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Tropical Depression EIGHT-E


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Tropical Depression Eight-E Discussion Number   2
NWS National Hurricane Center Miami FL       EP082017
200 PM PDT Tue Jul 18 2017

Strong northwesterly shear continues over the depression with deep
convection confined to the southern portion of the circulation.
Recent visible satellite images also show that there are a couple
of low-level vorticity centers rotating about the mean center.  A
recent ASCAT pass that caught the eastern portion of the depression
only revealed winds of around 20 kt.  However, the initial
intensity will remain a possibly generous 30 kt for this advisory
since the instrument did not sample the area of strongest
convection to the southwest of the center.

The strong vertical wind shear currently over the cyclone is
expected to continue during the next day or two, and the official
forecast show no strengthening during this time.  In about 3 days, a
more favorable upper-level pattern could materialize, but given the
uncertainty about the structure of the tropical cyclone at that
time and the potential interaction of nearby Tropical Storm Greg,
the NHC intensity forecast does not reflect much change in wind
speed.

The initial motion estimate is 270/4.  The track forecast remains
quite uncertain as the models show some interaction between the
depression and Tropical Storm Greg.  Most of the models indicate
that the depression will move slowly southwestward during the next
couple of days until Greg passes to the north in about 72 hours.
After that occurs, the cyclone should begin to move west-
northwestward at a faster forward speed under the influence of a
low- to mid-level ridge that is predicted to extend westward from
northwestern Mexico.  Due to the expected complex interaction
between, and possible merger of, the two tropical cyclones the
forecast track of the depression remains quite low.


FORECAST POSITIONS AND MAX WINDS

INIT  18/2100Z 14.9N 119.4W   30 KT  35 MPH
 12H  19/0600Z 14.7N 120.1W   30 KT  35 MPH
 24H  19/1800Z 14.4N 120.9W   30 KT  35 MPH
 36H  20/0600Z 14.0N 121.7W   30 KT  35 MPH
 48H  20/1800Z 13.7N 122.4W   30 KT  35 MPH
 72H  21/1800Z 13.7N 123.6W   35 KT  40 MPH
 96H  22/1800Z 14.0N 126.0W   35 KT  40 MPH
120H  23/1800Z 14.5N 131.0W   30 KT  35 MPH

$$
Forecaster Brown

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