683
WTNT44 KNHC 020850
TCDAT4
HURRICANE IMELDA DISCUSSION NUMBER 23
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092025
500 AM AST THU OCT 02 2025
THE CENTER OF IMELDA PASSED JUST SOUTH OF BERMUDA A FEW HOURS AGO,
WITH SUSTAINED HURRICANE FORCE WINDS REPORTED AT ONE OF THE
ELEVATED STATIONS THERE. SINCE THEN, THE CYCLONE HAS CONTINUED TO
PRODUCE A CENTRAL CONVECTIVE FEATURE, AND RADAR DATA FROM BERMUDA
SHOWS FRAGMENTS OF SPIRAL BANDS TO THE NORTH OF THE CENTER.
OVERALL, IT APPEARS THAT IMELDA IS CONTINUING THROUGH EXTRATROPICAL
TRANSITION, BUT THE PROCESS IS NOT FINISHED YET. SATELLITE
INTENSITY ESTIMATES HAVE DECREASED, AND BASED ON THESE THE INITIAL
INTENSITY IS LOWERED TO A POSSIBLY GENEROUS 75 KT.
THE INITIAL MOTION REMAINS QUICKLY EAST-NORTHEASTWARD OR 075/26 KT.
THIS GENERAL MOTION IS LIKELY TO CONTINUE FOR THE NEXT 12-24 H.
AFTER THAT, THE CYCLONE SHOULD PHASE WITH A DIGGING MID-LATITUDE
TROUGH THAT IS CURRENTLY NORTH OF THE SYSTEM, WITH THIS TROUGH
EVENTUALLY BECOMING A DEEP-LAYER CUT-OFF LOW OVER IMELDA'S
LOW-LEVEL CENTER. THIS EVOLUTION SHOULD CAUSE THE SURFACE CENTER TO
MOVE GENERALLY NORTHEASTWARD FROM 24-72 H WITH A DECREASE IN
FORWARD SPEED. AN EAST-NORTHEASTWARD MOTION IS EXPECTED BY THE END
OF THE FORECAST PERIOD AS THE CYCLONE GETS MORE EMBEDDED IN THE
MID-LATITUDE FLOW. THE NEW FORECAST TRACK IS SIMILAR TO THE
PREVIOUS TRACK THROUGH 72 H, AND THEN IS SLOWER THAN AND SOUTH OF
THE PREVIOUS TRACK AT 96 AND 120 H.
CURRENT TRENDS AND GLOBAL MODEL GUIDANCE SUGGEST THAT IMELDA SHOULD
COMPLETE EXTRATROPICAL TRANSITION LATER TODAY. PHASING WITH THE
ABOVE-MENTIONED MID-LATITUDE TROUGH SHOULD HELP THE SYSTEM MAINTAIN
ITS INTENSITY FOR THE NEXT 3-4 DAYS, AND THE INTENSITY FORECAST HAS
BEEN NUDGED UPWARD A BIT TO MATCH A BLEND OF THE GLOBAL MODEL WIND
FORECASTS. AFTER 96 H, THE GLOBAL MODELS FORECAST THE SYSTEM TO
WEAKEN QUICKLY AS THE SURFACE LOW SEPARATES FROM THE UPPER-LEVEL
CENTER, AND THIS IS ALSO REFLECTED IN THE NEW INTENSITY FORECAST.
KEY MESSAGES:
1. IMELDA'S CORE HAS PASSED BERMUDA, AND CONDITIONS ON THE ISLAND
ARE IMPROVING. HOWEVER, TROPICAL STORM CONDITIONS ARE EXPECTED TO
CONTINUE FOR A FEW MORE HOURS.
2. THE THREAT OF HEAVY RAINFALL ON BERMUDA HAS DIMINISHED.
3. SWELLS AND HIGH SURF FROM IMELDA ARE EXPECTED TO PRODUCE
DANGEROUS MARINE CONDITIONS AND RIP CURRENTS ALONG MUCH OF THE EAST
COAST OF THE UNITED STATES AND THE WESTERN ATLANTIC DURING THE NEXT
SEVERAL DAYS.
FORECAST POSITIONS AND MAX WINDS
INIT 02/0900Z 32.8N 61.9W 75 KT 85 MPH
12H 02/1800Z 33.5N 57.7W 70 KT 80 MPH...POST-TROP/EXTRATROP
24H 03/0600Z 35.0N 52.9W 65 KT 75 MPH...POST-TROP/EXTRATROP
36H 03/1800Z 37.2N 50.2W 60 KT 70 MPH...POST-TROP/EXTRATROP
48H 04/0600Z 39.8N 48.3W 55 KT 65 MPH...POST-TROP/EXTRATROP
60H 04/1800Z 42.8N 45.7W 55 KT 65 MPH...POST-TROP/EXTRATROP
72H 05/0600Z 45.8N 41.7W 50 KT 60 MPH...POST-TROP/EXTRATROP
96H 06/0600Z 49.2N 32.6W 50 KT 60 MPH...POST-TROP/EXTRATROP
120H 07/0600Z 50.8N 25.8W 40 KT 45 MPH...POST-TROP/EXTRATROP
FORECASTER BEVEN
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