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Tropical Storm Ileana Discussion Number   7
NWS National Hurricane Center Miami FL       EP112018
400 AM CDT Mon Aug 06 2018

A strong burst of deep convection consisting of some cloud top
temperatures of -85 to -90 deg C near the center has developed
during the past several hours. A Central Dense Overcast (CDO)
feature has developed as a result, and the Acapulco, Mexico, radar
indicates that a banded eye feature has developed in the center of
the CDO. Based on the radar data and a UW-CIMSS ADT estimate of
T3.6/57 kt, the initial intensity has been increased to 55 kt.

Ileana has begun to accelerate around the eastern periphery of
rapidly developing Tropical Storm John, and initial motion estimate
is now 310/15 kt. Little change was made to the previous forecast
track other than to nudge the forecast a little more to the right,
closer to Mexico, due to the more eastward initial position based
on the aforementioned radar data. Ileana is expected to continue
moving northwestward between Tropical Storm John and a deep-layer
ridge over Mexico. The NHC model guidance remains in good agreement
on this track scenario until dissipation or absorption occurs in
about 72 hours, and the new forecast track lies close to the HCCA
and FSSE consensus track model solutions.

The shear is forecast to decrease to around 15 kt over the next 24
hours, and the global model fields actually indicate that the shear
could be lower than that since most of the stronger outflow from
Tropical Storm John will remain north of Ileana. Based on the
expected lower shear conditions, a very moist atmosphere, SSTs
near 30 deg C, and the much improved internal structure noted in
radar data, Ileana is forecast to become a hurricane within the
next 24 hours. The official intensity forecast follows the upward
trend of the consensus models FSSE and HCCA, but is a little lower
and closer to the IVCN intensity consensus model.

The forecast tropical-storm-force wind radii in the new official
forecast has been expanded to the northeast based on recent ASCAT
wind data. Although the core of strongest winds are forecast to
remain offshore of the coast of southwestern Mexico, only a slight
deviation to the right of track and/or strong localized funneling
effects would bring hurricane-force winds onshore. As a result,
the government of Mexico has issued a Hurricane Watch from Punta
San Telmo to Playa Perula.

FORECAST POSITIONS AND MAX WINDS

INIT  06/0900Z 15.2N 100.3W   55 KT  65 MPH
 12H  06/1800Z 16.5N 102.3W   60 KT  70 MPH
 24H  07/0600Z 18.5N 105.1W   65 KT  75 MPH
 36H  07/1800Z 20.3N 107.8W   65 KT  75 MPH
 48H  08/0600Z 21.6N 110.2W   50 KT  60 MPH
 72H  09/0600Z...DISSIPATED

$$
Forecaster Stewart

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