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Hurricane Fernanda Discussion Number  10
NWS National Hurricane Center Miami FL       EP072023
500 PM HST Mon Aug 14 2023
 
This evening, Fernanda's inner-core structure is beginning to show 
signs of decay, with its well-defined eye becoming cloud filled on 
both visible and infrared satellite images. Earlier, a 2144 UTC 
AMSR2 microwave pass suggested the hurricane might be undergoing an 
eyewall replacement cycle, which could be partially responsible for 
its recent structural degradation. 0000 UTC subjective Dvorak 
intensity estimates from TAFB and SAB were 115 kt and 102 kt, 
respectively. Objective intensity estimates from UW-CIMSS have 
either leveled off or have begun to decline, with the most recent 
D-MINT estimate at 107 kt associated with the aforementioned AMSR2 
pass above. The initial intensity has been lowered to 105 kt this 
advisory given the continued decline since that time.
 
Fernanda has been moving a bit more poleward over the last 6 to 12
hours, with the latest estimated motion at 290/8 kt. The mid-level
ridging has been taking its time building back in to the north over
the past 24 hours, but is still forecast to do so over the next few
days, leading to Fernanda gradually accelerating to the
west-northwest. Beyond 48 hours, a weakening Fernanda should quickly
become more vertically shallow, resulting in the cyclone turning
more westward as it comes under the influence of the more extensive
North Pacific low-level subtropical ridge. The official forecast
continues to be very close to the prior forecast, other than a
short-term nudge further north given the initial motion. This track
remains close to both the simple and corrected consensus model
guidance.
 
In addition to a possible eyewall replacement cycle, Fernanda might
also be feeling the effects of some higher (15-20 kt) mid-level
vertical wind shear out of the south. Very dry mid-level
environmental air could also be attempting to wrap around the
southwest quadrant of the cyclone. Given these factors, it now seems
more likely Fernanda will continue weakening in the short-term, with
the rate of weakening increasing after it crosses the 26-C isotherm
in about 24-36 hours. Both the global and regional-hurricane models
now show Fernanda losing its organized convection in about 3 days,
with the latest NHC intensity forecast showing the system becoming a
post-tropical remnant low at that time.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  15/0300Z 16.5N 119.8W  105 KT 120 MPH
 12H  15/1200Z 17.0N 121.2W  100 KT 115 MPH
 24H  16/0000Z 17.4N 123.5W   90 KT 105 MPH
 36H  16/1200Z 17.6N 126.0W   70 KT  80 MPH
 48H  17/0000Z 17.8N 128.7W   50 KT  60 MPH
 60H  17/1200Z 18.0N 131.5W   40 KT  45 MPH
 72H  18/0000Z 18.1N 134.6W   30 KT  35 MPH...POST-TROP/REMNT LOW
 96H  19/0000Z 18.2N 141.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  20/0000Z 18.0N 147.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 
$$
Forecaster Papin
 
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