492
WTNT45 KNHC 271443
TCDAT5
TROPICAL STORM TAMMY DISCUSSION NUMBER 33
NWS NATIONAL HURRICANE CENTER MIAMI FL AL202023
1100 AM AST FRI OCT 27 2023
TAMMY APPEARS TO HAVE BECOME SEPARATE FROM THE FRONTAL ZONE IN
WHICH IT WAS FORMERLY EMBEDDED. SATELLITE IMAGERY SHOWS THAT
MODERATELY DEEP CONVECTION HAS DEVELOPED IN A FAIRLY SYMMETRICAL
PATTERN NEAR THE CENTER, AND THERE ARE ALSO CONVECTIVE BANDS
SURROUNDING THE CENTER. THIS CHANGE IN STRUCTURE INDICATES THAT
THE SYSTEM HAS EVOLVED BACK INTO A TROPICAL CYCLONE, SO ADVISORIES
ARE BEING RE-INITIATED ON TAMMY. EXTRAPOLATION OF EARLIER
SCATTEROMETER DATA SUGGEST THAT THE CURRENT INTENSITY IS AROUND 55
KT.
OVER THE NEXT FEW DAYS, THE ATMOSPHERIC AND OCEANIC ENVIRONMENT
FOR TAMMY SHOULD RESULT IN GRADUAL WEAKENING. THE CYCLONE IS
CURRENTLY OVER MARGINAL SSTS, AND WESTERLY VERTICAL WIND SHEAR IS
LIKELY TO INCREASE. LATER IN THE FORECAST PERIOD, TAMMY WILL
PROBABLY MOVE OVER SLIGHTLY WARMER WATERS, BUT DRY AIR AND STRONG
SHEAR WILL LIKELY CAUSE CONTINUED WEAKENING. THE OFFICIAL
INTENSITY FORECAST IS ON THE HIGH SIDE OF THE MODEL GUIDANCE AND
SHOWS THE CYCLONE WEAKENING TO A DEPRESSION IN 5 DAYS, ALTHOUGH
GIVEN THE ENVIRONMENT THIS MAY OCCUR SOONER.
THE STORM IS DRIFTING SLOWLY NORTHWESTWARD, WITH A MOTION NEAR
320/3 KT. TAMMY SHOULD TURN EASTWARD IN 12 TO 24 HOURS UNDER THE
INFLUENCE OF MID-LEVEL WESTERLY FLOW ON THE NORTH SIDE OF A
SUBTROPICAL RIDGE. LATER IN THE FORECAST PERIOD, THE SYSTEM IS
EXPECTED TO TURN SOUTHEASTWARD AND SOUTHWARD ON THE EASTERN SIDE OF
A SUBTROPICAL ANTICYCLONE AND WEST OF A BROAD TROUGH OVER THE
EASTERN ATLANTIC. THE OFFICIAL FORECAST IS SIMILAR TO, BUT
SOMEWHAT SLOWER THAN, THE MODEL CONSENSUS PREDICTION AND ROUGHLY IN
THE MIDDLE OF THE TRACK GUIDANCE SUITE.
GUSTY WINDS ARE EXPECTED IN BERMUDA THROUGH TONIGHT, AND A GALE
WARNING IS IN EFFECT FOR THAT ISLAND.
FORECAST POSITIONS AND MAX WINDS
INIT 27/1500Z 32.2N 61.1W 55 KT 65 MPH
12H 28/0000Z 32.4N 61.3W 55 KT 65 MPH
24H 28/1200Z 32.7N 59.9W 50 KT 60 MPH
36H 29/0000Z 32.5N 57.5W 45 KT 50 MPH
48H 29/1200Z 32.0N 54.5W 45 KT 50 MPH
60H 30/0000Z 30.7N 51.4W 40 KT 45 MPH
72H 30/1200Z 29.0N 50.0W 40 KT 45 MPH
96H 31/1200Z 27.5N 50.0W 35 KT 40 MPH
120H 01/1200Z 28.0N 51.0W 30 KT 35 MPH
FORECASTER PASCH
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