238
WTNT44 KNHC 302039
TCDAT4
HURRICANE IMELDA DISCUSSION NUMBER 17
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092025
500 PM EDT TUE SEP 30 2025
THE HURRICANE CONTINUES TO GRADUALLY BECOME BETTER ORGANIZED, WITH
CURVED BANDING FEATURES BECOMING MORE PROMINENT OVER THE
CIRCULATION. DEEPEST CONVECTION IS NOTED OVER THE WESTERN
SEMICIRCLE OF THE SYSTEM WITH TOPS TO NEAR -70 DEG C. UPPER-LEVEL
OUTFLOW IS FAIRLY WELL-DEFINED AT THIS TIME. THE ADVISORY
INTENSITY IS SET AT 75 KT WHICH IS IN LINE WITH FLIGHT-LEVEL WIND
OBSERVATIONS FROM THE PREVIOUS HURRICANE HUNTER MISSION.
SUBJECTIVE AND OBJECTIVE DVORAK ESTIMATES ARE A LITTLE LOWER.
ANOTHER AIR FORCE RESERVE UNIT AIRCRAFT IS SCHEDULED TO INVESTIGATE
IMELDA SOON TO CHECK ON THE INTENSITY AND STRUCTURE OF THE TROPICAL
CYCLONE.
IMELDA IS MOVING A LITTLE FASTER TOWARD THE EAST-NORTHEAST WITH A
MOTION ESTIMATE OF 060/10 KT. A MID-TROPOSPHERIC TROUGH NEAR THE
U.S. EAST COAST SHOULD CAUSE THE HURRICANE TO CONTINUE TO ACCELERATE
EAST-NORTHEASTWARD OVER THE NEXT COUPLE OF DAYS. THE FORECAST TRACK
BRINGS THE CENTER OF THE HURRICANE NEAR BERMUDA IN LESS THAN 36
HOURS, WITH TROPICAL STORM CONDITIONS EXPECTED TO REACH BERMUDA BY
TOMORROW AFTERNOON. THERE WILL LIKELY BE SOME BINARY INTERACTIONS
BETWEEN IMELDA AND HUMBERTO SINCE THE CIRCULATIONS OF THE TWO
SYSTEMS ARE GETTING VERY CLOSE TOGETHER. HOWEVER, IT IS DIFFICULT
TO SPECIFY HOW SIGNIFICANTLY THIS INTERACTION WILL AFFECT
IMELDA'S TRACK. THE OFFICIAL FORECAST IS NEAR THE SOUTHERN EDGE
OF THE MODEL GUIDANCE SUITE.
THE HURRICANE IS EXPECTED TO BE WITHIN AN ENVIRONMENT OF MODERATE
OR STRONGER VERTICAL WIND SHEAR, BUT IN A FAVORABLE THERMODYNAMIC
ENVIRONMENT DURING THE NEXT DAY OR SO. AN UPPER-LEVEL TROUGH TO
THE NORTHWEST OF IMELDA COULD CONTRIBUTE TO STRENGTHENING DUE TO
BAROCLINIC FORCING AND UPPER-LEVEL DIVERGENCE WHILE THE SYSTEM
NEARS BERMUDA. THIS COULD RESULT IN A FAIRLY POTENT, IF NOT AN
ENTIRELY TROPICAL, CYCLONE PASSING NEAR THE ISLAND TOMORROW. LATER
IN THE FORECAST PERIOD, THE GLOBAL MODELS SHOW THE SYSTEM MERGING
WITH A BROAD BAROCLINIC ZONE OVER THE NORTH ATLANTIC, AND THE
SIMULATED SATELLITE IMAGERY FROM THESE MODELS TAKES ON THE
APPEARANCE OF AN EXTRATROPICAL CYCLONE IN 2-3 DAYS.
KEY MESSAGES:
1. IMELDA IS EXPECTED BRING DAMAGING HURRICANE-FORCE-WINDS TO
BERMUDA WHEN IT PASSES NEAR OR OVER THAT ISLAND BY WEDNESDAY
AFTERNOON OR EVENING. A HURRICANE WARNING IS IN EFFECT FOR
BERMUDA.
2. IMELDA IS LIKELY TO CAUSE LARGE AND DAMAGING WAVES IN BERMUDA.
3. HEAVY RAINFALL COULD CAUSE FLASH FLOODING ACROSS BERMUDA
WEDNESDAY INTO THURSDAY.
4. 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 30/2100Z 29.4N 75.5W 75 KT 85 MPH
12H 01/0600Z 30.0N 73.1W 80 KT 90 MPH
24H 01/1800Z 31.2N 68.7W 85 KT 100 MPH
36H 02/0600Z 32.8N 63.4W 85 KT 100 MPH
48H 02/1800Z 34.9N 56.7W 80 KT 90 MPH
60H 03/0600Z 38.0N 51.5W 70 KT 80 MPH...POST-TROP/EXTRATROP
72H 03/1800Z 40.4N 49.1W 60 KT 70 MPH...POST-TROP/EXTRATROP
96H 04/1800Z 45.5N 43.0W 50 KT 60 MPH...POST-TROP/EXTRATROP
120H 05/1800Z 52.5N 32.0W 35 KT 40 MPH...POST-TROP/EXTRATROP
FORECASTER PASCH
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