000 AXPZ20 KNHC 111947 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 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 1800 UTC surface analysis and satellite imagery through 1945 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A Tehuantepec gap wind event is expected to begin early this evening 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 by 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... A tropical wave extends along 78W from the SW Caribbean Sea to along the coast of Colombia, moving west at 15 kt. Associated convection is north of the area over the Caribbean Sea. A tropical wave extends along 94W, moving west around 10 kt. Scattered moderate and isolated strong convection is noted from 10N to 15N between 92W and 97W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from near 10N75W to low pressure just north of Panama near 10N81W to 12N100W to 11N116W. The ITCZ extends from 11N116W to 11N121W, then resumes from 11N126W to 10N140W. Scattered moderate and isolated strong convection is noted from 08N to 14N between 105W and 111W, and from 08N to 13N between 126W and 140W. Scattered moderate convection is noted from 05N to 11N between 80W and 90W. 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 per recent altimeter data and ship observations, and 3 ft or less inside the Gulf of California. Hazy conditions may linger offshore of Baja California Norte this evening due to smoke from nearby inland fires. Patchy fog offshore of Baja California Norte to the southern California waters may reduce visibilities tonight through early Fri. 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... Moderate to locally fresh S to SW flow prevails south of the monsoon trough per recent scatterometer data. Long-period southerly swell persists across the offshore waters this afternoon with wave heights of 7-9 ft between the Galapagos Islands and Ecuador. North of the monsoon trough, winds remain mainly 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, then decaying Tue before the next set arrives later in the week. 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, except locally strong near 13N138W per recent scatterometer data. A mix of NE wind waves and SE to S swell is likely maintaining 7-10 ft seas in this region. Little change is expected over the next couple days as a weak low pressure or a trough moves along the ITCZ and supports fresh winds and locally higher seas west of 135W. Elsewhere, moderate to locally fresh southerly flow prevails south of the monsoon trough/ITCZ. Long-period southerly swell still dominates the waters south of 15N and east of 110W, with 8-10 ft seas south of the monsoon trough between 90W and 105W. This swell will gradually decay over the next couple days, allowing wave heights to subside below 8 ft by Fri night. Looking ahead, a broad 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 only marginally conducive, and any development should be slow to occur through early next week while the system moves west-northwestward. There is a low chance of tropical cyclone formation within the next five days. $$ Lewitsky