903 AXPZ20 KNHC 132116 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2116 UTC Thu Jun 13 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. ...TROPICAL WAVES... A tropical wave is near 89W extending from El Salvador southward to near 06N, moving west at around 15 kt. Scattered moderate convection is noted from 05N to 08N between 82W and 89W, and north of 11N between 89W and 93W. A tropical wave is near 105W moving west at around 15 kt. Scattered moderate and isolated strong convection is noted within 180 nm east of the wave from 09N to 14N. A tropical wave is near 129W moving west at around 10 kt. Only isolated to scattered showers are noted with this wave. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from Costa Rica near 10N85W to 12N95W to 10N103W to 11N110W to 09N119W. The ITCZ extends from 09N119W to 07N127W, then resumes from 06N130W to 05N140W. Scattered moderate convection is occurring within 180 nm of the monsoon trough between 95W and 102W, and within 120 nm north of the monsoon trough between 108W and 119W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... The pressure gradient between a high pressure ridge west of Baja California and a low pressure trough over the Gulf of California maintains gentle to moderate NW flow offshore. A partial 17Z scatterometer pass showed moderate NW winds prevailing off Baja California Norte and SW of Punta Eugenia. Earlier altimeter data indicated seas were running 4-6 ft in this region. Winds and seas off the Baja California coast will remain relatively unchanged through the middle of next week as the ridge persists offshore. Winds may pulse to fresh speeds during the evening hours near the coast north of Cabo San Lazaro through Sat night. Strong northerly gap winds will develop this evening over the Gulf of Tehuantepec and continue into Fri night, as the pressure gradient tightens in response to a high pressure center analyzed over eastern Mexico. Fresh to locally strong SW to W gap winds are expected over the northern Gulf of California tonight. A surface trough along the Baja California peninsula will support fresh SE flow across the central and southern Gulf of California through Fri. Winds in this region are expected to diminish to gentle to moderate speeds by Fri evening as the trough weakens. A new set of long period SW swell will reach the Mexican offshore waters by Sat, but seas are expected to remain less than 8 ft through early next week. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Nocturnal offshore flow will pulse to fresh to strong speeds in the Gulf of Papagayo through the middle of next week. The strongest winds will occur during the late night and early morning hours with the nocturnal drainage flow. Seas will peak near 8 ft downstream of the Gulf of Papagayo with each pulsing event. Elsewhere, gentle to moderate S to SW flow with scattered showers and thunderstorms will prevail south of the monsoon trough for the next several days. Otherwise, fairly tranquil conditions will persist off Central America under a weak pressure pattern. A new set of long period SW swell will reach the southern waters late Fri night. Seas will build to 8 ft between Ecuador and the Galapagos Islands over the weekend, then subside early next week. REMAINDER OF THE AREA... A ridge extends southeastward from 1021 mb high pressure analyzed near 27N133W toward the Revillagigedo Islands. The pressure gradient between the ridge and a weak trough west of the area is producing a small area of fresh winds, with seas to 8 ft near 15N139W per 15Z altimeter data. Generally moderate to locally fresh trades will persist through the weekend, while seas are expected to subside below 8 ft by Sat. Looking ahead, winds and seas may increase early next week as high pressure strengthens north of the region. A new set of long period SW swell will reach the far SW waters tonight, then propagate NE across the region through the weekend. Seas will build to 8 ft or greater south of the Equator by Fri and persist through the weekend. A reinforcing set of SW swell is expected to reach the far SW waters by Mon night, resulting in 8-10 ft seas south of the Equator and west of 105W through early next week. $$ Reinhart