Tropical Storm RACHEL

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TROPICAL STORM RACHEL DISCUSSION NUMBER   7
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP182014
800 PM PDT THU SEP 25 2014

While there is strong, deep convection associated with Rachel,
microwave and last light visible imagery indicate that the tropical
storm is still being sheared with the center at the edge of the
convective overcast.  Subjective Dvorak assessments from TAFB and
SAB as well as the CIMSS AMSU method suggest peak sustained winds of
about 45 kt, which is the initial intensity. While an upper-level
anticyclone is contributing toward about 15 kt of northeasterly
shear over Rachel currently, this should subside to quite low values
from 24 through 72 hr.  However, at the same time, Rachel's track
should take it over gradually cooler waters and into much drier,
stable air. The NHC intensity forecast calls for slow
intensification through two days, followed by gradual weakening.
This prediction is based upon a blend of the LGEM and SHIPS
statistical and GFDL dynamical models and is about the same as in
the previous advisory.

No in situ observations were available for the tropical-storm-force
wind radii, so no changes were made to the initial small size of
Rachel.  The global and regional hurricane models suggest that
Rachel will remain relatively small for the next few days, which is
the basis for the NHC wind radii forecast.

Rachel is moving toward the west-northwest at 13 kt, primarily being
steered by a mid-level subtropical ridge to its northeast.  The
tropical storm should round the western periphery of the ridge in
about two to three days.  After that time, Rachel will meander as a
decaying vortex in the weak lower tropospheric flow.  The NHC track
forecast is based upon the tightly clustered TVCE multi-model
ensemble and is about the same as that issued in the previous
advisory.


FORECAST POSITIONS AND MAX WINDS

INIT  26/0300Z 17.7N 111.9W   45 KT  50 MPH
 12H  26/1200Z 18.4N 113.4W   50 KT  60 MPH
 24H  27/0000Z 19.2N 114.7W   55 KT  65 MPH
 36H  27/1200Z 20.2N 115.6W   60 KT  70 MPH
 48H  28/0000Z 20.9N 116.2W   60 KT  70 MPH
 72H  29/0000Z 22.2N 116.3W   50 KT  60 MPH
 96H  30/0000Z 23.0N 116.0W   40 KT  45 MPH
120H  01/0000Z 23.0N 116.0W   25 KT  30 MPH

$$
Forecaster Landsea

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