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Tropical Depression Fifteen-E Discussion Number   5
NWS National Hurricane Center Miami FL       EP152017
200 PM PDT Tue Sep 12 2017

The depression is struggling to maintain deep convection in the face
of moderate to strong vertical shear.  All of the limited deep
convection is displaced about 60 nm west of its center. The TAFB and
SAB Dvorak Current Intensity values have not changed, so the initial
intensity remains 30 kt.

The dislocation of the deep convection should continue, as it's
being forced by strong easterlies due to an upper-level ridge to
the north of the depression.  Moderate shear should continue for the
next couple of days, limiting the opportunity for the depression to
intensify.  In about two days, the depression may begin interacting
with a developing tropical cyclone to its east.  (This new system
is currently in the Tropical Weather Outlook with a high chance of
formation within the next five days.)  One plausible scenario is for
the depression to be absorbed by the new tropical cyclone.  The
official intensity forecast instead shows gradual weakening as the
depression tracks slowly westward, due to an increasingly hostile
upper-level environment.  The intensity forecast is the same as the
previous one and is based upon a blend of the global models, the
LGEM statistical scheme, and the COAMPS mesoscale hurricane model.

The depression is moving toward the west at 12 kt, primarily being
steered by the deep-layer ridge to its north.  The depression should
continue moving in this general direction at a slower rate of
forward speed during the next couple of days.  At days three and
four, the low-level steering flow should weaken due to the
developing tropical cyclone to the depression's east.  The official
track forecast is based upon the model consensus minus the UKMET
(whose tracker latches on to the developing tropical cyclone
instead) and is about the same as the previous advisory.  This track
prediction has higher uncertainty than usual because of the
divergence of plausible outcomes for the depression.


FORECAST POSITIONS AND MAX WINDS

INIT  12/2100Z 15.6N 117.5W   30 KT  35 MPH
 12H  13/0600Z 15.2N 118.8W   35 KT  40 MPH
 24H  13/1800Z 14.9N 120.0W   35 KT  40 MPH
 36H  14/0600Z 15.1N 121.3W   30 KT  35 MPH
 48H  14/1800Z 15.3N 122.3W   30 KT  35 MPH
 72H  15/1800Z 15.5N 123.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  16/1800Z 15.5N 124.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  17/1800Z...DISSIPATED

$$
Forecaster Landsea

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