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Hurricane Fernanda Discussion Number   7
NWS National Hurricane Center Miami FL       EP072023
1100 PM HST Sun Aug 13 2023
 
Fernanda continues to rapidly intensify this evening. The
well-defined eye has warmed and continues to be surrounded by a
solid core of cold cloud tops around -70C. Microwave imagery from
earlier this evening showed a thick closed eyewall and a well
defined structure. Satellite intensity estimates have continued to
increase this evening as well, with subjective estimates from TAFB
and SAB T5.5/T6.0, respectively. CIMMS ADT/AiDT objective satellite
estimates are in a similar range. Using a blend of these estimates
the initial intensity for this advisory is set at 110 kt.
 
The hurricane continues to move generally westward to
west-northwestward at 280/7 kt.  Fernanda is being steered by a weak
mid-level ridge with a generally west to west-northwest motion
expected throughout the period. As the ridge begins to re-strengthen
in the next day or so, the hurricane will begin to move faster, 
with a gradually accelerating forward speed over the next several 
days. The official track forecast is quite similar to the prior 
one, with just a slight adjustment northward in the short term.
 
Fernanda is now a major hurricane and is in an environment that will 
continue to allow for further intensification.  Vertical wind shear 
is forecast to remain under 10 kt and with warm sea surface 
temperatures. Thereafter, Fernanda will move into an increasingly 
dry and stable environment, with mid-level relative humidity levels 
dropping below 40 percent in about 48 hrs. This will occur at the 
same time the SSTs also begin to drop off along the forecast track. 
These factors should lead to initially gradual, and then more rapid 
weakening. The latest NHC intensity forecast is above most of the 
guidance over the next 24 hours, but is closer to the consensus aids 
in days 2-4. However, there is some guidance that show an even 
faster decay than what is currently forecast, with the system 
becoming void of convection due to the very dry airmass.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  14/0900Z 15.6N 117.7W  110 KT 125 MPH
 12H  14/1800Z 15.9N 118.8W  125 KT 145 MPH
 24H  15/0600Z 16.5N 120.5W  110 KT 125 MPH
 36H  15/1800Z 17.0N 122.5W  100 KT 115 MPH
 48H  16/0600Z 17.3N 124.9W   85 KT 100 MPH
 60H  16/1800Z 17.3N 127.5W   70 KT  80 MPH
 72H  17/0600Z 17.5N 130.3W   60 KT  70 MPH
 96H  18/0600Z 18.0N 136.6W   40 KT  45 MPH
120H  19/0600Z 18.5N 142.7W   30 KT  35 MPH...POST-TROP/REMNT LOW
 
$$
Forecaster Kelly/Brown
 
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