000 AXPZ20 KNHC 240929 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 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 0600 UTC surface analysis and satellite imagery through 0915 UTC. ...SPECIAL FEATURES... Recently downgraded Tropical Storm John is inland the coast of southern Mexico near 17.3N 100.0W. or about 30 miles north- northwest of Acapulco, Mexico at 24/0900 UTC, moving northwest at 7 kt. Estimated minimum central pressure is 990 mb. Maximum sustained wind speed has diminished to 60 kt with gusts to 75 kt. Seas are in the 11 to 19 ft range. Satellite imagery shows that eye feature that was observed last night has now become obscured. The imagery reveals numerous strong convection that is within 120 nm of the center in the NE quadrant, within 210 nm of the center in the SE quadrant, within 150 nm of the center in the SW quadrant and within 60 nm of the NW quadrant. John is forecast to maintain a very slow westward motion. Very little motion is forecasted over the next several days. Additional rapid weakening is anticipated, and John is expected to become a tropical depression later today. Tropical Storm 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 to affect 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 for the remainder of the 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 heavy 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 14N108W to 14N121W to 10N130W 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 108W and 112W and within 30 nm of the trough between 126W and 129W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the Special Features section above for information on Tropical Storm 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. South to southwest fresh to strong winds with embedded patches of near gale winds on the outer periphery of Tropical Storm John were highlighted by a couple of ASCAT satellite data passes. These winds reach as far south of 09N and north to near 16N. Seas with these winds are 8 to 11 ft, except 9 to 14 ft within the patches of winds to near gale. For the forecast in addition to those conditions 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, moderate to fresh south to southwest winds will continue south of the monsoon trough through late in the week. Fresh to strong southwest winds will generally occur from 09N to 16N and east of 115W through Wed, with stronger southwest winds to near gale force expected east of 102W through at least Fri. Rough seas will accompany these gusty winds. Looking ahead, tropical cyclone formation is not expected for the next 7 days. $$ Aguirre