Official Discussion issued by the National Hurricane Center

Katia (AL122023) DATA RELEASED: 9/2/2023 2:00:00 PM UTC

Copy of official data

Tropical Storm Katia Discussion Number   5
NWS National Hurricane Center Miami FL       AL122023
200 PM CVT Sat Sep 02 2023

Satellite images indicate the center of Katia is on the southern 
side of a large central dense overcast.  Scatterometer data from 
this morning indicated maximum winds were at least 40-45 kt, and 
the latest TAFB Dvorak estimate was 45 kt.  The initial wind speed 
is raised to 45 kt from the last full advisory, similar to the 
morning update statement.

Katia continues moving north-northwestward, or 330/10 kt.  The 
motion should gradually bend toward the northwest today due to the 
storm moving between a large middle- to upper-level low to the west 
and a narrow mid-latitude ridge over the eastern Atlantic.  The 
northwestward motion is likely to continue until about Monday, when 
the system becomes weaker and Katia gets stuck in the low-level 
subtropical ridge.  The only notable change to the track forecast is 
that it has been adjusted to the east in the short-term due to the 
initial position and is very close to the previous one at the end.

The storm is probably near its peak intensity with all models 
showing an increase in dry mid-level air near the center later 
today.  Combined with moderate southerly shear, this should be 
enough to choke off deep convection in Katia's core and cause 
gradual weakening.  In about 2 days, the environment becomes quite 
dry, which should finish off any remaining thunderstorm activity, 
and Katia is forecast to degenerate into a remnant low at that time. 
The NHC intensity forecast is raised early on to reflect the higher 
initial wind speed and is blended back with the guidance by the end 
of the forecast period.


INIT  02/1500Z 23.9N  29.7W   45 KT  50 MPH
12H  03/0000Z 25.1N  30.8W   45 KT  50 MPH
24H  03/1200Z 26.2N  32.1W   40 KT  45 MPH
36H  04/0000Z 27.0N  33.5W   35 KT  40 MPH
48H  04/1200Z 27.6N  34.7W   30 KT  35 MPH...POST-TROP/REMNT LOW
60H  05/0000Z 28.5N  35.7W   25 KT  30 MPH...POST-TROP/REMNT LOW
72H  05/1200Z 29.1N  36.1W   25 KT  30 MPH...POST-TROP/REMNT LOW
96H  06/1200Z...DISSIPATED

Forecaster Blake