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FXUS21 KWNC 061934
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST FEBRUARY 06 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, FAR SOUTHERN
NEVADA, AND PARTS OF ARIZONA, SAT-TUE, FEB 17-20.
SLIGHT RISK OF HEAVY PRECIPITATION NEAR THE ALASKA COAST FROM ABOUT KODIAK TO
YAKUTAT, WED-FRI, FEB 14-16.
SLIGHT RISK OF HEAVY PRECIPITATION FOR CALIFORNIA, FAR SOUTHERN NEVADA, AND
ARIZONA, SAT-TUE, FEB 17-20.
SLIGHT RISK OF HEAVY PRECIPITATION FROM EASTERN TEXAS ACROSS THE GULF COAST AND
SOUTHERN ATLANTIC COAST STATES, FRI-TUE, FEB 16-20.
SLIGHT RISK OF HEAVY SNOW FOR THE KLAMATH AND SIERRA NEVADA MOUNTAIN RANGES IN
NORTHERN CALIFORNIA, SAT-TUE, FEB 17-20.
SLIGHT RISK OF HEAVY SNOW FOR THE HIGHER ELEVATIONS OF NORTHERN ARIZONA,
SAT-TUE, FEB 17-20.
SLIGHT RISK OF HIGH WINDS OVER THE NORTHEAST AND MID-ATLANTIC REGION, WED-SUN,
FEB 14-18.
DETAILED SUMMARY
FOR FRIDAY FEBRUARY 09 - TUESDAY FEBRUARY 13:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR WEDNESDAY FEBRUARY 14 - TUESDAY FEBRUARY 20: 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.
WHILE MINIMUM TEMPERATURES ARE NOT EXPECTED TO REACH HAZARD THRESHOLDS
ASSOCIATED WITH THE COLDER AIR, A SLIGHT RISK (20%-40%) OF HIGH WINDS (AT LEAST
20-25 MPH) IS POSTED FOR THE NORTHEAST AND MID-ATLANTIC REGION, WED-SUN, FEB
14-18. THIS IS BASED ON VARIOUS MODELS DEPICTING ENHANCED PRESSURE GRADIENTS,
AND THE PROBABILISTIC EXTREMES TOOL (PET) WIND GUIDANCE FROM THE EUROPEAN
ENSEMBLE MEAN (ECENS) AND CANADIAN ENSEMBLE MEAN (CMCE). TODAY’S GEFS PET WAS
MORE CONSERVATIVE AND FAVORED SUB-HAZARDOUS WIND SPEEDS TODAY.
DURING THE MIDDLE PART OF WEEK-2, MOISTURE IS EXPECTED TO INCREASE OVER EASTERN
AND SOUTHERN TEXAS ALONG THE WESTERN PORTION OF A STALLED BAROCLINIC ZONE THAT
EXTENDS FROM EASTERN TEXAS ACROSS THE GULF COAST AND SOUTH ATLANTIC COAST. AN
UPSTREAM MID-LEVEL TROUGH OVER NORTHERN BAJA AND NORTHWEST MEXICO IS EXPECTED
TO CONTRIBUTE TO WIDESPREAD RISING MOTION ACROSS THE SOUTHERN TIER OF THE
CONUS. THE COMBINATION OF THE WIDESPREAD RISING MOTION ASSOCIATED WITH THE
MID-LEVEL TROUGH AND THE STALLED BAROCLINIC ZONE FAVORS A SLIGHT RISK OF HEAVY
PRECIPITATION FROM EASTERN TEXAS EASTWARD ACROSS THE GULF COAST TO THE SOUTH
ATLANTIC COAST DURING THE SECOND HALF OF WEEK-2. THOUGH CONSIDERED A MARGINAL
RISK DUE TO LIMITED LOW-LEVEL GULF INFLOW, THE GEFS IN PARTICULAR PREDICTS AT
LEAST AN INCH OF RAIN DURING A 3-DAY PERIOD ACROSS THIS AREA, AND AT LEAST A
20% CHANCE THE PREDICTED PRECIPITATION AMOUNTS WILL REACH OR EXCEED THE 85TH
HISTORICAL PERCENTILE.
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, FAR 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 THE SOUTHERN HALF OF CALIFORNIA, FAR SOUTHERN
NEVADA, AND PARTS OF ARIZONA 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, INCREASED CHANCES FOR HEAVY SNOW ARE
FAVORED (LOCALLY AS MUCH AS 6-12 INCHES), SAT-TUE, FEB 17-20, CONSISTENT WITH
GEFS SNOW WATER EQUIVALENT (SWE) GUIDANCE.
OVER EASTERN TEXAS, THERE IS CURRENTLY MINOR STREAM AND RIVER FLOODING IN
PROGRESS. UP TO AN INCH OF RAIN IS FORECAST ACROSS THIS REGION DURING THE
WEEK-1 PERIOD, WITH ADDITIONAL PRECIPITATION EXPECTED DURING WEEK-2. THOUGH NO
FLOOD RISK IS POSTED FOR EASTERN TEXAS AT THIS TIME, IT IS STILL SOMETHING THAT
WARRANTS MONITORING.
A LARGE AREA OF SURFACE LOW PRESSURE CENTERED SOUTH OF THE ALEUTIAN ARCHIPELAGO
IS PREDICTED TO BRING ENHANCED ONSHORE FLOW, RESULTING IN A SLIGHT RISK OF
HEAVY PRECIPITATION TO THE SOUTHERN ALASKA COAST, FROM ABOUT KODIAK ISLAND
EASTWARD TO YAKUTAT, WED-FRI, FEB 14-16. 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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