[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT43 KNHC 120242
TCDAT3

Hurricane Leslie Discussion Number  63
NWS National Hurricane Center Miami FL       AL132018
1100 PM AST Thu Oct 11 2018

Satellite images indicate that Leslie has continued to strengthen.
A small eye has occasionally been apparent, although it has
recently become obscured by clouds.  ASCAT data showed peak winds
of 75 kt earlier, and given the low bias of that instrument at those
wind speeds, the initial wind speed is set to 80 kt.  Leslie should
begin to weaken in about 24 hours as the hurricane encounters cool
waters and a higher-shear environment.  Intensity guidance is
tightly clustered around the previous NHC prediction, and little
change is made in the new advisory.  By 72 hours, a combination of
very dry air aloft, waters near 23.5C, and high shear should cause
Leslie to lose convection and transition into a post-tropical
cyclone.

Leslie continues to accelerate east-northeastward with an initial
motion estimate of 070/23 kt.  The hurricane should move rapidly
in that general direction for the next day or so ahead of a
mid-latitude trough, then bend eastward and southward as the main
steering mechanism switches to the eastern Atlantic subtropical
ridge.  There is still a large guidance spread, over 700 miles at
day 3, but the main change to report is that more of the models are
continuing the east-northeastward track longer, possibly due to
Leslie becoming a stronger system.  The official forecast is
shifted to the east, but is still well to the southwest of the
model consensus, ironically similar to last night's forecast.

Leslie is a fairly large tropical cyclone and the forecast wind
radii encompass Madeira Island within 36 hours.  Consequently, a
tropical storm warning has been issued for that island.  It is the
first known tropical storm warning for that place, and there are
no known tropical storms in the historical record anywhere
within 100 miles of that island, with the closest being Vince of
2005.

FORECAST POSITIONS AND MAX WINDS

INIT  12/0300Z 30.9N  33.9W   80 KT  90 MPH
 12H  12/1200Z 32.1N  29.8W   80 KT  90 MPH
 24H  13/0000Z 33.3N  23.5W   75 KT  85 MPH
 36H  13/1200Z 34.0N  18.0W   65 KT  75 MPH
 48H  14/0000Z 33.5N  15.5W   55 KT  65 MPH
 72H  15/0000Z 31.5N  15.0W   35 KT  40 MPH...POST-TROPICAL
 96H  16/0000Z 29.0N  18.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  17/0000Z 28.0N  24.0W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Blake
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