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Hurricane Fernanda Discussion Number   8
NWS National Hurricane Center Miami FL       EP072023
500 AM HST Mon Aug 14 2023
 
Fernanda has continued to intensify this morning.  The 10 nmi- 
diameter eye is very well defined and is surrounded by a ring of
-70 deg C or colder convective cloud tops.  The hurricane's
upper-level outflow pattern remains quite symmetric.  Dvorak data
T-numbers for the system are now around 6.0 which supports an
intensity of 115 kt, i.e. category 4 intensity.  This is also in
good agreement with objective ADT estimates from UW-CIMSS.
 
A westward to west-northwestward track continues with an initial
motion estimate of about 280/7  kt.  There are no significant
changes to the track forecast reasoning from the previous
advisory.  A weak mid-tropospheric ridge to the north of
Fernanda should gradually strengthen over the next several days.
This should result in a continued west-northwestward or slightly
north of westward movement with some increase of forward speed over
the next several days.  Late in the forecast period, the weakening
cyclone should move mostly westward, following the low-level
environmental flow.  The official track forecast is close to both
the simple and corrected dynamical model consensus guidance.
 
The hurricane should traverse SSTs of 28-29 deg C today while
remaining in a low-vertical wind shear environment.  Therefore some
additional strengthening will probably occur today.  By early
tomorrow and thereafter, Fernanda should begin to encounter the
drier low- to mid-level air mass that is seen in the GOES-18
lower-level water vapor imagery not far to the west-northwest of the
tropical cyclone.  This, along with cooler ocean waters, should
result in steady weakening of the system over the next 2-5 days.
The official intensity forecast calls for Fernanda to degenerate
into a post-tropical cyclone at 96 h. However, based on the
latest simulated satellite imagery from the global models, a faster
rate of weakening is certainly possible.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  14/1500Z 15.8N 118.5W  115 KT 130 MPH
 12H  15/0000Z 16.3N 119.6W  125 KT 145 MPH
 24H  15/1200Z 17.0N 121.4W  105 KT 120 MPH
 36H  16/0000Z 17.4N 123.6W   90 KT 105 MPH
 48H  16/1200Z 17.6N 126.2W   75 KT  85 MPH
 60H  17/0000Z 17.8N 128.9W   60 KT  70 MPH
 72H  17/1200Z 18.0N 131.8W   45 KT  50 MPH
 96H  18/1200Z 18.3N 137.9W   35 KT  40 MPH...POST-TROPICAL
120H  19/1200Z 18.5N 144.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 
$$
Forecaster Pasch
 
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