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Tropical Storm Otis Discussion Number  22
NWS National Hurricane Center Miami FL       EP152017
800 PM PDT Sat Sep 16 2017

Convection has increased near the center of Otis since the last
advisory, and an AMSR-2 pass around 2030 UTC indicated that the
tropical storm was beginning to develop an inner-core.  A consensus
of Dvorak current intensity estimates from TAFB and SAB supports
raising the initial intensity to 40 kt.

Otis is expected to remain over moderate SSTs and within a low-shear
environment for the next 24 to 36 h.  Given that the storm finally
appears to be supporting persistent deep convection near the center,
at least a little more intensification seems likely, and this is
supported by the statistical-dynamical models.  After about 48 h,
lower SSTs and some increase in shear should cause the cyclone to
gradually weaken.  The new intensity forecast is a little higher
than the previous forecast for the first 48 h, but still shows Otis
becoming a remnant low by 96 h.

Otis has continued to move very slowly westward, and has not yet
turned northward, toward a weakness in the subtropical ridge.  All
of the global models still indicate that this turn is imminent, but
regardless of when exactly it occurs, little overall movement is
expected for the next 72 h.  Beyond that time, a faster
west-southwest track is still anticipated as the remnants of Otis
become steered primarily by the low-level tradewinds. Little change
overall has been made to the track forecast.


FORECAST POSITIONS AND MAX WINDS

INIT  17/0300Z 15.9N 127.3W   40 KT  45 MPH
 12H  17/1200Z 16.3N 127.7W   40 KT  45 MPH
 24H  18/0000Z 17.0N 127.8W   45 KT  50 MPH
 36H  18/1200Z 17.9N 127.8W   45 KT  50 MPH
 48H  19/0000Z 18.3N 128.0W   40 KT  45 MPH
 72H  20/0000Z 18.3N 128.8W   35 KT  40 MPH
 96H  21/0000Z 17.1N 131.4W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  22/0000Z 16.5N 134.5W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Zelinsky

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