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Tropical Storm Hilary Discussion Number  32
NWS National Hurricane Center Miami FL       EP092017
200 AM PDT Sat Jul 29 2017

The deep convection associated with Hilary has lost some
organization since the last advisory, with little or no convection
currently occurring over the western semicircle. Satellite
intensity estimates range from 45-65 kt, and recent ASCAT data
showed winds of at best 50 kt.  Based on these, the initial
intensity is nudged down to a possibly generous 55 kt.  The system
will be moving over progressively cooler water and into a more
stable environment, which should cause a steady weakening.  By 48
hours, Hilary is forecast to become a remnant low over 23C waters,
and the cyclone is forecast to dissipate completely after 96 hr.

The initial motion is now 305/9.  As mentioned in the previous
advisory, a mid-level ridge extending from southern California
west-southwestward across the eastern Pacific should steer Hilary
on this general path for the next couple of days.  The forecast then
gets more complicated due to potential interaction with TS Irwin.
The guidance is in less good agreement than earlier, with the
possibilities ranging from the Canadian model merging the two
systems in 72 h to the ECMWF showing them dissipating in close
proximity to one another near 120 h.  The track guidance suggests a
west-northwestward to westward turn for Hilary as Irwin or its
remnants move around the eastern and northern sides, and the
official forecast follows this scenario.  The new forecast track is
similar to the previous track for the first 36-48 h and then is
nudged to the south thereafter.


FORECAST POSITIONS AND MAX WINDS

INIT  29/0900Z 20.7N 120.8W   55 KT  65 MPH
 12H  29/1800Z 21.7N 122.3W   50 KT  60 MPH
 24H  30/0600Z 22.9N 124.3W   40 KT  45 MPH
 36H  30/1800Z 24.1N 126.6W   30 KT  35 MPH
 48H  31/0600Z 24.9N 128.8W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  01/0600Z 25.5N 131.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  02/0600Z 25.5N 133.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  03/0600Z...DISSIPATED

$$
Forecaster Beven

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