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Tropical Storm Karen Discussion Number 2
NWS National Hurricane Center Miami FL AL122019
1100 AM AST Sun Sep 22 2019
Radar and satellite imagery shows that convection associated with
Karen has lost some organization since advisories were initiated
early this morning. However, surface observations and a very
recently arriving ASCAT data show that the circulation is
well-defined, and is currently passing through the southern Windward
Islands. Given the current sprawling structure, nearby dry
mid-level air, and moderate northwesterly shear, no significant
strengthening is expected through 48 hours. In fact, the system may
have trouble surviving over the eastern Caribbean Sea as the global
models predict an increase in northeasterly upper-level winds over
the system on Monday. Once the cyclone moves north of Puerto Rico,
the shear is forecast to decrease, and some strengthening is
indicated in the official forecast, but this will depend on the
structure of the system at that time. At this time, the long range
intensity forecast is quite uncertain.
The initial motion estimate is 290/11 kt. The track guidance is in
good agreement on Karen turning northwestward, and then northward
around the southwestern portion of a deep-layer ridge during the
next day or two. A northward motion should continue into mid-week
as a weakness in the ridge remains over the western Atlantic.
After that time, models suggest that another ridge will begin to
build over the southeastern U.S. and far western Atlantic which may
cause Karen to slow down by the end of the forecast period. The
updated NHC track forecast is very close to the previous advisory
and lies near the consensus models.
A Tropical Storm Watch has been issued for Puerto Rico and the U.S.
and British Virgin Islands.
1. Tropical-storm-force winds and heavy rainfall will continue to
affect the southern Windward Islands through tonight.
2. Karen is forecast to approach Puerto Rico, and the U.S. and
British Virgin Islands on Tuesday, and a tropical storm watch has
been issued. Tropical-storm-force winds, heavy rainfall, and flash
flooding is possible on these islands.
FORECAST POSITIONS AND MAX WINDS
INIT 22/1500Z 12.5N 61.7W 35 KT 40 MPH
12H 23/0000Z 13.1N 63.1W 35 KT 40 MPH
24H 23/1200Z 14.2N 64.1W 35 KT 40 MPH
36H 24/0000Z 15.4N 65.0W 35 KT 40 MPH
48H 24/1200Z 16.9N 65.6W 35 KT 40 MPH
72H 25/1200Z 20.7N 65.5W 45 KT 50 MPH
96H 26/1200Z 23.4N 65.3W 50 KT 60 MPH
120H 27/1200Z 25.3N 65.8W 55 KT 65 MPH