000
WTPZ45 KNHC 020850
TCDEP5
 
Tropical Storm Octave Discussion Number   9
NWS National Hurricane Center Miami FL       EP152025
200 AM PDT Thu Oct 02 2025
 
The overall satellite presentation of Octave has changed little 
since the previous advisory, though the previously well-defined 
curved banding to the south and west of the center has become more 
ragged in recent hours.  The cyclone continues to be affected by 
moderate easterly shear, analyzed at around 17 kt by UW-CIMSS.  This 
shear is restricting outflow in the eastern semicircle and keeping 
the low-level center near the eastern edge of the deep convection.  
Recent subjective Dvorak estimates from TAFB and SAB were 3.5/55 kt 
and 4.0/65 kt, respectively, while UW-CIMSS objective estimates have 
ranged from 48 to 59 kt over the past few hours. Based on a blend of 
these data, and with little change in the overall structure, the 
initial intensity is held at 55 kt.

Octave is moving slightly north of due west, or 280 degrees at 7 kt. 
A west to west-northwest motion is expected during the next few days 
as the cyclone is steered along the southern flank of a subtropical 
ridge to its north.  After day 3, Octave should slow as a longwave 
trough approaches from the northwest, weakening the ridge and 
overall steering flow.  A developing disturbance or tropical 
cyclone offshore of the southwestern or west-central coast of 
Mexico is then forecast to erode the subtropical ridge to the east 
of Octave, causing the cyclone to turn eastward by days 4 and 5.  
The updated NHC forecast has been adjusted slightly southward to 
account for Octave’s more westward recent motion and the latest 
model trends.  Considerable along- and cross-track spread remains 
in the extended range, and the forecast track represents a blend of 
the multi-model consensus and AI-based guidance.

Octave will remain over warm water and within a moist environment 
during the next few days.  However, vertical wind shear is expected 
to fluctuate between moderate and strong levels during the next 36 
hours, which should prevent significant intensification.  As a 
result, little change in strength is forecast during this period. 
Some modest strengthening is possible between 48 and 96 hours as 
shear decreases, though cooling sea surface temperatures and 
gradually drier mid-level air should limit intensification.  Octave 
is still forecast to reach hurricane strength by days 3 and 4, 
remaining below some of the more aggressive hurricane regional model 
solutions.  By day 5, weakening is likely as Octave moves into a 
more stable, drier air mass and encounters increasing southeasterly 
shear.  The forecast remains close to the previous one and lies near 
the higher end of the guidance envelope.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  02/0900Z 12.1N 117.9W   55 KT  65 MPH
 12H  02/1800Z 12.3N 118.6W   55 KT  65 MPH
 24H  03/0600Z 12.8N 119.8W   55 KT  65 MPH
 36H  03/1800Z 13.3N 121.1W   55 KT  65 MPH
 48H  04/0600Z 13.9N 122.4W   55 KT  65 MPH
 60H  04/1800Z 14.4N 123.5W   60 KT  70 MPH
 72H  05/0600Z 14.9N 124.0W   65 KT  75 MPH
 96H  06/0600Z 15.6N 123.4W   65 KT  75 MPH
120H  07/0600Z 15.6N 121.1W   50 KT  60 MPH
 
$$
Forecaster Jelsema (CPHC)