000 AXPZ20 KNHC 161526 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Sun Jun 16 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...SPECIAL FEATURES... Central America and southern Mexico Heavy Rainfall Event: A broad area of low pressure has developed over northern Central America and southern Mexico. This weather pattern, known as a Central American Gyre (CAG), enhances moist SW flow off the Pacific and into the coastal terrain of Central America and southern Mexico. This moist flow can persist for several days, resulting in life- threatening conditions that include flooding and mudslides. Numerous heavy showers and thunderstorms have already impacted the coasts of Guatemala and the Mexican state of Chiapas. This pattern is expected to persist through at least the middle of the week across northern Central America and southern Mexico. This will increase the threat to life and property as the event persists. The main areas impacted by the heavy rainfall will be northwest Nicaragua, southwest Honduras northwest Nicaragua, and coastal sections of Honduras, El Salvador, Guatemala, and the Mexican state of Chiapas. Farther south, the moist southwest flow was also causing persistent heavy rainfall across Costa Rica and Panama, although this will be diminishing today as the focus shifts northward to northern Central America. Additionally, dangerous surf could impact Chiapas, Guatemala and El Salvador today through the next few days. The persistence of the moist pattern and strong onshore flow will create very hazardous conditions to the region and could be life-threatening. Please refer to your local meteorological office bulletins for more detailed information. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough is displaced farther north than usual due to the ongoing Central American Gyre. It now extends off the coast of Mexico near a 1003 mb low pressure at 15N95W, and continues to 07N125W. The ITCZ extends from 07N125W 06N140W. Numerous moderate to isolated strong convection is noted from 10N to 15N between 85W and 105W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Refer to the section above for details on the Central American Gyre. A large cluster of showers and thunderstorms is active off Chiapas in southern Mexico, associated with a broad area of low pressure over the region known as the Central American Gyre. These thunderstorms are probably causing widespread lightning, gusty winds and locally rough seas off Chiapas and Oaxaca. Fresh to strong NE to E winds are noted in this region with seas 7 to 10 ft. Meanwhile, a 1027 mb high pressure is located well NW of the region near 34N140W. Pressure gradient between this high pressure and lower pressure over the Colorado River Valley is creating gale force winds off the California coast. Because of that, this is driving fresh to locally strong winds across the waters just west of Guadalupe Island off Baja California Norte. This is also sending NW swell across the Baja California offshore water, with combined seas are 8 to 12 ft north of Punta Eugenia. In the Gulf of California, light to gentle winds are noted with seas 2 to 4 ft, highest near the entrance of the Gulf. Mostly gentle to moderate breezes and slight to moderate seas persist elsewhere with 5 to 7 ft seas. Smoke from agricultural fires in Mexico are causing haze particularly off Colima, Jalisco and Nayarit. For the forecast, fresh to strong SW winds, rough seas, and numerous showers and thunderstorms will impact the offshore waters of southern Mexico through Thu, primarily off Chiapas and Oaxaca. This weather is associated with a broad area of low pressure over the region known as the Central American Gyre. Dangerous surf is also possible today through the next few days in this region. Farther north, fresh to strong winds and rough seas will persist off Baja California Norte through Mon, primarily beyond 120 nm offshore. Large swell of 8 to 12 ft will move into the waters off Baja California today, and persist mainly north of Cabo San Lazaro before subsiding by Tue night. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... With the monsoon trough displaced farther north than usual, this is bringing fresh to strong winds across the Guatemala, El Salvador and Nicaragua offshore waters. Seas are 7 to 10 ft in this area within S to SW swell. Across the rest of the Central American offshore waters, winds are gentle to moderate with 5 to 7 ft seas within S to SW swell. Strong thunderstorms continue to impact mainly northern Central America off Guatemala, El Salvador and Nicaragua which is bringing heavy rain and frequent lightning. These storms could cause hazardous marine conditions. In the Ecuador and Galapagos Island offshore waters, winds are moderate with seas 5 to 8 ft within S to SW swell. For the forecast, fresh to strong SW winds, rough seas and numerous showers and thunderstorms will persist through Thu across the offshore waters of northern Central America, associated with a broad area of low pressure known as a Central American Gyre. Dangerous surf is also possible today through the next few days in this region. Farther south, seas to 8 ft in S swell will continue around the Galapagos Islands through Tue. ...REMAINDER OF THE AREA... Broad ridging dominates the waters north of the ITCZ and monsoon trough, anchored by a 1027 mb high pressure centered near 34N140W. Across waters north of 20N, winds are moderate to fresh with NW swell propagating into the area bringing seas 8 to 12 ft north of 25N between 115W and 130W. From the ITCZ and monsoon trough to 20N and west of 120W, winds are gentle to moderate with 6 to 8 ft seas in mixed swell. East of 120W, winds are light to gentle with 5 to 6 ft seas within SW swell. South of the monsoon trough and ITCZ, winds are mostly gentle to moderate with 6 to 8 ft seas in SW to S swell. For the forecast, strengthening high pressure centered NW of the area will dominate waters west of 120W into the weekend. Fresh to strong winds from the California Channel Islands southward are likely to dip south of 30N at times through Tue. Seas will build to 8 to 12 ft by Sun night into Mon, mainly north of 20N between 120W and 130W, and subside below 8 ft by Tue night into Wed. SW flow south of the monsoon trough is forecast to continue this morning between 90W and 115W, supporting seas of 6 to 8 ft. Thunderstorms will persist near the monsoon trough and east of 110W or so through the next couple of days. Seas to 8 ft will hover around 03S near the Galapagos Islands through the weekend. $$ Christensen