982
WTPA41 PHFO 020249
TCDCP1
TROPICAL DEPRESSION IONA DISCUSSION NUMBER 24
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI CP012025
ISSUED BY NWS NATIONAL HURRICANE CENTER MIAMI FL
500 PM HST FRI AUG 01 2025
SATELLITE IMAGERY INDICATES THAT CONVECTION ASSOCIATED WITH IONA
REMAINS FRAGMENTED AND DISORGANIZED, WITH THE LOW-LEVEL CIRCULATION
BECOMING INCREASINGLY BROAD AND DIFFUSE UNDER PERSISTENT
WEST-NORTHWEST SHEAR. THE CENTER IS EXPOSED AND BECOMING LESS
DEFINED, AND A RECENT ASCAT PASS DETECTED PEAK WINDS OF ONLY AROUND
25 KT IN THE NORTHEASTERN QUADRANT. SUBJECTIVE DVORAK CURRENT
INTENSITY ESTIMATES FROM SAB, HFO, AND JTWC RANGED FROM 1.5/25 KT TO
2.5/35 KT. BASED ON THESE DATA AND THE DEGRADED SATELLITE
APPEARANCE, THE INITIAL INTENSITY IS LOWERED TO 30 KT.
THE INITIAL MOTION IS ESTIMATED AT 295/15 KT. IONA IS EXPECTED TO
CONTINUE WEST-NORTHWESTWARD THROUGH THE WEEKEND WHILE GRADUALLY
SLOWING, STEERED BY THE SOUTHERN FLANK OF A LOW- TO MID-LEVEL
SUBTROPICAL RIDGE TO THE NORTH. A NORTHWESTWARD TURN REMAINS LIKELY
BY LATE THIS WEEKEND OR EARLY NEXT WEEK AS THE SYSTEM APPROACHES A
WEAKNESS IN THE RIDGE. THE LATEST TRACK FORECAST REMAINS SIMILAR TO
THE PREVIOUS ADVISORY AND IS CLOSE TO THE CONSENSUS AIDS, WITH ONLY
MINOR ADJUSTMENTS.
GIVEN THE INCREASINGLY DEGRADED STRUCTURE OF IONA AND THE LACK OF
DEEP CONVECTION, LITTLE TO NO REORGANIZATION IS ANTICIPATED.
PERSISTENT WESTERLY SHEAR, INTERACTION WITH AN UPPER-LEVEL TROUGH,
AND THE INTRUSION OF MID- TO UPPER-LEVEL DRY AIR SHOULD CONTINUE TO
INHIBIT STRENGTHENING. WHILE MOST DYNAMICAL MODEL GUIDANCE DEPICTS
IONA GRADUALLY OPENING INTO A TROUGH BY EARLY NEXT WEEK, THE CURRENT
DISORGANIZED STATE SUGGESTS THAT DEGENERATION INTO A REMNANT LOW OR
TROUGH COULD OCCUR AT ANY TIME OVER THE WEEKEND. THE UPDATED
FORECAST MAINTAINS IONA AS A TROPICAL CYCLONE BRIEFLY, BUT THE
SYSTEM IS EXPECTED TO DISSIPATE BY 72 HOURS OR SOONER.
THIS IS THE LAST ADVISORY ISSUED BY THE CENTRAL PACIFIC HURRICANE
CENTER ON THIS SYSTEM. FUTURE ADVISORIES WILL BE ISSUED BY RSMC
TOKYO, JAPAN. ADVISORIES ISSUED BY RSMC TOKYO ARE FOUND ON THE WEB
AT:
WWW.JMA.GO.JP/JMA/JMA-ENG/JMA-CENTER/RSMC-HP-PUB-EG/RSMC_HP.HTM
FOR U.S. INTERESTS, SEE ADVISORIES ISSUED BY THE JOINT TYPHOON
WARNING CENTER (JTWC) IN HONOLULU, HAWAII. ADVISORIES ISSUED BY JTWC
CAN BE FOUND ON THE WEB AT:
WWW.METOC.NAVY.MIL/JTWC/JTWC.HTML
FORECAST POSITIONS AND MAX WINDS
INIT 02/0300Z 15.8N 179.5W 30 KT 35 MPH
12H 02/1200Z 16.8N 178.3E 30 KT 35 MPH
24H 03/0000Z 18.0N 175.8E 30 KT 35 MPH
36H 03/1200Z 19.1N 173.6E 30 KT 35 MPH
48H 04/0000Z 20.6N 171.6E 30 KT 35 MPH
60H 04/1200Z 22.1N 169.7E 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 05/0000Z...DISSIPATED
FORECASTER GIBBS (CPHC)
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