042
WTNT44 KNHC 130234
TCDAT4
TROPICAL STORM SEAN DISCUSSION NUMBER 9
NWS NATIONAL HURRICANE CENTER MIAMI FL AL192023
1100 PM AST THU OCT 12 2023
SEAN CONTINUES TO BE A SHEARED TROPICAL CYCLONE. THE EXPOSED
LOW-LEVEL CENTER IS GRADUALLY BECOMING MORE DISPLACED FROM THE
DEEPEST CONVECTION IN THE NORTHEAST QUADRANT. SURPRISINGLY,
SATELLITE WIND DATA THAT PARTIALLY CAPTURED THE CENTER OF THE STORM
REVEALED WINDS OF 38-39 KT. THEREFORE, DESPITE SEAN'S RAGGED
APPEARANCE, THE INITIAL INTENSITY IS RAISED TO 40 KT FOR THIS
ADVISORY.
THE CYCLONE IS ACCELERATING WEST-NORTHWESTWARD AT AN ESTIMATED
300/12 KT. SEAN IS BEING STEERED BY A WEAK RIDGE CENTERED OVER THE
EASTERN TROPICAL ATLANTIC. THIS RIDGE IS EXPECTED TO BUILD WESTWARD
AND KEEP SEAN ON A WEST-NORTHWESTWARD TO NORTHWESTWARD TRACK WITH A
DECREASE IN FORWARD SPEED THROUGH THE FORECAST PERIOD. THE
GUIDANCE ENVELOPE IS DECENTLY CLUSTERED, AND THE LATEST ADVISORY
LIES CLOSE TO THE VARIOUS CONSENSUS AIDS AND JUST SOUTH OF THE
PREVIOUS TRACK FORECAST.
ENVIRONMENTAL CONDITIONS ARE GENERALLY NOT CONDUCIVE FOR ADDITIONAL
STRENGTHENING. PERSISTENT MODERATE-TO-STRONG DEEP-LAYER VERTICAL
WIND SHEAR AND AN INCREASINGLY DRY AIRMASS SHOULD INHIBIT FURTHER
DEVELOPMENT OF THE STORM. THE MODEL GUIDANCE ENVELOPE SHOWS SEAN
GRADUALLY WEAKENING FOR THE NEXT COUPLE OF DAYS. BY THE END OF THE
WEEKEND, THE STORM IS EXPECTED TO LOSE ITS CONVECTIVE ORGANIZATION
AND BECOME A REMNANT LOW. THE LATEST NHC INTENSITY PREDICTION HAS
BEEN SLIGHTLY RAISED IN THE NEAR-TERM FORECAST HOURS BASED ON
SEAN'S INITIAL INTENSITY. DISSIPATION IS STILL ANTICIPATED WITHIN
4 DAYS.
FORECAST POSITIONS AND MAX WINDS
INIT 13/0300Z 14.1N 39.5W 40 KT 45 MPH
12H 13/1200Z 14.9N 40.8W 40 KT 45 MPH
24H 14/0000Z 16.1N 42.3W 35 KT 40 MPH
36H 14/1200Z 17.3N 43.6W 35 KT 40 MPH
48H 15/0000Z 18.4N 44.7W 30 KT 35 MPH
60H 15/1200Z 19.2N 45.6W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 16/0000Z 20.1N 46.6W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 17/0000Z...DISSIPATED
FORECASTER BUCCI
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