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Tropical Storm Bill Discussion Number   3
NWS National Hurricane Center Miami FL       AL022021
1100 PM AST Mon Jun 14 2021

Deep convection has increased in a cluster to the northeast of the 
estimated center.  Scatterometer measurements showed a couple of 
40-41 kt vectors over the southeastern quadrant of the cyclone.  On 
this basis, the estimated intensity is increased to 40 kt, which 
makes this the second tropical storm of the season, albeit a rather 
high-latitude one.  The system is in an environment of fairly 
strong southwesterly shear, but the diffluent upper-level flow has 
apparently contributed to some strengthening in a seemingly hostile 
environment.  Some additional short-term strengthening could occur 
but by 36 hours, the cyclone should merge with a baroclinic zone 
while approaching Newfoundland and become extratropical.  This 
transition is also shown by the FSU cyclone phase analyses of the 
GFS model fields.
 
Bill is moving fairly swiftly northeastward, or 055/20 kt.  The 
track forecast appears to be straightforward.  The flow ahead of a 
large mid-tropospheric trough near the United States east coast 
should accelerate the system northeastward for the next day or two, 
and until the system dissipates.  The NHC track forecast is similar 
to the previous one and not far from the model consensus.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  15/0300Z 36.7N  69.8W   40 KT  45 MPH
 12H  15/1200Z 38.9N  65.1W   45 KT  50 MPH
 24H  16/0000Z 42.6N  59.6W   40 KT  45 MPH
 36H  16/1200Z 46.5N  54.5W   35 KT  40 MPH...POST-TROP/EXTRATROP
 48H  17/0000Z...DISSIPATED
 
$$
Forecaster Pasch
 
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