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Tropical Storm Irwin Discussion Number  36
NWS National Hurricane Center Miami FL       EP102017
200 AM PDT Mon Jul 31 2017

Irwin finally appears to be suffering from the effects of cooler
water.  Deep convection associated with the cyclone has decreased
in coverage overnight, but the convection that remains is organized
in a band over the eastern portion of the circulation.  Dvorak
T-numbers have started to decrease, and a blend of the various T-
and CI-numbers yields an initial wind speed estimate of 50 kt.
Irwin will be moving over SSTs of 22 to 23 deg C during the next 12
to 24 hours, which should cause the cyclone to quickly weaken.
In fact, Irwin is likely to degenerate to a remnant low in about
24 hours, when the deep convection dissipates.  The global models
suggest that the low will dissipate in about 72 hours.

Irwin is moving north-northwestward at about 11 kt.  The cyclone is
expected to continue on a north-northwestward heading today, then
slow down and turn northwestward on Tuesday as it moves around the
remnant circulation of Hilary.  The latest track guidance is in
good agreement and no significant change from the previous NHC
track forecast was needed.

FORECAST POSITIONS AND MAX WINDS

INIT  31/0900Z 20.7N 126.7W   50 KT  60 MPH
 12H  31/1800Z 22.4N 127.5W   40 KT  45 MPH
 24H  01/0600Z 24.7N 128.7W   30 KT  35 MPH...POST-TROP/REMNT LOW
 36H  01/1800Z 26.5N 130.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  02/0600Z 27.8N 131.2W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  03/0600Z...DISSIPATED

$$
Forecaster Brown

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