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Tropical Depression Sandra Discussion Number   6
NWS National Hurricane Center Miami FL       EP192021
Issued by NWS Central Pacific Hurricane Center Honolulu HI
100 PM PST Mon Nov 08 2021
 
Sandra's recently exposed and increasingly elongated low-level 
center lies to the west and southwest of an area of pulsing deep 
convection, due to persistent southwesterly vertical wind shear. A 
recent ASCAT pass indicated that winds were below tropical-storm- 
force, and the initial intensity for this advisory is estimated to 
be 30 kt, despite subjective Dvorak intensity estimates of 2.5/35 kt 
from TAFB/SAB. 

Guidance indicates that southwesterly shear near 20 kt will 
persist, potentially increasing in magnitude tomorrow, as the 
cyclone remains between an upper-level anticyclone to the east and a 
trough to the northwest. This environment is not conducive for a 
tropical cyclone's survival, and Sandra is forecast to degenerate 
into a remnant low on Tuesday before dissipating on Wednesday, if 
not sooner. The updated intensity forecast is in close agreement 
with HCCA guidance, as well as the GFS and ECMWF global model 
solutions. 

The initial motion estimate for this advisory is 310/08 kt, which 
represents a bit of a northward jog in the cyclone's track. This 
motion is expected to be temporary as surface high pressure is 
forecast to build northwest of Sandra over the next day or two. 
This will usher the decaying, increasingly shallow low toward the 
west as it becomes steered by the low-level trade wind flow. The 
updated track forecast follows a similar trajectory as the previous, 
after accounting for the recent jog toward the north, and follows a 
tightly clustered guidance suite.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  08/2100Z 15.5N 117.5W   30 KT  35 MPH
 12H  09/0600Z 15.5N 118.6W   30 KT  35 MPH
 24H  09/1800Z 15.3N 120.9W   25 KT  30 MPH...POST-TROP/REMNT LOW
 36H  10/0600Z 14.9N 123.4W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  10/1800Z...DISSIPATED
 
$$
Forecaster Birchard
 
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