[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT44 KNHC 120236
TCDAT4

Tropical Storm Karl Discussion Number   2
NWS National Hurricane Center Miami FL       AL142022
1000 PM CDT Tue Oct 11 2022

Bursts of deep convection have continued to develop this evening
near and to the northeast of the estimated center.  Data from the
earlier reconnaissance mission into Karl showed that the circulation
was elongated along a south-southeast to north-northwest axis with
at least a couple of swirls that are likely rotating around the
mean center.  The plane did not find flight-level or SFMR winds any
stronger than what was reported before the release of the previous
advisory. Therefore, the initial intensity is maintained at 35 kt,
which is slightly above the latest Dvorak satellite estimates.  The
next reconnaissance mission into Karl is scheduled for Wednesday
morning.

Karl is moving north-northwestward or 330/5 kt, and this general
motion is expected to continue through Wednesday.  After that time,
a ridge of high pressure is forecast to build to the northwest of
Karl over northern Mexico.  The flow around the southeastern flank
of that anticyclone is expected to cause Karl to turn southwestward
Wednesday night.  This motion should then bring the cyclone near the
coast of Mexico within the watch area on Thursday.  The latest
dynamical model guidance depicts a sharper turn Wednesday night and
the official forecast was adjusted southward, and a bit faster than
the previous forecast at 36 h and beyond.  This southward
adjustment required the government of Mexico to extend the Tropical
Storm Watch southward to Roca Partida.  The new NHC track forecast
is close to the simple consensus aids and is also in good
agreement with the ECMWF model.

Karl is currently located within an environment of generally light
southwesterly shear and over warm sea surface temperatures.  This
should allow some strengthening tonight or on Wednesday.  After that
time, increasing northwesterly shear and decreasing mid-level
relative humidity are likely to cause some weakening before
landfall. After Karl moves onshore, rapid decay is expected due to
the mountainous terrain, and Karl is likely to dissipate in around
72 hours.

Key Messages:

1. Heavy rainfall could produce flash flooding in the Isthmus of
Tehuantepec and in the southern Sierra Madre Oriental mountains and
adjacent coastal areas with possible mudslides in areas of higher
terrain.

2. Tropical storm conditions are possible in the watch area in
Mexico starting Thursday.


FORECAST POSITIONS AND MAX WINDS

INIT  12/0300Z 20.5N  94.9W   35 KT  40 MPH
 12H  12/1200Z 21.0N  95.3W   40 KT  45 MPH
 24H  13/0000Z 21.4N  95.6W   45 KT  50 MPH
 36H  13/1200Z 21.1N  95.9W   45 KT  50 MPH
 48H  14/0000Z 20.2N  96.2W   40 KT  45 MPH
 60H  14/1200Z 19.4N  96.6W   35 KT  40 MPH...INLAND
 72H  15/0000Z 19.1N  97.1W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  16/0000Z...DISSIPATED

$$
Forecaster Brown
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