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Tropical Storm LESLIE


Tropical Storm Leslie Discussion Number  46
NWS National Hurricane Center Miami FL       AL132018
500 PM AST Sun Oct 07 2018

Late-arriving ASCAT data from shortly after 1200 UTC indicated that
Leslie is still producing winds of just below 45 kt, primarily in
the southwest and northeast quadrants of the tropical storm.
Assuming at least a little undersampling has occurred, this would
support an initial intensity of 45 or 50 kt, while an average of
more recent intensity estimates from SAB, TAFB, and the UW-CIMSS
is 50 kt.  The initial value is therefore held at 50 kt.

Regardless of the exact initial intensity of Leslie, only slight
fluctuations are expected over the next 24 to 36 hours while Leslie
is over fairly cool SSTs, in part because it will be crossing its
own previous track multiple times.  Beyond 48 h, the intensity
guidance is now in better agreement that some intensification
will occur, and Leslie is forecast to become a hurricane once again
by the end of the week. The NHC intensity forecast is a little
higher than the previous advisory by the end of the forecast
period, and is close to IVCN at all times.

Leslie is still moving east-southeastward with an initial speed of 9
kt, and this general motion will likely continue for at least the
next day or two while the tropical storm is steered by westerly flow
associated with a mid-latitude trough to its north.  Most of the
global models still forecast that Leslie will separate from the
trough in a few days and turn southeastward, and there are still
large differences on exactly when that will occur. The deterministic
runs of the GFS and ECMWF have come into better agreement on the
future track of Leslie, but the ensembles of those models indicate
that the range of possible tracks hasn't actually decreased.
Confidence in the track forecast therefore remains quite low.  In
general, the guidance suite has shifted to the south and west,
particularly between 36 and 96 h.  The official track forecast has
been shifted in that direction to bring it closer to the track
consensus. However, it should be emphasized that confidence in the
track forecast remains low at this time.


INIT  07/2100Z 35.9N  49.9W   50 KT  60 MPH
 12H  08/0600Z 35.4N  48.2W   50 KT  60 MPH
 24H  08/1800Z 34.3N  45.7W   50 KT  60 MPH
 36H  09/0600Z 32.8N  43.2W   55 KT  65 MPH
 48H  09/1800Z 31.2N  41.3W   55 KT  65 MPH
 72H  10/1800Z 28.2N  38.8W   60 KT  70 MPH
 96H  11/1800Z 28.6N  33.0W   65 KT  75 MPH
120H  12/1800Z 30.5N  27.0W   60 KT  70 MPH

Forecaster Zelinsky