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Tropical Storm Terry Discussion Number 16
NWS National Hurricane Center Miami FL EP182021
300 AM CST Mon Nov 08 2021
The overall convective organization of the low-latitude Tropical
Storm Terry has become somewhat ragged looking since the previous
advisory, although there has been a recent small burst of deep
convection near and northeast of the estimated low-level center. A
0255Z ASCAT-A scatterometer pass indicated that surface winds had
decreased to 29 kt northeast of the center during the earlier
convective waning period. However, the recent increase in convection
with cloud tops of around -85C may have locally enhanced those ASCAT
wind speeds and, thus, Terry's intensity has only been lowered to 35
kt.
Terry's initial motion estimate remains west-northwestward, or
295/12 kt. There are no significant changes to the previous track
forecast or synoptic reasoning. Terry and it is expected to continue
moving west-northwestward through today, followed by a turn toward
the west on Tuesday. A general westward motion is forecast on days
2-5 as a sprawling deep-later ridge to the north of the cyclone is
expected to remain entrenched across most of the eastern North
Pacific. The new NHC track forecast is very similar to the previous
advisory track, and lies along the southern edge of the tightly
packed simple- and corrected-consensus track model envelope.
ASCAT-A and ASCAT-B scatterometer surface wind data from 0300-0400Z
showed that Terry's low-level wind field had become elongated
east-to-west, and that the radius of maximum winds had also
increased to at least 70 nmi in the northeastern quadrant. Although
the deep-layer vertical wind shear is expected to remain relatively
low at less than 10 kt, the GFS and ECMWF global models are
forecasting moderate mid-level shear to undercut the otherwise
favorable upper-level outflow layer, resulting in a continued
disruption of the convective pattern. As a result, gradual weakening
is expected during the 5-day period, with Terry now forecast to
become a tropical depression later today. Otherwise, no other
changes were made to the previous intensity forecast, with the new
NHC intensity forecast closely following a blend of the simple and
corrected-consensus intensity model guidance.
FORECAST POSITIONS AND MAX WINDS
INIT 08/0900Z 9.6N 105.1W 35 KT 40 MPH
12H 08/1800Z 10.0N 107.0W 30 KT 35 MPH
24H 09/0600Z 10.5N 109.4W 30 KT 35 MPH
36H 09/1800Z 10.7N 112.0W 30 KT 35 MPH
48H 10/0600Z 10.9N 114.6W 25 KT 30 MPH
60H 10/1800Z 10.9N 117.2W 25 KT 30 MPH
72H 11/0600Z 10.9N 119.9W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 12/0600Z 10.7N 125.5W 15 KT 15 MPH...POST-TROP/REMNT LOW
120H 13/0600Z...DISSIPATED
$$
Forecaster Stewart
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