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Potential Tropical Cyclone Fourteen-E Discussion Number   5
NWS National Hurricane Center Miami FL       EP142017
300 PM MDT Wed Aug 30 2017

Satellite images indicate that the convection pattern of the system
is becoming better organized, with a large curved band in the
southern semicircle. ASCAT data from earlier indicated peak winds of
33 kt, and since the pass caught less than half of the circulation,
it is assumed higher winds were not sampled.  Thus the initial wind
speed is set to 35 kt.  However, the low still does not have a
well-defined center, with the elongated circulation containing
several low-level swirls, so it will stay a potential tropical
cyclone.  Slow strengthening is considered most likely due to the
poor initial organization.  If the circulation consolidates, the
upper-level winds and water temperatures are still conducive to
strengthening. The NHC forecast is similar to the previous one, just
a bit above the model consensus.  In a couple of days, the cyclone
should weaken while it traverses either land or the cooler waters
west of the Baja peninsula.

A long-term motion of the system is 345/6.  The disturbance should
move on this general course around a weak ridge over central
Mexico, before taking a more westward turn as it runs into a ridge
over the southwestern United States.  Models are in fairly good
agreement on the cyclone moving very close to Baja California Sur
from 36 hours to 96 hours, although again there has been a small
eastward trend in the guidance.  Thus, the official forecast is
shifted to the east as well.  A tropical storm warning has been
issued for the west coast of Mexico due to the changes in the
forecast.  Since the disturbance still lacks a well-defined center
and there is considerable spread in the model guidance, this
official track forecast has greater-than-usual uncertainty.

It is also important to note that very heavy rain is falling over
portions of western Mexico and Baja California Sur, which is
already causing threatening flash floods and mudslides. Regardless
of exactly how strong the cyclone becomes, this should be a
significant hazard.


FORECAST POSITIONS AND MAX WINDS

INIT  30/2100Z 20.1N 108.8W   35 KT  40 MPH...POTENTIAL TROP CYCLONE
 12H  31/0600Z 20.9N 109.2W   40 KT  45 MPH...TROPICAL STORM
 24H  31/1800Z 22.0N 109.7W   50 KT  60 MPH
 36H  01/0600Z 23.1N 110.2W   55 KT  65 MPH
 48H  01/1800Z 24.3N 110.8W   50 KT  60 MPH...INLAND
 72H  02/1800Z 27.0N 113.0W   40 KT  45 MPH...INLAND
 96H  03/1800Z 28.5N 116.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  04/1800Z 29.0N 118.5W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Blake

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