977 
 WTNT43 KNHC 250837
 TCDAT3
 
 Subtropical Depression Leslie Discussion Number   8
 NWS National Hurricane Center Miami FL       AL132018
 500 AM AST Tue Sep 25 2018
 
 No significant changes have occurred with Leslie overnight.  Deep
 convection is generally confined to the eastern half of the
 circulation as dry air continues to wrap into the western portion
 of the cyclone.  Satellite images indicate that the circulation has
 become stretched from north to south, likely due to the approach of
 a cold front that is currently located a few hundred miles to the
 northwest of Leslie.  The initial intensity is held at 30 kt based
 on the earlier ASCAT data.
 
 The cold front is expected to merge with Leslie by tonight, causing
 extratropical transition.  While transitioning, Leslie is forecast
 to strengthen for a couple of days due to significant baroclinic
 forcing, and the NHC intensity forecast takes the peak winds just
 below hurricane force at 36 and 48 hours.  Later in the week, the
 extratropical system is expected to cut off and gradually lose its
 frontal features.  Although this will likely cause some weakening,
 it should also allow the system to regain subtropical
 characteristics.  The NHC intensity forecast is fairly similar to
 the previous one and near the IVCN consensus model.  This forecast
 is also in fairly good agreement with the GFS and ECMWF models,
 which are usually reliable intensity models for large subtropical
 systems like Leslie.  Based on the latest guidance, Leslie is now
 expected to transition back to a subtropical cyclone in 96 hours.
 
 Leslie has jogged to the southeast during the past several hours,
 but an eastward to northeastward motion is expected during the next
 day or so as Leslie makes its extratropical transition.  After that
 time, a turn to the north is expected followed by a slow westward
 motion when Leslie cuts off from the mid-latitude flow. The models
 are in fairly good agreement on this looping motion, and the NHC
 track forecast follows the various consensus aids.
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  25/0900Z 31.9N  46.2W   30 KT  35 MPH
  12H  25/1800Z 32.1N  44.8W   40 KT  45 MPH
  24H  26/0600Z 32.7N  41.9W   50 KT  60 MPH...POST-TROP/EXTRATROP
  36H  26/1800Z 34.5N  40.5W   60 KT  70 MPH...POST-TROP/EXTRATROP
  48H  27/0600Z 36.1N  41.1W   60 KT  70 MPH...POST-TROP/EXTRATROP
  72H  28/0600Z 36.0N  45.0W   55 KT  65 MPH...POST-TROP/EXTRATROP
  96H  29/0600Z 35.3N  48.2W   55 KT  65 MPH...SUBTROPICAL STORM
 120H  30/0600Z 35.0N  50.0W   50 KT  60 MPH
 
 $$
 Forecaster Cangialosi
 
 

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