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Tropical Storm Irwin Discussion Number  32
NWS National Hurricane Center Miami FL       EP102017
200 AM PDT Sun Jul 30 2017

Infrared and earlier microwave satellite pictures show that
Irwin remains fairly well organized. An 0308 UTC AMSU microwave
overpass revealed a curved band over the southeastern portion of
the circulation and a mid-level eye-like feature.  Recent ASCAT data
suggest that Irwin is slightly stronger than earlier estimates, so
the initial wind speed has been set at 50 kt for this advisory.
Irwin is forecast to move north of the 26 deg C isotherm later this
morning, and over even colder waters within the next 36 to 48 hours.
As a result, Irwin is expected to gradually weaken over the next few
days, and the cyclone is forecast to become a remnant low late
Monday.  The new NHC wind speed forecast is identical to the
previous advisory and close to the various consensus aids.

Irwin has begun its much anticipated northward acceleration, with
recent satellite fixes indicating a motion of 350/8 kt. The tropical
storm is forecast to turn north-northwestward today and continue to
accelerate in south-southeasterly low- to mid-level flow in the wake
of Hilary. In 36 to 48 hours, Irwin is forecast to turn
northwestward and slow down when it approaches Hilary's remnant
low.  The dynamical model guidance is tightly clustered through 48
h, with some spread later in the period. The NHC track is similar
to the previous advisory and is near the middle of the guidance
envelope.


FORECAST POSITIONS AND MAX WINDS

INIT  30/0900Z 17.1N 125.0W   50 KT  60 MPH
 12H  30/1800Z 18.7N 125.5W   45 KT  50 MPH
 24H  31/0600Z 20.9N 126.7W   40 KT  45 MPH
 36H  31/1800Z 23.2N 128.1W   35 KT  40 MPH
 48H  01/0600Z 25.2N 129.8W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  02/0600Z 27.5N 132.3W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  03/0600Z 28.5N 133.5W   15 KT  15 MPH...POST-TROP/REMNT LOW
120H  04/0600Z...DISSIPATED

$$
Forecaster Brown

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