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Tropical Storm COSME


Tropical Storm Cosme Discussion Number   3
NWS National Hurricane Center Miami FL       EP032019
800 PM PDT Sat Jul 06 2019

There has been little overall change in the tropical storm's
organization since the previous advisory.  Deep convection continues
to burst over the northeastern portion of Cosme's circulation,
however it remains well removed from the center.  The initial wind
speed has been maintained at 45 kt, which is based on earlier ASCAT
data and is still above the most recent Dvorak intensity estimates.

It appears that Cosme is unlikely to strengthen any more.  Dry air
to the northwest of the cyclone and the sprawling structure of the
system should hinder intensification while the system moves over
26-27 degree Celsius water during the next 12-18 hours.  After that
time, Cosme will reach cooler SSTs and gradual weakening should
begin, and the cyclone is forecast to become post-tropical within a
couple of days, if not sooner.  The updated NHC intensity forecast
is in good agreement with the latest statistical guidance and the
various consensus aids.

Visible satellite imagery has revealed several cloud swirls rotating
within the storm's circulation, which has made tracking the center
of the system a little more difficult than usual.  Using a mean
center of the various swirls yields an initial motion estimate of
300/10 kt.  Cosme should continue to be steered west-northwestward
during the next 12-24 hours by a mid-level ridge extending westward
from northwestern Mexico.  By Monday, the western portion of the
ridge is expected to weaken which should induce a slower
northwestward motion.  Later in the period, the remnant low should
turn back toward the west-northwest or northwest within the
low-level trade wind flow.  The guidance envelope did not change
much this cycle and the new NHC track forecast is essentially an
update of the previous advisory.


INIT  07/0300Z 16.7N 117.1W   45 KT  50 MPH
 12H  07/1200Z 17.4N 118.4W   45 KT  50 MPH
 24H  08/0000Z 18.3N 119.7W   40 KT  45 MPH
 36H  08/1200Z 19.3N 120.7W   35 KT  40 MPH
 48H  09/0000Z 20.0N 121.4W   30 KT  35 MPH...POST-TROP/REMNT LOW
 72H  10/0000Z 21.1N 123.2W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  11/0000Z 21.5N 125.8W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  12/0000Z...DISSIPATED

Forecaster Brown