938
WTNT43 KNHC 290854
TCDAT3
HURRICANE HUMBERTO DISCUSSION NUMBER 19
NWS NATIONAL HURRICANE CENTER MIAMI FL AL082025
500 AM AST MON SEP 29 2025
HUMBERTO HAS GONE THROUGH SOME INNER-CORE STRUCTURAL CHANGES.
EARLIER AIRCRAFT DATA INDICATED THAT THE HURRICANE HAD A DOUBLE
EYEWALL STRUCTURE, BUT A 29/0546 UTC AMSR2 MICROWAVE PASS INDICATES
THAT THE INNER EYEWALL IS STARTING TO GET OVERTAKEN BY THE OUTER
EYEWALL. GIVEN THE THE APPARENT CONTINUED WEAKENING OF THE INNER
EYEWALL AS INFERRED FROM GOES-19 IMAGERY SINCE THE TIME OF THE
MICROWAVE PASS, HUMBERTO'S MAXIMUM SUSTAINED WINDS ARE PROBABLY NEAR
THE LOWER END OF THE RECENT OBJECTIVE AND SUBJECTIVE ESTIMATES, SO
THE INITIAL INTENSITY IS NUDGED DOWNWARD SLIGHTLY TO 115 KT.
ANOTHER AIR FORCE PLANE WILL BE IN HUMBERTO IN A FEW HOURS TO BETTER
ASSESS THE INTENSITY.
HUMBERTO IS STILL MOVING NORTHWESTWARD, OR 320 DEGREES AT 12 KT IN
THE FLOW ON THE SOUTH-SOUTHWEST SIDE OF A SUBTROPICAL HIGH. THE
MAJOR HURRICANE IS EXPECTED TO GRADUALLY TURN TO THE NORTH OVER THE
NEXT 24 HOURS AS THE HIGH SHIFTS TO THE EAST AND WEAKENS. AFTER
THAT, A TROUGH IS EXPECTED TO AMPLIFY OVER THE NORTH ATLANTIC, AND
THAT SHOULD CAUSE HUMBERTO TO TURN SHARPLY AND ACCELERATE
EAST-NORTHEASTWARD TUESDAY NIGHT AND WEDNESDAY. THE NHC FORECAST IS
SIMILAR TO THE PREVIOUS ONE THROUGH 24 H, BUT THEN HAS BEEN SHIFTED
SLIGHTLY TO THE NORTHWEST, OR LEFT, OF THE PREVIOUS FORECAST AFTER
THAT TIME, CLOSE TO THE LATEST MODEL CONSENSUS. CONFIDENCE IN THE
TRACK FORECAST IS HIGH THROUGH 48 H. WHILE THERE IS HIGH CONFIDENCE
THAT THE CORE OF HUMBERTO WILL MISS BERMUDA, THERE IS A POSSIBILITY
OF TROPICAL-STORM-FORCE WINDS OCCURRING THERE LATE TUESDAY AND
WEDNESDAY IN HUMBERTO'S OUTER BANDS.
THE INTENSITY OF HUMBERTO WILL LIKELY FLUCTUATE OVER THE NEXT 12 H
OR SO, BUT GRADUAL WEAKENING IS EXPECTED AFTER THAT DUE TO
INCREASING SHEAR AND DECREASING SSTS. EXTRATROPICAL TRANSITION IS
EXPECTED TO BE COMPLETE IN 60-72 HOURS WHEN THE SYSTEM IS FORECAST
TO MERGE WITH THE AFOREMENTIONED MID- TO UPPER-LEVEL TROUGH AND
DEVELOP FRONTAL FEATURES. THE NHC INTENSITY FORECAST IS BETWEEN THE
MIDDLE AND HIGHER END OF THE GUIDANCE ENVELOPE. THE HURRICANE IS
EXPECTED TO GROW IN SIZE AS IT GAINS LATITUDE DURING THE NEXT FEW
DAYS, WHICH WILL RESULT IN A LARGE AREA OF ROUGH SEAS. SEE KEY
MESSAGES BELOW FOR MORE INFORMATION.
KEY MESSAGES:
1. TROPICAL-STORM-FORCE WINDS COULD BEGIN TO AFFECT BERMUDA BY LATE
TUESDAY, AND A TROPICAL STORM WATCH IS IN EFFECT FOR THE ISLAND.
INTERESTS THERE SHOULD CONTINUE TO MONITOR THE PROGRESS OF HUMBERTO.
2. DANGEROUS MARINE CONDITIONS, INCLUDING HIGH SURF AND
LIFE-THREATENING RIP CURRENTS, ARE AFFECTING BEACHES OF THE NORTHERN
CARIBBEAN, BAHAMAS, AND BERMUDA. THE DANGEROUS SURF CONDITIONS ARE
EXPECTED TO BEGIN AFFECTING MUCH OF THE EAST COAST OF THE U.S.
TODAY.
FORECAST POSITIONS AND MAX WINDS
INIT 29/0900Z 27.2N 66.9W 115 KT 130 MPH
12H 29/1800Z 28.6N 68.0W 115 KT 130 MPH
24H 30/0600Z 30.9N 68.9W 105 KT 120 MPH
36H 30/1800Z 33.3N 68.7W 95 KT 110 MPH
48H 01/0600Z 35.4N 66.7W 90 KT 105 MPH
60H 01/1800Z 36.9N 61.7W 85 KT 100 MPH
72H 02/0600Z 39.0N 54.5W 80 KT 90 MPH...POST-TROP/EXTRATROP
96H 03/0600Z...DISSIPATED
FORECASTER HAGEN
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