947 AXPZ20 KNHC 170357 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Mon Jun 17 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 0300 UTC. ...SPECIAL FEATURES... Central America and southern Mexico Heavy Rainfall Event: A broad area of low pressure persists over northern Central America and southern Mexico. This weather pattern, known as a Central American Gyre (CAG), directs moist SW flow from the Pacific Ocean into the coastal terrain of Central America and southern Mexico. This pattern will persist at least through midweek, enhancing heavy rainfall and strong thunderstorms. This can cause 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. The main areas impacted by the heavy rainfall will be northwest Nicaragua, southwest Honduras, El Salvador, coastal sections of Guatemala and the Mexican state of Chiapas. Additionally, dangerous surf conditions will impact these coastal areas through the next few days. Please refer to your local meteorological and emergency management office bulletins for more detailed information. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A monsoon trough extends southwestward from the coast of Guerrero State in Mexico through 13N114W to 08N128W. An ITCZ continues westward from 08N128W to beyond 07N140W. Numerous moderate to scattered strong convection is noted south of the monsoon trough from 13N to 16N between 91W and 97W. Scattered moderated convection is seen farther south from 08N to 12N between 87W and 111W...and near the ITCZ from 06N to 08N west of 134W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Refer to the Special Features section above for details on heavy rainfall. A large cluster of showers and thunderstorms is active off Chiapas and Oaxaca in southern Mexico, associated with a broad area of low pressure over the region known as the Central American Gyre. These thunderstorms are 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 1028 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. Mostly gentle to moderate breezes and slight to moderate seas persist elsewhere with 5 to 7 ft seas. For the forecast, fresh to strong SW to W winds, rough to very rough seas, and numerous heavy showers and strong thunderstorms will impact the offshore waters of southern Mexico through Thu, primarily off Chiapas, Oaxaca and southeastern Guerrero. This inclement weather is associated with a broad area of low pressure over the region known as the Central American Gyre. Dangerous surf is also anticipated through Thu along the coastal areas of this region. Farther north, fresh to strong NW winds and very rough seas will persist off Baja California Norte through Tue morning, primarily beyond 120 nm offshore. Large swell of 8 to 10 ft will linger in these waters mainly north of Cabo San Lazaro through Mon evening before gradually subsiding through Tue night. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Refer to the Special Features section above for details on heavy rainfall. 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 8 to 11 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 to W winds, rough to very rough seas and numerous heavy showers and strong thunderstorms will persist through Fri 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 anticipated through Thu along the coastal areas of this region. Farther south, rough seas in moderate to large southerly swell will continue near the Galapagos Islands and offshore of Ecuador through Tue. ...REMAINDER OF THE AREA... Broad ridging dominates the waters north of the ITCZ and monsoon trough, anchored by a 1028 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. $$ Chan