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TROPICAL STORM HENRI DISCUSSION NUMBER   6
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082015
500 AM AST THU SEP 10 2015

There has been little change in the cloud pattern of Henri since
the previous advisory.  The tropical storm remains sheared with the
low-level center displaced to the west of the main area of deep
convection.  The initial wind speed is held at 35 kt, which could
be conservative based on the earlier scatterometer data.  This
intensity estimate is on the high side of the latest Dvorak
analyses.

Henri is currently being affected by 15-20 kt of west-southwesterly
wind shear and dry air has wrapped around the west and south sides
of the circulation.  The shear is expected to lessen later today,
and that could allow Henri to gain some strength. However,
significant intensification is not expected as the cyclone should
cross the north wall of the Gulf Stream in 36-48 hours, where a
sharp gradient in sea surface temperatures exist. Henri is forecast
to lose tropical characteristics in a little over 2 days, when it is
expected to be over cold water.  Most of the guidance shows the
extratropical low dissipating by day 5, and the NHC forecast
follows suit.

The tropical storm has been moving erratically during the last
several hours, but the general motion has been slowly northward.  A
faster northward motion is expected to begin later today and
continue for the next 24 to 36 hours as a subtropical ridge
strengthens to the east of Henri.  After that time, an even faster
northeastward and then eastward motion is predicted when the cyclone
becomes embedded in the mid-latitude westerlies.  The models are in
good agreement on this overall scenario, and little change was made
to the previous track forecast.

The latter part of this forecast, when the storm is expected to be
post-tropical, is based on guidance provided by NOAA's Ocean
Prediction Center.

FORECAST POSITIONS AND MAX WINDS

INIT  10/0900Z 31.4N  61.0W   35 KT  40 MPH
 12H  10/1800Z 33.0N  61.3W   40 KT  45 MPH
 24H  11/0600Z 35.9N  60.9W   45 KT  50 MPH
 36H  11/1800Z 39.3N  59.7W   50 KT  60 MPH
 48H  12/0600Z 43.0N  56.5W   45 KT  50 MPH
 72H  13/0600Z 48.0N  45.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
 96H  14/0600Z 46.5N  29.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
120H  15/0600Z...DISSIPATED

$$
Forecaster Cangialosi

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