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Hurricane John Discussion Number   7
NWS National Hurricane Center Miami FL       EP102024
900 PM CST Mon Sep 23 2024
 
John has continued to strengthen this evening with a small tight 
inner core, which was well depicted in SSMIS microwave images around 
00z. Infrared imagery depicts an eye with cold cloud tops near -80 C 
wrapping around the core. Subjective intensity estimates have 
continued to increase this evening with data-T values of T5.5 from 
both SAB and TAFB, with final-T values constrained due to the rapid 
intensification. Given the most recent satellite depiction and using 
the data-T values, the intensity for this advisory is increased to 
105 kt. John is now a major category 3 hurricane.
 
The hurricane could still strengthen some more over the next couple 
of hours before it makes landfall along the coast of southern 
Mexico. After John moves inland, rapid weakening is forecast over 
the higher terrain with the small inner core quickly deteriorating. 
The rate of weakening could occur faster than what is currently 
forecast and the 24 h forecast point is held for continuity inland 
as it is possible the system could dissipate sooner.
 
John continues to move northward around 7 kt.  This current motion 
should continue as John nears the coast, making landfall in the next 
couple of hours and will continue to move inland on Tuesday. The 
cyclone is forecast to slow its forward motion as it moves inland 
and dissipates.
 
 
KEY MESSAGES:
 
1. John is expected to be a major hurricane as it reaches the coast 
of southern Mexico within the Hurricane Warning area in the next 
couple of hours. Damaging hurricane-force winds and a 
life-threatening storm surge are expected within portions of the 
hurricane warning area.
 
2. Slow-moving Hurricane John will bring very heavy rainfall to 
coastal portions of southwest 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.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  24/0300Z 16.3N  98.8W  105 KT 120 MPH
 12H  24/1200Z 17.0N  98.9W   55 KT  65 MPH...INLAND
 24H  25/0000Z 17.5N  99.1W   25 KT  30 MPH...POST-TROP/INLAND
 36H  25/1200Z...DISSIPATED
 
$$
Forecaster Kelly
 
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