000 AXPZ20 KNHC 110831 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0830 UTC Thu Jun 11 2020 Tropical Weather Discussion for the eastern Pacific Ocean from the Equator to 32N, east of 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 0800 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A Tehuantepec gap wind event is expected to begin this afternoon as a cold front crosses the western Gulf of Mexico. An enhanced pressure gradient will develop between building high pressure across eastern Mexico and lower pressures associated with the monsoon trough, which will support strengthening northerly gap winds. Expect strong to near gale-force winds to prevail in the Tehuantepec region tonight through early next week, with a brief period of marginal gale- force winds expected late tonight. Combined seas will build to 8-12 ft early Fri in mixed northerly wind waves and southerly swell. Please see the latest NWS High Seas Forecast at https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for details. ...TROPICAL WAVES... An eastern Pacific tropical wave extends along 91W, moving west around 10-15 kt. Scattered moderate convection is noted N of 06N within 90 nm of the wave axis. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N76W to 11N100W to 11N113W. The ITCZ extends from 11N113W to 1012 mb low pressure near 10N122W to 09N140W. Numerous strong convection is noted N of 10N between 87W and 89W. Elsewhere, scattered moderate isolated strong convection is occurring within 60 nm of the monsoon trough between 92W and 98W, and within 150 nm of the ITCZ between 130W and 138W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section for more details about the Gulf of Tehuantepec Gale Warning. A weak high pressure ridge persists across the northern waters. Recent scatterometer data shows light to gentle winds prevail across the forecast waters under a weak pressure pattern. Wave heights are generally 4-7 ft over the offshore waters, and 3 ft or less inside the Gulf of California. Hazy conditions may linger offshore of Baja California Norte today due to smoke from nearby inland fires. Winds off Baja California will strengthen Fri night into this weekend as a high pressure ridge builds eastward over the region. A brief period of fresh SW gap winds is expected Fri night over the northern Gulf of California. Increasing NW swell will build wave heights to 8-9 ft in the Baja California Norte waters this weekend. Marine conditions will improve early next week. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gentle to locally moderate S to SW flow prevails south of the monsoon trough, per recent scatterometer data. Long-period southerly swell persists across the offshore waters tonight. An earlier altimeter pass indicated wave heights were 7-9 ft between the Galapagos Islands and Ecuador. North of the monsoon trough, winds remain light and variable and seas are running 5-7 ft in southerly swell. Cross-equatorial S to SW swell will continue impacting the region while gradually decaying through Fri. Fresh winds will pulse across the Papagayo region tonight and Fri night. Wave heights will briefly subside this weekend, before another set of southerly swell crosses the region late Sun through Mon. REMAINDER OF THE AREA... A broad high pressure ridge remains across the forecast waters roughly north of 15N and west of 100W. Moderate to fresh trades are occurring west of 130W between the ridge and the ITCZ. A mix of NE wind waves and SE to S swell is likely maintaining 7-9 ft seas in this region. Little change is expected over the next couple days as a low pressure trough moves along the ITCZ and supports fresh winds and locally higher seas west of 135W. Elsewhere, moderate southerly flow is shown in scatterometer data south of the monsoon trough/ITCZ, with locally fresh winds near a couple of spot lows noted near 10N122W and 11N131W. Long- period southerly swell still dominates the waters south of 15N and east of 110W, with 8-9 ft seas south of the monsoon trough between 90W and 100W. This swell will gradually decay over the next couple days, allowing wave heights to subside below 8 ft by Fri night. Looking ahead, an area of low pressure is forecast to form well south or south-southwest of the southern tip of Baja California Sur this weekend. Environmental conditions are expected to be conducive for gradual development, and a tropical depression could form in the early part of next week while the system moves west-northwestward away from Mexico. There is a medium chance of tropical cyclone formation within the next five days. $$ B Reinhart