Tropical Storm RACHEL
ZCZC MIATCDEP3 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM RACHEL DISCUSSION NUMBER 22
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182014
200 PM PDT MON SEP 29 2014
Rachel continues to slowly weaken. Visible satellite imagery shows
its exposed low-level center located on the south side of a small
patch of deep convection, with the remnant mid-level circulation
displaced well to the northeast. The cyclone's current ragged
structure is partly a result of persistent south-southwesterly shear
of around 25 kt as diagnosed by UW-CIMSS analyses. A 1715 UTC AMSU
microwave pass also suggested that dry and stable air has been
wrapping around the circulation of the storm. The initial intensity
estimate is lowered to 45 kt based on peak winds of 43 kt from a
1714 UTC ASCAT-B pass.
With strong southwesterly shear expected to continue and
thermodynamic conditions likely to become even more unfavorable,
further steady weakening is expected. These hostile environmental
factors should cause Rachel to weaken to a remnant low in about 24
hours and dissipate in 2-3 days, as shown in global model guidance.
The new NHC intensity forecast represents an update of the previous
one and is in good agreement with the multi-model consensus.
Rachel has been drifting steadily northward, and the initial motion
estimate is 360/02. In the next 12 hours or so, a slow northward
motion is likely to continue, so long as the cyclone maintains
enough vertical integrity. After that time, Rachel should
transition into a shallower vortex and be carried generally
west-southwestward with a modest increase in forward speed. The NHC
track forecast is adjusted a bit to the right and is somewhat south
and west of the ECMWF, GFS, and multi-model consensus model, TVCE.
FORECAST POSITIONS AND MAX WINDS
INIT 29/2100Z 23.0N 117.5W 45 KT 50 MPH
12H 30/0600Z 23.2N 117.6W 35 KT 40 MPH
24H 30/1800Z 23.1N 118.0W 30 KT 35 MPH...POST-TROP/REMNT LOW
36H 01/0600Z 23.0N 118.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 01/1800Z 22.8N 118.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 02/1800Z 22.6N 120.0W 15 KT 15 MPH...POST-TROP/REMNT LOW
96H 03/1800Z...DISSIPATED
$$
Forecaster Kimberlain/Lewitsky
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