097
FXUS21 KWNC 191953
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST JANUARY 19 2024
SYNOPSIS: LINGERING STORMINESS FROM A SIGNIFICANT SYSTEM OCCURRING DURING THE
WEEK-1 PERIOD RESULTS IN ENHANCED RISK FOR HEAVY PRECIPITATION FOR PORTIONS OF
THE SOUTHEASTERN CONTIGUOUS U.S. (CONUS) AT THE ONSET OF WEEK-2. STORMY PACIFIC
ONSHORE FLOW IS FORECAST TO CONTINUE FOR NORTHERN PORTIONS OF THE WEST COAST
EARLY IN THE FORECAST PERIOD, LEADING TO INCREASED POTENTIAL FOR HEAVY
PRECIPITATION AND HEAVY SNOW FOR THE HIGHER ELEVATIONS OF THE PACIFIC
NORTHWEST. MULTIPLE MODEL ENSEMBLES DEPICT A SECOND ROUND OF STORMY WEATHER
MOVING INTO THE WEST COAST LATE IN WEEK-2, ENHANCING CHANCES FOR HEAVY
PRECIPITATION FOR PORTIONS OF CALIFORNIA. STRONG SURFACE HIGH PRESSURE OVER THE
YUKON FAVORS ARCTIC AIR MOVING INTO INTERIOR ALASKA AND RESULTING IN A CHANCE
FOR EXCEPTIONALLY COLD TEMPERATURES.
HAZARDS
SLIGHT RISK FOR HEAVY PRECIPITATION FOR PORTIONS OF THE MID-ATLANTIC, SOUTHEAST
U.S., TENNESSEE, AND LOWER MISSISSIPPI VALLEYS, SAT, JAN 27.
SLIGHT RISK FOR HEAVY PRECIPITATION FOR PORTIONS OF THE PACIFIC NORTHWEST,
SAT-SUN, JAN 27-28.
SLIGHT RISK FOR HEAVY SNOW FOR THE CASCADE MOUNTAINS, SAT-SUN, JAN 27-28.
SLIGHT RISK FOR HEAVY PRECIPITATION FOR PORTIONS OF CALIFORNIA AND SOUTHWESTERN
OREGON, WED-FRI, JAN 31-FEB 2.
MODERATE RISK FOR MUCH BELOW-NORMAL TEMPERATURES FOR MUCH OF CENTRAL AND
SOUTHWESTERN ALASKA, SAT-MON, JAN 27-28.
SLIGHT RISK FOR MUCH BELOW-NORMAL TEMPERATURES FOR PORTIONS OF CENTRAL AND
SOUTHWESTERN ALASKA, SAT-MON, JAN 27-29.
SLIGHT RISK FOR HIGH WINDS FOR COASTAL PORTIONS OF ALASKA FROM KODIAK ISLAND TO
SITKA, SAT-MON, JAN 27-29.
DETAILED SUMMARY
FOR MONDAY JANUARY 22 - FRIDAY JANUARY 26:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR SATURDAY JANUARY 27 - FRIDAY FEBRUARY 02: MULTIPLE MODELS DEPICT A
SHORTWAVE MID-LEVEL TROUGH MOVING OFF THE ROCKIES DURING WEEK-, SUPPORTING
INCREASED CHANCES FOR HEAVY PRECIPITATION AS IT MOVES EASTWARD. WHILE THE
EFFECTS OF THIS SYSTEM ARE NOW MOSTLY WITHIN THE WEEK-1 PERIOD, THE ENHANCED
POTENTIAL FOR HEAVY PRECIPITATION CONTINUES INTO WEEK-2. THE ECMWF AND GEFS
PROBABILISTIC EXTREMES TOOLS (PETS) BOTH INDICATE AT LEAST A 20% PROBABILITY OF
3-DAY PRECIPITATION EXCEEDING THE 85TH PERCENTILE AND AT LEAST 1 INCH FOR MUCH
OF THE SOUTHEASTERN CONUS. THIS IS NOTEWORTHY SINCE DAILY MODEL SOLUTIONS
SUGGESTS THAT THE HIGHEST POTENTIAL FOR HEAVY PRECIPITATION ENDS BEFORE THE
ONSET OF WEEK-2, WITH ONLY LINGERING POTENTIAL FOR HEAVY PRECIPITATION ON THE
27TH AS THE SYSTEM MOVES OFFSHORE. THEREFORE, A SLIGHT RISK FOR HEAVY
PRECIPITATION IS POSTED FOR PORTIONS OF THE LOWER MISSISSIPPI AND TENNESSEE
VALLEYS, AS WELL AS PARTS OF THE MID-ATLANTIC AND SOUTHEAST U.S. FOR JAN 27.
THERE IS CONTINUED CONFIDENCE REGARDING ENHANCED CHANCES FOR PERIODS OF HEAVY
PRECIPITATION FOR THE PACIFIC NORTHWEST EARLY IN THE FORECAST PERIOD, WITH
ENSEMBLE SOLUTIONS DEPICTING A SHORTWAVE TROUGH NEAR THE COAST AT THE BEGINNING
WEEK-2 BEFORE RIDGING BUILDS OVER THE WESTERN CONUS. BOTH THE ECMWF AND GEFS
PETS INDICATE AT LEAST A 20% PROBABILITY OF 3-DAY PRECIPITATION EXCEEDING THE
85TH PERCENTILE AND 2 INCHES EARLY IN THE FORECAST PERIOD, WITH DAILY MODEL
SOLUTIONS SUGGESTING THE HIGHEST PROBABILITIES FOR JAN 27-28. THE CASCADE
MOUNTAINS HAVE A SLIGHT RISK OF HEAVY SNOW POSTED FOR JAN 27-28 FOLLOWING THE
FORECAST REASONING OUTLINED ABOVE FOR HEAVY PRECIPITATION. THERE IS ALSO
GROWING EVIDENCE THAT A SECOND SYSTEM FAVORED TO MOVE INTO THE WEST COAST LATE
IN THE FORECAST PERIOD HAS THE POTENTIAL TO BRING IMPACTFUL PRECIPITATION TO
PORTIONS OF CALIFORNIA. THE ECMWF AND GEFS PETS BOTH INDICATE A 20% PROBABILITY
OF 3-DAY PRECIPITATION EXCEEDING 2 INCHES FOR PORTIONS OF SOUTHWESTERN OREGON
AND CALIFORNIA NORTH OF POINT CONCEPTION, SO A SLIGHT RISK FOR HEAVY
PRECIPITATION IS POSTED FOR JAN 31-FEB 2.
ENSEMBLE SOLUTIONS FROM THE GEFS, ECMWF, AND CMCE ALL INDICATE A ROBUST SURFACE
HIGH PRESSURE SYSTEM OVER THE YUKON EARLY THE WEEK-2 PERIOD, RESULTING IN A
PUSH OF VERY COLD AIR INTO THE ALASKAN INTERIOR. THIS IS REFLECTED IN THE PETS,
WHICH INDICATE AT LEAST A 20% PROBABILITY OF MINIMUM TEMPERATURES FALLING BELOW
THE 15TH PERCENTILE DURING THE PERIOD JAN 27-29, WITH HIGHER PROBABILITIES AND
THE POTENTIAL FOR TEMPERATURES BELOW -40F FOR CENTRAL ALASKAN INTERIOR.
THEREFORE, A SLIGHT RISK FOR MUCH BELOW NORMAL TEMPERATURES IS HIGHLIGHTED FOR
CENTRAL AND SOUTHWESTERN ALASKA, JAN 27-29, WITH AN EMBEDDED MODERATE RISK
(>40% CHANCE) JAN 27-28.
THE YUKON HIGH PRESSURE ALSO FAVORS INCREASED LIKELIHOOD FOR STRONG OUTFLOW GAP
WINDS ALONG SOME COASTAL AREAS, THUS A SLIGHT RISK FOR HIGH WINDS IS POSTED
FROM KODIAK ISLAND TO SITKA FOR JAN 27-29.
FORECASTER: DANNY BARANDIARAN
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