[Tropical] Tropical Cyclone Discussion

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WTNT41 KNHC 122042
TCDAT1

Tropical Depression Eleven Discussion Number   5
NWS National Hurricane Center Miami FL       AL112020
500 PM AST Wed Aug 12 2020

Satellite imagery this afternoon shows some changes in the
convection associated with Tropical Depression Eleven, as the
showers and thunderstorms are now occuring more in curved bands and
less in sheared bursts.  This is likely due to the southeasterly
shear which has been affecting the depression finally letting up.
However, this change has not caused the satellite intensity
estimates to change significantly since the last advisory, so the
initial intensity is again 30 kt.

The initial motion remains a little north of due west, or
280/13 kt. There is almost no change to the forecast philosophy and
little change to the forecast track since the last advisory.  A
westward motion is expected to continue for another 6-12 h due to
easterly flow on the south side of a strong subtropical ridge
situated to the north of the cyclone.  After that, the global
models forecast a slight weakness to develop within the ridge,
allowing the cyclone to turn west-northwestward and continue that
motion through 96 h.  Between 96-120 h, the western end of the
ridge is forecast to weaken more, which should cause a turn toward
the northwest.  The new NHC forecast track remains just to the left
of the various consensus models.

The cyclone should be in an environment of light to moderate shear
through the next 48 h or so.  The intensity forecast again calls
for a peak intensity of 50 kt during this time, which is at the
high end of the intensity guidance.  After 60 h, the cyclone is
expected to encounter moderate to strong southwesterly shear
associated with a large upper-level trough over the southwestern
Atlantic.  This should cause at least steady weakening, and several
of the global models continue to forecast the cyclone to degenerate
to a tropical wave before 120 h.  The new intensity forecast again
expects the system to last longer than the global models, but still
shows weakening due to the shear after 72 h.  The new forecast has
only minor changes from the previous forecast.


FORECAST POSITIONS AND MAX WINDS

INIT  12/2100Z 12.7N  45.7W   30 KT  35 MPH
 12H  13/0600Z 13.0N  47.5W   35 KT  40 MPH
 24H  13/1800Z 14.0N  49.9W   40 KT  45 MPH
 36H  14/0600Z 15.2N  52.2W   45 KT  50 MPH
 48H  14/1800Z 16.6N  54.8W   50 KT  60 MPH
 60H  15/0600Z 17.8N  57.3W   50 KT  60 MPH
 72H  15/1800Z 19.1N  59.7W   50 KT  60 MPH
 96H  16/1800Z 21.5N  64.5W   40 KT  45 MPH
120H  17/1800Z 24.5N  67.0W   30 KT  35 MPH

$$
Forecaster Beven
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