957
WTNT44 KNHC 080253
TCDAT4
TROPICAL STORM ISAIAS DISCUSSION NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092026
1000 PM CDT WED OCT 07 2026
AIRCRAFT DATA AND SATELLITE TRENDS INDICATE ISAIAS HAS CONTINUED
INTENSIFYING THIS EVENING. THE CENTER OF THE TROPICAL CYCLONE IS
EMBEDDED UNDERNEATH A SMALL CENTRAL DENSE OVERCAST WITH VERY COLD
TOPS ASSOCIATED WITH DEEP CONVECTION. UPPER-LEVEL OUTFLOW IS
OBSERVED IN ALL QUADRANTS, THOUGH IT REMAINS SOMEWHAT RESTRICTED TO
THE SOUTHWEST DUE TO MODERATE VERTICAL WIND SHEAR. DATA FROM THE AIR
FORCE HURRICANE HUNTERS INDICATES THE CENTRAL PRESSURE HAS FALLEN TO
988 MB, AND ON THE LAST FIX THEY REPORTED A CIRCULAR EYEWALL OPEN TO
THE SOUTHWEST. BASED ON THESE DEVELOPMENTS, THE INITIAL INTENSITY IS
RAISED TO 60 KT.
AIRCRAFT FIXES INDICATE THE CENTER IS STILL MOVING TOWARD THE
EAST-NORTHEAST (070/8 KT). THE SYSTEM IS EXPECTED TO ACCELERATE
NORTHEASTWARD TOMORROW AND THEN NORTHWARD ON FRIDAY WITHIN THE FLOW
BETWEEN A DEEPENING TROUGH OVER THE SOUTH-CENTRAL UNITED STATES AND
A STRENGTHENING SUBTROPICAL RIDGE OVER THE WESTERN ATLANTIC. THIS
STEERING PATTERN IS FORECAST TO BRING THE CENTER OF ISAIAS TO THE
NORTHERN GULF COAST LATE FRIDAY NIGHT INTO EARLY SATURDAY. THERE
WERE NO MAJOR CHANGES TO THE GUIDANCE SUITE, WITH THE AI-BASED
MODELS GENERALLY FASTER AND FARTHER RIGHT THAN THE PHYSICS-BASED
MODELS. THE NHC FORECAST CONTINUES TO LEAN MORE HEAVILY ON THE
BETTER-PERFORMING CORRECTED CONSENSUS (HCCA) AND GOOGLE DEEPMIND
(GDMI) AIDS, REMAINING ON THE FASTER AND RIGHT SIDE OF THE GUIDANCE
ENVELOPE. THE INLAND TRACK AT 60-72 H WAS SHIFTED WESTWARD AS MORE
MODELS NOW SHOW ISAIAS BECOMING CAPTURED BY THE CUTOFF LOW OVER THE
SOUTHEASTERN UNITED STATES.
CONTINUED STRENGTHENING IS EXPECTED DURING THE NEXT DAY OR SO AS
ISAIAS MOVES OVER VERY WARM WATERS IN A MOIST ENVIRONMENT WITH
MODERATE VERTICAL WIND SHEAR. GIVEN ITS SMALL SIZE AND FORMATIVE
INNER CORE, RAPID INTENSIFICATION IS A DISTINCT POSSIBILITY, AND THE
NHC FORECAST LIES ON THE HIGH END OF THE INTENSITY GUIDANCE. THE
SHEAR IS PREDICTED TO MARKEDLY INCREASE ON FRIDAY WHILE ISAIAS
APPROACHES THE NORTHERN GULF COAST, BUT THE SYSTEM IS EXPECTED TO
REMAIN A DANGEROUS HURRICANE THROUGH LANDFALL. GUSTY WINDS ARE
EXPECTED WELL INLAND AFTER LANDFALL GIVEN THE ANTICIPATED EXPANSION
OF THE WIND FIELD AND FAST FORWARD SPEED OF THE STORM.
HURRICANE, STORM SURGE, AND TROPICAL STORM WARNINGS HAVE BEEN
ISSUED WITH THIS ADVISORY FOR PORTIONS OF THE NORTHERN GULF COAST.
KEY MESSAGES:
1. ISAIAS IS EXPECTED TO STRENGTHEN AND BE A STRONG HURRICANE WHEN
IT APPROACHES THE NORTHERN GULF COAST ON FRIDAY. A LIFE-THREATENING
STORM SURGE IS EXPECTED ALONG A PORTION OF THE NORTHERN GULF COAST,
AND A STORM SURGE WARNING IS NOW IN EFFECT FROM THE MOUTH OF THE
MISSISSIPPI RIVER TO STEINHATCHEE, FLORIDA. RESIDENTS IN THE WARNING
AREA SHOULD FOLLOW ADVICE GIVEN BY LOCAL OFFICIALS AND EVACUATE IF
TOLD TO DO SO.
2. DAMAGING HURRICANE FORCE-WINDS ARE EXPECTED OVER PORTIONS OF THE
FLORIDA PANHANDLE, SOUTHERN ALABAMA, AND SOUTHERN MISSISSIPPI, AND A
HURRICANE WARNING IS NOW IN EFFECT FROM OCEAN SPRINGS, MISSISSIPPI
TO THE BAY/GULF COUNTY LINE, FLORIDA. RESIDENTS IN THESE AREAS
SHOULD PREPARE FOR THE POSSIBILITY OF LONG-DURATION POWER OUTAGES.
3. ISAIAS WILL BRING AREAS OF HEAVY RAINFALL TO THE CENTRAL U.S.
GULF COAST AND MUCH OF THE SOUTHEAST FRIDAY INTO THE WEEKEND. FLASH
AND URBAN FLOODING, ALONG WITH ISOLATED RIVER FLOODING, WILL BE
POSSIBLE.
4. ISAIAS COULD BRING GUSTY WINDS AND AREAS OF HEAVY RAIN TO THE
WESTERN PORTION OF THE YUCATAN PENINSULA THROUGH THURSDAY.
FORECAST POSITIONS AND MAX WINDS
INIT 08/0300Z 22.9N 91.9W 60 KT 70 MPH
12H 08/1200Z 23.4N 90.7W 75 KT 85 MPH
24H 09/0000Z 24.7N 89.1W 85 KT 100 MPH
36H 09/1200Z 26.8N 87.9W 95 KT 110 MPH
48H 10/0000Z 29.6N 87.3W 90 KT 105 MPH
60H 10/1200Z 32.5N 87.5W 50 KT 60 MPH...INLAND
72H 11/0000Z 35.1N 88.0W 25 KT 30 MPH...POST-TROP/INLAND
96H 12/0000Z...DISSIPATED
FORECASTER REINHART
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