000 AXPZ20 KNHC 142145 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2020 UTC Sat Dec 14 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N83W to 07N110W. A segment of the ITCZ continues from 07N110W to 10N120W. Another segment extends from 11N125W to 11N132W, and another from 11N135W to 09N140W. Scattered moderate convection was noted from 07N to 09N between 83W and 86W. Scattered moderate isolated strong convection was noted from 11N to 14N between 120W and 122W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A weak cold front is moving into the northern portion of Baja California Norte this afternoon, and will dissipate this evening. High pressure building in the wake of the front off the coast of California will tighten the pressure gradient and strengthen winds over the waters off Baja California Norte tonight into Sun. The area of high pressure will weaken, and winds will diminish over this area early next week. 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 falling 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 Mon night 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... The latest 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 12N135W and 11N125W respectively. The low pressures owe their existence in part to a persistent mid to upper trough centered near 16N135W. Concurrent altimeter data shows 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