376 
 WTNT41 KNHC 072033
 TCDAT1
 
 TROPICAL STORM JOAQUIN DISCUSSION NUMBER  41
 NWS NATIONAL HURRICANE CENTER MIAMI FL       AL112015
 500 PM AST WED OCT 07 2015
 
 Joaquin has begun its transition into an extratropical cyclone.
 The cyclone's cloud pattern has become rather asymmetric, with the
 center partially exposed on the west side of weakening deep
 convection.  In addition, cold air is wrapping into the western
 periphery of the circulation, with a warm frontal band becoming
 better defined well northeast of the center.  Earlier ASCAT data
 still showed a large area of 55 to 60 kt winds, so the initial wind
 speed is held at 60 kt.
 
 The storm should gradually lose strength while it moves over
 progressively colder waters north of the Gulf Stream.  Deep
 convection should disappear tonight when the SSTs drop below 20C,
 and Joaquin is expected to become post-tropical at that time. Global
 models are in good agreement on the cyclone becoming a large
 extratropical low on Thursday when frontal features are forecast to
 form near the center. The official intensity forecast is basically
 an update of the previous one, and remains in close agreement with
 the GFS forecast.
 
 Joaquin is speeding eastward at 32 kt, embedded in strong westerly
 flow north of the subtropical ridge, which should keep the cyclone
 moving to the east or east-northeast at a slower forward speed for
 another day or two. Thereafter, the cyclone should slow down even
 more and turn east-southeastward due to it coming under the
 influence of a developing deep-layer trough over western Europe.
 The guidance continues to migrate southward, and the official
 forecast is moved in that direction, near a blend of the Florida
 State Superensemble and the ECMWF models.
 
 The track, intensity, and wind radii forecasts for 12 hours and
 beyond are primarily based upon guidance provided by the Ocean
 Prediction Center.
 
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  07/2100Z 41.5N  41.0W   60 KT  70 MPH
  12H  08/0600Z 42.0N  35.3W   50 KT  60 MPH...POST-TROPICAL
  24H  08/1800Z 42.7N  28.3W   45 KT  50 MPH...POST-TROP/EXTRATROP
  36H  09/0600Z 43.6N  23.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
  48H  09/1800Z 43.8N  19.4W   35 KT  40 MPH...POST-TROP/EXTRATROP
  72H  10/1800Z 43.0N  14.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
  96H  11/1800Z 41.5N  10.0W   30 KT  35 MPH...POST-TROP/EXTRATROP
 120H  12/1800Z...DISSIPATED
 
 $$
 Forecaster Blake