588
WTNT41 KNHC 220833
TCDAT1
TROPICAL STORM OSCAR DISCUSSION NUMBER 13
NWS NATIONAL HURRICANE CENTER MIAMI FL AL162024
500 AM EDT TUE OCT 22 2024
OSCAR IS AT BEST BARELY A TROPICAL STORM AT THIS TIME. WHILE
CONVECTION ASSOCIATED WITH THE SYSTEM HAS INCREASED SINCE THE LAST
ADVISORY, MOST OF IT IS OCCURRING IN CLUSTERS WELL AWAY FROM THE
CENTER IN THE EASTERN SEMICIRCLE, AND THERE IS ONLY MINIMAL
CONVECTION NEAR THE CENTER. ALSO, WHILE 850 MB FLIGHT-LEVEL WINDS
WERE AS HIGH AS 45-50 KT DURING AN EARLIER AIR FORCE RESERVE
HURRICANE HUNTER MISSION, DROPSONDE AND SFMR DATA SUGGESTS THOSE
WINDS WERE HAVING TROUBLE MIXING DOWN TO THE SURFACE. THE SYSTEM
WILL BE MAINTAINED AS A 35-KT TROPICAL STORM PENDING THE NEXT RECON
FLIGHT AND WHETHER CONVECTION WILL INCREASE FURTHER DURING THE
UPCOMING DIURNAL MAXIMUM.
THE GLOBAL MODELS ARE IN GOOD AGREEMENT THAT A DEVELOPING MID- TO
UPPER-LEVEL TROUGH OVER THE SOUTHWESTERN ATLANTIC WILL CAUSE
BAROCLINIC CYCLOGENESIS NEAR OR NORTH OF OSCAR DURING THE NEXT
24-48 H. THE UKMET SHOWS OSCAR BECOME THE MAIN FOCUS FOR THE
DEVELOPMENT AND BECOMING A LARGE EXTRATROPICAL LOW, WHILE THE GFS
DEVELOPS A SECOND LOW TO THE NORTH OF OSCAR WITH OSCAR BECOMING
ABSORBED INTO THE NEW SYSTEM. THE ECMWF AND CANADIAN MODELS
FORECAST A BLEND OF THESE SCENARIOS, WITH THE BAROCLINIC LOW FORMING
CLOSE TO OSCAR. GIVEN OSCAR'S ORGANIZATION AND CURRENT TRENDS IN
SATELLITE IMAGERY, THE INTENSITY FORECAST LEANS TOWARDS THE GFS
SOLUTION, WITH OSCAR BECOMING A POST-TROPICAL LOW IN LESS THAN 24 H
AND THEN BEING ABSORBED BY THE NEW LOW IN 36-48 H.
THE INITIAL MOTION IS NOW 030/10 KT. INTERACTION WITH THE ABOVE
MENTIONED TROUGH SHOULD STEER OSCAR GENERALLY NORTHEASTWARD WITH AN
INCREASE IN FORWARD SPEED UNTIL IT IS ABSORBED BY THE NEW
BAROCLINIC LOW. THE NEW FORECAST TRACK IS SIMILAR TO THE PREVIOUS
TRACK.
KEY MESSAGES:
1. THROUGH TUESDAY, LOCALIZED FLASH FLOODING WILL BE POSSIBLE ACROSS
THE SOUTHEASTERN BAHAMAS AS WELL AS THE TURKS AND CAICOS ISLANDS.
WITH RAINFALL EASING ACROSS CUBA, FLOODING FROM RAINFALL WHICH HAS
ALREADY OCCURRED COULD REMAIN A CONCERN FOR THE NEXT SEVERAL DAYS.
2. TROPICAL STORM CONDITIONS ARE EXPECTED IN PORTIONS OF THE
SOUTHEASTERN AND CENTRAL BAHAMAS TODAY.
FORECAST POSITIONS AND MAX WINDS
INIT 22/0900Z 22.7N 74.8W 35 KT 40 MPH
12H 22/1800Z 23.8N 73.8W 35 KT 40 MPH
24H 23/0600Z 25.7N 71.7W 35 KT 40 MPH...POST-TROPICAL
36H 23/1800Z 28.5N 69.5W 35 KT 40 MPH...POST-TROP/EXTRATROP
48H 24/0600Z...DISSIPATED
FORECASTER BEVEN
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