000 AXPZ20 KNHC 110300 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0300 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 0000 UTC surface analysis and satellite imagery through 0230 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A Tehuantepec gap wind event is expected to begin on Thu as a cold front crosses the western Gulf of Mexico. The enhanced pressure gradient between building high pressure across eastern Mexico and the lower pressures associated with the monsoon trough will support strengthening northerly gap winds. Expect strong to near gale-force winds to prevail in the Tehuantepec region Thu night through early next week, with a brief period of marginal gale-force winds expected late Thu night. 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 is near 89W, moving westward around 10-15 kt. Scattered moderate convection is noted from 05N to 10N within 120 nm of the wave axis. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N76W to 11N91W to 09N117W. The ITCZ extends from 12N118W to 1011 mb low pressure near 10N121W to 10N135W to 07N140W. Numerous strong convection is noted from 09N to 12N east of 87W. Scattered moderate isolated strong convection is occurring within 120 nm of the ITCZ between 131W and 137W. Elsewhere, scattered moderate convection is noted within 90 nm of the monsoon trough between 107W and 117W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section for more details about the Gulf of Tehuantepec Gale Warning. Areas of smoke noted in GOES-16 visible satellite imagery are likely producing hazy conditions offshore of Baja California Norte. A weak high pressure ridge prevails across the northern waters. Earlier scatterometer data showed mainly gentle winds across the region, including the Gulf of California. Some locally moderate winds are possible this evening near Punta Eugenia and Los Cabos. Recent altimeter data indicates 5-7 ft seas offshore of Guerrero and Oaxaca. Elsewhere, seas are 4-6 ft over the Baja California offshore waters, and 3 ft or less inside the Gulf of California. Winds off Baja California will strengthen Fri into this weekend as an enhanced pressure gradient develops between building offshore high pressure and low pressure troughing over the SW United States and NW Mexico. 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... Long-period southerly swell persists across the regional offshore waters this evening. Seas were recently analyzed to 7-9 ft over the waters south of 08N and east of 93W, except in the lee of the Galapagos Islands. Generally, moderate SW monsoon flow continues across the waters south of the monsoon trough, with light and variable winds noted north of 10N. Cross-equatorial S-SW swell will continue impacting the region while gradually decaying through Fri. This swell could produce hazardous surf conditions along the coasts of Panama and Costa Rica, as well as rough seas near the Azuero Peninsula and the entrance to the Gulf of Panama. Wave heights will briefly subside into this weekend, before another set of southerly swell crosses the region late Sun through Mon. REMAINDER OF THE AREA... A broad high pressure ridge prevails across the forecast waters roughly north of 15N and west of 100W. Fresh trades are noted in earlier scatterometer data west of 130W, between this ridge and the ITCZ. Several altimeter passes in this region indicate seas remain 7-9 ft in mixed NE wind waves and SE to S swell. These trades may diminish slightly as a weakening cold front reaches the far NW portion on Thu. However, a low pressure trough that will develop along the ITCZ will likely maintain fresh winds and locally higher seas west of 135W into Fri. Moderate to fresh southerly flow continues south of the monsoon trough/ITCZ across the basin to 140W. Long-period southerly swell dominates the waters south of 15N and east of 110W this evening, with 8-9 ft seas noted 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. $$ B Reinhart