080
WTNT43 KNHC 010245
TCDAT3
HURRICANE HUMBERTO DISCUSSION NUMBER 26
NWS NATIONAL HURRICANE CENTER MIAMI FL AL082025
1100 PM AST TUE SEP 30 2025
HUMBERTO CONTINUES TO PRODUCE A VERY LARGE AREA OF DEEP CONVECTION,
PRIMARILY TO THE NORTHEAST OF ITS CIRCULATION CENTER. HOWEVER, A
2106 UTC GPM MICROWAVE PASS RECEIVED AFTER THE PRIOR ADVISORY STILL
SHOWED THE LOW-LEVEL CENTER WAS MOSTLY EXPOSED ON THE SOUTHWEST EDGE
OF THE CIRRUS CANOPY. SATELLITE ESTIMATES HAVE ONLY BEEN IN THE
45-55 KT RANGE FOR THE LAST 6-12 HOURS. HOWEVER, A RECENTLY RECEIVED
ASCAT PASS SHOWED A PEAK WIND RETRIEVAL OF 61 KT, AND ASSUMING THE
SIGNIFICANT LOW BIAS OF THIS INSTRUMENT AT HURRICANE INTENSITY, THE
INITIAL INTENSITY IS BEING HELD AT 70 KT FOR THIS ADVISORY. WIND
RADII WERE ALSO ADJUSTED BASED ON THE SCATTEROMETER DATA.
THE HURRICANE APPEARS TO HAVE MADE AN EAST-NORTHEASTWARD TURN, BUT
HAS NOT ACCELERATED, WITH THE MOTION ESTIMATED AT 065/9 KT. A
LONGWAVE MID-LATITUDE TROUGH LOCATED TO THE NORTH OF HUMBERTO IS
QUICKLY DROPPING SOUTHWARD AND WILL SOON START TO IMPINGE UPON THE
HURRICANE'S CIRCULATION. THE RESULTING INTERACTION SHOULD CAUSE A
STRENGTHENING FRONTAL BOUNDARY TO FORM TO THE NORTHEAST OF
HUMBERTO'S CENTER. IN FACT, THE SCATTEROMETER DATA ALREADY SHOWS
THIS BOUNDARY BEGINNING TO DEVELOP IN THE CONVECTION. THE GLOBAL AND
HURRICANE-REGIONAL MODEL FIELDS NOW SHOW HUMBERTO'S CIRCULATION
QUICKLY BECOMING INDISTINGUISHABLE FROM THE INTENSIFYING BAROCLINIC
ZONE IN 18-24 H. THE LATEST NHC TRACK AND INTENSITY FORECAST WILL
NOW SHOW HUMBERTO MERGING WITH THIS BOUNDARY BY THAT TIME. THE
REMNANT VORTICITY OF THE STORM MAY ULTIMATELY BE ADVECTED
TOWARDS IMELDA'S CIRCULATION BEYOND THAT TIME FRAME, AS IT ALSO
INTERACTS WITH THE SAME BOUNDARY.
REGARDLESS OF HUMBERTO'S EVOLUTION, THE HURRICANE, IN COMBINATION
WITH IMELDA IS PRODUCING A LARGE AREA OF HAZARDOUS MARINE CONDITIONS
OVER THE WESTERN AND CENTRAL ATLANTIC, WHERE LIFE-THREATENING RIP
CURRENTS ARE EXPECTED TO AFFECT BEACHES THROUGHOUT THE REGION
THROUGH THE WEEK.
KEY MESSAGES:
1. DANGEROUS MARINE CONDITIONS, INCLUDING HIGH SURF AND
LIFE-THREATENING RIP CURRENTS, WILL CONTINUE TO AFFECT BEACHES OF
THE NORTHERN CARIBBEAN, BAHAMAS, BERMUDA, AND MUCH OF THE EAST COAST
OF THE UNITED STATES THROUGH THE WEEK.
FORECAST POSITIONS AND MAX WINDS
INIT 01/0300Z 34.8N 68.5W 70 KT 80 MPH
12H 01/1200Z 35.3N 67.4W 65 KT 75 MPH
24H 02/0000Z...MERGED WITH A FRONTAL BOUNDARY
FORECASTER PAPIN
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