Tropical Storm MARIE

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TROPICAL STORM MARIE DISCUSSION NUMBER   5
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP132014
800 PM PDT FRI AUG 22 2014

Marie appears to be on the verge of intensifying rapidly.  The
cyclone is in the process of developing a central dense overcast,
consisting of very cold-topped convection.  Numerous outer bands are
also present.  The upper-level outflow over the storm is well
established, suggesting an expanding warm core.  Dvorak intensity
estimates are a consensus T3.5/55 kt from TAFB and SAB, with
UW-CIMSS ADT values around 4.0.  A blend of these data are used to
set the initial intensity to 60 kt.

Marie continues on a steady west-northwestward course, with the
initial motion estimated to be 285/13.  A continued west-
northwestward motion at a slightly slower forward speed is expected
through 48 hours while the cyclone moves along the southwestern side
of a mid-level ridge extending west-southwestward from the eastern
United States into the eastern Pacific.  A bend in the track toward
the northwest is anticipated after 72 hours as Marie reaches the
western end of the aforementioned ridge.  The track guidance is
generally in good agreement on this scenario, and the track forecast
is little changed from the previous one despite a slight shift in
the guidance to the north this cycle.

The stage is set for Marie to rapidly intensify during the next day
or two, with global models forecasting a nearly ideal environment
for strengthening.  The SHIPS model output bolsters this idea,
indicating a 54 percent likelihood of a 30-kt increase in intensity
during the next 24 hours.  The official forecast is at or above the
upper end of the intensity guidance through 72 hours.  Given the
very favorable large-scale conditions, it is possible that the
intensity forecast may not be strong enough in the short term.  Then
again, it cannot be ruled out that unpredictable internal dynamics
such as eyewall replacement cycles could prevent Marie from
realizing its full potential. By days 4 and 5, the passage of Marie
over sharply lower sea surface temperatures should hasten weakening,
even though the shear should be relatively low.  The intensity
forecast late in the period remains above the nearly all the
guidance but is closest to SHIPS model output.


FORECAST POSITIONS AND MAX WINDS

INIT  23/0300Z 13.7N 104.8W   60 KT  70 MPH
 12H  23/1200Z 14.2N 106.3W   75 KT  85 MPH
 24H  24/0000Z 14.9N 108.3W   95 KT 110 MPH
 36H  24/1200Z 15.5N 110.1W  115 KT 135 MPH
 48H  25/0000Z 16.3N 111.9W  125 KT 145 MPH
 72H  26/0000Z 18.4N 115.2W  125 KT 145 MPH
 96H  27/0000Z 20.8N 119.2W  105 KT 120 MPH
120H  28/0000Z 23.2N 123.8W   75 KT  85 MPH

$$
Forecaster Kimberlain

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