295 
 WTNT43 KNHC 282047
 TCDAT3
 
 Subtropical Storm Leslie Discussion Number  10
 NWS National Hurricane Center Miami FL       AL132018
 500 PM AST Fri Sep 28 2018
 
 Central convection associated with Post-Tropical Storm Leslie has
 gradually increased during the last couple of days and is now
 organized into a group of bands that wraps most of the way around
 the center.  In addition, scatterometer data show that the cyclone
 has lost much of its large baroclinic wind field, and that the
 radius of maximum winds has contracted from 120-180 n mi yesterday
 to 90 n mi or less today.  While the storm has also developed a warm
 core and shed some of its baroclinic characteristics, it is embedded
 in a large deep-layer low pressure system, and thus it is designated
 subtropical instead of tropical.  The initial intensity is set at 45
 kt based on the scatterometer data.
 
 Leslie has been moving generally westward for the the past few
 days.  The large-scale models forecast a general southwesterly
 motion for the next 3-4 days as the cyclone is steered by a segment
 of the subtropical ridge to its west and another large deep-layer
 low forming to its east over the eastern Atlantic, with a decrease
 in forward speed near the end of the forecast period as the ridge
 to the west weakens.  The forecast guidance is tightly clustered
 through 120 h, and the forecast track is near the center of the
 guidance envelope and the consensus models.
 
 The forecast track takes the center of Leslie over increasing sea
 surface temperatures during the next several days, although the
 temperatures may not be as warm as those indicated in the SHIPS
 model.  The global models suggest that little change in strength
 will occur during the first 48-72 h as Leslie gradually develops
 the upper-level outflow pattern of a tropical cyclone and
 transitions to a tropical storm.  After that time, they are in good
 agreement that the cyclone will strengthen.  Based on this, the
 intensity forecast shows only modest intensification during the
 first 48 h, followed by strengthening to a probably conservative
 60 kt.  The forecast also calls for transition to a tropical storm
 between 48-72 h, with the caveat that this could occur earlier.
 
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  28/2100Z 36.1N  48.1W   45 KT  50 MPH
  12H  29/0600Z 35.4N  49.6W   45 KT  50 MPH
  24H  29/1800Z 34.4N  51.2W   45 KT  50 MPH
  36H  30/0600Z 33.8N  52.2W   50 KT  60 MPH
  48H  30/1800Z 33.2N  53.1W   50 KT  60 MPH
  72H  01/1800Z 32.5N  54.5W   55 KT  65 MPH...TROPICAL STORM
  96H  02/1800Z 31.0N  56.0W   60 KT  70 MPH
 120H  03/1800Z 31.0N  57.0W   60 KT  70 MPH
 
 $$
 Forecaster Beven
 
 

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