ZCZC MIATCDAT3 ALL
TTAA00 KNHC DDHHMM

Subtropical Storm Leslie Discussion Number  12
NWS National Hurricane Center Miami FL       AL132018
500 AM AST Sat Sep 29 2018

The deep convection has become more concentrated near the center
during the past several hours indicating that Leslie is gradually
acquiring some tropical characteristics, but the cyclone is still
too attached to a complex deep-layer low. On this basis, Leslie is
still considered a subtropical storm in this advisory with an
initial intensity of 40 kt.  Global models indicate that the
subtropical cyclone will continue to be embedded within strong
northerly shear during the next 2 days or so. After that time, the
shear is forecast to relax and with a warm ocean along the cyclone's
path, Leslie is forecast to become fully tropical and reach
hurricane status by the end of the forecast period. SHIPS model and
its derivatives strengthen Leslie significantly, but the NHC
forecast is a little less aggressive, and it follows the intensity
consensus.

Leslie has been moving toward the southwest or 230 degrees at 6 kt,
steered by the flow around the western side of the large deep-layer
low in which Leslie is embedded.  Since this steering pattern is
not expected to change, Leslie will probably continue on the same
general track for the next 3 to 4 days. After that time, the large
low weakens and the cyclone will become steered slowly northward by
the flow ahead of an approaching mid-latitude trough. Nevertheless,
Leslie is forecast to meander over the north-central Atlantic for
several more days. This is the solution provided by most of the
global models, and the NHC forecast follows very closely the
multi-model consensus aids and the corrected consensus HCCA.

Large swells previously generated by Leslie when it was a stronger
extratropical low have already reached Bermuda, and will soon reach
the Lesser and Greater Antilles. These swells are expected to reach
portions of the east coast of the United States by Sunday. These
swells could cause life-threatening surf and rip currents.

FORECAST POSITIONS AND MAX WINDS

INIT  29/0900Z 35.2N  50.3W   40 KT  45 MPH
 12H  29/1800Z 34.4N  51.3W   45 KT  50 MPH
 24H  30/0600Z 33.8N  52.2W   45 KT  50 MPH
 36H  30/1800Z 33.5N  53.3W   50 KT  60 MPH
 48H  01/0600Z 33.2N  54.0W   50 KT  60 MPH...TROPICAL CYCLONE
 72H  02/0600Z 32.3N  55.0W   60 KT  70 MPH
 96H  03/0600Z 31.0N  55.5W   65 KT  75 MPH
120H  04/0600Z 32.0N  56.0W   70 KT  80 MPH

$$
Forecaster Avila

NNNN