000 AXPZ20 KNHC 290232 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 020 UTC Thu Jun 29 2017 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 0215 UTC. ...TROPICAL WAVES... A tropical wave is over northern Central America along 86W/87W N of 09N. The wave, combined with the monsoon trough, is generating some shower and thunderstorm activity over parts of Central America. A second tropical wave is along 97W north of 09N moving west at 10 to 15 kt, with minimal convection associated with the wave. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends across Panama and Costa Rica to 11N90W to 10N100W to 12N110W to 11N118W. The ITCZ continues from 11N118W to 09N130W to 07N140W. Scattered moderate isolated strong convection is from 06N to 11N between 89W and 93W, and from 06N to 10N between 120W and 134W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Visible satellite imagery continues to show the remnant low of Dora spinning near 20.5N115W, with a central pressure of 1010 mb. A well defined swirl of low clouds is associated with this system. Winds of 20-25 kt are still noted within 60 nm of the center, with seas to 8 ft. It will continue to weaken tonight, then dissipate on Thursday. Gentle to moderate winds are noted over the remaining waters west of Baja California, with light to gentle winds prevailing elsewhere, with the exception of moderate to locally fresh southerly winds across the northern Gulf of California. Latest scatterometer data confirmed the presence of these winds, forecast to persist through Thursday night. Similar wind speeds are expected again across the northern Gulf of California Saturday night through Monday as the pressure gradient tightens across the area between a ridge to the west and a trough over inland Mexico. Seas are 3-4 ft in the northern Gulf of California, and also near the entrance of the Gulf, with seas of 1-3 ft elsewhere. Seas of 4-6 ft are observed across the offshore forecast waters west of Baja California, outside the influence of the remnant low of Dora. Seas of 4-5 ft are expected west of Baja California and between Los Cabos and Manzanillo on Thursday. On this day, seas will increase to 6-7 ft in long period SW swell across forecast zones PMZ025 (States of Michoacan and Guerrero to 250 nm offshore) and PMZ027 (States of Oaxaca and Chiapas, including the Gulf of Tehuantepec). OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gentle to moderate SW to W winds are expected across most of the region, except for southerly winds between Ecuador and the Galapagos Islands. Cross equatorial SW swell continues to propagate across the region with seas of 8 to 9 ft. Seas of 6-7 ft will dominate most of the forecast waters W of 80W late on Thursday. Expect fresh to locally strong winds and building seas to 8 ft across the Gulf of Papagayo and downwind to 89W Thursday night through late Friday morning. REMAINDER OF THE AREA... A ridge dominates the waters N of 15N W of 120W, producing mainly light to gentle winds and seas generally under 6 ft. As the remnant low of Dora dissipates late Thursday, the ridge will build farther east, reaching again the Revillagigedo Islands. Cross equatorial long period SW swell will continue to propagate into the southern waters, building seas to 8-10 ft mainly east of 125W south of 08N into Thursday. Seas of 6-7 ft will reach much of the coast of Central America and SW Mexico by late Thursday. On Saturday, northerly swell will reach the north waters buiding seas to 8 ft, mainly across the area north of 27N between 120W and 127W. Looking ahead, a broad area of low pressure is expected to form this weekend a few hundred miles south of the southern coast of Mexico. However, environmental conditions have become less conducive for much additional development while the system moves west-northwestward early next week. $$ GR