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Tropical Storm Rosa Discussion Number  26
NWS National Hurricane Center Miami FL       EP202018
800 AM PDT Mon Oct 01 2018

Most of Rosa's deep convection has been sheared northeastward
over portions of the Baja California peninsula, Sonora, and the
southwestern United States.  Locally heavy rains are already
occurring over those areas.  Assuming a gradual weakening of the
cyclone since the last scatterometer overpass, and blending Dvorak
intensity estimates from TAFB and SAB, gives a current intensity
estimate of 40 kt.  Since the cyclone will continue to be influenced
by strong shear, cooler waters, and then interact with land,
continued weakening is likely over the next day or so.  Rosa is
expected to degenerate into a remnant low by the time it reaches the
southwestern United States on Tuesday.

The system is moving north-northeastward, or 030/10 kt.  Rosa
should continue to be steered on that heading, to the east of a
broad mid-level trough off the California coast.  Some increase in
forward speed is expected after Rosa's remnants move into the
Desert Southwest.  The official track forecast remains very close to
the multi-model consensus.

Key Messages:

1. The main hazard expected from Rosa or its remnants is very heavy
rainfall in Baja California, northwestern Sonora, and the U.S.
Desert Southwest.  These rains are expected to produce
life-threatening flash flooding and debris flows in the deserts, and
landslides in mountainous terrain.  For more information about
potential rainfall in that area, please see products from the
Weather Prediction Center and your local NWS forecast office.

2. Tropical storm conditions are affecting portions of the
central and northern Baja California peninsula,  especially over
higher elevations.  These conditions could spread into the northern
Gulf of California later tonight. Interests in those locations
should monitor the progress of Rosa.


FORECAST POSITIONS AND MAX WINDS

INIT  01/1500Z 27.5N 116.5W   40 KT  45 MPH
 12H  02/0000Z 28.9N 115.6W   35 KT  40 MPH
 24H  02/1200Z 31.3N 114.3W   30 KT  35 MPH
 36H  03/0000Z 34.3N 112.9W   20 KT  25 MPH...POST-TROP/INLAND
 48H  03/1200Z 37.0N 112.0W   15 KT  15 MPH...POST-TROP/INLAND
 72H  04/1200Z...DISSIPATED

$$
Forecaster Pasch

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