000 AXPZ20 KNHC 291526 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1356 UTC Sat Jun 29 2019 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: High pressure over the NW Gulf of Mexico combined with a tropical wave passing south of the Tehuantepec region is producing minimal N to NE gale conditions over the Gulf of Tehuantepec. Winds are expected to diminish below gale force today. Fresh to strong northerly winds will continue to blow across the Tehuantepec area through Mon morning. Please see the latest High Seas Forecast issued by the National Hurricane Center under AWIPS/WMO headers FZPN03 KNHC/HSFEP2 or at website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for details. A tropical wave is moving westward through the tropical eastern north Pacific, with axis near 106/107W. A Madden Julian Oscillation is currently propagating across the eastern north Pacific forecast waters. The MJO is providing favorable large scale lift and active convection across the area, as noted in the monsoon trough/ITCZ section below. This favorable large scale environment will be conducive for continued active weather, with the tropical wave providing a focus for a potential tropical cyclone to develop late this weekend or early next week. There is currently a high chance that a tropical depression will develop along this tropical wave during the next 48 hours. ...TROPICAL WAVES... A tropical wave is near 95W, moving W around 10 kt. Convection is limited near the wave axis. A tropical wave is along 106W/107W moving W around 10 kt. Scattered moderate to isolated strong convection is noted from 06N to 11N between 101W and 108W. See Special Features section for more details. The axis of a tropical wave is near 139W/140W from 01N to 19N, moving W around 10 kt. Scattered moderate isolated strong convection is noted from 07N to 11N between 135W and 140W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 08N83W to 10N95W to low pres near 08N105W to 08N115W. The ITCZ extends from 08N115W TO 09N137W. A Madden Julian Oscillation that is propagating across the region is helping for an active monsoon trough. In addition to convection associated with the waves, scattered moderate to isolated strong convection is observed within 180 nm S of the trough between 85W and 88W. Similar convection is also noted from 06N to 11N between 113W and 121W, and from 08N to 11N between 130W and 135W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section for more details about the current Gulf of Tehuantepec Gale Warning. Elsewhere relatively tranquil marine conditions are expected for the next several days over the Gulf of California, and the offshore waters of Baja California. Late afternoon and evening winds along the Pacific coast of the Baja Peninsula will reach around 20 kt for the next few days, but otherwise typical early summer conditions will prevail under modest high pressure. Long period SW swell will reach the entire W coast of Baja California by Mon, with seas in the 6 to 8 ft range affecting the offshore forecast waters Mon through Wed. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Winds across the Gulf of Papagayo will strengthen late Sun night, then pulse each night through Wed night. Elsewhere moderate offshore winds will prevail north of the monsoon trough, with moderate S-SW winds south of the monsoon trough the next few days. S to SW long-period swell will propagate north of the equator on Sun, increasing offshore wave heights to near 7 ft, and then further to 8-9 ft by late Mon. REMAINDER OF THE AREA... At 29/1500 UTC, Alvin is downgraded to a remnant low centered near 20.7N 102.5W moving NW at 7 kt. Estimated minimum central pressure is 1007 mb. The combination of shear and a more stable environment had helped to weaken the system. Maximum sustained wind speed is 25 kt with gusts to 35 kt. A very well defined swirl of low clouds is noted in visible satellite imagery associated with Alvin. The remnant low will continue to move west-northwestward to northwestward until it dissipates in about 18 to 24 hours. At 1500 UTC, the last advisory was issued by the National Hurricane Center on this system. Outside of Alvin, a broad ridge dominates the northern forecast waters. Moderate trades prevail south of this ridge and west of 125W, with seas in the 5 to 8 ft range in mixed swell. Little change in the overall pattern is expected for several more days. Trades will strengthen slightly in the W central waters this weekend into early next week, with seas building to between 8 and 10 ft. $$ GR