282 
WTPZ43 KNHC 070436
TCDEP3

Tropical Depression Thirteen-E Special Discussion Number   1
NWS National Hurricane Center Miami FL       EP132018
1000 PM PDT Mon Aug 06 2018

Microwave data from this evening indicate that a small low pressure
area has formed within an area of disturbed weather (Invest 94E)
that we have been monitoring for several days.  The data indicate
that the well-defined low is embedded within a growing ball of
convection, along with tight banding near the center. The initial
wind speed is set to 30 kt in accordance with a special 0400 UTC
classification from TAFB.  Gradual strengthening is forecast over
the next couple of days until the system passes over cooler waters.
Most of the guidance is indicating only slow intensification due to
northeasterly shear, although some caution should be advised since
the depression is fairly small.

An uncertain estimate of initial motion is 270/9 kt.  The
subtropical ridge to the north is expected to steer the system
westward for the next day or two, then the forecast gets tricky.
The GFS-based guidance is showing Hurricane John weakening the
ridge enough to cause a northward or north-northeastward turn of the
new tropical cyclone by Thursday, while the ECMWF and its ensemble
show the system avoiding any binary interaction with John, and
continuing west-northwestward. With such widely divergent guidance,
the first forecast will stay close to the consensus, and perhaps
later guidance can nail down the specifics of any poleward turn.


FORECAST POSITIONS AND MAX WINDS

INIT  07/0500Z 14.5N 124.3W   30 KT  35 MPH
 12H  07/1200Z 14.4N 125.4W   40 KT  45 MPH
 24H  08/0000Z 14.4N 127.2W   45 KT  50 MPH
 36H  08/1200Z 14.7N 128.7W   50 KT  60 MPH
 48H  09/0000Z 15.2N 129.9W   55 KT  65 MPH
 72H  10/0000Z 17.0N 130.5W   55 KT  65 MPH
 96H  11/0000Z 19.5N 131.0W   50 KT  60 MPH
120H  12/0000Z 22.0N 132.5W   40 KT  45 MPH

$$
Forecaster Blake