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Tropical Storm Hilary Discussion Number  29
NWS National Hurricane Center Miami FL       EP092017
800 AM PDT Fri Jul 28 2017

Cloud tops near the center of Hilary continue to warm this morning,
and a consensus of objective and subjective Dvorak intensity
estimates suggests a decreased initial intensity of 55 kt.  An AMSR
pass at 0913 UTC showed a band of deep convection spiraling into the
center.  There is also a pronounced dry slot, indicative of the
drier environment that the cyclone is moving into.  Hilary is
crossing the 26 C SST isotherm this morning, so the window for any
reintensification is closing quickly, despite the insistence of the
HWRF and GFS which both show a hurricane in 24 hours.  Instead, the
official forecast continues to follow the statistical models, which
depict steady weakening until Hilary becomes a remnant low.  The
intensity forecast is a little lower than indicated in the previous
advisory based on the lower initial intensity, but no significant
changes have been made.

The low-level center of the tropical storm was briefly visible this
morning, and the initial motion is a fairly confident 305/7.  There
has been a significant shift in the guidance toward the north for
this advisory, especially the GFS and the GFS-based hurricane
models. The 06Z GFS in particular has shifted nearly 500 nm to the
northeast at day 5 and no longer shows any significant interaction
between Irwin and Hilary. The 00Z ECMWF also shifted a little north,
but not nearly to the same extent.  Interaction between the
two cyclones, and the eventual absorption of Irwin by Hilary, is
still expected for now, as shown by the UKMET and ECMWF.  Based on
the changes in the guidance, the official forecast has been shifted
north, but still lies well south of the multi-model consensus aids.
It does, however, fall near the middle of the ECMWF and GFS ensemble
tracks.


FORECAST POSITIONS AND MAX WINDS

INIT  28/1500Z 19.2N 118.4W   55 KT  65 MPH
 12H  29/0000Z 19.9N 119.5W   50 KT  60 MPH
 24H  29/1200Z 20.9N 121.3W   45 KT  50 MPH
 36H  30/0000Z 21.8N 123.2W   40 KT  45 MPH
 48H  30/1200Z 22.8N 125.4W   35 KT  40 MPH
 72H  31/1200Z 24.0N 129.4W   25 KT  30 MPH
 96H  01/1200Z 24.8N 132.6W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  02/1200Z 26.5N 135.0W   20 KT  25 MPH...POST-TROP/REMNT LOW

$$
Forecaster Zelinsky

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