000 AXPZ20 KNHC 270920 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Tue Nov 27 2018 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 0600 UTC surface analysis and satellite imagery through 0900 UTC. ...SPECIAL FEATURE... A gale sarning remains in effect for the Gulf of Tehuantepec. The pressure gradient between strong high pressure in eastern Mexico and lower pressures south of Tehuantepec is supporting 30- 40 kt northerly winds, as indicated from ASCAT pass at 0354 UTC. Max seas will build to 13-14 ft this morning. Gale conditions will persist through early Wed, then rapidly diminish Wed and Wed night across the region. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N84W to 08N92W to 11N102w to a 1010 mb low near 11N105W to 08N123W. The ITCZ continues from 08N123W to 07N130W to beyond 08N140W. Scattered moderate convection is noted within 60 nm of the trough axis between 87W and 120W. Scattered moderate isolated strong convection from 04N to 07N between 134W and 139W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of California: Moderate to fresh northerly winds are expected across the north and central Gulf of California today, with seas of 3-5 ft. Winds are expected to increase to 20-25 kt with seas of 5-7 ft across the northern Gulf Thu night and Fri as a cold front sweeps across the area. Marine guidance indicates that large long-period NW swell associated with a cold front approaching 30N140W will reach the waters W of Baja California Norte beginning late tonight, and the southern tip of Baja California by late Wed night. Building seas of 9-14 ft are forecast to propagate across the waters north of about 23N and W of 115W by early Thu morning. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Enhanced infrared imagery from GOES-E continues to show a plume of volcanic ash originating from the Fuego volcano in southern Guatemala. The plume is tracking in a west-northwest direction, becoming diffuse in SW Mexico near the coast of Chiapas. The anticipated volume of ash within this plume remains light and does not warrant an ashfall advisory at this time. Gulf of Papagayo: Fresh northeast winds will pulse across the Gulf each night through Saturday. Elsewhere, the monsoon trough will meander between 08N and 10N during the rest of the week, with gentle to moderate winds on either side of the trough, with 5 to 7 ft seas expected. REMAINDER OF THE AREA... A broad area of low pressure, embedded in the monsoon trough near 11N105W, continues to produce disorganized shower and thunderstorm activity. Environmental conditions are forecast to become conducive for some gradual development and a tropical depression could form during the next few days. The disturbance is currently moving slowly westward, but is forecast to turn northward later this week. The pressure gradient between a 1024 mb high centered near 29N133W and lower pressures near the ITCZ supports an area of fresh NE winds over the waters from 09N to 11N between 125W and 135W depicted in scatterometer data. This area of trades will shrink today, and its 8-10 ft seas will merge with the large NW swell event sweeping across the forecast waters during the next few days. Seas will rapidly build to 12 to 18 ft in northwestern waters later today. The leading edge of the 8 ft seas is expected to reach the Revillagigedo Islands by early on Thu. $$ Mundell