989 AXPZ20 KNHC 240406 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Tue Sep 24 2024 Tropical Weather Discussion for the eastern Pacific Ocean from 03.4S to 30N, east of 120W including the Gulf of California, and from the Equator to 30N, between 120W and 140W. The following information is based on satellite imagery, weather observations, radar, and meteorological analysis. Based on 0000 UTC surface analysis and satellite imagery through 0345 UTC. ...SPECIAL FEATURES... Major Hurricane John is centered near 16.3N 98.8W at 24/0300 UTC, moving north at 7 kt. Estimated minimum central pressure is 959 mb. Maximum sustained wind speed is 105 kt with gusts to 120 kt. Seas are in the 12 to 19 ft range. Latest satellite imagery shows John is continuing to intensify as noted by the presence of an eye feature that is surrounded by a solid thick ring of very cold cloud top numerous strong convection. This convection is within 120 nm of the center in the E semicircle, also within 90 nm of the center in the SW quadrant and within 60 nm of the center in the NW quadrant. Similar convection is seen from 16N to 19N between 100W and 104W. Numerous moderate to isolated strong convection is from 12N to 15N between 96W and 102W. On the current forecast track, the center of John is forecast to move inland along the coast of southern Mexico in the next couple of hours. John will continue to move inland over southern Mexico on Tue. John is now a category 3 hurricane on the Saffir-Simpson Hurricane Wind Scale. Some additional strengthening is possible the next couple of hours before John makes landfall. After landfall, the system will rapidly weaken over the high terrain of southern Mexico. Hurricane John is expected to produce 6 to 12 inches of rain with isolated totals around 15 inches across the coastal areas of Chiapas. In areas along and near the Oaxaca coast to southeast Guerrero, between 10 and 20 inches of rain with isolated totals near 30 inches can be expected through Thu. Swells associated with John are forecast to continue affecting the coast of southern Mexico during the next couple of days, with the potential for dangerous surf and rip currents much of the week. Please see local statements for more information. Please read the latest HIGH SEAS FORECAST issued by the National Hurricane Center at website - https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml and the latest John NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. A Central American Gyre will generate periods of excessive rainfall over southern Mexico and Central America this week, as well as the adjacent western Caribbean and eastern Pacific waters between 80W and 95W. This scenario, combined with daytime heating and orographic lifting, could produce dangerous flash flooding and mudslides across the area. Furthermore, strong to near gale force winds, rough seas and thunderstorms are forecast to affect the offshore waters between Costa Rica and El Salvador through the end of the week. Please follow the forecasts from your local weather offices for more detailed information. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 14N110W to 14N123W to 10N129W to 12N140W. Aside from convection related to John and the Central American Gyre, scattered moderate convection is seen within 120 nm south of the trough between 110W and 113W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the Special Features section above for information on Hurricane John and on the Central American Gyre (CAG). A high pressure ridge extends southeastward from a 1023 mb high center that is located well northwest of the area to near 25N125W. The gradient between it and relatively lower pressure in northwest Mexico is allowing for generally gentle to moderate northwest to north winds to exist over the offshore waters. Light to gentle northwest winds are over the Gulf of California. Seas are 1 to 3 ft over the Gulf, except for higher seas of 3 to 5 ft at the entrance to the Gulf. Fresh to near strong winds are likely occurring in the periphery of Hurricane John with seas of 8-10 ft. For the forecast aside that described above for Hurricane John, high pressure will maintain generally gentle to moderate northwest to north winds over the offshore waters. Winds are forecast to increase to fresh speeds over most of the offshore waters starting Wed, with little change expected going into the early part of the upcoming weekend. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Please refer to the Special Features section above for information on the Central American Gyre (CAG). Moderate to fresh southwest winds are over the offshore waters of Central America north of Guatemala while gentle to moderate winds are elsewhere. Seas are 6 to 9 ft in west swell over the offshore waters of Guatemala. Seas are 4 to 7 ft over the remainder of the offshore waters. Moderate to strong convection is occurring from 05N to 10N between 81W and 90W, including in the waters off the coasts of Panama and Costa Rica. Strong winds and rough seas will occur near convection. For the forecast, moderate to fresh southwest winds will continue in the wake of major Hurricane John off the coast of Central America through north of Guatemala through Wed night. West to northwest swell will propagate generally eastward in the wake of John, through the waters of Guatemala tonight, expanding farther east toward El Salvador on Tue, and toward Nicaragua Wed. Periods of strong convection will also occur over most of the Central America offshore waters through at least through Wed. ...REMAINDER OF THE AREA... The gradient related to high pressure ridging over the area is supporting moderate to fresh northeast winds west of about 130W, and gentle to moderate winds east of 130W. Seas are 6 to 8 ft with these winds. Elsewhere, fresh to locally strong southwest winds continue south of the monsoon trough east of 125W and north of 09N. For the forecast, SW winds become well established south of the monsoon trough as the trough slowly lifts northward over the next few days. Fresh to strong SW winds will occur generally north of 09N and east of 110W through Wed, with strong southwest winds continuing east of 105W through at least Fri. Rough seas will accompany these gusty winds. Looking ahead, a trough of low pressure located several hundred miles southwest of southwestern Mexico is producing disorganized showers and thunderstorms. Development of this system is no longer expected as it moves eastward towards the coast of southern Mexico the next few days. $$ Aguirre