[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT44 KNHC 130233
TCDAT4

Tropical Storm Karl Discussion Number   7
NWS National Hurricane Center Miami FL       AL142022
1000 PM CDT Wed Oct 12 2022

Shear is having a greater influence on Karl this evening, with
GOES-16 proxy-visible satellite imagery showing the low-level
center now exposed to the northwest of a strong cluster of deep
convection.  An Air Force Reserve Hurricane Hunter aircraft
investigating the storm found a similar peak 850-mb flight-level
wind as earlier today (57 kt), but the SFMR readings have not been
as high.  However, the strongest winds from earlier were directly
east of the center, and the current aircraft has not sampled that
area of the storm.  Plus, the central pressure was found to have
fallen to 1000 mb during this mission.  Therefore, the initial
intensity remains 50 kt.

The center does not look like it's moved very much during the past
few hours, and that is confirmed by the aircraft fixes.  A mid-level
high located over west-central Mexico and a large-amplitude
mid-latitude trough over the United States are expected to impart
northerly or northwesterly flow over Karl on Thursday, which should
push the cyclone southward into the Bay of Campeche during the next
couple of days.  The track guidance has again shifted eastward a bit
on this cycle, but most of that is related to Karl's adjusted
initial position and not with any particular change in forecast
reasoning.  The updated NHC track is nudged eastward from the
previous prediction, especially during the first 48 hours, and it
shows Karl reaching the coasts of Tabasco or Veracruz states in
Mexico by Saturday morning.

Deep-layer shear has increased to near 20 kt out of the west, and
that magnitude is unlikely to decrease during the next few days.
Even though ocean temperatures are about 28 degrees Celsius, a
combination of the continued shear and surrounding dry mid-level
air is expected to cause a gradual weakening trend while Karl
approaches the Bay of Campeche coast of Mexico.  The NHC intensity
forecast lies between the aggressive statistical-dynamical guidance
(which show a little bit of strengthening) and the regional
hurricane models and consensus aids (which show almost immediate
weakening).  Fast weakening is expected after Karl reaches land,
and the system is forecast to degenerate into a remnant low, or
even dissipate, by late Saturday.


Key Messages:

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

2. Tropical storm conditions are possible in the watch area in
Mexico beginning late Friday.


FORECAST POSITIONS AND MAX WINDS

INIT  13/0300Z 22.4N  94.3W   50 KT  60 MPH
 12H  13/1200Z 22.0N  94.0W   50 KT  60 MPH
 24H  14/0000Z 21.1N  93.7W   50 KT  60 MPH
 36H  14/1200Z 20.1N  93.5W   45 KT  50 MPH
 48H  15/0000Z 19.1N  93.6W   40 KT  45 MPH
 60H  15/1200Z 18.1N  94.2W   40 KT  45 MPH...INLAND
 72H  16/0000Z 16.9N  94.7W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  17/0000Z...DISSIPATED

$$
Forecaster Berg
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