164
WTPZ44 KNHC 251444
TCDEP4
TROPICAL STORM ISELLE DISCUSSION NUMBER 9
NWS NATIONAL HURRICANE CENTER MIAMI FL EP092026
800 AM PDT TUE AUG 25 2026
ISELLE CONTINUES TO PRODUCE A LARGE AREA OF DEEP CONVECTION NEAR
AND WELL NORTHEAST OF THE CENTER. A GCOM-AMSR2 MICROWAVE
PASS FROM A FEW HOURS AGO SHOWED THAT THE SYSTEM IS ON THE EDGE OF
THE CONVECTIVE MASS, AND THE LOW-LEVEL CENTER IS DISPLACED TO THE
SOUTHWEST OF THE MID-LEVEL CIRCULATION. SATELLITE ESTIMATES SUPPORT
KEEPING ISELLE A 60-KT TROPICAL STORM FOR THIS ADVISORY. GRADUAL
WEAKENING IS ANTICIPATED DURING THE NEXT FEW DAYS DUE TO PERSISTENT
WESTERLY SHEAR, COOLING WATERS AND A DRY MID-LEVEL ATMOSPHERE.
ISELLE SHOULD LOSE ALL DEEP CONVECTION IN ABOUT 2 DAYS DUE TO A
HOSTILE ENVIRONMENT, AND POST-TROPICAL STATUS IS ANTICIPATED AFTER
THAT TIME. MODEL GUIDANCE IS IN VERY GOOD AGREEMENT ON THE SLOW
DECAY, AND NO SIGNIFICANT CHANGES WERE MADE TO THE LAST NHC
FORECAST.
MICROWAVE FIXES INDICATE THAT ISELLE HAS TURNED, AND IS NOW MOVING
WEST-NORTHWESTWARD AT ABOUT 9 KT. THIS GENERAL HEADING SHOULD
CONTINUE FOR THE NEXT COUPLE OF DAYS DUE TO RIDGING EXTENDING FROM
THE SOUTHERN UNITED STATES. AS THE STORM WEAKENS, IT SHOULD TURN
MORE WESTWARD BY DAY 3 DUE TO THE CYCLONE BECOMING STEERED MORE BY
THE LOW-LEVEL FLOW. THERE HAS BEEN A MODEST LEFTWARD SHIFT IN THE
GUIDANCE, CONSISTENT WITH A WEAKENING SYSTEM, SO THE NEW FORECAST IS
SHIFTED TO THE LEFT, LYING BETWEEN THE NOAA CORRECTED-CONSENSUS
MODEL HCCA AND THE GOOGLE DEEPMIND ENSEMBLE MEAN.
FORECAST POSITIONS AND MAX WINDS
INIT 25/1500Z 20.9N 121.1W 60 KT 70 MPH
12H 26/0000Z 21.4N 122.5W 55 KT 65 MPH
24H 26/1200Z 22.0N 124.1W 45 KT 50 MPH
36H 27/0000Z 22.7N 126.0W 40 KT 45 MPH
48H 27/1200Z 23.3N 127.9W 35 KT 40 MPH
60H 28/0000Z 23.8N 129.8W 30 KT 35 MPH...POST-TROP/REMNT LOW
72H 28/1200Z 24.2N 131.6W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 29/1200Z...DISSIPATED
FORECASTER BLAKE
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page