ZCZC MIATCDEP1 ALL
TTAA00 KNHC DDHHMM

TROPICAL STORM ESTELLE DISCUSSION NUMBER   8
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP062016
300 AM MDT SUN JUL 17 2016

A large increase in both the areal coverage and depth of the central
convective cloud mass has occurred since the previous advisory due
to the development of a irregularly shaped CDO. Cloud tops near the
alleged center have been -80C and colder during the past couple of
hours. Recent SSMI/S and AMSU microwave passes indicate that the
low-level circulation center has become better defined, and has also
moved closer to the strongest convection and farther into the CDO.
As a result, satellite intensity estimates from TAFB and SAB have
increased to a consensus T3.5/55 kt. However, UW-CIMSS ADT and NHC
objective Dvorak estimates are only T2.8/41 kt and T3.0/45 kt,
respectively. Given that the aforementioned microwave images still
indicated some southward tilt to the mid-level center due to modest
northerly vertical shear, the initial intensity has only been
increased to 50 kt for this advisory.

The initial motion estimate is westward or 280/08 kt. A motion
between west and west-northwest is expected for the next 96 hours as
Estelle moves along the southern periphery of a strong deep-layer to
its north. After that time, a strong mid-latitude upper-level
trough/low currently located near 25N/119W is forecast to dig
southwestward and erode the ridge, allowing Estelle to turn
northwestward into the developing weakness in the subtropical high.
The new NHC model guidance remains tightly packed, and the official
forecast track is just an update of the previous advisory track, and
follows a blend of the GFS, ECMWF, and Florida State Superensemble
(FSSE) models.

Moderate northerly to northwesterly shear is forecast to affect
Estelle for the next 36 hours, so only modest intensification is
expected. After that, however, the vertical shear is forecast to
decrease to around 5 kt through the end of the period, resulting in
more substantial strengthening through 72 h while the cyclone
remains over favorable SSTs. By 96 h, gradual weakening is forecast
to ensue as Estelle begins to move over sub-25C ocean temperatures.
The NHC intensity forecast is similar to the previous advisory, and
remains above the model consensus IVCN and the SHIPS/LGEM models,
but close to the FSSE intensity forecast.

FORECAST POSITIONS AND MAX WINDS

INIT  17/0900Z 16.2N 111.1W   50 KT  60 MPH
 12H  17/1800Z 16.6N 112.2W   60 KT  70 MPH
 24H  18/0600Z 17.1N 113.7W   65 KT  75 MPH
 36H  18/1800Z 17.6N 115.3W   70 KT  80 MPH
 48H  19/0600Z 17.8N 117.1W   75 KT  85 MPH
 72H  20/0600Z 18.3N 121.1W   85 KT 100 MPH
 96H  21/0600Z 18.9N 125.8W   70 KT  80 MPH
120H  22/0600Z 20.7N 131.1W   50 KT  60 MPH

$$
Forecaster Stewart

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