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TROPICAL DEPRESSION EIGHT DISCUSSION NUMBER   4
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082015
500 PM AST WED SEP 09 2015

The depression's cloud pattern has not become better organized so
far today, and the low-level center is exposed a short distance to
the west-southwest of the main area of deep convection.  The deep
convection itself is not well organized, with scant evidence of
banding features.  Final data T-numbers from TAFB and SAB support
keeping the intensity at 30 kt.  The vertical wind shear over the
system, which is currently near 20 kt from the southwest, is
predicted by the global models to relax somewhat over the next
24 to 48 hours.  This would allow for some strengthening, as
indicated in the official forecast.  By 72 hours, the cyclone
should be located over cold waters and the global models depict it
as embedded within a baroclinic zone.  Therefore the system is
forecast to be extratropical around that time.

The depression is still drifting east-southeastward or 115/3 kt.
Over the next couple of days, a mid-level ridge is predicted to
build to the east and northeast of the cyclone while a trough
drops into the eastern United States.  This evolution of the
steering pattern should cause the cyclone to move northward at an
increasing forward speed into Friday.  Afterwards, the flow ahead
of the trough should cause the system to turn eastward at an even
faster forward speed within the mid-latitude westerlies.  The
official track forecast is roughly in the middle of the dynamical
guidance suite.

FORECAST POSITIONS AND MAX WINDS

INIT  09/2100Z 30.6N  60.4W   30 KT  35 MPH
 12H  10/0600Z 31.9N  60.8W   35 KT  40 MPH
 24H  10/1800Z 33.9N  61.0W   40 KT  45 MPH
 36H  11/0600Z 36.9N  60.9W   45 KT  50 MPH
 48H  11/1800Z 40.7N  59.4W   50 KT  60 MPH
 72H  12/1800Z 47.0N  51.0W   45 KT  50 MPH...POST-TROP/EXTRATROP
 96H  13/1800Z 48.5N  37.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
120H  14/1800Z 48.0N  18.0W   35 KT  40 MPH...POST-TROP/EXTRATROP

$$
Forecaster Pasch

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