Tropical Weather Discussion
Issued by NWS
Issued by NWS
337 AXPZ20 KNHC 160341 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 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 0000 UTC surface analysis and satellite imagery through 0330 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 been ongoing for hours today along the coast of Guatemala and the Mexican state of Chiapas. The pattern is expected to persist through at least the middle of next week across northern Central America and southern Mexico, with the threat to life and property increasing 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 Sun as the focus shifts northward to northern Central America. 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 extends off the coast of Mexico near 16N99W to 12N117W to 08N125W. The ITCZ extends from 08N125W to beyond 07N140W. Numerous moderate to isolated strong convection is noted from 13N to 17N between 92W and 97W. Scattered moderate convection is noted from 04N to 16N between 79W and 110W. ...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. Meanwhile, moderate to fresh NE to E winds are noted in this region with seas 6 to 7 ft. Farther north, fresh to strong NW winds continue to approach the waters just west of Guadalupe Island off Baja California Norte. Combined seas are 8 to 11 ft north fo Punta Eugenia, primarily due to NW swell. These winds and seas are influenced by their portion between 1029 mb high pressure near 35N140W and lower pressure over the lower Colorado River valley. Mostly gentle to moderate breezes and slight to moderate seas persist elsewhere with 5 to 7 ft seas. For the forecast, 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 into mid week before subsiding by Wed. Meanwhile, off southern Mexico, expect fresh SW winds and building seas starting tonight off Chiapas as a broad area of low pressure, continues to develop over southern Mexico and northern Central America. Winds and seas will increase further off Chiapas and Oaxaca through the early part of the week as the Central American Gyre intensifies and persists. ...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 winds across the Guatemala, El Salvador and Nicaragua offshore waters. Seas are 7 to 8 ft in this area within S to SW swell. Across the rest of the Central American offshore waters, winds are moderate with 5 to 7 ft seas. Strong thunderstorms continue to impact mainly northern Central America off Guatemala, bringing heavy rain and frequent lightning. These storms could cause hazardous marine conditions. In the Ecuador and Galapagos Island offshore waters, winds are moderate to locally fresh. Seas are 5 to 7 ft within S swell. For the forecast, the broad area of low pressure known as a Central American Gyre will cause an increase in winds, rough seas and widespread showers and thunderstorms across much of offshore waters through mid week. Conditions will continue to improve over the Gulf of Panama tonight. 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 1030 mb high pressure near 35N140W. Moderate to fresh winds prevail across waters north of the monsoon trough and west of 115W with seas 6 to 9 ft. East of 115W, gentle to moderate winds are noted south of the monsoon trough to 05N. Seas are 5 to 7 ft across the rest of the Pacific waters. Fresh to strong winds are beginning to filter through the far northeastern waters, N of 26N between 119W and 129W with seas 8 to 11 ft within NW 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 early next week. Seas will build to 8 to 12 ft by Sun night into Mon, mainly north of 20N between 120W and 130W. SW flow south of the monsoon trough is forecast to continue tonight between 90W and 115W, supporting seas of 6 to 8 ft. Similar winds and seas are likely to return there by the end of the weekend into early next week. 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. $$ AReinhart