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Tropical Storm Aletta Discussion Number   6
NWS National Hurricane Center Miami FL       EP022018
300 AM MDT Thu Jun 07 2018

The cloud pattern has become a little better organized and the
low-level center appears to be more embedded within the deep
convection than several hours ago. Although the outflow is fair,
there are still shear at some level affecting the cyclone by
observing the motion of the cirrus clouds.  T-numbers from all
agencies including the UW-CIMSS objective values have increased to
3.5 on the Dvorak scale, so the initial intensity has been increased
to 55 kt.

Guidance suggests some modest intensification, although there is a
difference between the GFS-based SHIPS model and the ECMWF-based
one.  The latter is less aggressive and barely forecast Aletta
to become a hurricane.  The NHC follows the intensity consensus and
the FSU super-ensemble, and calls for Aletta to become a hurricane
within the next 12 to 24 hours. After 3 days, the environment
becomes unfavorable and a gradual weakening should then begin.

Aletta is moving toward the west or 280 degrees at about 6 kt
around the periphery of a subtropical ridge over Mexico. This
pattern should continue to steer the cyclone on a general
westward course for a day or two, and then the cyclone sould turn to
the west-northwest or northwest toward a weakness of the ridge.  The
NHC forecast is very close to the FSU super-ensemble, and is in the
middle of the wide guidance envelope bounded by the GFS to the north
and the ECMWF to the south.



FORECAST POSITIONS AND MAX WINDS

INIT  07/0900Z 14.6N 109.2W   55 KT  65 MPH
 12H  07/1800Z 14.7N 110.0W   65 KT  75 MPH
 24H  08/0600Z 14.9N 111.0W   70 KT  80 MPH
 36H  08/1800Z 15.3N 111.7W   75 KT  85 MPH
 48H  09/0600Z 15.7N 112.5W   75 KT  85 MPH
 72H  10/0600Z 17.0N 114.0W   65 KT  75 MPH
 96H  11/0600Z 18.0N 116.0W   45 KT  50 MPH
120H  12/0600Z 18.0N 117.5W   30 KT  35 MPH

$$
Forecaster Avila

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