146
WTNT44 KNHC 131442
TCDAT4
TROPICAL STORM SEAN DISCUSSION NUMBER 11
NWS NATIONAL HURRICANE CENTER MIAMI FL AL192023
1100 AM AST FRI OCT 13 2023
SEAN'S STRUCTURE AND OVERALL SATELLITE APPEARANCE HAVE BEGUN TO
DEGRADE. DEEP CONVECTION ASSOCIATED WITH THE TROPICAL STORM IS
LIMITED IN BOTH STRENGTH AND COVERAGE AS A RESULT OF DRY SURROUNDING
AIR AND CONTINUED WESTERLY WIND SHEAR, AND HAS DECREASED NOTICEABLY
IN THE LAST FEW HOURS. RECENT INTENSITY ESTIMATES RANGE FROM ABOUT
25 TO 45 KT, BUT ARE GENERALLY LOWER THAN THEY WERE FOR THE PREVIOUS
ADVISORY. THE INITIAL INTENSITY IS THEREFORE LOWERED TO 35 KT FOR
THIS ADVISORY.
CONTINUED GRADUAL WEAKENING IS EXPECTED FOR THE NEXT SEVERAL DAYS AS
SEAN MOVES THROUGH A STABLE ENVIRONMENT. SIMULATED SATELLITE OUTPUT
FROM SEVERAL MODELS SUGGESTS THAT SEAN MAY CONTINUE TO PRODUCE
OCCASIONAL BURSTS OF CONVECTION FOR ANOTHER DAY OR TWO, BUT THESE
SHOULD BECOME LESS ORGANIZED IN TIME. THIS SHOULD CAUSE SEAN TO
BECOME A POST-TROPICAL REMNANT LOW BY SUNDAY, BUT RECENT TRENDS
SUGGEST THIS COULD HAPPEN MUCH SOONER. SEAN'S WIND'S SHOULD
GRADUALLY DECREASE AS ITS CONVECTION WANES, AND IT IS FORECAST TO
OPEN INTO A TROUGH BY MONDAY.
THE TROPICAL STORM HAS CONTINUED TO MOVE WEST-NORTHWESTWARD FOR THE
LAST FEW HOURS. A TURN NORTHWESTWARD IS FORECASTED BY EVERY
AVAILABLE DYNAMICAL MODEL AND IS EXPECTED TO BEGIN AT ANY TIME, BUT
SINCE SEAN HASN'T TURNED YET, THE NHC TRACK FORECAST HAD TO BE
ADJUSTED WESTWARD AGAIN WITH THIS ADVISORY. OTHERWISE, NO
SIGNIFICANT CHANGES WERE MADE TO THE FORECAST REASONING, WITH THE
MODELS IN GOOD AGREEMENT ON SEAN'S TRACK FOR THE NEXT FEW DAYS UNTIL
IT DISSIPATES.
FORECAST POSITIONS AND MAX WINDS
INIT 13/1500Z 14.6N 41.7W 35 KT 40 MPH
12H 14/0000Z 15.3N 42.6W 35 KT 40 MPH
24H 14/1200Z 16.6N 44.0W 30 KT 35 MPH
36H 15/0000Z 17.5N 45.0W 30 KT 35 MPH
48H 15/1200Z 18.1N 46.1W 25 KT 30 MPH...POST-TROP/REMNT LOW
60H 16/0000Z 18.6N 47.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 16/1200Z...DISSIPATED
FORECASTER D. ZELINSKY
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