501
FXUS21 KWNC 041821
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT OCTOBER 04 2026
SYNOPSIS: A STALLED FRONTAL BOUNDARY OVER THE GULF COAST, ALONG WITH DEEP
TROPICAL MOISTURE IS FAVORED TO PRODUCE WIDESPREAD HEAVY AND POTENTIALLY
HAZARDOUS PRECIPITATION AND ELEVATED WIND SPEEDS ACROSS THE REGION THROUGH THE
MIDDLE OF WEEK-2, PARTICULARLY ALONG THE CENTRAL AND EASTERN GULF COAST. LOW
PRESSURE AT THE SURFACE AND MID-LEVELS IS FAVORED TO TRANSIT FROM THE BERING
SEA TO THE GULF OF ALASKA, BRINGING THE POTENTIAL FOR HIGH WINDS AND HEAVY
PRECIPITATION FOR MUCH OF THE SOUTHERN AND SOUTHEASTERN COAST OF THE STATE
THROUGH THE MIDDLE OF THE FORECAST PERIOD.
HAZARDS
SLIGHT RISK OF HEAVY PRECIPITATION FOR PARTS OF THE UPPER TEXAS COAST, MUCH OF
THE LOWER MISSISSIPPI AND TENNESSEE VALLEYS, SOUTHEAST, MID-ATLANTIC, AND MUCH
OF NEW ENGLAND, MON-TUE, OCT 12-13.
SLIGHT RISK OF HIGH WINDS FOR MOST OF THE GULF COAST, MON-FRI, OCT 12-16.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PARTS OF SOUTHCENTRAL AND SOUTHEASTERN
ALASKA, MON-FRI, OCT 12-16.
SLIGHT RISK OF HIGH WINDS ACROSS THE ALEUTIANS, ALASKA PENINSULA, AND COASTAL
PORTIONS OF SOUTHWESTERN, SOUTHCENTRAL, AND SOUTHEASTERN ALASKA, MON-FRI, OCT
12-16.
FLOODING POSSIBLE FOR MUCH OF THE GULF COAST REGION INCLUDING NORTHERN AND
CENTRAL FLORIDA.
DETAILED SUMMARY
FOR WEDNESDAY OCTOBER 07 - SUNDAY OCTOBER 11:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR MONDAY OCTOBER 12 - SUNDAY OCTOBER 18: THE GEFS AND ECENS CONTINUE TO BE IN
GOOD AGREEMENT ON THE LARGE-SCALE HEIGHT PATTERN, WITH THE 7-DAY AVERAGE HEIGHT
PATTERN FEATURING A MEAN RIDGE AXIS NEAR THE WEST COAST, A BROAD TROUGH OVER
THE CENTRAL AND INTERIOR EASTERN CONTIGUOUS U.S. (CONUS), ZONAL FLOW ACROSS THE
NORTH ATLANTIC, AND A TROUGH OVER THE BERING SEA AND WESTERN ALASKA. SOUTH AND
EAST OF THE MID-LEVEL TROUGHING PREDICTED EAST OF THE ROCKY MOUNTAINS, A
STATIONARY FRONT IS FORECAST TO EXTEND FROM NEAR THE GULF COAST TO THE
SOUTHEAST COAST. THIS PATTERN SUPPORTS A PROLONGED PERIOD OF EPISODIC HEAVY
RAINFALL FOR MUCH OF THE GULF COAST, FLORIDA, TENNESSEE, AND FROM THE
APPALACHIANS EASTWARD TO THE ATLANTIC COAST THROUGH THE FIRST FEW DAYS OF
WEEK-2, WHERE A SLIGHT RISK FOR HEAVY PRECIPITATION IS POSTED, OCT 12-13. FOR
APPROXIMATELY THE MID-ATLANTIC AND MUCH OF NEW ENGLAND, THE HEAVY PRECIPITATION
IS EXPECTED TO COME MOSTLY FROM A NORTHERN STREAM TROUGH MOVING ACROSS THE
GREAT LAKES REGION.THE GEFS AND ECENS PROBABILISTIC EXTREMES TOOLS (PETS) AGREE
ON AT LEAST A 20% CHANCE OF 3-DAY PRECIPITATION TOTALS EXCEEDING THE 85TH
PERCENTILE AND ONE INCH ACROSS THE DESIGNATED HAZARD AREA THROUGH DAY 10, WITH
THE ECENS TOPPING OUT NEAR 30%. THIS IS ALSO WELL SUPPORTED BY THE UNCALIBRATED
PRECIPITATION FORECASTS FROM THESE ENSEMBLE MEANS. SHORTLY BEFORE THE START OF
WEEK-2, WPC PREDICTS A WAVE WILL DEVELOP OVER OR NEAR THE WESTERN AND CENTRAL
PORTION OF THE STATIONARY FRONT SITUATED NEAR THE GULF COAST. SURFACE HIGH
PRESSURE MOVING OFF THE MID-ATLANTIC COAST WILL HELP STRENGTHEN AND SUSTAIN THE
MOIST, SOUTHERLY, ONSHORE FLOW FROM THE GULF OF AMERICA NORTHWARD INTO THE GULF
COAST STATES AND SOUTHEAST. WHETHER OR NOT THIS WAVE DISTURBANCE BECOMES A
FULL-FLEDGED TROPICAL SYSTEM, OR WHETHER IT ORIGINATES ENTIRELY FROM THE BAY OF
CAMPECHE IS UNCLEAR AT THIS TIME. AS OF TODAY (OCT 4), THE NATIONAL HURRICANE
CENTER HAS A 40% (MEDIUM) CHANCE OF TROPICAL CYCLONE FORMATION WITHIN THE NEXT
7-DAYS OVER THE BAY OF CAMPECHE. A SLIGHT RISK OF HIGH WINDS (AT LEAST 25 MPH)
IS ALSO POSTED FOR MOST OF THE GULF COAST, OCT 12-16, WHICH IS TIED TO THE
ELEVATED POTENTIAL OF LOWER SURFACE PRESSURE OVER THE GULF. THIS IS SUPPORTED
BY PREDICTED GEFS/ECENS SURFACE LOW PRESSURE CENTER DISTRIBUTIONS, AND THE
ECENS WIND PET.
ANTICIPATED HEAVY RAINFALL AND STRONG ONSHORE FLOW, COMBINED WITH EXPECTED
ENHANCED RAINFALL TOTALS FROM WEEK-1 (RANGING FROM 2-7+ INCHES NEAR THE COAST),
COULD LEAD TO WIDESPREAD POTENTIAL FOR URBAN AND FLASH FLOODING ACROSS THE
CENTRAL AND EASTERN GULF COAST. THEREFORE A FLOODING POSSIBLE HAZARD REMAINS
VALID FOR THE AFFECTED REGION, WHICH INCLUDES NORTHERN AND PORTIONS OF CENTRAL
FLORIDA. CAUTION IS HIGHLY ADVISED WITH REGARD TO FLOODED ROADS AND WATERWAYS
AND IF WIDESPREAD FLOODING IS OCCURRING IN YOUR AREA, UNNECESSARY TRAVEL IS
STRONGLY DISCOURAGED.
FOR THE WESTERN CONUS, MODEL ENSEMBLE SOLUTIONS FAVOR MID-LEVEL TROUGHING AND
SOMEWHAT COOLER TEMPERATURES EARLY IN WEEK-2, GIVING WAY TO RIDGING AND WARMER
TEMPERATURES FOR THE SECOND HALF OF THE OUTLOOK PERIOD. THE POSSIBILITY OF
RENEWED HEAT IN SOUTHERN CALIFORNIA WILL NEED TO BE REASSESSED, NOTING AREAS
AROUND LOS ANGELES YESTERDAY REACHED BETWEEN 100-105 F. IN ADDITION, WITH THE
TROPICAL EASTERN PACIFIC CONTINUING TO BE VERY ACTIVE, THERE IS AN ELEVATED
CHANCE OF INCREASED MOISTURE INFLUX INTO THE SOUTHWEST DUE TO RECURVING
TROPICAL CYCLONES AND/OR GULF SURGES. CONDITIONS WILL BE REASSESSED TOMORROW TO
SEE IF THERE IS ENOUGH CONFIDENCE TO JUSTIFY ANY TEMPERATURE OR PRECIPITATION
RISKS FOR THE SOUTHWEST.
AN AMPLIFIED 500-HPA TROUGH OVER THE BERING SEA AND WESTERN ALASKA IS LIKELY TO
PROMOTE A SERIES OF LOW PRESSURE SYSTEMS THAT TRACK FROM THE BERING SEA AND
ALASKA PENINSULA EASTWARD TO THE GULF OF ALASKA. THIS FAVORS WIDESPREAD ONSHORE
FLOW TO MOST OF COASTAL SOUTHERN ALASKA, AND RESULTS IN 2-3 INCH PRECIPITATION
AMOUNTS ACCORDING TO THE GEFS AND ECENS MODEL ENSEMBLES. UNCALIBRATED AND PET
PRECIPITATION GUIDANCE SUPPORTS THIS HAZARD AT LEAST INTO THE MIDDLE PORTION OF
WEEK-2, WITH PRECIPITATION TOTALS EXCEEDING THE 85TH PERCENTILE. AN EVEN
GREATER CONCERN REGARDING IMPACTS FOR THE STATE WOULD BE FOR HIGH WINDS, AS
THIS IS THE TIME OF YEAR WHEN WESTERN PACIFIC TYPHOONS OFTEN RECURVE INTO THE
TEMPERATE WESTERLIES AND HAVE A SIGNIFICANT IMPACT ON THE CIRCULATION PATTERN
DOWNSTREAM OVER ALASKA. THE SPECIFIC DETAILS REGARDING TIMING AND INTENSITY OF
IMPACTS ARE VERY UNCERTAIN, BUT FOR NOW A BROAD SLIGHT RISK OF HIGH WINDS IS
DEPICTED FOR THE ENTIRE SOUTHERN COAST OF ALASKA, OCT 12-16, FOR WIND SPEEDS OF
AT LEAST 40 MPH.
FORECASTER: ANTHONY ARTUSA
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