000 AXPZ20 KNHC 161500 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1245 UTC Mon Dec 16 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: a strong cold front will move across the western Gulf of Mexico through Tue. High pressure will build southward across the Sierra Madre Oriental in the wake of the front. The pressure gradient between this building high pressure, and the equatorial trough in the eastern north Pacific will usher in the next gale force gap wind event Tue night. This will be a strong gap wind event, with wind speeds possibly reaching minimal storm force Wed night. Seas will build in excess of 20 ft during this event. Gale conditions are expected to continue through the weekend. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 08N78W to 07N87W. The ITCZ continues from 07N87W to 08N99W to 06N117W to 08N140W. Scattered moderate convection is noted from 06N to 10N between 102W and 107W. Scattered moderate isolated strong convection was noted from 06N to 10N between 110W and 116W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the special features section for details on a gap wind event with winds possibly reaching storm force by early Thu. A ridge extends from high pressure centered near 35N127W to near the Revillagigedo Islands. The pressure gradient between this ridge and a surface trough across the Gulf of California is supporting moderate to fresh winds off the coast of Baja California Norte. Northerly swell continues to propagate across the forecast area, with seas near 11 ft off the coast of Baja California Norte. Seas greater than 8 ft are covering the offshore waters W of 105W. The area of high pressure will weaken Tue and will loosen the pressure gradient, diminishing winds off most of Baja California offshores. High pressure building over the Great Basin region will support fresh to near gale force NW winds across the Gulf of California tonight through early Wed. Strong winds will funnel through the mountain passages of Baja California Norte into the Sebastian Vizcaino Bay tonight through Tue night. The NW swell will slowly subside, and seas will fall below 8 ft by Tue. A fresh set of NW swell will propagate into the waters off Baja California Norte Wed evening and propagate SE to near the Revillagigedo Islands through the upcoming weekend. Seas will build to near 11 ft off Baja California Norte with this new set of NW swell. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate to fresh winds are expected across the Gulf of Papagayo, increasing to fresh to strong Wed, and continuing through the upcoming weekend. Elsewhere, gentle to moderate south to southwest monsoon flow will persist across the offshore waters of Costa Rica, Panama, Colombia, and Ecuador, while light to gentle flow will dominate across the Gulf of Panama. REMAINDER OF THE AREA... High pressure of 1027 mb is centered near 35N127W. The pressure gradient between this area of high pressure and lower pressure in the vicinity of the ITCZ is supporting moderate to fresh trade winds N of the ITCZ to near 25N and W of 120W. Subsiding NW swell continues across the forecast waters. Seas 8 ft or greater cover much of the waters N of 07N and W of 105W. The NW swell will continue to gradually subside over the next couple of days, and areal coverage of seas 8 ft or greater will decrease. A cold front will move from the north central Pacific into the region by this afternoon, reaching from 30N125W to 26N133W by late Tue, before starting to weaken from near 31N117W to near 25N124W by late Wed. While the front will initially weaken the subtropical ridge as it moves into the area, high pressure building behind the front will allow trade winds to increase west of 130W by mid week. A new round of long-period NW swell in excess of 8 ft will accompany the front with seas building to 12 ft N of 25N W of 125W. $$ AL