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Tropical Storm Emilia Discussion Number   4
NWS National Hurricane Center Miami FL       EP062018
900 AM MDT Thu Jun 28 2018

Deep convection continues in the western semicircle of the cyclone,
although a fair portion of the eastern side of the low-level
circulation is exposed due to shear.  Satellite classifications are
essentially the same as 6 hours ago, so the initial wind speed will
stay 35 kt. Global models are in good agreement that the wind shear
will decrease over the next 24 hours, which should promote
strengthening. In a couple of days, Emilia is predicted to move over
cool SSTs and through a drier environment, causing its inevitable
weakening to begin.  The official forecast is essentially an update
of the previous one, showing a gradual increase in strength until
late Friday, then weakening on Sunday.  Emilia should become a
remnant low by 96 hours as it moves over SSTs of about 23C.

Emilia has been a challenging storm to track because of limited
microwave passes and an elongated low-level structure.  Even with
1-min GOES-16 visible data, it is difficult to tell how embedded
the center of Emilia is within the deep convection.  The available
data suggest the storm has slowed a little bit and turned to the
right, so my motion estimate is 290/12 kt.  A mid-level ridge over
Mexico and the adjacent eastern Pacific should gradually weaken
during the next few days, resulting in a reduction of Emilia's
forward speed. The biggest change from the last forecast cycle is
that there could be a more substantial break in the subtropical
ridge in the medium-range period, allowing the storm to continue a
more west-northwestward motion, rather than taking a climatological
westward turn. This track is dependent on how strong the cyclone is
at that time and, since Emilia is forecast to be rather weak at
long range, the official forecast is on the southern side of the
guidance envelope, albeit with a northward adjustment since the last
advisory.


FORECAST POSITIONS AND MAX WINDS

INIT  28/1500Z 14.4N 112.4W   35 KT  40 MPH
 12H  29/0000Z 15.1N 114.1W   40 KT  45 MPH
 24H  29/1200Z 15.9N 116.2W   45 KT  50 MPH
 36H  30/0000Z 16.6N 118.0W   50 KT  60 MPH
 48H  30/1200Z 17.2N 119.7W   50 KT  60 MPH
 72H  01/1200Z 18.6N 123.0W   40 KT  45 MPH
 96H  02/1200Z 20.5N 126.5W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  03/1200Z 21.5N 131.0W   20 KT  25 MPH...POST-TROP/REMNT LOW

$$
Forecaster Blake

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