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TROPICAL STORM IAN DISCUSSION NUMBER  14
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL102016
500 PM AST THU SEP 15 2016

A scatterometer overpass shows that the circulation of Ian is losing
definition as the cyclone accelerates northeastward, with the system
elongating north to south.  The scatterometer did not sample the
maximum winds, and the subtropical cyclone satellite intensity
estimates are unchanged.  Based on this, the initial intensity
remains a likely conservative 45 kt.  Ian is forecast to merge with
a baroclinic zone and undergo extratropical transition during the
next 12-36 hours, and in the process it is expected to strengthen to
at least storm-force before it is absorbed by another extratropical
low. The new intensity forecast is an update of the previous
forecast based on the global models and guidance from the Ocean
Prediction Center.

Ian continues to accelerate northeastward and the initial motion is
now 040/30 kt.  A northeastward motion with an additional increase
in forward speed is expected before the cyclone is absorbed.  The
new forecast track remains near the center of the tightly clustered
track guidance.

FORECAST POSITIONS AND MAX WINDS

INIT  15/2100Z 39.6N  47.7W   45 KT  50 MPH
 12H  16/0600Z 43.2N  42.7W   55 KT  65 MPH...POST-TROPICAL
 24H  16/1800Z 49.5N  34.5W   60 KT  70 MPH...POST-TROP/EXTRATROP
 36H  17/0600Z 55.5N  26.5W   60 KT  70 MPH...POST-TROP/EXTRATROP
 48H  17/1800Z 61.0W  18.5W   60 KT  70 MPH...POST-TROP/EXTRATROP
 72H  18/1800Z...ABSORBED BY EXTRATROPICAL LOW

$$
Forecaster Beven

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