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Hurricane Iona Discussion Number   7
NWS Central Pacific Hurricane Center Honolulu HI   CP012025
Issued by NWS National Hurricane Center Miami FL
1100 AM HST Mon Jul 28 2025
 
After rapidly strengthening overnight, the cloud pattern and
overall structure of Iona has changed little during the past 6
hours.  A fairly symmetric Central Dense Overcast is seen over the
center in geostationary satellite imagery, but there has been no
recent microwave data to examine the inner core structure. The
latest subjective satellite intensity estimates are T4.0/65 kt
from SAB, and T3.5/55 kt from both PHFO and JTWC.  Objective
estimates remain lower, although it is possible that the small size 
of the cyclone is making it difficult for those techniques to 
capture the true intensity.  The initial intensity for this advisory 
will remain 65 kt, in line with the higher subjective estimate from 
SAB.
 
Iona is located within a low-shear environment and over sea surface
temperatures of around 28C.  Those conditions favor strengthening,
however some nearby dry mid-level air may have been entrained in 
the circulation which likely caused the recent pause in
intensification.  Given the favorable upper-air pattern and warm 
sea surface temperatures, additional strengthening appears likely.  
The regional hurricane models are more aggressive this cycle and 
indicate that Iona could be near or at major hurricane strength in 
a day or so.  As a result, the lastest official forecast calls 
for rapid strengthening during the next 24 hours and the peak 
intensity is raised slightly from the previous advisory.  Around 
midweek, slightly lower SSTs and an increase in vertical
wind shear are expected to cause gradual weakening through the
remainder of the forecast period.  The updated NHC intensity 
forecast is close to the regional models through 24 hours, and then 
follows the latest multi-model (IVCN) consensus aid after that time.
 
Iona is moving westward or 270 degrees at 9 kt.  The storm is
forecast to move along the southern portion of a subtropical ridge
that is well established over the central Pacific.  This steering
pattern should take the storm westward during the next day or so,
followed by a faster west-northwestward motion after midweek. The
updated track forecast is once again near the center of the model
envelope, close to the various consensus aids.  Confidence remains
high that Iona will stay well south of the Hawaiian Islands.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  28/2100Z 10.6N 151.0W   65 KT  75 MPH
 12H  29/0600Z 10.6N 152.6W   80 KT  90 MPH
 24H  29/1800Z 10.6N 155.0W   95 KT 110 MPH
 36H  30/0600Z 10.7N 157.7W   90 KT 105 MPH
 48H  30/1800Z 10.9N 161.0W   80 KT  90 MPH
 60H  31/0600Z 11.2N 164.5W   65 KT  75 MPH
 72H  31/1800Z 11.7N 168.1W   55 KT  65 MPH
 96H  01/1800Z 12.9N 175.2W   45 KT  50 MPH
120H  02/1800Z 14.7N 178.5E   40 KT  45 MPH
 
$$
Forecaster Brown
 
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