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Tropical Storm Karl Forecast Discussion


000
WTNT44 KNHC 132035
TCDAT4

Tropical Storm Karl Discussion Number  10
NWS National Hurricane Center Miami FL       AL142022
400 PM CDT Thu Oct 13 2022

The partially exposed center of Karl is evident in visible satellite
imagery this afternoon. The convective overcast has a sharp edge on
the northwestern side of the circulation, indicating that strong
west-northwesterly shear continues to impinge on the cyclone. Recent
satellite-derived wind data indicate that tropical-storm-force winds
are occurring mainly downshear of the center, where the deepest
convection has been ongoing today. Despite finding a slightly lower
minimum pressure than this morning, the Air Force Hurricane Hunters
reported flight-level winds and SFMR data early this afternoon that
support lowering the initial intensity to 40 kt for this advisory, 
which is consistent with recent ASCAT wind data.

The hostile environmental conditions that Karl is contending with 
are not expected to improve during the next day or so. Moderate 
west-northwesterly shear and continued intrusions of drier mid-level 
air should make it difficult for Karl's convective organization to 
improve much. The latest guidance suggests that little change in 
strength or even slight weakening is possible during the next 24-36 
hours as the storm moves toward the coast. The NHC track forecast 
still shows Karl moving onshore as a tropical storm on Friday night 
or early Saturday, then quickly weakening and eventually 
dissipating over the mountainous terrain of southern Mexico by 
Saturday night.

Karl is moving south-southeastward at a faster forward speed than 
earlier today (155/6 kt). This general motion should continue 
through tonight, followed by a southward to south-southwestward 
motion on Friday as Karl moves around the eastern periphery of a 
mid-level ridge over west-central Mexico. The NHC track forecast has 
once again been adjusted slightly eastward in the direction of the 
latest multi-model consensus aids. There are still some along-track 
differences noted in the guidance, with the slower GFS and HWRF 
solutions moving Karl inland later than the rest of the global 
models. Following a consensus approach, the NHC forecast is somewhat 
faster than the previous one and shows Karl just inland by 36 h.


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 are expected to begin within a portion
of the warning area in southern Mexico by late Friday.


FORECAST POSITIONS AND MAX WINDS

INIT  13/2100Z 20.9N  93.5W   40 KT  45 MPH
 12H  14/0600Z 20.1N  93.2W   35 KT  40 MPH
 24H  14/1800Z 19.1N  93.1W   35 KT  40 MPH
 36H  15/0600Z 18.3N  93.5W   30 KT  35 MPH...INLAND
 48H  15/1800Z 17.5N  94.3W   25 KT  30 MPH...POST-TROP/INLAND
 60H  16/0600Z...DISSIPATED

$$
Forecaster Reinhart



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