688 
 WTPZ44 KNHC 041454
 TCDEP4
 
 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