000
WTNT45 KNHC 160837
TCDAT5

TROPICAL STORM IAN DISCUSSION NUMBER  16
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL102016
500 AM AST FRI SEP 16 2016

Cloud tops have warmed near the center of Ian overnight, but the
cloud pattern in geostationary imagery still resembles that of a
tropical cyclone.  A small mid-level eye and a banding convective
structure are also seen in a 0417 UTC AMSR-2 overpass from GCOM-W1.
The initial intensity is set to 50 kt based on the latest ST3.0
classification from TAFB and the fast forward speed of the cyclone,
which now exceeds 40 kt.  Ian should become extratropical within 12
hours and then be absorbed by another front near or northeast of
Iceland in about 48 hours, as indicated by the latest ECMWF and
UKMET model solutions.

The AMSR-2 pass mentioned above and a 0544 UTC SSM/I pass were
helpful in locating the low-level center of Ian, and the initial
motion estimate is a somewhat uncertain 040/42.  The cyclone should
continue moving quickly northeastward ahead of a large upper-level
trough until it is absorbed.  The new NHC track forecast is based on
a blend of the tightly clustered global model guidance.

The track, intensity, and wind radii forecasts are based largely on
guidance from the Ocean Prediction Center.

FORECAST POSITIONS AND MAX WINDS

INIT  16/0900Z 45.2N  40.8W   50 KT  60 MPH
 12H  16/1800Z 50.1N  34.4W   50 KT  60 MPH...POST-TROP/EXTRATROP
 24H  17/0600Z 57.2N  25.4W   50 KT  60 MPH...POST-TROP/EXTRATROP
 36H  17/1800Z 61.8N  18.7W   50 KT  60 MPH...POST-TROP/EXTRATROP
 48H  18/0600Z...ABSORBED

$$
Forecaster Brennan