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HURRICANE RACHEL DISCUSSION NUMBER 20
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182014
200 AM PDT MON SEP 29 2014
Although Rachel's cloud pattern is still fairly circular on
satellite images, the area of deepest convection has been gradually
shrinking. The imagery also suggests increasing southwesterly
shear, with high clouds extending farther to the northeast of the
cyclone with time. Dvorak intensity estimates remain at 65 kt from
both TAFB and SAB, so the initial wind speed also remains at that
value. Rachel is not likely to remain a hurricane much longer
since the global models show that southwesterly shear will persist
and increase over the next day or two. Steady weakening is
forecast, and the official intensity forecast is the same as the
previous one and very close to the intensity model consensus, IVCN.
The cyclone is expected to degenerate to remnant low status in a
couple of days.
Microwave imagery indicates that the center of circulation is
displaced a little to the south of the center of the cloud mass.
Blending microwave and geostationary satellite fixes yields an
initial motion of about 360/4 kt. With the system forecast to
become increasingly shallow over the next few days, it will likely
be steered by the weak low- to mid-level flow, and decelerate even
further. Thus, Rachel is not expected to move much over the next
day or so. By the latter part of the forecast period, the
post-tropical remnant low should move southwestward to
west-southwestward, following the tradewind flow. The official
track forecast is close to the previous one and is similar to the
latest ECMWF global model prediction.
Only slight adjustments to the wind radii were made, based on data
from a couple of recent ASCAT overpasses.
FORECAST POSITIONS AND MAX WINDS
INIT 29/0900Z 22.8N 117.5W 65 KT 75 MPH
12H 29/1800Z 23.1N 117.6W 55 KT 65 MPH
24H 30/0600Z 23.3N 117.6W 45 KT 50 MPH
36H 30/1800Z 23.3N 117.7W 35 KT 40 MPH
48H 01/0600Z 23.2N 117.9W 30 KT 35 MPH...POST-TROP/REMNT LOW
72H 02/0600Z 22.8N 118.6W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 03/0600Z 22.5N 119.5W 20 KT 25 MPH...POST-TROP/REMNT LOW