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Tropical Storm Lee Discussion Number  10
NWS National Hurricane Center Miami FL       AL142017
500 AM AST Sun Sep 17 2017

Lee remains sheared this morning, with the center of circulation
just beneath the northern edge of the cloud mass.  Consequently, the
initial intensity is held at 35 kt and agrees with the subjective
Dvorak intensity estimates from TAFB and SAB.  The cyclone is
forecast to remain in an upper wind environment of strong
west-northwesterly shear through the forecast period.  The global
and statistical models all show no intensification of Lee through 36
hours or so, followed by a gradual weakening trend through day 5.
In fact, the GFS and ECMWF show dissipation in less than 4 days.
Only the HWRF hurricane model indicates modest strengthening around
the 48 hour period.  The official forecast is similar to the
previous package and reflects Lee degenerating into a remnant low in
4 days.

The initial motion is estimated to be westward, or 280/6 kt.  The
cyclone is currently moving within the easterly mid-level flow
produced by a subtropical ridge anchored to the north.  This ridge
is forecast to erode in 36 hours, allowing Lee to gradually turn
west-northwestward and continue tracking in this fashion through 5
days.  A slight adjustment to the right of the previous advisory was
made to lie more closely to the HCCA technique and a blend of the
ECMWF and GFS global models.

FORECAST POSITIONS AND MAX WINDS

INIT  17/0900Z 13.0N  35.4W   35 KT  40 MPH
 12H  17/1800Z 13.1N  36.4W   35 KT  40 MPH
 24H  18/0600Z 13.4N  37.9W   35 KT  40 MPH
 36H  18/1800Z 14.2N  39.7W   35 KT  40 MPH
 48H  19/0600Z 15.0N  41.3W   30 KT  35 MPH
 72H  20/0600Z 17.1N  44.7W   30 KT  35 MPH
 96H  21/0600Z 18.9N  48.4W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  22/0600Z 20.3N  52.3W   20 KT  25 MPH...POST-TROP/REMNT LOW

$$
Forecaster Roberts

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