586 

WTPZ44 KNHC 240245

TCDEP4

 

Tropical Storm Iselle Discussion Number   3

NWS National Hurricane Center Miami FL       EP092026

800 PM PDT Sun Aug 23 2026

 

The most recent ASCAT and OSCAT passes have shown that the strongest 

winds with Iselle are around 40 to 45 kt. UW-CIMSS objective 

estimates are in the 35-55 kt range, and the most recent TAFB 

subjective Dvorak estimate is T3.0/45 kt. With all of that data in 

consideration, the intensity has been held at 45 kt for this 

advisory. However, recent observations at Isla Clarion have recorded 

sustained winds around 30 to 35 kt, gusting up to around 40 kt and 

a surface pressure of 1002 mb. Thus in light of that data, the 

central pressure for Iselle has been lowered to 999 mb.

 

The initial motion estimate is northwestward, or 310 degrees at 8 

kt.  A continued northwestward motion is expected through Monday 

while Iselle is steered by ridging over the southwestern United 

States and northwestern Mexico. As the ridge builds in some more to 

the north of the cyclone, a gradual turn toward the west-northwest 

is expected on Tuesday and Wednesday.  The current NHC track is very 

similar to the previous track, only minor adjustments in speed and 

location have been made. The track remains very close to the lastest 

HFIP Corrected Consensus (HCCA) model and the Google DeepMind 

(GDMI). There is a good amount of spread in the track forecast 

towards the later portion of the forecast, thus the confidence is 

slightly below average.

 

Iselle will be traveling over warm water and within a moist 

environment with weak to moderate vertical wind shear for the next 

day or so, but westerly vertical wind shear should increase to the 

15-20 kt range by Tuesday or sooner.  Strengthening is expected for 

the next 36 h. The current NHC intensity forecast is on the higher 

end of the guidance, thus it is possible that Iselle might not quite 

make it to hurricane status. After this period, the cyclone will 

move into a more hostile environment with stronger shear, colder 

sea-surface temperatures, and some slightly drier air. As such, the 

storm should progressively get weaker beyond a couple of days. 

 

 

FORECAST POSITIONS AND MAX WINDS

 

INIT  24/0300Z 17.1N 115.3W   45 KT  50 MPH

 12H  24/1200Z 18.1N 116.4W   50 KT  60 MPH

 24H  25/0000Z 19.4N 117.8W   60 KT  70 MPH

 36H  25/1200Z 20.4N 119.6W   65 KT  75 MPH

 48H  26/0000Z 21.0N 121.4W   60 KT  70 MPH

 60H  26/1200Z 21.5N 123.1W   55 KT  65 MPH

 72H  27/0000Z 21.9N 125.1W   50 KT  60 MPH

 96H  28/0000Z 22.8N 128.8W   40 KT  45 MPH

120H  29/0000Z 23.6N 132.5W   30 KT  35 MPH...POST-TROP/REMNT LOW

 

$$

Forecaster Katz/Cangialosi