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TROPICAL DEPRESSION FOUR-E DISCUSSION NUMBER   5
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP042016
300 PM MDT THU JUL 07 2016

Recent ASCAT data indicate that the tropical depression has an
elongated circulation and is still producing maximum winds around
30 kt.  Although deep convection has been increasing in coverage
during the day, it is not all that organized and is primarily
confined to the eastern and southern semicircles.  In addition, dry
air appears to be wrapping into the western part of the
circulation.  Since the cyclone's structure has not yet improved,
and the system is about to move over the cold wake of Hurricane
Blas, it may take a little more time before significant
strengthening can occur.  In fact, the GFS and ECMWF models, which
should have a good handle on the ambient environment, do not show
significant deepening of the cyclone for another 48 hours or so.
Therefore, the NHC official intensity forecast has been adjusted
downward during the first couple of days, with the depression
possibly not becoming a tropical storm until tomorrow.  More
significant strengthening is expected after 48 hours, but even that
could be tempered by interaction with Blas's cold wake.  The NHC
intensity forecast is at the low end of the guidance through 48
hours and then near the IVCN intensity consensus thereafter.

The scatterometer data showed that the low-level center is located
a little farther south than previously estimated, and the initial
motion is now 275/7 kt.  A strong mid-tropospheric ridge extending
westward from northern Mexico is forecast to keep the cyclone on a
westward course for the next 3 days.  By days 4 and 5, the ridge is
expected to weaken a bit, which will allow the cyclone to turn
west-northwestward.  The NHC official track forecast was shifted
slightly southward during the first three days to account for the
updated initial position.  Otherwise, the guidance remains tightly
clustered, and there is high confidence in the track forecast.

FORECAST POSITIONS AND MAX WINDS

INIT  07/2100Z 12.4N 111.7W   30 KT  35 MPH
 12H  08/0600Z 12.6N 112.8W   30 KT  35 MPH
 24H  08/1800Z 12.9N 114.4W   35 KT  40 MPH
 36H  09/0600Z 13.0N 116.1W   40 KT  45 MPH
 48H  09/1800Z 13.1N 118.0W   50 KT  60 MPH
 72H  10/1800Z 12.9N 121.8W   75 KT  85 MPH
 96H  11/1800Z 14.0N 125.5W   85 KT 100 MPH
120H  12/1800Z 16.0N 129.0W   85 KT 100 MPH

$$
Forecaster Berg

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