135
WTNT44 KNHC 090858
TCDAT4
HURRICANE ISAIAS DISCUSSION NUMBER 11
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092026
400 AM CDT FRI OCT 09 2026
ISAIAS HAS INTENSIFIED OVERNIGHT. NOAA AND AIR FORCE RESERVE
HURRICANE HUNTER DATA SHOWED THAT THE MAXIMUM FLIGHT-LEVEL WINDS
HAVE INCREASED UP TO 107 KT, WITH A BETTER-DEFINED EYE AND A
SHRINKING EYEWALL. THESE CHANGES ARE ALSO PRESENT ON SATELLITE
IMAGERY, WITH A MORE SYMMETRIC PRESENTATION ALONG WITH A WARMING
EYE/COOLING EYEWALL. THE AVAILABLE DATA SUGGEST A CURRENT INTENSITY
OF 95 KT FOR THIS ADVISORY.
ISAIAS WILL LIKELY BECOME A MAJOR HURRICANE SOON WITH THE IMPROVING
SATELLITE IMAGERY, AND IT COULD CONTINUE TO INTENSIFY FOR THE NEXT
12 HOURS OR SO WHILE IT MOVES OVER VERY WARM AND DEEP WATER.
HOWEVER, A LARGE INCREASE IN SHEAR IS ANTICIPATED BEFORE LANDFALL,
WHICH WILL PROBABLY CAUSE SOME WEAKENING TO OCCUR. THIS IS A TENUOUS
SPOT BECAUSE IT WOULD ONLY TAKE ABOUT A 6H DELAY IN THE ONSET OF THE
SHEAR TO BRING A STRONGER HURRICANE THAN EXPECTED ONSHORE. THE NEW
FORECAST EXPLICITLY IS A BIT HIGHER THAN THE LAST ONE, BUT OUR BEST
FORECAST AT THIS TIME IS FOR A HIGH-END CATEGORY 2 INTENSITY AT
LANDFALL, WHICH IS ABOUT THE SAME AS BEFORE. REGARDLESS OF ITS
EXACT WIND SPEED AT LANDFALL, ISAIAS WILL BE A DANGEROUS HURRICANE
WITH SIGNIFICANT STORM SURGE, DAMAGING WINDS, AND FLOODING RAINS.
THE WIND FIELD IS ALSO PREDICTED TO GROW DUE TO A TROUGH
INTERACTION, AND SOME OF THESE IMPACTS WILL EXTEND WELL AWAY FROM
THE CENTER. AFTER LANDFALL, GUSTY WINDS ARE EXPECTED TO REACH WELL
INLAND OVER PORTIONS OF THE SOUTHEASTERN UNITED STATES.
ISAIAS HAS TURNED TOWARDS THE NORTH-NORTHEAST (020/13 KT), AND
THE HURRICANE IS EXPECTED TO TURN NORTHWARD AND ACCELERATE LATER
TODAY DUE TO INCREASING FLOW BETWEEN AN UPPER TROUGH NEAR THE
NORTHWESTERN GULF COAST AND A SUBTROPICAL RIDGE EXTENDING ACROSS
THE WESTERN ATLANTIC. LANDFALL IS EXPECTED TO OCCUR WITHIN THE
HURRICANE WARNING AREA FRIDAY NIGHT OR EARLY SATURDAY. THE NEW
FORECAST IS ALMOST THE SAME AS BEFORE, VERY NEAR THE GOOGLE DEEPMIND
GUIDANCE, WHICH HAS BEEN VERY ACCURATE FOR ISAIAS.
KEY MESSAGES:
1. A LIFE-THREATENING STORM SURGE IS EXPECTED FROM THE MOUTH OF THE
MISSISSIPPI RIVER TO SUWANNEE, FLORIDA. RESIDENTS IN THE WARNING
AREA SHOULD FOLLOW ADVICE GIVEN BY LOCAL OFFICIALS AND EVACUATE
IMMEDIATELY IF TOLD TO DO SO.
2. DAMAGING HURRICANE FORCE-WINDS ARE EXPECTED OVER PORTIONS OF THE
FLORIDA PANHANDLE, SOUTHERN ALABAMA, AND SOUTHERN MISSISSIPPI WHERE
A HURRICANE WARNING IS IN EFFECT. RESIDENTS IN THESE AREAS SHOULD
PREPARE FOR THE POSSIBILITY OF LONG-DURATION POWER OUTAGES.
3. DAMAGING WIND GUSTS ARE POSSIBLE OVER MUCH OF CENTRAL AND
NORTHERN ALABAMA, EXTREME EASTERN MISSISSIPPI, AND PORTIONS OF
WESTERN AND NORTHERN GEORGIA, ESPECIALLY IN AREAS OF HIGHER TERRAIN.
ADDITIONAL TROPICAL STORM AND HIGH WIND WATCHES AND WARNINGS MAY BE
REQUIRED FOR PORTIONS OF THAT AREA LATER TODAY. RESIDENTS SHOULD
SECURE LOOSE OUTDOOR ITEMS, AVOID DRIVING HIGH-PROFILE VEHICLES,
AND PREPARE FOR POWER OUTAGES.
4. ISAIAS WILL BRING AREAS OF HEAVY RAINFALL TO THE CENTRAL U.S.
GULF COAST AND MUCH OF THE SOUTHEAST THROUGH THE WEEKEND.
CONSIDERABLE FLASH AND URBAN FLOODING, ALONG WITH SIGNIFICANT RIVER
FLOODING, WILL BE POSSIBLE.
FORECAST POSITIONS AND MAX WINDS
INIT 09/0900Z 26.4N 88.0W 95 KT 110 MPH
12H 09/1800Z 28.4N 87.3W 105 KT 120 MPH
24H 10/0600Z 31.0N 87.1W 65 KT 75 MPH...INLAND
36H 10/1800Z 33.5N 87.5W 35 KT 40 MPH...POST-TROP/INLAND
48H 11/0600Z 35.5N 86.7W 25 KT 30 MPH...POST-TROP/INLAND
60H 11/1800Z 38.2N 83.1W 15 KT 15 MPH...POST-TROP/INLAND
72H 12/0600Z...DISSIPATED
FORECASTER BLAKE
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