531
WTPZ43 KNHC 290257
TCDEP3
HURRICANE RACHEL DISCUSSION NUMBER 19
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182014
800 PM PDT SUN SEP 28 2014
Rachel has made a little bit of a resurgence since the previous
advisory, with a well-defined 15-20 nmi diameter low- to mid-level
eye apparent in various microwave satellite images. Visible
satellite imagery during the past few hours also indicates a small
ring of overshooting cloud tops beginning to encircle a ragged,
cloud-filled eye. The only reason the initial intensity is being
maintained at 65 kt is due to the lack of persistence in the recent
increase in the inner-core convection.
The initial motion estimate is 355/4 kt, which is based primarily on
microwave satellite fix positions. The most recent NHC track model
guidance has become less divergent since the previous advisory,
with the 18Z GFS model now taking Rachel more westward after 24
hours. Overall, the models are in pretty good agreement on steering
currents collapsing during the next 48 hours, resulting in Rachel
becoming nearly stationary during that time, followed by a westward
or southwestward drift as a remnant low pressure system. The
official forecast track is similar to the previous advisory
advisory track and the consensus model TVCE.
Rachel is currently over 26C sea-surface temperatures, and the
small cyclone will be moving over slightly cooler water during the
next 48 hours. The cooler water, in combination with increasing
southwesterly vertical wind shear in excess of 25 kt by 36 hours,
should induce gradual weakening throughout the forecast period with
Rachel degenerating into a remnant low pressure system by 48 hours
or so. This intensity forecast is consistent with a blend of the
intensity consensus model IVCN and the Decay-SHIPS model.
FORECAST POSITIONS AND MAX WINDS
INIT 29/0300Z 22.5N 117.6W 65 KT 75 MPH
12H 29/1200Z 22.8N 117.6W 55 KT 65 MPH
24H 30/0000Z 23.0N 117.6W 45 KT 50 MPH
36H 30/1200Z 22.9N 117.8W 35 KT 40 MPH
48H 01/0000Z 22.8N 117.9W 30 KT 35 MPH...POST-TROP/REMNT LOW
72H 02/0000Z 22.5N 118.4W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 03/0000Z 22.4N 119.3W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 04/0000Z...DISSIPATED
$$
Forecaster Stewart
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