUARY 15 - MONDAY FEBRUARY 19:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR TUESDAY FEBRUARY 20 - MONDAY FEBRUARY 26: TODAY’S MODEL ENSEMBLE SOLUTIONS
FEATURE A SURFACE LOW PRESSURE SYSTEM NEAR THE CALIFORNIA COAST AT THE OUTSET
OF WEEK-2, BRINGING CONTINUED ENHANCED PROBABILITIES FOR HEAVY PRECIPITATION TO
THE REGION AT THE BEGINNING OF THE FORECAST PERIOD. BOTH THE ECMWF AND GEFS
PROBABILISTIC EXTREMES TOOLS (PETS) INDICATE AT LEAST A 40% CHANCE OF 3-DAY
TOTAL PRECIPITATION EXCEEDING THE 85TH PERCENTILE AND 1 INCH FOR MUCH OF
CALIFORNIA AND ARIZONA AS WELL AS ADJACENT PORTIONS OF NEVADA FOR FEB 20-22,
WITH THE CONSENSUS AMONG ENSEMBLES SHOWING THE HIGHEST PROBABILITIES DURING
DAYS 8 AND 9, THEREFORE A MODERATE RISK FOR HEAVY PRECIPITATION IS POSTED FOR
THE REGION COVERING FEB 20-21. THE PETS ALSO INDICATE A 20% PROBABILITY OF
3-DAY TOTAL PRECIPITATION TO EXCEED THE 85TH PERCENTILE AND 1 INCH FOR THE
ENTIRE WEST COAST AND PORTIONS OF THE DESERT SOUTHWEST THROUGHOUT THE FORECAST
PERIOD, ALTHOUGH THERE IS A DROP-OFF IN SIGNAL AND INCREASED UNCERTAINTY FOR
THE VERY END OF WEEK-2. THEREFORE A SLIGHT RISK OF HEAVY PRECIPITATION IS
POSTED FOR THE ABOVE REGION FOR DAYS 8-13, FEB 20-25. A FLOODING POSSIBLE
HAZARD ALSO REMAINS IN PLACE FOR MUCH OF CALIFORNIA WITH ONGOING ENHANCED
PRECIPITATION ANTICIPATED DURING THE FORECAST 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 CENTRAL
CALIFORNIA ON DAY-8 TO THE PACIFIC NORTHWEST BY DAY 11. THIS IS REFLECTED IN
SNOW AND WIND HAZARDS POSTED TODAY FOR THE WEST COAST. THE GEFS SNOW WATER
EQUIVALENT (SWE) PET SUPPORTS A MODERATE RISK FOR HEAVY SNOW FOR THE SIERRA
NEVADAS FOR DAYS 8-9, INDICATING CLOSE TO 40% PROBABILITIES OF 3-DAY SWE
EXCEEDING 2 INCHES AT THE BEGINNING OF WEEK-2, WITH PROBABILITIES OF AT LEAST
20% EXTENDING AS FAR EASTWARD AND EXPANDING NORTHWARD TO COVER THE CENTRAL AND
NORTHERN ROCKIES. LATER IN WEEK-2 ALONG THE WEST COAST, PROBABILITIES EXCEEDING
20% FOR 3-DAY SWE EXCEEDING THE 85TH PERCENTILE EXPAND NORTHWARD TO INCLUDE THE
CASCADES AS WELL. THEREFORE, SLIGHT RISKS FOR HEAVY SNOW ARE POSTED FOR MUCH OF
THE CENTRAL AND NORTHERN ROCKIES AND NORTHERN GREAT BASIN, AND THE SIERRA
NEVADA AND KLAMATH RANGES FOR FEB 20-25, AS WELL AS THE CASCADE RANGE FOR FEB
23-25. 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. 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 20-21 AND NORTH OF CAPE MENDOCINO FOR FEB 23-25.
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 20-24, 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
22-24, WARRANTING A SLIGHT RISK FOR HIGH WINDS FOR THESE REGIONS.
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
20-23 FROM THE ALASKAN PENINSULA EASTWARD TO YAKUTAT, THEREFORE A SLIGHT RISK
FOR 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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