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Tropical Storm HARVEY


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Tropical Storm Harvey Discussion Number   3
NWS National Hurricane Center Miami FL       AL092017
1100 PM AST Thu Aug 17 2017

Since an Air Force Hurricane Hunter aircraft departed the storm a
few hours ago, the cloud pattern of Harvey hasn't changed much.
Dvorak intensity estimates from both TAFB and SAB are 30 kt,
and based on the earlier aircraft measurements the current
intensity is held at 35 kt.  The storm is in a moderate easterly
shear environment, which should allow only slow strengthening for
the next couple of days.  After that, the dynamical models indicate
that a decrease in shear should occur.  As noted earlier, however,
the GFS and ECMWF global models do not show strengthening of Harvey
and in fact practically dissipate it during the forecast period.
This suggests something unfavorable in the environment besides shear
ahead of the system, perhaps some drier air or subsidence.  The
official intensity forecast shows modest strengthening and is
generally close to the model consensus which includes the
statistical/dynamical guidance and the regional hurricane models
(that do show some strengthening).

The motion continues westward or 270/16.  There is no change to the
track forecast philosophy from the previous advisory package.
Harvey should remain embedded in the flow on the south side of a
strong mid-level ridge throughout most of the forecast period,
which should steer the system on a continued westward track.  Near
the end of period, the guidance suggests a slightly more northward
motion with some deceleration.  The official forecast track is near
the dynamical model consensus and very close to the previous NHC
track.

FORECAST POSITIONS AND MAX WINDS

INIT  18/0300Z 13.0N  57.4W   35 KT  40 MPH
 12H  18/1200Z 13.2N  59.9W   35 KT  40 MPH
 24H  19/0000Z 13.6N  63.3W   40 KT  45 MPH
 36H  19/1200Z 13.9N  67.0W   45 KT  50 MPH
 48H  20/0000Z 14.1N  70.9W   50 KT  60 MPH
 72H  21/0000Z 14.8N  78.6W   60 KT  70 MPH
 96H  22/0000Z 16.0N  85.5W   60 KT  70 MPH
120H  23/0000Z 17.5N  89.0W   55 KT  65 MPH...INLAND

$$
Forecaster Pasch

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