Tropical Storm John Forecast Discussion

962 
WTPZ45 KNHC 241435
TCDEP5

Tropical Storm John Discussion Number   9
NWS National Hurricane Center Miami FL       EP102024
900 AM CST Tue Sep 24 2024

John has been rapidly weakening since it moved inland last night,
and the maximum sustained winds are now estimated to be around 35
kt.  The storm still has a well-defined mid-level center, but
surface observations suggest that the low-level circulation is
less defined and could be opening into a trough.  A strong band of
thunderstorms to the east of the estimated center continues to
produce heavy rains across portions of southern Mexico.

There is quite a bit of uncertainty in the future of John.  One 
possibility is that the storm dissipates over Mexico, with a trough 
or low reforming back offshore and lingering in that location for 
much of the rest of the week.  The other possibility is that John 
itself hangs on as a tropical depression or storm.  For now, the 
official forecast generally follows the previous scenario and shows 
John weakening to a tropical depression later today and lingering 
near the coast of southern and southwestern Mexico until the end of 
the week. It is hoped that additional data and model runs later 
today will help provide some clarity on the system's future.

Even though the future of John is uncertain, there is high 
confidence that heavy rains will continue in portions of southern 
and southwestern Mexico during the next couple of days.  See the Key 
Messages below for additional information on that hazard.


KEY MESSAGES:

1. Slow-moving John will continue to bring very heavy rainfall to 
coastal portions of southern and southwestern Mexico through the 
upcoming week. This heavy rainfall will likely cause significant and 
possibly catastrophic, life-threatening flash flooding and mudslides 
to the Mexican States of Chiapas, Oaxaca, and southeast Guerrero, 
particularly in areas near the coast and along the up-slope portion 
of areas of higher terrain.

2. John could still produce tropical storm conditions for the next 
couple of hours in the tropical storm warning area.


FORECAST POSITIONS AND MAX WINDS

INIT  24/1500Z 17.7N 100.5W   35 KT  40 MPH...INLAND
 12H  25/0000Z 17.7N 101.1W   30 KT  35 MPH...INLAND
 24H  25/1200Z 17.3N 101.1W   30 KT  35 MPH...OVER WATER
 36H  26/0000Z 17.1N 100.8W   30 KT  35 MPH
 48H  26/1200Z 17.4N 100.7W   25 KT  30 MPH...INLAND
 60H  27/0000Z 17.7N 100.8W   25 KT  30 MPH...INLAND
 72H  27/1200Z...DISSIPATED

$$
Forecaster Cangialosi