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Tropical Storm Bill Discussion Number   6
NWS National Hurricane Center Miami FL       AL022021
500 PM AST Tue Jun 15 2021
 
Bill is well on its way to becoming an extratropical cyclone.  The
convective pattern has become quite asymmetric with the center
exposed to the southwest of the weakening thunderstorms.  The
center itself has become stretched, and in fact, surrounding
observations suggest that the surface center may no longer
be closed.  In addition, a warm front appears to be forming on
the storm's southeast side.  Based on these trends, it seems very
likely that Bill won't be around for long as a tropical storm. The
initial intensity is held at 50 kt based on the earlier ASCAT data,
but that could be a little generous.
 
The initial motion remains a very fast 055/31 kt.  A continued fast
east-northeast to northeast motion in the mid-latitude jet stream
is expected until the cyclone dissipates within the next 12-24
hours near Atlantic Canada.  Some weakening seems likely prior to
dissipation due to the cyclone moving over much colder SSTs while
remaining in a strong wind shear environment.
 
Due to the system's fast forward speed, the strong winds will
remain confined to the south and east sides of the cyclone.

FORECAST POSITIONS AND MAX WINDS
 
INIT  15/2100Z 41.6N  59.6W   50 KT  60 MPH
 12H  16/0600Z 44.7N  55.9W   45 KT  50 MPH...POST-TROP/EXTRATROP
 24H  16/1800Z...DISSIPATED
 
$$
Forecaster Cangialosi
 
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