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Tropical Storm Karl Forecast Discussion


000
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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