446
WTNT44 KNHC 300248
TCDAT4
TROPICAL STORM IMELDA DISCUSSION NUMBER 14
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092025
1100 PM EDT MON SEP 29 2025
SATELLITE IMAGERY AND REPORTS FROM AN AIR FORCE RESERVE HURRICANE
HUNTER AIRCRAFT INDICATE THAT IMELDA HAS LOST SOME ORGANIZATION
SINCE THE LAST ADVISORY. THE AIRCRAFT DATA SHOWS A BROAD CENTER
WITH A RADIUS OF MAXIMUM WINDS OF AT LEAST 35 N MI, AND THE
SATELLITE IMAGERY CURRENTLY SHOWS NO ORGANIZED CONVECTION NEAR THE
AIRCRAFT-REPORTED CENTER. IN ADDITION, SATELLITE FIXES FROM TAFB
AND SAB WERE WELL TO THE NORTHEAST OF THE AIRCRAFT POSITION,
SUGGESTING THE VORTEX HAS A SIGNIFICANT VERTICAL TILT. DESPITE
THE RAGGED STRUCTURE, THE AIRCRAFT-REPORTED WINDS SUPPORT KEEPING
AN INITIAL INTENSITY OF 55 KT.
THE INITIAL MOTION IS NOW 010/7 KT. A TURN TOWARD THE NORTHEAST IS
EXPECTED TONIGHT, FOLLOWED BY A TURN TOWARD THE EAST-NORTHEAST AND
A FASTER FORWARD SPEED. THIS CHANGE IS DUE PARTLY TO HURRICANE
HUMBERTO ERODING THE STEERING INFLUENCE OF A SUBTROPICAL RIDGE EAST
OF BERMUDA, AND PARTLY DUE TO A DEEP-LAYER TROUGH THAT IS DIGGING
SOUTHWARD TO THE NORTH AND NORTHWEST OF IMELDA. THE TRACK GUIDANCE
OVERALL IS A BIT SLOWER THAN EARLIER, AND BASED ON THIS THE NEW
FORECAST TRACK IS A LITTLE SLOWER THAN THE PREVIOUS TRACK. THE NEW
FORECAST TRACK INDICATES THAT TROPICAL STORM CONDITIONS ARE
EXPECTED TO BEGIN ON THE ISLAND OF BERMUDA IN 36-48 H.
IMELDA IS CURRENTLY IN AN UPPER-LEVEL WIND ENVIRONMENT THAT HAS
MODERATE SHEAR, BUT IS STRONGLY DIVERGENT, AND THIS IS FORECAST TO
CONTINUE FOR THE NEXT 36-48 H. THIS SHOULD ALLOW SOME
STRENGTHENING. HOWEVER, THE CURRENT STATE OF THE STORM IS NOT
CONDUCIVE, AND THUS THE NEW INTENSITY FORECAST CALLS FOR SLOWER
STRENGTHENING THAN THE PREVIOUS FORECAST. IN 48-60 H, THE SHEAR
INCREASES, AND INTERACTION WITH THE DEEP-LAYER TROUGH WILL LIKELY
START THE EXTRATROPICAL TRANSITION PROCESS. THIS SHOULD BE COMPLETE
BY 72 H. WHILE THERE MAY BE "STING JET" WINDS DURING THE TRANSITION
AS MENTIONED IN THE PREVIOUS DISCUSSION, THE GUIDANCE IS IN GOOD
AGREEMENT THAT THE SYSTEM SHOULD STEADILY DECAY AFTER THE TRANSITION
IS COMPLETE. OVERALL, THE NEW INTENSITY FORECAST IS A LITTLE WEAKER
COMPARED TO THE PREVIOUS FORECAST.
KEY MESSAGES:
1. IMELDA IS EXPECTED TO INTENSIFY INTO A HURRICANE TUESDAY OR
TUESDAY NIGHT WITH THE CYCLONE APPROACHING BERMUDA DURING THE DAY
WEDNESDAY AS A HURRICANE. A HURRICANE WATCH IS IN EFFECT FOR THE
ISLAND OF BERMUDA DUE TO THE EXPECTED ONSET OF TROPICAL STORM
CONDITIONS BEGINNING WEDNESDAY AFTERNOON.
2. LOCALLY HEAVY RAINFALL ACROSS COASTAL SECTIONS OF SOUTHEAST
NORTH CAROLINA COULD CAUSE ISOLATED FLASH AND URBAN FLOODING
THROUGH TONIGHT. AS IMELDA PASSES NEAR BERMUDA, 2 TO 4 INCHES – 50
TO 100 MM – OF RAINFALL IS EXPECTED FROM WEDNESDAY INTO THURSDAY.
3. SWELLS AND HIGH SURF FROM BOTH HUMBERTO AND IMELDA ARE EXPECTED
TO PRODUCE DANGEROUS MARINE CONDITIONS AND RIP CURRENTS ALONG MUCH
OF THE EAST COAST OF THE UNITED STATES DURING THE NEXT SEVERAL DAYS.
FORECAST POSITIONS AND MAX WINDS
INIT 30/0300Z 28.4N 77.2W 55 KT 65 MPH
12H 30/1200Z 29.2N 76.3W 60 KT 70 MPH
24H 01/0000Z 30.1N 74.1W 65 KT 75 MPH
36H 01/1200Z 31.1N 70.7W 75 KT 85 MPH
48H 02/0000Z 32.4N 66.0W 80 KT 90 MPH
60H 02/1200Z 33.8N 60.7W 75 KT 85 MPH
72H 03/0000Z 35.2N 55.7W 65 KT 75 MPH...POST-TROP/EXTRATROP
96H 04/0000Z 39.4N 50.3W 55 KT 65 MPH...POST-TROP/EXTRATROP
120H 05/0000Z 43.1N 46.6W 45 KT 50 MPH...POST-TROP/EXTRATROP
FORECASTER BEVEN
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page