016
WTNT44 KNHC 112036
TCDAT4
TROPICAL STORM SEAN DISCUSSION NUMBER 4
NWS NATIONAL HURRICANE CENTER MIAMI FL AL192023
500 PM AST WED OCT 11 2023
SEAN REMAINS POORLY ORGANIZED THIS AFTERNOON. SATELLITE IMAGES SHOW
A RAGGED CONVECTIVE PATTERN WITH THE LOW-LEVEL CENTER LOCATED ON THE
WEST SIDE OF A FRAGMENTED CURVED BAND, A BIT MORE NORTH THAN
PREVIOUSLY ESTIMATED. THE DVORAK ESTIMATES REMAIN STEADY AT T2.5/35
KT, SO THE INITIAL INTENSITY IS HELD AT 35 KT. HOWEVER, AS MENTIONED
THIS MORNING, THIS WIND SPEED ESTIMATE COULD BE A LITTLE GENEROUS
BASED ON THE EARLIER ASCAT PASS.
THE STORM IS CURRENTLY EXPERIENCING MODERATE TO STRONG SOUTHWESTERLY
WIND SHEAR, AND MAY ONLY HAVE A BRIEF OPPORTUNITY TO STRENGTHEN
OVER THE NEXT COUPLE OF DAYS BEFORE IT MOVES INTO AN ENVIRONMENT OF
DRIER AIR BY THE END OF THE WEEK. OVER THE WEEKEND, ANOTHER ROUND OF
SHEAR SHOULD CAUSE SEAN TO ULTIMATELY WEAKEN AND THEN DEGENERATE
INTO A REMNANT LOW IN 4 TO 5 DAYS. THE NHC INTENSITY FORECAST HAS
NOT CHANGED MUCH FROM THE PREVIOUS ADVISORY AND IS WITHIN THE
GUIDANCE ENVELOPE.
SEAN IS MOVING WEST-NORTHWESTWARD AT ABOUT 11 KT, AND IS EXPECTED TO
CONTINUE MOVING IN THIS GENERAL DIRECTION OVER THE NEXT DAY OR TWO.
AFTER 48 HOURS, THE STORM WILL BEGIN TO TURN TO THE NORTHWEST AS IT
MOVES ALONG THE SOUTHWESTERN PORTION OF A MID-LEVEL RIDGE TO ITS
NORTHEAST. OVER THE WEEKEND, A TURN BACK TO THE WEST-NORTHWEST OR
WEST IS ANTICIPATED AS A LOW- TO MID-LEVEL RIDGE RE-ESTABLISHES
ITSELF TO THE NORTH OF SEAN AND IT BECOMES A MORE SHALLOW CYCLONE.
THE NHC TRACK FORECAST HAS BEEN SHIFTED NORTHWARD OF THE PREVIOUS
ONE OVER THE ENTIRE FORECAST PERIOD BASED ON THE INITIAL POSITION
AND SUBSEQUENT MODEL GUIDANCE.
FORECAST POSITIONS AND MAX WINDS
INIT 11/2100Z 11.6N 35.3W 35 KT 40 MPH
12H 12/0600Z 12.1N 36.5W 35 KT 40 MPH
24H 12/1800Z 12.7N 38.1W 40 KT 45 MPH
36H 13/0600Z 13.4N 39.7W 40 KT 45 MPH
48H 13/1800Z 14.3N 41.1W 40 KT 45 MPH
60H 14/0600Z 15.3N 42.3W 35 KT 40 MPH
72H 14/1800Z 16.4N 43.6W 35 KT 40 MPH
96H 15/1800Z 18.1N 46.1W 30 KT 35 MPH
120H 16/1800Z 18.7N 50.2W 30 KT 35 MPH...POST-TROP/REMNT LOW
FORECASTER CAMPOSANO/CANGIALOSI
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