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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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