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TROPICAL STORM RACHEL DISCUSSION NUMBER  13
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP182014
800 AM PDT SAT SEP 27 2014

Rachel continues to exhibit an occasional eye-like feature in
infrared satellite imagery, and this was also seen in an AMSR2 pass
just after 0900 UTC. However, the overall convective pattern is not
terribly impressive, with only a small area of deep convection near
the center and little in the way of banding. The initial intensity
remains 55 kt based on the latest Dvorak estimates from TAFB and
SAB. With the inner core trying to organize, there is the potential
for Rachel to reach hurricane intensity during in the next 12 to 18
hours before the thermodynamic environment becomes more hostile.
After that time, Rachel will be moving over marginal SSTs and into
an increasingly dry and stable atmosphere, which should result in
steady weakening. The new NHC forecast shows Rachel peaking in 12
hours, and after that time is close to the IVCN intensity consensus
while the cyclone decays.

The initial motion estimate is 325/07. Rachel should continue
turning poleward while it moves into a weakness in the subtropical
ridge during the next 24 hours. After that time, the decaying
cyclone will be caught in a region of weak steering currents, and a
slow north-northwestward motion is shown at 36 to 48 hours. Later in
the period, the shallow cyclone should begin moving southwestward as
it comes under the influence of a low-level ridge over the
northeastern Pacific. The track model guidance still shows a fair
amount of spread, but the GFS and GFDL models have continued to
trend southward this cycle. As a result, the TVCE multi-model
consensus has shifted to the left, and the latest NHC track has been
adjusted in that direction at 36 to 48 hours. Otherwise, the new
NHC forecast is largely an update of the previous advisory when
accounting for the initial position and motion.

FORECAST POSITIONS AND MAX WINDS

INIT  27/1500Z 19.6N 116.1W   55 KT  65 MPH
 12H  28/0000Z 20.3N 116.5W   65 KT  75 MPH
 24H  28/1200Z 21.2N 116.9W   60 KT  70 MPH
 36H  29/0000Z 21.7N 117.1W   55 KT  65 MPH
 48H  29/1200Z 21.9N 117.2W   50 KT  60 MPH
 72H  30/1200Z 21.7N 117.5W   35 KT  40 MPH
 96H  01/1200Z 21.0N 118.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  02/1200Z 20.0N 118.5W   20 KT  25 MPH...POST-TROP/REMNT LOW

$$
Forecaster Brennan

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