939
FXUS21 KWNC 161928
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT SEPTEMBER 16 2024
SYNOPSIS: A STALLED FRONTAL BOUNDARY COUPLED WITH POTENTIALLY INCREASING
TROPICAL ACTIVITY OVER THE WESTERN CARIBBEAN AND GULF OF MEXICO RESULT IN THE
POTENTIAL FOR HEAVY PRECIPITATION AND HIGH WINDS FOR PORTIONS OF FLORIDA. HIGH
WINDS ARE ALSO POSSIBLE OVER THE NORTHERN AND CENTRAL PLAINS IN THE WAKE OF A
COLD FRONT FORECAST TO MOVE THROUGH THE NORTHERN TIER AT THE OUTSET OF WEEK-2.
LOW PRESSURE AT THE SURFACE AND ALOFT OVER THE ALEUTIAN ISLANDS IS FAVORED TO
BRING HEAVY PRECIPITATION TO THE SOUTHERN AND SOUTHEAST COAST OF ALASKA FOR
MUCH OF WEEK-2.
HAZARDS
MODERATE RISK OF HEAVY PRECIPITATION FOR THE SOUTHERN FLORIDA PENINSULA,
TUE-THU, SEP 24-26.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PORTIONS OF FLORIDA, AND COASTAL
SOUTHEAST U.S. AND MID-ATLANTIC, TUE-THU, SEP 24-26.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PORTIONS OF THE ALASKAN SOUTHERN COAST
AND PANHANDLE, TUE-SAT, SEP 24-28.
SLIGHT RISK OF HIGH WINDS FOR THE SOUTHERN FLORIDA PENINSULA, TUE-THU, SEP
24-26.
SLIGHT RISK OF HIGH WINDS FOR PORTIONS OF THE NORTHERN AND CENTRAL PLAINS,
TUE-THU, SEP 24-26.
DETAILED SUMMARY
FOR THURSDAY SEPTEMBER 19 - MONDAY SEPTEMBER 23:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR TUESDAY SEPTEMBER 24 - MONDAY SEPTEMBER 30: TODAY’S MODEL SOLUTIONS DEPICT
A STALLED FRONTAL BOUNDARY ALONG THE SOUTHEAST COAST OF THE CONTIGUOUS U.S.
(CONUS) AT THE OUTSET OF WEEK-2. THIS COINCIDES WITH AN INCREASED POTENTIAL FOR
TROPICAL CYCLONE (TC) ACTIVITY OVER THE WESTERN CARIBBEAN AND GULF OF MEXICO.
WITH THESE FACTORS IN PLAY THERE IS THE POTENTIAL FOR HEAVY PRECIPITATION AND
HIGH WINDS FOR THE SOUTHEAST U.S., PARTICULARLY FOR CENTRAL AND SOUTHERN
FLORIDA. THIS IS WELL-SUPPORTED BY THE GEFS AND ECMWF PROBABILISTIC EXTREMES
TOOL (PETS) FOR HEAVY PRECIPITATION, WHICH INDICATE AT LEAST A 20% CHANCE OF
3-DAY PRECIPITATION TOTALS EXCEEDING THE 85TH PERCENTILE AND 1 INCH FOR MUCH OF
FLORIDA AND ALONG THE COAST OF THE SOUTHEAST U.S. EARLY IN WEEK-2. THE ECMWF
FAVORS MORE WIDESPREAD COVERAGE INLAND BUT THIS APPEARS TO BE AN ARTIFACT OF A
WET BIAS IN THE ECMWF PET. A SLIGHT RISK FOR HEAVY PRECIPITATION IS POSTED FOR
MUCH OF FLORIDA AND UP THE SOUTHEAST COAST AS FAR NORTH AS THE OUTER BANKS FOR
SEP 24-26. ADDITIONALLY, A MODERATE RISK OF HEAVY PRECIPITATION IS POSTED FOR
THE FLORIDA PENINSULA SOUTH OF A LINE FROM TAMPA BAY TO CAPE CANAVERAL, ALSO
FOR SEP 24-26, WHERE MODEL GUIDANCE PLACES THE HIGHEST CHANCE FOR HEAVY
PRECIPITATION. FINALLY, GIVEN THE POTENTIAL FOR INCREASED TC ACTIVITY BEING A
COMPONENT OF THIS WEATHER HAZARD A SLIGHT RISK FOR HIGH WINDS FOR SEP 24-26 IS
ISSUED FOR THE SAME AREA IN FLORIDA HIGHLIGHTED FOR A MODERATE RISK OF HEAVY
PRECIPITATION.
MODEL SOLUTIONS DEPICT A PAIR OF COLD FRONTS SITUATED ACROSS THE GREAT PLAINS
AT THE OUTSET OF WEEK-2, ALONG WITH THE POTENTIAL FOR HIGH WINDS ASSOCIATED
WITH THESE FRONTS. THE GEFS AND ECWMF PETS INDICATE A 20% PROBABILITY OF WIND
SPEEDS EXCEEDING THE 85TH PERCENTILE AND AT LEAST 20MPH FOR PORTIONS OF THE
NORTHERN AND CENTRAL PLAINS EARLY IN THE FORECAST PERIOD, THEREFORE A SLIGHT
RISK OF HIGH WINDS IS POSTED FOR SEP 24-26. THE PETS ALSO INDICATE THE
POTENTIAL FOR HIGH WINDS ASSOCIATED WITH THE SECOND FRONT FURTHER SOUTH IN
NORTHERN TEXAS, BUT HAZARD THRESHOLDS ARE NOT FORECAST TO BE EXCEEDED SO NO
HAZARD IS ISSUED AT THIS TIME.
THERE IS GOOD CONSENSUS AMONG MODEL ENSEMBLES WITH REGARD TO AN AMPLIFIED
MID-LEVEL TROUGH AND ASSOCIATED SURFACE LOW PRESSURE OVER THE ALEUTIAN ISLANDS
IN PLACE AT THE START OF WEEK-2 AND REMAINING IN PLACE THROUGHOUT THE WEEK.
ADDITIONALLY THERE HAS BEEN INCREASED TC ACTIVITY IN THE WESTERN PACIFIC, WHICH
IS EXPECTED TO CONTINUE FOR THE NEAR FUTURE WITH THE JOINT TYPHOON WARNING
CENTER CURRENTLY MONITORING MULTIPLE AREAS OF INTEREST IN THE WESTERN PACIFIC.
LIKE THE SOUTHEAST CONUS, THESE CONVERGING FACTORS HAVE THE POTENTIAL TO BRING
HEAVY PRECIPITATION TO THE SOUTHERN AND SOUTHEAST COAST OF ALASKA. THIS IS
SUPPORTED BY THE ECMWF AND GEFS PETS, WHICH INDICATE THE POTENTIAL FOR 3-DAY
PRECIPITATION TOTALS TO EXCEED 3 INCHES FOR PORTIONS OF THE SOUTHERN COAST AND
PANHANDLE OF ALASKA FOR MUCH OF WEEK-2. UNCERTAINTY INCREASES LATER IN THE
FORECAST PERIOD SO FOR NOW A SLIGHT RISK OF HEAVY PRECIPITATION IS POSTED FOR
THE SOUTHERN COAST AND PANHANDLE OF ALASKA FOR SEP 24-28, AND THIS SITUATION
WILL BE CLOSELY MONITORED IN THE COMING DAYS. WHILE THERE IS THE POSSIBILITY OF
INCREASED WINDS ASSOCIATED WITH THIS SYSTEM HAZARDOUS CRITERIA ARE NOT
ANTICIPATED TO BE MET SO NO ASSOCIATED HAZARD IS POSTED AT THIS TIME.
FORECASTER: DANNY BARANDIARAN
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