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Tropical Storm Norma Discussion Number  16
NWS National Hurricane Center Miami FL       EP172017
300 AM MDT Mon Sep 18 2017

Norma is a small tropical cyclone, with one main curved band in the
eastern semicircle and an easy-to-find center.  Dvorak estimates
are virtually unchanged from 6 hours ago and support the same
initial wind speed of 45 kt.  Norma should begin to gradually
weaken later today as it moves over cooler SSTs and into a drier,
more stable airmass.  The latest forecast is a blend of the
previous NHC prediction and the model consensus since guidance is
tightly clustered on the future weakening.  Most of the global
models show convection disappearing within 2 days, so Norma is
now forecast to become a remnant low by that time.

Norma is now moving west-northwestward, continuing to be steered by
a ridge over northwestern Mexico.  This general track is expected
for the next few days with a gentle curve toward the north-northwest
predicted as Norma moves around the southwestern portion of the
ridge.  The new forecast is shifted westward, on the western side of
the model consensus closer to the ECMWF, which had the more offshore
track idea for some time before the bulk of the guidance.

FORECAST POSITIONS AND MAX WINDS

INIT  18/0900Z 21.4N 111.8W   45 KT  50 MPH
 12H  18/1800Z 21.5N 112.6W   40 KT  45 MPH
 24H  19/0600Z 21.8N 113.6W   35 KT  40 MPH
 36H  19/1800Z 22.2N 114.6W   30 KT  35 MPH
 48H  20/0600Z 22.8N 115.3W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  21/0600Z 24.2N 115.8W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  22/0600Z...DISSIPATED

$$
Forecaster Blake

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