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Tropical Storm HILARY


Tropical Storm Hilary Discussion Number  28
NWS National Hurricane Center Miami FL       EP092017
200 AM PDT Fri Jul 28 2017

The structure of Hilary has changed little over the past several
hours, as a small area of convection persists near the center
mainly in the southeastern quadrant.  Recent satellite intensity
estimates range from 45-70 kt, and based on these, the initial
intensity remains a possibly generous 60 kt.

Hilary should cross the 26C isotherm in 12-18 h, and given the
current level of convective organization, significant re-
intensification seems unlikely during that time.  After that, the
cyclone is forecast to move over steadily decreasing sea surface
temperatures and into a drier air mass, and this combination should
result in steady weakening.  The cyclone is now forecast to weaken
to a depression in about 72 h over 24C sea surface temperatures and
degenerate to a remnant low shortly thereafter.  The new intensity
forecast shows a faster weakening than the previous forecast after
12 h, and it is in best overall agreement with the SHIPS and LGEM
models.  It is possible that interaction with Tropical Storm Irwin
could lead to a faster decay than currently forecast.

The initial motion is 300/7, a little to the right of that in the
previous advisory.  A mid-level ridge to the north of Hilary is
expected to steer the cyclone generally west-northwestward for 48 h
or so.  Around 72 h, a westward turn appears likely as the cyclone
interacts with, and eventually absorbs Irwin.  After this event,
Hilary or its remnants should resume a west-northwestward motion as
the weakening system is steered by the low-level flow.  The new
forecast track is nudged north of the previous track, but it lies
south of the consensus models, which have shifted northward since
the last advisory.


INIT  28/0900Z 18.7N 117.9W   60 KT  70 MPH
 12H  28/1800Z 19.3N 119.0W   60 KT  70 MPH
 24H  29/0600Z 20.3N 120.6W   55 KT  65 MPH
 36H  29/1800Z 21.1N 122.6W   45 KT  50 MPH
 48H  30/0600Z 21.9N 124.9W   40 KT  45 MPH
 72H  31/0600Z 22.5N 129.0W   30 KT  35 MPH
 96H  01/0600Z 23.5N 132.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  02/0600Z 25.0N 135.0W   20 KT  25 MPH...POST-TROP/REMNT LOW

Forecaster Beven