600
WTNT44 KNHC 150231
TCDAT4
TROPICAL DEPRESSION SEAN DISCUSSION NUMBER 17
NWS NATIONAL HURRICANE CENTER MIAMI FL AL192023
1100 PM AST SAT OCT 14 2023
DEEP CONVECTION CONTINUES TO BURST NEAR SEAN'S CENTER, AND AS A
RESULT, DVORAK ESTIMATES FROM TAFB AND SAB REMAIN T2.0/30 KT. IN
ADDITION, A RECENT ASCAT-B PASS SHOWED WINDS A LITTLE OVER 25 KT,
AND ALL THESE ESTIMATES SUPPORT MAINTAINING SEAN AS A 30-KT
TROPICAL DEPRESSION. WITH RELATIVELY LOW VERTICAL SHEAR, WARM SEA
SURFACE TEMPERATURES OF 28-29 DEGREES CELSIUS, AND AN UNSTABLE
ATMOSPHERE, THE ENVIRONMENT IS JUST CONDUCIVE ENOUGH FOR ADDITIONAL
BURSTS OF CONVECTION. THE BIGGEST LIMITING FACTOR IS A LACK OF
MID-LEVEL MOISTURE, WITH RELATIVE HUMIDITIES RUNNING ABOUT 50
PERCENT. CONSEQUENTLY, THE CONVECTION IS LIKELY TO BECOME LESS
PERSISTENT AND LESS ORGANIZED, AND GLOBAL MODELS INDICATE THAT
SEAN'S SMALL CIRCULATION SHOULD OPEN UP INTO A TROUGH OVER THE NEXT
DAY OR TWO. THE NHC FORECAST SHOWS SEAN DEGENERATING INTO A REMNANT
LOW IN 24 HOURS AND THEN DISSIPATING BY 48 HOURS, BUT IT'S ALSO
POSSIBLE THAT THE SYSTEM REMAINS A TROPICAL DEPRESSION RIGHT UP
UNTIL IT OPENS UP INTO A TROUGH.
SEAN CONTINUES TO MOVE NORTHWESTWARD, OR 305/7 KT. AS IT BECOMES A
WEAKER SYSTEM, THE DEPRESSION IS EXPECTED TO BECOME INCREASINGLY
STEERED BY LOWER-LEVEL RIDGING. AS A RESULT, SEAN IS EXPECTED TO
TURN WEST-NORTHWESTWARD OVERNIGHT AND THEN WESTWARD BY EARLY MONDAY,
JUST BEFORE OR AS IT DEGENERATES INTO A TROUGH. THE NHC TRACK
FORECAST IS VERY CLOSE TO THE PREVIOUS PREDICTION AND THE LATEST
TVCA MULTI-MODEL CONSENSUS.
FORECAST POSITIONS AND MAX WINDS
INIT 15/0300Z 16.9N 45.5W 30 KT 35 MPH
12H 15/1200Z 17.3N 46.6W 30 KT 35 MPH
24H 16/0000Z 17.7N 48.4W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 16/1200Z 18.1N 50.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 17/0000Z...DISSIPATED
FORECASTER BERG
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