640
WTNT44 KNHC 141444
TCDAT4
TROPICAL DEPRESSION SEAN DISCUSSION NUMBER 15
NWS NATIONAL HURRICANE CENTER MIAMI FL AL192023
1100 AM AST SAT OCT 14 2023
SEAN CONTINUES TO HAVE A LACKLUSTER SATELLITE APPEARANCE, WITH
INTERMITTENT BURST OF CONVECTION NEAR THE CENTER THIS MORNING.
EARLIER NOTED CONVECTIVE BURSTS WERE FAIRLY SHORT LIVED, AND DIDN'T
HAVE MUCH ORGANIZATION. LATEST SUBJECTIVE AND OBJECTIVE SATELLITE
INTENSITY ESTIMATES RANGE FROM 25 TO 35 KT. WITH FINAL-T NUMBERS
FROM SAB AND TAFB BOTH T1.5, WITH CI NUMBERS OF T1.5/T2.5,
RESPECTIVELY. GIVEN A BLEND OF THESE VALUES AND THE CURRENT
SATELLITE IMAGERY, THE INITIAL INTENSITY FOR THIS ADVISORY IS
LOWERED TO 30 KT.
SEAN IS MOVING NORTHWESTWARD OR 305 DEGREES AT ABOUT 7 KT. THE
CYCLONE SHOULD CONTINUE TO MOVE NORTHWESTWARD TODAY AROUND THE
SOUTHWESTERN EDGE OF A MID-LEVEL RIDGE. ON SUNDAY, A TURN BACK
TOWARD THE WEST-NORTHWEST IS ANTICIPATED AS SEAN CONTINUES TO
WEAKEN INTO A MORE SHALLOW VORTEX AND THUS WILL BE STEERED BY THE
LOW-LEVEL WIND FLOW. HOW QUICKLY SEAN WEAKENS WILL DEPICT WHEN THE
SYSTEM TURNS BACK WEST-NORTHWESTWARDS. THE NHC FORECAST IS SIMILAR
TO THE PREVIOUS ADVISORY AND LIES NEAR THE MIDDLE OF THE GUIDANCE
ENVELOPE.
SEAN IS MOVING INTO AN INCREASINGLY DRY MID-LEVEL AIRMASS, WHICH IS
WELL DEPICTED ON GOES-16 WATER MID-LEVEL WATER VAPOR IMAGERY. THIS
MORE STABLE AND DRY ENVIRONMENT SHOULD CAUSE ADDITIONAL WEAKENING
DURING THE NEXT COUPLE OF DAYS. GLOBAL MODELS DEPICT THAT SEAN WILL
STRUGGLE TO PRODUCE DEEP CONVECTION BY THIS EVENING AND INTO SUNDAY.
THE TIME OF THE SYSTEM DEGENERATING INTO A REMNANT LOW HAS BEEN
MOVED UP TO 24 HOURS, BUT THAT COULD OCCUR EVEN SOONER. THE
CIRCULATION IS EXPECTED TO OPEN UP INTO A TROUGH IN 60 HOURS, AND
DISSIPATION IS NOW INDICATED IN THE OFFICIAL FORECAST BY THAT TIME.
FORECAST POSITIONS AND MAX WINDS
INIT 14/1500Z 16.0N 44.2W 30 KT 35 MPH
12H 15/0000Z 16.6N 45.0W 30 KT 35 MPH
24H 15/1200Z 17.2N 46.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 16/0000Z 17.7N 48.1W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 16/1200Z 17.9N 50.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
60H 17/0000Z...DISSIPATED
FORECASTER KELLY
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