[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 142038
TCDAT4

Tropical Storm Karl Discussion Number  14
NWS National Hurricane Center Miami FL       AL142022
400 PM CDT Fri Oct 14 2022

The deep convection associated with Karl collapsed around midday,
with dry air and deep-layer shear continuing to take a toll on the
cyclone. The second half of the previous Air Force Hurricane Hunter
mission found the minimum pressure had increased to around 1003 mb,
and the peak 850-mb flight-level winds were only 39 kt. Some ASCAT
passes across the eastern portion of the circulation showed at least
25-30 kt winds in the southeastern quadrant, with some higher
tropical-storm-force vectors flagged as marginal. Based on these
data and the latest satellite estimates, the initial intensity is
lowered to 35 kt. This could be generous given the current lack of
convection, but another Air Force Hurricane Hunter aircraft is
scheduled to investigate the storm this evening.

The last few aircraft fixes and earlier ASCAT data indicated the
center of Karl was not moving very much. Although the long-term
motion is estimated at 195/4 kt, the near-term motion appears to be
more of a west-southwestward drift. The shallow cyclone is expected
to move generally southwestward during the next day or so as it
becomes steered by a low-level ridge to the north. More of the
latest track models show the center of Karl moving slower and more
southwestward across the Bay of Campeche on Saturday, and so the NHC
forecast has been adjusted westward from the previous track. Karl
will likely struggle to generate more organized convection in the
near term given the persistent shear and lack of mid-level moisture
in its environment. Therefore, the NHC forecast now shows Karl
weakening to a depression by early Saturday and degenerating into a
post-tropical remnant low in 24 h, when it is near the coast of
southern Mexico. Dissipation should occur soon thereafter due to
the increased likelihood of land interaction.


Key Messages:

1. Heavy rainfall associated with Karl could produce flash flooding,
with mudslides in areas of higher terrain, across portions of
Veracruz, Tabasco, Chiapas and Oaxaca states in Mexico.

2. Tropical storm conditions, especially in gusts, are expected to
within a portion of the warning area in southern Mexico this
evening.


FORECAST POSITIONS AND MAX WINDS

INIT  14/2100Z 19.5N  92.9W   35 KT  40 MPH
 12H  15/0600Z 19.1N  93.1W   30 KT  35 MPH
 24H  15/1800Z 18.4N  93.8W   25 KT  30 MPH...POST-TROP/REMNT LOW
 36H  16/0600Z...DISSIPATED

$$
Forecaster Reinhart
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