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Post-Tropical Cyclone Leslie Discussion Number   9
NWS National Hurricane Center Miami FL       AL132018
1100 AM AST Tue Sep 25 2018

Leslie has become a post-tropical cyclone.  Conventional and
microwave satellite imagery show that Leslie's surface circulation
has become elongated along an intruding baroclinic zone indicated
by a recent 1158 UTC ASCAT-A pass.  Any deep convection appears to
be developing due to dynamic forcing.  A rather large stratocumulus
cloud shield and associated cooler, stable air is quickly advecting
into the area as well. The initial intensity is maintained at 30 kt
for this last advisory.

Leslie is forecast to strengthen during the next couple of days due
to baroclinic processes. The official forecast, based on the GFS and
European global models, and the SHIPS statistical intensity
guidance, shows an increase of the sustained winds to hurricane
force in 2 days, around the same period that the shear drops below
10 kt.  The non-tropical low is then forecast to move south of the
strong upper-level westerlies and detach from the frontal boundary.
According to the global models and the Florida State Cyclone Phase
forecast, Leslie should make a transition from a frontal system to
an asymmetric shallow warm-core seclusion.  Beyond day 3, guidance
suggests that Leslie will acquire subtropical characteristics and a
more symmetric, deepening warm-core low while meandering in weaker
steering currents.  The intensity forecast follows this scenario and
is based on the aforementioned global and statistical models.

Leslie is now moving eastward at a slightly faster forward motion,
about 10 kt.  A turn to the north is expected in 36 hours followed
by a slower westward motion as Leslie slips south of the
mid-latitude westerlies.  Through the remaining portion of the
forecast, Leslie should move at a slower speed generally westward
as a ridge builds to the north. NHC forecast is nudged toward the
TVCN consensus through 48 hours, then follows more closely to the
GFEX (GFS/ECMWF) consensus model.

This is the last advisory issued by the National Hurricane Center on
Leslie.  Additional information on this system can be found in High
Seas Forecasts issued by the National Weather Service, under AWIPS
header NFDHSFAT1, WMO header FZNT01 KWBC, and available on the Web
at https://ocean.weather.gov/shtml/NFDHSFAT1.shtml.

FORECAST POSITIONS AND MAX WINDS

INIT  25/1500Z 31.6N  44.4W   30 KT  35 MPH...POST-TROPICAL
 12H  26/0000Z 32.1N  42.5W   40 KT  45 MPH...POST-TROP/EXTRATROP
 24H  26/1200Z 33.6N  40.1W   50 KT  60 MPH...POST-TROP/EXTRATROP
 36H  27/0000Z 35.6N  39.9W   60 KT  70 MPH...POST-TROP/EXTRATROP
 48H  27/1200Z 36.1N  41.7W   65 KT  75 MPH...POST-TROP/EXTRATROP
 72H  28/1200Z 35.5N  45.3W   60 KT  70 MPH...SUBTROPICAL STORM
 96H  29/1200Z 34.6N  48.1W   55 KT  65 MPH...SUBTROPICAL STORM
120H  30/1200Z 34.4N  49.6W   50 KT  60 MPH...SUBTROPICAL STORM

$$
Forecaster Roberts

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