000 AXPZ20 KNHC 150305 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 202 UTC Sun Dec 15 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 0000 UTC surface analysis and satellite imagery through 0300 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N84W to 06N105W 1010 mb low pressure near 06N110W. ITCZ continues from 06N110W to 1010 mb low pressure near 12N125W, to another low near 12N137W then beyond 12N140W. Scattered moderate convection is noted from 11N to 13N between 132W and 136W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... High pressure building off the coast of California will tighten the pressure gradient and strengthen winds over the waters off Baja California Norte tonight into Sun. The high pressure will weaken through early next week, and winds will diminish over this area. Long period NW swell continues to propagate across the waters off Baja California. Seas of 10 to 12 ft will prevail over the waters off Baja California Norte. Seas in excess of 8 ft will continue across the waters N of the Revillagigedo Islands. Seas will start to subside early next week, and fall below 8 ft Tue. A fresh set of NW swell will propagate into the waters off Baja California Norte Wed night. High pressure building over the Great Basin north of the area will support fresh to strong NW winds across the Gulf of California late Mon through Tue night. Looking ahead in the Gulf of Tehuantepec, a strong cold front will move into the northwest Gulf of Mexico Mon night, shift southward across the western Gulf of Mexico, reaching the Bay of Campeche 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, and seas building in excess of 20 ft on Wed. 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 through the forecast period. 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... Earlier scatterometer satellite data shows persistent fresh to strong trade winds mainly from 10N to 18N between 120W and 140W. This is in an area between two weak low pressure systems near the ITCZ and higher pressure over the subtropics north of the area. The strongest winds are within 120 nm north of each of the low pressure areas, centered near 12N125W and 12N137W respectively. The low pressures near 12N137W owes its existence in part to a persistent mid to upper trough centered near 16N135W. Concurrent altimeter data showed seas of 8 to 12 ft north of roughly 05N and west of 115W, attributable to a component of long period NW swell, mixed with shorter period NE swell and wind waves in the area of fresh to strong trades. By Sun the mid to upper level trough lifts out and low pressure areas weaken, just as the high pressure north of the area shifts eastward ahead of a cold front approaching the area from the northwest. This will allow the trade winds to diminish slightly. The seas will subside as well as the current swell gradually decays. Looking ahead to mid week, the front will sweep southeast over the waters north of 15N from early next week through the middle of next week. Another round of large, long-period NW swell will accompany the front across most of this region. $$ Christensen