Eastern Pacific Basin Tropical Cyclones

Tropical Storm Lester Forecast Discussion


459 
WTPZ43 KNHC 171437
TCDEP3

Tropical Storm Lester Discussion Number   8
NWS National Hurricane Center Miami FL       EP132022
1000 AM CDT Sat Sep 17 2022

Lester's overnight improvement in organization was short lived. 
Several microwave overpasses during the last few hours show a 
distinct lack of organized convective banding, and little evidence 
that a well-defined circulation still exists. It is possible that 
close proximity to land has severely disrupted Lester's structure 
since it has been very difficult to locate the cyclone's center in 
traditional IR or Visible imagery this morning. With the center of 
Lester well-hidden below higher clouds, the uncertainty in the 
initial position and motion are unusually high, which also 
translates to high uncertainty in the intensity estimate since the 
Dvorak technique is very dependent on center location. The initial 
intensity of 35 kt is based on a blend of recent Dvorak fixes, but 
should be considered within that uncertain context.

Significant strengthening is not supported by any guidance and 
appears unlikely with Lester so close to land, so the biggest threat 
will be very heavy rain leading to flash and urban flooding across 
portions of the southwest coast of Mexico. Mudslides will also be 
possible in areas of high terrain. That threat will exist over a 
wide area regardless of Lester's position or intensity, and will 
persist today even after Lester dissipates. Users are therefore 
urged to not put much weight into the specifics of the NHC track and 
intensity forecasts, which shows Lester moving inland and 
dissipating later today. This scenario is supported by all of the 
dynamical models, with some (like the ECMWF, UKMET and CMC models) 
indicating that Lester may have already moved inland.

Key Messages:

1. Heavy rains from Lester will continue for portions of coastal
southern Mexico into Sunday. This rainfall may produce flash and
urban flooding, along with possible mudslides in areas of higher
coastal terrain.

2. Tropical storm conditions are possible along portions of the 
coast of southwestern Mexico today. 

FORECAST POSITIONS AND MAX WINDS

INIT  17/1500Z 16.0N  99.0W   35 KT  40 MPH
 12H  18/0000Z 17.3N  99.9W   25 KT  30 MPH...POST-TROP/INLAND
 24H  18/1200Z...DISSIPATED

$$
Forecaster D. Zelinsky




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