Hurricane Gilma Forecast Discussion

652 
WTPZ42 KNHC 271448
TCDEP2

Hurricane Gilma Discussion Number  38
NWS National Hurricane Center Miami FL       EP072024
500 AM HST Tue Aug 27 2024

Gilma is unraveling quickly.  The center is now exposed, with all
the convection off to the east, thanks to westerly vertical wind
shear, which is finally taking a toll on the cyclone.  Current
intensity estimates from TAFB and SAB are 90 and 77 kt,
respectively, due to constraints.  Recent objective satellite
estimates from UW-CIMSS range from 55 to 69 kt.  The initial
intensity is lowered to 65 kt for this advisory as a blend of the
data.

Gilma has sped up a bit and is now moving westward, or 270/11 kt.
A subtropical ridge north of Gilma should continue to steer the
system generally westward to west-northwestward, with a slight
increase in forward speed over the next day or so.  The NHC
forecast has been adjusted very slightly to the south of the
previous track prediction and is in best agreement with the TCVE
consensus aid.

Stronger westerly vertical wind shear and the entrainment of
dry and stable environmental air are taking a toll on Gilma.  As a
result, Gilma's center is now exposed, with the convective area
becoming displaced farther to the east of the low-level center.  The
areal coverage and intensity of the convection to the east of the
center has also been decreasing over the past several hours.
Therefore, intensity estimates for Gilma have been rapidly
decreasing.  Gilma is forecast to weaken to a tropical storm later
today.  Although Gilma is likely to become a low-end tropical
storm in 24-36 h, some model guidance suggests that the cyclone may
continue to have pulsing deep convection, which should be enough to
maintain some tropical storm force winds in the northern semi-circle
through Thursday.  After that, westerly wind shear is forecast to
increase even more, which should cause Gilma to lose its convection
and become a remnant low sometime around Thursday night.  It is
possible that Gilma could become a remnant low sooner than
forecast.

Future information on this system can be found in advisories issued
by the Central Pacific Hurricane Center beginning at 1100 AM HST.
Future Tropical Cyclone Discussions will be issued under AWIPS
header HFOTCDCP2 and WMO header WTPA42 PHFO.  Products will
continue to be available on the web at hurricanes.gov.


FORECAST POSITIONS AND MAX WINDS

INIT  27/1500Z 18.5N 140.7W   65 KT  75 MPH
 12H  28/0000Z 18.6N 142.4W   55 KT  65 MPH
 24H  28/1200Z 18.9N 144.6W   45 KT  50 MPH
 36H  29/0000Z 19.4N 146.8W   40 KT  45 MPH
 48H  29/1200Z 19.9N 149.1W   40 KT  45 MPH
 60H  30/0000Z 20.3N 151.3W   35 KT  40 MPH
 72H  30/1200Z 20.8N 153.7W   30 KT  35 MPH...POST-TROP/REMNT LOW
 96H  31/1200Z 22.2N 158.3W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  01/1200Z...DISSIPATED

$$
Forecaster Hagen/Brown