ZCZC MIATCDEP3 ALL
TTAA00 KNHC DDHHMM

TROPICAL STORM RACHEL DISCUSSION NUMBER  11
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP182014
800 PM PDT FRI SEP 26 2014

Geostationary and microwave satellite imagery show a much improved
structure for Rachel this evening.  A pronounced curved band has
developed and wrapped around the center of the cyclone, while a
mid-level eye is seen in 2002Z AMSR-E, 2130Z AMSU, and 0127Z SSMIS
microwave passes.  Correspondingly, the Dvorak classifications from
TAFB and SAB have jumped up to a 3.5.  This supports a 55 kt
intensity, which may be conservative as the CIMSS AMSU method
suggests maximum sustained winds of about 75 kt.  It appears likely
that Rachel is responding to a reduction in the vertical shear, as
it has now dropped below 10 kt.  Rachel has about 24 to 36 hr of
conducive environmental conditions remaining before the atmosphere
that it moves into becomes quite dry and stable. In about three
days, the vertical shear increases which should hasten the demise of
this system.  The NHC intensity prediction is based upon the IVCN
multi-model ensemble through 48 hr and upon the HWRF and GFDL
hurricane models after that time. The peak intensity indicated here
is above that from the previous advisory due to the jump in the
initial intensity.

The aforementioned AMSU pass also provided some guidance from the
CIRA size technique for the initial tropical-storm-force wind radii,
which have been expanded outward some as a result.  The forecast
wind radii, however, are anticipated to not grow much, based upon a
blend of the dynamical and climatological models.

Rachel's center apparently reformed southwestward closer to the
deep convection earlier today, as suggested by a late arriving
WindSat microwave pass.  While the uncertainty in the initial
position is low, the current motion is a bit ambiguous due to the
reformation.  It is estimated that the cyclone's center is moving
toward the west-northwest at around 10 kt, primarily due to
steering imparted by a mid-level subtropical ridge to its
northeast.  A vigorous shortwave trough near California is
anticipated to induce a break in the ridge and allow Rachel to turn
toward the north-northwest at a slower rate of forward speed by
Sunday.  In about three days, a decaying Rachel will start
meandering in the weak low-level flow west of Baja California.  The
NHC track forecast is based upon the TVCE multi-model ensemble,
which shows substantial divergence in solutions late in the
forecast period, and is slightly east of the track shown in the
previous advisory.


FORECAST POSITIONS AND MAX WINDS

INIT  27/0300Z 18.4N 115.3W   55 KT  65 MPH
 12H  27/1200Z 19.1N 116.1W   60 KT  70 MPH
 24H  28/0000Z 20.0N 116.4W   65 KT  75 MPH
 36H  28/1200Z 20.9N 116.7W   65 KT  75 MPH
 48H  29/0000Z 21.5N 116.9W   55 KT  65 MPH
 72H  30/0000Z 22.1N 116.8W   40 KT  45 MPH
 96H  01/0000Z 22.0N 117.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  02/0000Z 21.5N 117.5W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Landsea

NNNN