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Tropical Storm KAREN


Tropical Storm Karen Discussion Number  10
NWS National Hurricane Center Miami FL       AL122019
1100 AM AST Tue Sep 24 2019

Satellite imagery and reports from an Air Force Reserve Hurricane
Hunter aircraft show that there has been little change in either
the structure or the intensity of Karen since the last advisory.
The broad and elongated low-level center is located to the north of
the strong convection, and the aircraft has reported a central
pressure of 1007 mb and maximum 1500 ft flight-level winds of 35 kt
south of the center.  The initial intensity is held at 35 kt for
this advisory.

The initial motion is now 360/7.  Karen is in a complex steering
environment that includes a low- to mid-level ridge to the east and
northeast, Tropical Storm Jerry to the north-northwest, and a large
mid- to upper-level trough extending from near Jerry to eastern
Cuba.  These weather systems should steer Karen generally northward
today, followed by a north-northeastward motion that should
continue for a couple of days.  This motion should bring the center
of Karen near or over Puerto Rico and the Virgin Islands this
afternoon, then into the open Atlantic tonight.  During the 72-120
h period, the large-scale models forecast a low- to mid-level ridge
to build near Karen, which will significantly slow its forward
motion.  The new forecast track will continue the trend of the
previous forecast and the ECMWF model in showing the ridge building
enough to turn Karen west-southwestward by 120 h.  However, other
models suggest a looping motion or little motion during the 96-120
h, and this part of the forecast track is quite uncertain.

The large-scale models forecast the shear that has been affecting
Karen to diminish during the next couple of days, which should
allow the cyclone to gradually strengthen.  From 72-120 h, the
storm is expected to start entraining dry air, which could limit
intensification despite the otherwise favorable shear and sea
surface temperature environment.  The new intensity forecast is
unchanged from the previous forecast, and it lies between the
weaker dynamical models and the stronger statistical-dynamical

Key Messages:

1.  Karen is expected to bring heavy rainfall, flash floods and
mudslides to Puerto Rico and the U.S. and British Virgin Islands
today, where a tropical storm warning is in effect.  The rainfall
and potential flooding will likely continue on Wednesday even as the
center of Karen moves away from Puerto Rico and the Virgin Islands.


INIT  24/1500Z 17.5N  65.8W   35 KT  40 MPH
 12H  25/0000Z 19.1N  65.4W   35 KT  40 MPH
 24H  25/1200Z 21.3N  64.9W   40 KT  45 MPH
 36H  26/0000Z 23.6N  64.1W   45 KT  50 MPH
 48H  26/1200Z 25.5N  63.4W   50 KT  60 MPH
 72H  27/1200Z 27.8N  62.0W   55 KT  65 MPH
 96H  28/1200Z 28.0N  62.5W   60 KT  70 MPH
120H  29/1200Z 27.5N  65.0W   60 KT  70 MPH

Forecaster Beven