Pacific Hurricane Feed

Tropical Storm Terry Forecast Discussion


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 

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.


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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