ZCZC MIATCDEP4 ALL
TTAA00 KNHC DDHHMM

TROPICAL STORM KEVIN DISCUSSION NUMBER  16
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP142015
800 AM PDT FRI SEP 04 2015

Kevin's cloud pattern consists of a large circular mass of very deep
convection, with the low- to mid-level centers nearly co-located as
of several hours.  Since that time, satellite data indicate that the
cyclone has begun the process of decoupling due to the 25 kt of
south-southwesterly vertical shear affecting it. Although Dvorak
intensity estimates were T3.5/55 kt from TAFB and SAB at 1200 UTC,
the initial wind speed is kept at 50 kt due to the weakening that
has likely begun.

Even stronger shear associated with a potent mid- to upper-level
trough to the northwest of Kevin should result in a complete
separation of the cyclone's low- to mid-level circulations within 24
hours, according to global models. Substantially drier air behind
the trough should also be entrained by the cyclone, which should
cause a collapse of deep convection during the next or so.  Global
models depict Kevin becoming a remnant low in about 36 hours and
show dissipation by 72 hours.  The new intensity forecast shows
faster weakening than the previous one, with remnant low status and
dissipation also indicated sooner.

Based on fixes from a series of microwave passes overnight, the
cyclone has been moving a little east of due north, and the initial
motion estimate is 010/07.  Kevin should turn due north soon when
the trough to its northwest sinks southward.  As Kevin decouples
during the next 24 hours, a deceleration is forecast by the model
guidance. A bend in the track toward the northwest and west-
northwest is also anticipated during this time, when Kevin meets
the opposing flow around the low-level subtropical ridge over the
eastern Pacific. The new track forecast is on the right side of the
guidance envelope at first, primarily due to the north-northeasterly
motion overnight but is shifted a bit southward once Kevin becomes a
remnant low.


FORECAST POSITIONS AND MAX WINDS

INIT  04/1500Z 21.2N 115.2W   50 KT  60 MPH
 12H  05/0000Z 22.1N 115.4W   45 KT  50 MPH
 24H  05/1200Z 22.9N 116.0W   35 KT  40 MPH
 36H  06/0000Z 23.3N 116.9W   30 KT  35 MPH...POST-TROP/REMNT LOW
 48H  06/1200Z 23.4N 118.1W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  07/1200Z...DISSIPATED

$$
Forecaster Kimberlain

NNNN