487
FXUS21 KWNC 161943
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST FEBRUARY 16 2024
SYNOPSIS: MID-LEVEL LOW PRESSURE FORECAST INITIALLY OVER THE GULF OF ALASKA IS
PREDICTED TO SHIFT SOUTHWARD AND EASTWARD THROUGHOUT WEEK-2, WHILE A SECONDARY
AREA OF MID-LEVEL LOW PRESSURE IS FORECAST TO FORM NEAR THE CALIFORNIA COAST AT
THE ONSET OF THE PERIOD. THIS PATTERN IS ANTICIPATED TO BRING PERIODS OF HEAVY
PRECIPITATION (RAIN AND HIGH ELEVATION SNOW) TO MUCH OF THE WEST COAST AND
POSSIBLE FLOODING ACROSS PORTIONS OF CENTRAL AND NORTHERN CALIFORNIA AND
SOUTHWESTERN OREGON. THERE ARE ALSO INCREASED CHANCES FOR HIGH WINDS EXTENDING
ACROSS THE WEST COAST AND INTERIOR WEST, AND HIGH ELEVATION SNOW ACROSS MANY
PARTS OF THE INTERIOR WEST. A SERIES OF SURFACE LOWS TRACKING ACROSS THE
EASTERN CONTIGUOUS U.S. (CONUS) MAY BRING HEAVY SNOW TO NORTHEASTERN PORTIONS
OF THE LOWER 48 AT THE BEGINNING OF THE PERIOD, IN ADDITION TO EPISODIC HIGH
WINDS ACROSS PARTS OF THE EASTERN CONUS FROM THE BEGINNING TO MIDDLE OF WEEK-2.
SURFACE LOW PRESSURE SYSTEMS OVER THE GULF OF ALASKA COMBINED WITH SURFACE HIGH
PRESSURE ACROSS THE ALASKA MAINLAND, YUKON, AND BRITISH COLUMBIA INCREASES THE
RISK FOR HIGH GAP WINDS FOR COASTAL PORTIONS OF SOUTHERN ALASKA.
HAZARDS
MODERATE RISK OF HEAVY SNOW FOR THE SIERRA NEVADA, MON-WED, FEBRUARY 26-28.
SLIGHT RISK OF PERIODS OF HEAVY SNOW FOR THE SIERRA NEVADA, KLAMATH, AND
CASCADE MOUNTAINS, SUN-THU, FEBRUARY 25-29.
SLIGHT RISK OF PERIODS OF HEAVY PRECIPITATION FROM CENTRAL CALIFORNIA NORTH
THROUGH THE PACIFIC NORTHWEST, SUN-THU, FEBRUARY 25-29.
SLIGHT RISK OF EPISODIC HIGH WINDS FOR MUCH OF THE HIGH PLAINS WESTWARD,
SUN-TUE, FEBRUARY 25-27.
SLIGHT RISK OF PERIODS OF HEAVY SNOW FOR THE NORTHERN AND CENTRAL ROCKIES, AND
GREAT BASIN, MON-FRI, FEB 26-MAR 1.
SLIGHT RISK OF EPISODIC HIGH WINDS FOR PORTIONS OF THE EASTERN CONUS, SAT-TUE,
FEB 24-27.
SLIGHT RISK OF PERIODS OF HEAVY SNOW FOR PARTS OF THE GREAT LAKES AND
NORTHEASTERN CONUS, SAT-SUN, FEB 24-25.
SLIGHT RISK FOR PERIODS OF HIGH WINDS FOR SOUTHERN COASTAL PORTIONS OF ALASKA,
SAT-WED, FEB 24-28.
POSSIBLE FLOODING FOR SOUTHWESTERN OREGON AND NORTHERN AND CENTRAL CALIFORNIA.
DETAILED SUMMARY
FOR MONDAY FEBRUARY 19 - FRIDAY FEBRUARY 23:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR SATURDAY FEBRUARY 24 - FRIDAY MARCH 01: MID-LEVEL TROUGHING PREDICTED OVER
THE GULF OF ALASKA AT THE ONSET OF WEEK-2 IS SLIGHTLY MORE AMPLIFIED COMPARED
TO YESTERDAY, TRANSLATING TO STRONGER SIGNALS OF ENHANCED PRECIPITATION FOR THE
WEST. PROBABILITIES OF ENHANCED INTEGRATED VAPOR TRANSPORT (IVT) FOR THE WEST
COAST REMAIN SIGNIFICANTLY LOWER THAN WEEK-1. THE SLIGHT RISK OF PERIODS OF
HEAVY PRECIPITATION REMAINS POSTED FOR NORTHERN AND CENTRAL CALIFORNIA AND THE
PACIFIC NORTHWEST FOR FEB 25-29, WITH AN ACCOMPANYING SLIGHT RISK FOR HEAVY AT
HIGH ELEVATIONS FOR THE SIERRA NEVADA, KLAMATH, AND CASCADE MOUNTAINS. THE GEFS
AND ECENS PROBABILISTIC EXTREMES TOOLS (PETS) SHOW INCREASED WET SIGNALS
COMPARED TO YESTERDAY, SHOWING AN INCREASE FROM 20% YESTERDAY TO 30% CHANCES
TODAY, OF 3-DAY LIQUID EQUIVALENT EXCEEDING THE 85TH PERCENTILE AND ONE INCH
FOR PARTS OF THE WEST COAST. THE ECENS PET INDICATES AT LEAST A 40% CHANCE OF
EXCEEDING THESE THRESHOLDS ACROSS THE SIERRA NEVADA, SUPPORTING THE INCLUSION
OF A MODERATE RISK OF HEAVY SNOW FOR THE REGION, FEB 26-28. THE SOUTHERN EXTENT
OF THE FLOOD RISK HAS BEEN REMOVED IN TODAY'S OUTLOOK GIVEN THAT THE GREATEST
CHANCES FOR HEAVY PRECIPITATION IS FURTHER NORTH, THUS POSSIBLE FLOODING IS
POSTED FOR NORTHERN AND CENTRAL CALIFORNIA AND SOUTHWESTERN OREGON.
AS THE MID-LEVEL TROUGH SHIFTS INLAND, A SERIES OF SURFACE LOWS AND ASSOCIATED
FRONTS ARE ANTICIPATED TO IMPACT MANY PARTS OF THE INTERIOR WEST. THE GEFS SNOW
WATER EQUIVALENT (SWE) PET SHOWS A SIGNIFICANT INCREASE IN SPATIAL AND TEMPORAL
COVERAGE OF AT LEAST A 20% CHANCE OF 3-DAY TOTALS EXCEEDING THE 85TH PERCENTILE
AND HALF AN INCH COMPARED TO YESTERDAY. THUS THE SLIGHT RISK OF PERIODS OF
HEAVY SNOW HAS BEEN EXPANDED TO A BROADER AREA ACROSS THE NORTHERN AND CENTRAL
ROCKIES, AND GREAT BASIN, FEB 26-MAR 1. THIS PATTERN ALSO SUPPORTS THE
EXPANSION OF THE SLIGHT RISK OF HIGH WINDS ACROSS MANY PARTS OF THE WEST
COMPARED TO YESTERDAY, EXTENDING FROM THE WEST COAST EASTWARD TO THE HIGH
PLAINS, FEB 25-27. PETS SHOW AT LEAST A 20% CHANCE OF WIND SPEEDS EXCEEDING THE
85TH PERCENTILE AND 20 MPH IN THE HIGHLIGHTED RISK AREA.
THE MID-LEVEL TROUGH IS PREDICTED TO REMAIN OVER THE INTERIOR WEST FROM THE
MIDDLE TO END OF WEEK-2, INCREASING CHANCES FOR PERIODS OF POTENTIAL HAZARDS
FOR MUCH OF THE PERIOD. GIVEN THIS ANTICIPATED PATTERN, A SLIGHT RISK OF
EPISODIC HIGH WINDS IS DESIGNATED FOR MUCH OF THE HIGH PLAINS THROUGHOUT
WEEK-2, WHERE PETS SHOW AT LEAST A 20% CHANCE OF WIND SPEEDS EXCEEDING THE 85TH
PERCENTILE AND 20 MPH.
THERE IS SIGNIFICANT UNCERTAINTY REGARDING THE SPECIFIC DETAILS OF THE
FORMATION AND EVOLUTION OF STORMS ACROSS THE EASTERN CONUS. IN GENERAL,
MULTIPLE MODELS INDICATE THE POTENTIAL FOR SURFACE LOW FORMATION OVER
SOUTHEASTERN CANADA AND THE NORTHEAST AT THE BEGINNING OF WEEK-2, WHICH COULD
BRING PERIODS OF HEAVY SNOW TO THE NORTHEASTERN CONUS AND HEAVY LAKE EFFECT
SNOW TO THE GREAT LAKES AREA, SUPPORTING A SLIGHT RISK OF HEAVY SNOW FOR THESE
AREAS, FEB 24-25. THIS STORM IN ADDITION TO POSSIBLE SURFACE LOWS FORMING OVER
THE CENTRAL CONUS AND TRACKING NORTHEASTWARD SUPPORT AN INCREASED RISK OF HIGH
WINDS ACROSS PARTS OF THE EAST. THUS A SLIGHT RISK OF EPISODIC HIGH WINDS ARE
DESIGNATED FOR PARTS OF THE EASTERN CONUS, FEB 24-27. ALTHOUGH THERE IS A
POTENTIAL FOR ENHANCED RAIN ACROSS LOCALIZED PARTS OF THE SOUTHEASTERN CONUS,
THE SLIGHT RISK FOR HEAVY PRECIPITATION ACROSS THIS AREA IN YESTERDAY'S OUTLOOK
IS DISCONTINUED TODAY DUE TO WEAKER SIGNALS FOR HEAVY PRECIPITATION IN MULTIPLE
MODELS AND INCREASED UNCERTAINTY REGARDING THIS FEATURE.
A SERIES OF STRONG LOW PRESSURE SYSTEMS ARE PREDICTED TO FORM OVER THE GULF OF
ALASKA. THESE SURFACE LOWS COMBINED WITH ADJACENT SURFACE HIGH PRESSURE OVER
THE MAINLAND, YUKON, AND BRITISH COLUMBIA MAY SUPPORT LOCALIZED HIGH GAP WINDS.
THEREFORE A SLIGHT RISK OF HIGH WINDS IS POSTED FOR SOUTHERN COASTAL ALASKA
EXTENDING FROM THE ALASKA PENINSULA TO THE SOUTHEAST, FEB 24-28. PETS SHOW AT
LEAST A 20% CHANCE OF WIND SPEEDS EXCEEDING THE 85TH PERCENTILE AND 40 MPH FOR
MUCH OF THIS AREA.
FORECASTER: MELISSA OU
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