ZCZC MIATCDEP5 ALL
TTAA00 KNHC DDHHMM

TROPICAL STORM HILDA DISCUSSION NUMBER   5
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP102015
800 PM PDT THU AUG 06 2015

The cloud pattern of Hilda has not changed much since the previous
advisory.  The cyclone has a couple of curved convective bands with
a small symmetric central dense overcast.  Recent microwave data
also indicates that the inner core has not become any better
organized during the afternoon.  A blend of the subjective and
objective Dvorak T-numbers support maintaining an initial intensity
of 50 kt.

Hilda is expected to remain in an environment of low vertical wind
shear and over warm sea surface temperatures during the next couple
of days.  These conditions favor intensification and the NHC
forecast brings Hilda to hurricane strength within the next 24
hours. The new official forecast shows a slightly higher peak
intensity in about 48 hours, which is a blend of the latest
statistical guidance.  After that time, a drier and more stable air
mass and increasing southwesterly shear around 96 h are expected to
induce weakening.  The NHC forecast is below the model guidance
late in the forecast period, since the small tropical cyclone is
likely to spin down more quickly as a result of the strong shear.

The tropical storm is moving due west or 270 degrees at 12 kt.
The forecast reasoning remains the same as before.  Hilda is
expected to turn west-northwestward in about 36 hours when it nears
the western periphery of a subtropical ridge to its north.  In
about 96 hours, Hilda is forecast to turn northwestward due to a
developing weakness in the subtropical ridge.  The model guidance
is in good agreement through day 3, but diverge somewhat thereafter.
The ECMWF and UKMET show a faster forward motion and are along the
western edge of the guidance envelope.  Meanwhile, the GFS and HWRF
are along the eastern edge.  The updated NHC forecast is similar to
the previous advisory and near the GFS ensemble mean late in the
period.


FORECAST POSITIONS AND MAX WINDS

INIT  07/0300Z 12.7N 134.6W   50 KT  60 MPH
 12H  07/1200Z 12.7N 136.3W   60 KT  70 MPH
 24H  08/0000Z 13.0N 138.5W   70 KT  80 MPH
 36H  08/1200Z 13.7N 140.5W   80 KT  90 MPH
 48H  09/0000Z 14.5N 142.5W   80 KT  90 MPH
 72H  10/0000Z 16.3N 146.1W   70 KT  80 MPH
 96H  11/0000Z 17.8N 148.5W   60 KT  70 MPH
120H  12/0000Z 19.0N 150.0W   40 KT  45 MPH

$$
Forecaster Brown

NNNN