Tropical Storm JULIAN Advisory Sun Aug 29

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Tropical Depression Eleven Discussion Number   1
NWS National Hurricane Center Miami FL       AL112021
1100 PM AST Sat Aug 28 2021

Before sunset this evening, visible satellite images showed that a
well-defined low level circulation was developing in association
with the disturbance over the subtropical central Atlantic.
However, up until a couple of hours ago, the system lacked
sufficient organized deep convection to be considered a tropical
cyclone by definition. Since that time, a deep convective burst has
increased in size near, and to the east of the estimated
center. In addition, a curved band has begun to develop over the
southeastern portion of the circulation. Based on this increase in
convective organization, advisories are being initiated on Tropical
Depression Eleven. There was no ASCAT data this evening over the
cyclone, so the initial intensity of 30 kt is based on the latest
Dvorak CI number from TAFB.

The initial motion of the depression is 050/10 kt. The cyclone is
embedded in southwesterly flow to the southeast of a mid- to
upper-level trough and an associated cold front. This flow is
forecast to increase as the cold front approaches the cyclone,
resulting in the system accelerating northeastward over the next day
or so. Once the cyclone interacts with this frontal boundary in a
couple of days, a turn to the north is expected. The model guidance
is in very good agreement on this scenario, and the NHC track
forecast lies in the middle of the consensus tracks.

Baroclinic forcing and upper-level diffluence should aid in
intensifying the depression over the next 24 h, despite increasing
shear. By 36 h, the combination of interaction with the cold front
and passage over much cooler waters should result in extratropical
transition. The system is then forecast to become absorbed by a
larger low pressure system by midweek. The NHC intensity forecast
is near the various multi-model consensus solutions.


FORECAST POSITIONS AND MAX WINDS

INIT  29/0300Z 33.0N  49.7W   30 KT  35 MPH
 12H  29/1200Z 34.6N  47.1W   35 KT  40 MPH
 24H  30/0000Z 36.8N  43.4W   45 KT  50 MPH
 36H  30/1200Z 39.5N  39.2W   50 KT  60 MPH...POST-TROP/EXTRATROP
 48H  31/0000Z 43.4N  36.4W   45 KT  50 MPH...POST-TROP/EXTRATROP
 60H  31/1200Z 47.9N  36.3W   40 KT  45 MPH...POST-TROP/EXTRATROP
 72H  01/0000Z...DISSIPATED

$$
Forecaster Latto