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Tropical Storm Karen Discussion Number  18
NWS National Hurricane Center Miami FL       AL122019
1100 AM AST Thu Sep 26 2019

Karen has been maintaining a cluster of convection to the west of
its center, but visible satellite images and wind data from NOAA
buoy 40149 to the northeast suggest that the low-level circulation
is becoming elongated.  This structure has been confirmed by a
late-arriving ASCAT pass, and that data also show that Karen is
producing winds to 40 kt within the deep convection.

Karen is embedded in the flow between a mid-level high centered over
the central Atlantic and a mid- to upper-level low which is slowly
retrograding westward over the Bahamas.  This is maintaining a
north-northeastward motion of 015/12 kt.  The central Atlantic high
is expected to weaken over the next 2 days, while a new high
develops over the western Atlantic, causing Karen to make a
clockwise loop well to the southeast of Bermuda.  Once the western
Atlantic high becomes established, Karen is then expected to move
generally westward on days 3 through 5.  There have been no
significant changes among the track models, and the new NHC track
forecast is therefore very similar to the previous one.

Relatively light winds aloft and warm ocean waters could allow
Karen to maintain its intensity for another day or two.  After that
time, however, an increase in northerly shear will likely allow
ambient dry air to infiltrate into the circulation further.  The
dynamical models--which we're now heavily favoring in our
forecasts--are showing gradual weakening and even a loss of
organized deep convection in a few days.  Therefore, Karen is now
forecast to degenerate into a remnant low by day 3.  The low is
expected to plow into strong southwesterly shear on days 4 and 5
while it moves westward over the southwestern Atlantic, which should
keep it as a remnant low or possibly cause it to open up into a
trough of low pressure.


FORECAST POSITIONS AND MAX WINDS

INIT  26/1500Z 26.6N  63.3W   40 KT  45 MPH
 12H  27/0000Z 27.6N  62.5W   40 KT  45 MPH
 24H  27/1200Z 28.1N  61.1W   35 KT  40 MPH
 36H  28/0000Z 28.0N  60.4W   35 KT  40 MPH
 48H  28/1200Z 27.8N  60.6W   30 KT  35 MPH
 72H  29/1200Z 27.3N  63.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  30/1200Z 27.1N  66.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  01/1200Z 27.0N  69.0W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Berg

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