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Tropical Storm Bill Discussion Number   5
NWS National Hurricane Center Miami FL       AL022021
1100 AM AST Tue Jun 15 2021
 
Bill remains a fairly well organized tropical storm.  Microwave
satellite data indicate that the cyclone still has a fairly tight 
core and curved bands on the north and west sides of the 
circulation.  However, drier air is wrapping into the southeast 
portion of the storm, and convection has been decreasing in 
intensity over the past couple of hours.  A very recent ASCAT-A pass 
showed maximum winds of 45-50 kt southeast of the center.  
Therefore, the initial intensity is nudged up to 50 kt.
 
The tropical storm is racing northeastward, and the latest initial
motion is estimated to be 055/33 kt.  Bill is embedded in the
mid-latitude jet stream and a continued fast northeastward motion
is expected during the next day or two.  This motion should take
the storm over much cooler waters on the north side of the Gulf
Stream Current in about 12 hours.  These cold waters, drier air,
and mid-latitude dynamics should cause Bill to transition to an
extratropical cyclone later today.  All of the models agree that
the extratropical cyclone should dissipate in 24 to 36 hours over
or near Atlantic Canada.
 
Bill will likely remain at about the same intensity until it
dissipates by late Wednesday.  It should be noted that given the
fast forward speed, most of the strong winds will be on the
southeast side of the system.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  15/1500Z 40.5N  62.0W   50 KT  60 MPH
 12H  16/0000Z 43.4N  58.5W   50 KT  60 MPH...POST-TROP/EXTRATROP
 24H  16/1200Z 47.5N  54.0W   45 KT  50 MPH...POST-TROP/EXTRATROP
 36H  17/0000Z...DISSIPATED
 
$$
Forecaster Cangialosi
 
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