360
FXUS21 KWNC 052039
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST FEBRUARY 05 2024
SYNOPSIS: A BREAK IN THE PERSISTENT STORM ACTIVITY ACROSS CALIFORNIA AND THE
SOUTHWEST IS EXPECTED LATER IN WEEK-1 AND DURING THE FIRST HALF OF WEEK-2.
AFTER THAT, HOWEVER, THERE ARE SIGNIFICANTLY INCREASED CHANCES OF HEAVY
PRECIPITATION RETURNING TO THE REGION, THOUGH IT IS UNCLEAR AT THIS TIME HOW
THIS EXPECTED RETURN OF ENHANCED STORMINESS MAY COMPARE TO THAT OF RECENT DAYS
AND WEEKS. OTHER AREAS OF THE NATION BEING MONITORED AT THIS TIME FOR
WEATHER-RELATED HAZARDS INCLUDE THE GULF COAST/SOUTH ATLANTIC COAST, AND THE
SOUTHERN COAST OF ALASKA FOR POTENTIALLY HEAVY PRECIPITATION, AND THE NORTHEAST
WHICH MAY EXPERIENCE EPISODES OF HIGH WINDS DURING WEEK-2.
HAZARDS
MODERATE RISK OF HEAVY PRECIPITATION FOR SOUTHERN CALIFORNIA, FRI-MON, FEB
16-19.
SLIGHT RISK OF HEAVY PRECIPITATION NEAR THE ALASKA COAST FROM ABOUT KODIAK TO
YAKUTAT, TUE-FRI, FEB 13-16.
SLIGHT RISK OF HEAVY PRECIPITATION FOR CALIFORNIA, FAR SOUTHERN NEVADA, AND
ARIZONA, FRI-MON, FEB 16-19.
SLIGHT RISK OF HEAVY PRECIPITATION FOR THE GULF COAST AND SOUTHERN ATLANTIC
COAST STATES, FRI-MON, FEB 16-19.
SLIGHT RISK OF HEAVY SNOW FOR THE KLAMATH AND SIERRA NEVADA MOUNTAIN RANGES IN
NORTHERN CALIFORNIA, FRI-MON, FEB 16-19.
SLIGHT RISK OF HEAVY SNOW FOR THE HIGHER ELEVATIONS OF NORTHERN ARIZONA,
FRI-MON, FEB 16-19.
SLIGHT RISK OF HIGH WINDS OVER THE NORTHEAST AND MID-ATLANTIC REGION, TUE-SAT,
FEB 13-17.
DETAILED SUMMARY
FOR THURSDAY FEBRUARY 08 - MONDAY FEBRUARY 12:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR TUESDAY FEBRUARY 13 - MONDAY FEBRUARY 19: PERSISTENT SURFACE LOW PRESSURE
OVER THE CANADIAN MARITIMES WILL USHER IN RELATIVELY COLDER AIR ACROSS MUCH OF
THE EASTERN CONTIGUOUS U.S. (CONUS) DURING THE WEEK-2 FORECAST PERIOD. A SLIGHT
RISK (20%-40%) OF HIGH WINDS (AT LEAST 20-25 MPH) IS POSTED FOR THE NORTHEAST
AND MID-ATLANTIC REGION, TUE-SAT, FEB 13-17. THIS IS BASED ON VARIOUS MODELS
DEPICTING ENHANCED PRESSURE GRADIENTS, AND THE PROBABILISTIC EXTREMES TOOL
(PET) WIND GUIDANCE FROM THE EUROPEAN ENSEMBLE MEAN (ECENS). TODAY’S GEFS PET
WAS MORE CONSERVATIVE AND FAVORED SUB-HAZARDOUS WIND SPEEDS TODAY.
INCREASING SOUTHERLY RETURN FLOW OVER THE GULF COAST STATES LATER IN THE PERIOD
WARRANTS A SLIGHT RISK OF HEAVY PRECIPITATION FROM FRI-MON, FEB 16-19. THIS
RISK AREA EXTENDS EASTWARD INTO THE SOUTHERN ATLANTIC REGION. THERE IS AT LEAST
A 20% CHANCE THE PREDICTED PRECIPITATION AMOUNTS WILL REACH OR EXCEED THE 85TH
HISTORICAL PERCENTILE, AND PET GUIDANCE FROM THE GEFS, ECENS, AND CANADIAN
ENSEMBLE MEAN (CMCE) FAVOR RAINFALL AMOUNTS OF AN INCH OR MORE OVER A 3 DAY
PERIOD.
A MUCH-NEEDED BREAK IN STORM ACTIVITY IS ANTICIPATED ACROSS THE WESTERN CONUS
LATER IN WEEK-1 AND DURING THE FIRST HALF OF WEEK-2, WHICH SHOULD ALLOW
REGIONAL STREAMS AND RIVER LEVELS TO SUBSIDE. BY THE SECOND HALF OF WEEK-2,
PRECIPITATION IS EXPECTED TO RETURN TO CALIFORNIA AND THE DESERT SOUTHWEST.
PART OF THE RETURNING PRECIPITATION IS ASSOCIATED WITH A PROMINENT MID-LEVEL
TROUGH AND ACCOMPANYING BROAD SURFACE LOW PRESSURE AREA CENTERED NEAR THE
ALEUTIANS, PREDICTED TO EXTEND SOUTHEASTWARD TOWARDS THE U.S. WEST COAST.
NORTHERN STREAM SYSTEMS SUCH AS THESE ARE NORMALLY DRIER THAN THEIR SUBTROPICAL
COUNTERPARTS, WHICH HAVE A PRONOUNCED SOUTHWESTERLY COMPONENT WHICH ALLOWS
THESE SO-CALLED “ATMOSPHERIC RIVERS” (AR) TO TAP INTO DEEPER TROPICAL MOISTURE.
PART OF THE RETURNING PRECIPITATION TO THE WEST, ESPECIALLY LATE IN WEEK-2,
COULD BE RELATED TO AR ACTIVITY, AS MODESTLY DEPICTED BY THE CW3E INTEGRATED
VAPOR TRANSPORT (IVT) TOOL. A SLIGHT RISK OF HEAVY PRECIPITATION IS THEREFORE
POSTED FOR CALIFORNIA, SOUTHERN NEVADA, AND ARIZONA DURING THE SECOND HALF OF
THE WEEK-2 FORECAST PERIOD. AN EMBEDDED MODERATE RISK (40%-60%) OF HEAVY
PRECIPITATION IS POSTED FOR SOUTHERN CALIFORNIA DURING THE SAME TIME. THE GEFS
AND ECENS PET GUIDANCE DEPICTS 1-2 INCHES OF PRECIPITATION ACROSS THIS GENERAL
AREA. IN THE HIGHER ELEVATIONS OF THE KLAMATH AND SIERRA NEVADA MOUNTAINS IN
CALIFORNIA, AND THE MOGOLLON RIM IN NORTHERN ARIZONA, HEAVY SNOW IS FAVORED (AT
LEAST 6-12 INCHES), FRI-MON, FEB 16-19.
A LARGE AREA OF SURFACE LOW PRESSURE CENTERED SOUTH OF THE ALEUTIAN ARCHIPELAGO
IS PREDICTED TO BRING ENHANCED ONSHORE FLOW AND RESULTING SLIGHT RISK OF HEAVY
PRECIPITATION TO THE SOUTHERN ALASKA COAST, FROM ABOUT KODIAK ISLAND EASTWARD
TO YAKUTAT, TUE-FRI, FEB 13-16. ACCORDING TO UNCALIBRATED ECENS PRECIPITATION
GUIDANCE, THERE IS AT LEAST A 40%-50% CHANCE OF PRECIPITATION AMOUNTS EXCEEDING
1-INCH ACROSS THIS REGION, AND AT LEAST A 20% CHANCE OF PRECIPITATION AMOUNTS
EXCEEDING 2 INCHES DURING THE FIRST FEW DAYS OF THE FORECAST PERIOD.
FORECASTER: ANTHONY ARTUSA
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