892
WTPZ44 KNHC 252041
TCDEP4
TROPICAL STORM ISELLE DISCUSSION NUMBER 10
NWS NATIONAL HURRICANE CENTER MIAMI FL EP092026
200 PM PDT TUE AUG 25 2026
THE STRUCTURE OF ISELLE HAS SIGNIFICANTLY DEGRADED DURING THE PAST
SEVERAL HOURS, WITH THE LOW-LEVEL CIRCULATION FURTHER DETACHING
FROM THE MID-LEVEL CENTER LOCATED WELL TO THE NORTHEAST. THIS
CHANGE HAS CAUSED ANY DEEP CONVECTION TO BE LOCATED WELL AWAY FROM
THE CENTER NEAR THE OLD MID-LEVEL CENTER AND IS REPRESENTATIVE OF
A WEAKENING CYCLONE. A RECENT ASCAT SCATTEROMETER PASS SHOWED PEAK
WINDS OF ABOUT 45 KT, SO THE INITIAL INTENSITY IS SET TO 50 KT,
CONSISTENT WITH THE LOW BIAS OF THE INSTRUMENT.
FURTHER WEAKENING IS ANTICIPATED DUE TO CONTINUED SHEAR,
PROGRESSIVELY COOLER WATER AND DRY AIR ENTRAINMENT NEAR THE CORE OF
THE CYCLONE. PERHAPS BECAUSE OF THE POOR INITIAL STRUCTURE,
ISELLE ISN'T EXPECTED TO BE A PARTICULARLY RESILIENT CYCLONE, AND
NO MODEL SHOWS ORGANIZED DEEP CONVECTION BEYOND 36 HOURS. THE NEW
NHC INTENSITY FORECAST IS LOWER THAN THE LAST ONE, KEEPING THE SAME
GENERAL RATE OF WEAKENING, BUT IT SHOWS A MUCH EARLIER TRANSITION
INTO A REMNANT LOW.
SATELLITE FIXES SHOW THAT THE STORM CONTINUES TO MOVE TO THE
WEST-NORTHWEST, AND LITTLE CHANGE IN TRACK IS ANTICIPATED 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 THURSDAY DUE TO THE CYCLONE BECOMING STEERED MORE BY THE
LOW-LEVEL FLOW. THE GUIDANCE IS SHIFTING SOUTHWARD, CONSISTENT
WITH A DECAYING SYSTEM, SO THE NEW FORECAST IS SHIFTED EQUATORWARD,
CLOSEST TO THE GOOGLE DEEPMIND ENSEMBLE MEAN.
FORECAST POSITIONS AND MAX WINDS
INIT 25/2100Z 21.0N 121.8W 50 KT 60 MPH
12H 26/0600Z 21.3N 123.0W 40 KT 45 MPH
24H 26/1800Z 21.8N 124.7W 35 KT 40 MPH
36H 27/0600Z 22.4N 126.6W 30 KT 35 MPH...POST-TROP/REMNT LOW
48H 27/1800Z 23.0N 128.7W 30 KT 35 MPH...POST-TROP/REMNT LOW
60H 28/0600Z 23.5N 130.6W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 28/1800Z...DISSIPATED
FORECASTER BLAKE/EVANS
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page