Hurricane Gilma Forecast Discussion

000
WTPZ42 KNHC 220837
TCDEP2

Hurricane Gilma Discussion Number  16
NWS National Hurricane Center Miami FL       EP072024
200 AM PDT Thu Aug 22 2024

Gilma has continued to intensify while exhibiting a well-defined 
eye on geostationary satellite imagery, and convective cloud tops 
colder than -70 deg C are evident around the eyewall.   The cloud 
pattern is fairly symmetric in appearance, and upper-level outflow 
is well defined over all quadrants of the circulation.  The current 
intensity estimate is raised to 100 kt based on a subjective Dvorak 
classification from TAFB and various objective estimates from 
UW-CIMSS.  This makes Gilma the first major hurricane of the 2024 
east Pacific season.

Center fixes show a fairly slow forward speed toward the 
west-northwest, with an initial motion estimate of 290/5 kt.  A 
mid-tropospheric trough near the California coast has broken down 
the subtropical ridge to the north of Gilma, resulting in a weaker 
than normal steering current.  Over the next several days, the ridge 
is expected to build back rather slowly, resulting in only a gradual 
increase in the tropical cyclone's forward speed over the forecast 
period.  The official track forecast is about the same as the one 
from the previous NHC advisory, and is near the southern side of the 
model suite.

Some additional strengthening is expected, since the system has a 
well-defined inner core and is in an environment of low shear while 
situated over warm waters.  The short-term intensity forecast 
reflects current trends and is in line with much of the regional 
dynamical hurricane model guidance.  In the next day or two, the 
SSTs below Gilma are expected to gradually decrease.  Later in the 
forecast period, the cyclone will be moving into a drier and more 
stable air mass.  These factors should cause slow weakening, and the 
official intensity forecast is similar to the previous one.  
Overall, the NHC intensity forecast is on the high end of the model 
guidance.


FORECAST POSITIONS AND MAX WINDS

INIT  22/0900Z 16.6N 124.2W  100 KT 115 MPH
 12H  22/1800Z 16.9N 125.0W  110 KT 125 MPH
 24H  23/0600Z 17.2N 126.3W  105 KT 120 MPH
 36H  23/1800Z 17.5N 127.7W   95 KT 110 MPH
 48H  24/0600Z 17.8N 129.3W   90 KT 105 MPH
 60H  24/1800Z 18.0N 131.0W   85 KT 100 MPH
 72H  25/0600Z 18.3N 132.6W   80 KT  90 MPH
 96H  26/0600Z 18.6N 136.0W   70 KT  80 MPH
120H  27/0600Z 19.0N 140.0W   60 KT  70 MPH

$$
Forecaster Pasch