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Tropical Storm Irwin Discussion Number  38
NWS National Hurricane Center Miami FL       EP102017
200 PM PDT Mon Jul 31 2017

The deep convection associated with Irwin has been decreasing
throughout the day, and it is currently limited to a fairly small
area near and to the east of the center.  The Dvorak classifications
have decreased, and an average of the latest intensity estimates
from TAFB, SAB, and ADT values from CIMSS at the University of
Wisconsin support lowering the initial wind speed to 40 kt.

Satellite data show that dry and stable air is wrapping into the
circulation.  This stable air mass combined with cool SSTs should
lead to additional weakening, and Irwin will likely become a
remnant low tonight or on Tuesday.  The remnant low is expected to
continue to spin down, and ultimately dissipate in 2 to 3 days.  The
NHC intensity forecast is an update of the previous one, and
it follows the trend of the guidance.

Irwin continues to move north-northwestward on the west side of a
mid-level high following the path of Post-Tropical Cyclone Hilary.
This motion is expected to continue for about another day.
Thereafter, a decrease in forward speed and a slight turn to the
northwest is predicted as the shallow remnant low moves in the
low-level flow.  The NHC track forecast is a little slower
than the previous one to come into better agreement with the latest
consensus models.

FORECAST POSITIONS AND MAX WINDS

INIT  31/2100Z 22.7N 127.7W   40 KT  45 MPH
 12H  01/0600Z 24.2N 128.5W   35 KT  40 MPH
 24H  01/1800Z 26.1N 129.7W   30 KT  35 MPH...POST-TROP/REMNT LOW
 36H  02/0600Z 27.4N 131.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  02/1800Z 28.5N 132.1W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  03/1800Z...DISSIPATED

$$
Forecaster Cangialosi

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