ZCZC MIATCDEP5 ALL
TTAA00 KNHC DDHHMM

TROPICAL STORM IVETTE DISCUSSION NUMBER  18
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP102016
800 PM PDT SAT AUG 06 2016

Visible and infrared satellite imagery indicate that all of Ivette's
deep convection has been sheared away by moderate-to-strong
southwesterly vertical wind shear, leaving the low-level circulation
center fully exposed more than 80 n mi southwest of any convection.
Satellite intensity estimate from TAFB and SAB have decreased as a
result, and the latest UW-CIMSS intensity estimate is T2.7/39 kt.
Allowing for some vortex spin down since the previous advisory
intensity of 45 kt, the initial intensity has been lowered to 40 kt
for this advisory.

Ivette has continued to move west-northwestward, or 290/10 kt.  This
general motion should continue for the next 36 hours or so while the
cyclone moves toward a weakness in the subtropical ridge around
139W-140W longitude. After that time, however, Ivette is expected to
be a vertically shallow remnant low pressure system that will be
steered westward and then west-southwestward by the low-level
tradewind flow. The new NHC track forecast is essentially just an
extension of the previous advisory track and lies a little south of
the multi-model consensus TVCN due to more rapid weakening than
previously expected.

Ivette still has a very robust low-level circulation and is moving
over near-28C SSTs, so redevelopment of deep convection seems likely
tonight after 0600Z during the convective maximum period, which
should allow the cyclone to retain tropical storm status. However,
by 24 hours and beyond, strong southwesterly shear of 25 kt or more,
along with considerably drier mid-level air and SSTs of around 26C,
should cause any remaining convection to dissipate. As a result,
Ivette is forecast to become a remnant low pressure system by 36
hours, with dissipation expected by 96 hours, if not sooner. The
official intensity forecast closely follows a blend of the SHIPS and
LGEM intensity model solutions.

FORECAST POSITIONS AND MAX WINDS

INIT  07/0300Z 16.7N 136.4W   40 KT  45 MPH
 12H  07/1200Z 17.2N 137.7W   35 KT  40 MPH
 24H  08/0000Z 17.9N 139.3W   30 KT  35 MPH
 36H  08/1200Z 18.4N 140.9W   30 KT  35 MPH...POST-TROP/REMNT LOW
 48H  09/0000Z 18.5N 142.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  10/0000Z 17.9N 146.4W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  11/0000Z...DISSIPATED

$$
Forecaster Stewart

NNNN