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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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