[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT42 KNHC 270850
TCDAT2

Tropical Storm Karen Discussion Number  21
NWS National Hurricane Center Miami FL       AL122019
500 AM AST Fri Sep 27 2019

Karen's status as a tropical cyclone is becoming increasingly
dubious. In a trio of ASCAT passes that arrived yesterday evening,
the circulation of the cyclone was indistinguishable from a surface
boundary that extends south from the remnants of post-tropical
cyclone Jerry. This suggests that Karen's circulation may no longer
be well-defined. Furthermore, deep convection near the center of
Karen has generally decreased and become less organized since last
night. Satellite-based intensity estimates support maintaining the
intensity of Karen at 35 kt, but this could be generous given that
the max winds observed in the earlier ASCAT data were lower.

Regardless of the exact starting intensity of the cyclone, gradual
weakening is expected for the next few days. There is unanimous
agreement among the dynamical models on this scenario. Simulated
satellite imagery from the GFS and ECMWF models show the cyclone
devoid of deep convection within 36 hours, if not sooner.
Increasingly hostile upper-level winds should then prevent the
cyclone from reorganizing and it is forecast to dissipate in about
four days.

It has been difficult to locate the center of Karen overnight and
the initial motion estimate is uncertain but also unchanged
(055/7 kt). The global models are forecasting that Karen will
continue to move on this general heading through this morning before
it stalls tonight. A building ridge to the north should cause Karen
or its remnants to start moving westward over the weekend.

FORECAST POSITIONS AND MAX WINDS

INIT  27/0900Z 28.3N  61.2W   35 KT  40 MPH
 12H  27/1800Z 28.8N  60.1W   35 KT  40 MPH
 24H  28/0600Z 29.1N  59.6W   30 KT  35 MPH
 36H  28/1800Z 29.3N  60.1W   30 KT  35 MPH...POST-TROP/REMNT LOW
 48H  29/0600Z 29.3N  61.3W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  30/0600Z 29.0N  64.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  01/0600Z...DISSIPATED

$$
Forecaster Zelinsky
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