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Hurricane Fernanda Discussion Number  14
NWS National Hurricane Center Miami FL       EP072023
500 PM HST Tue Aug 15 2023
 
Fernanda continues weakening this evening. The overall structure of
the hurricane on visible and infrared satellite has not changed
much, with its central dense overcast remaining mostly intact.
However, recent microwave imagery from GMI and SSMIS show the
inner-core structure has degraded more quickly, with the low- and
mid-level eye signatures no longer aligned, and the deepest
convection becoming increasingly displaced west of the low-level
center. Subjective intensity estimates were both down to T4.5/77 kt
from TAFB and SAB, but some of the objective intensity estimates,
such as UW-CIMSS ADT remain a bit higher, up near 90 kt. The initial
intensity this advisory is set at 80 kt, closer to the lower end of
the intensity guidance range.
 
Fernanda's inner core is becoming increasingly ragged, likely due to
the unfavorable combination of mid-level shear undercutting its
outflow, very dry mid-level environmental air, and sea-surface
temperatures which are quickly decreasing. These factors foreshadow
weakening, likely rapid, over the next few days, and Fernanda is
expected to become a post-tropical remnant low in about 48 hours.
This forecast is in good agreement with the global and
regional-hurricane model guidance which shows the cyclone losing
organized deep convection around that time frame.
 
The motion of Fernanda remains just poleward of due west, but a bit
faster than before at 280/12 kt, as the mid-level ridge to its north
has become better established. The track guidance this cycle has
actually shifted a bit south, possibly in response to the storm
quickly weakening in the short-term forecast and becoming more
steered by the low-level trade wind flow. Thus, the latest NHC track
forecast has been shifted a bit to the south of the prior one, but
not quite as far as HCCA and TVCE consensus aids.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  16/0300Z 17.3N 124.1W   80 KT  90 MPH
 12H  16/1200Z 17.4N 126.1W   65 KT  75 MPH
 24H  17/0000Z 17.5N 128.9W   55 KT  65 MPH
 36H  17/1200Z 17.6N 131.7W   40 KT  45 MPH
 48H  18/0000Z 17.7N 134.7W   30 KT  35 MPH...POST-TROP/REMNT LOW
 60H  18/1200Z 17.9N 137.7W   30 KT  35 MPH...POST-TROP/REMNT LOW
 72H  19/0000Z 17.9N 140.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  20/0000Z 18.0N 146.7W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  21/0000Z 18.1N 152.3W   25 KT  30 MPH...POST-TROP/REMNT LOW
 
$$
Forecaster Papin
 
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