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POST-TROPICAL CYCLONE JOAQUIN DISCUSSION NUMBER  42
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL112015
1100 PM AST WED OCT 07 2015

Satellite imagery indicates that the system no longer resembles a
tropical cyclone, with a disorganized area of multi-layered
cloudiness sheared off well to the northeast of the ill-defined
low-level center.  However, model analyses and surface data
indicate that the cyclone is not yet embedded within a frontal
zone, and therefore is not extratropical at this time.  Nonetheless,
since the system lacks sufficient organized deep convection to
qualify as a tropical cyclone, Joaquin is being declared as a post-
tropical cyclone, and advisories are being terminated.  Cyclone
phase space analyses from Florida State University indicate that the
system will become extratropical in about 12 hours, and this is
also shown in the official forecast.  The current intensity is set
at 55 kt in agreement with a recent scatterometer overpass.  Global
models show a gradual spindown of the cyclone over the next several
days, and so does the official forecast.

Post-tropical Joaquin continues to move rapidly toward the east,
or 080/30 kt, while embedded in strong mid-latitude westerlies.
The steering current is forecast to gradually weaken as a mid-level
trough deepens near the Greenwich meridian, and the cyclone should
move at a progressively slower forward speed over the period.  In
2-3 days, the system is forecast to turn southeastward ahead of
the abovementioned trough.  There is fairly good agreement among
the global models on this scenario.

The track, intensity, and wind radii forecasts are primarily based
upon guidance provided by the NOAA Ocean Prediction Center.

FORECAST POSITIONS AND MAX WINDS

INIT  08/0300Z 42.0N  37.0W   55 KT  65 MPH...POST-TROPICAL
 12H  08/1200Z 42.5N  32.5W   50 KT  60 MPH...POST-TROP/EXTRATROP
 24H  09/0000Z 42.8N  26.5W   45 KT  50 MPH...POST-TROP/EXTRATROP
 36H  09/1200Z 42.5N  22.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
 48H  10/0000Z 42.5N  19.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
 72H  11/0000Z 42.0N  14.5W   35 KT  40 MPH...POST-TROP/EXTRATROP
 96H  12/0000Z 40.5N  11.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
120H  13/0000Z 39.0N  10.5W   35 KT  40 MPH...POST-TROP/EXTRATROP

$$
Forecaster Pasch

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