000 AXPZ20 KNHC 270321 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 151 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 0000 UTC surface analysis and satellite imagery through 0300 UTC. ...SPECIAL FEATURE... A Gale Warning is in effect for the Gulf of Tehuantepec. The pressure difference between strong high pressure building southward along the eastern slopes of the Sierra Madre mountains in Mexico and lower pressure south of Mexico is supporting gale force winds in the 30-40 kt range over the Gulf of Tehuantepec. Seas are forecast to build to 10-14 ft in and downstream of the Gulf late tonight into early Tue morning. These marine conditions will likely persist through late Tue night. Winds are expected to diminish below gale force by Wed morning, and to 20 kt or less by Thu morning. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N85W to a 1010 mb low near 08N90W to a second 1010 mb low near 10N105W to a third 1010 mb low near 09N110W to another 1010 mb low near 09N119W to 07N123W. The ITCZ continues from 07N123W to 06N130W to beyond 08N140W. Scattered moderate isolated strong convection is noted N of 06N E of 80W to the coast of Colombia, and from 05N to 10N W of 134W. Similar convection is within about 75 nm N quadrant of low near 09N119W. ...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 tonight and Tue with seas of 3-5 ft. Then, 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 moves across the area. Light to gentle northwest to north winds along with seas of 5 to 7 in a NW swell are across the offshore waters west of the Baja California Peninsula. Marine guidance depicts that an extensive set of long-period NW swell associated with a cold front presently well northwest of the discussion area will reach the waters west of Baja California Norte beginning late Tue night into Wed morning and the southern tip of Baja California Sur by late Wed night into Thu. Building seas of 8-12 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 and become diffuse as it crosses into SW Mexico and near the coast of Chiapas. The volume of ash within this plume remains light and does not warrant an ashfall advisory at this time. Gulf of Papagayo: Moderate to at times fresh northeast winds will pulse across the Gulf each night through the end of the week. Elsewhere, the monsoon trough will meander between 08N and 10N during the rest of the week, with gentle to moderate northeast winds north of the trough, and gentle to moderate southwest winds to the south of the trough. Seas north and south of the trough will be in the range of 5 to 7 ft in cross-equatorial SW swell through at least Wed. REMAINDER OF THE AREA... A broad area of low pressure, analyzed along the monsoon trough near 10N105W or about several hundred miles southwest of Acapulco, Mexico, 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 northwestward by Tuesday, and then could turn northward or north- northeastward later this week. Showers and thunderstorms remain poorly organized in association with another area of low pressure located near 09N119W or about 1200 miles south-southwest of the southern tip of the Baja California peninsula. Strong upper-level winds are expected to prevent significant development of this system during the next couple of days while it remains nearly stationary. The pressure gradient between a 1023 mb high center analyzed near 29N130W and lower pressure near the ITCZ supports an area of fresh to strong NE winds over the waters from 09N to 16N W of 130W, and from 09N to 13N between 120W and 130W. This area of trades will shrink westward, and will cover mainly W of 130W over the next 12-24 hours. Large-long period NW swell associated with a strong cold front currently located northwest of the discussion area will propagate southeastward through the northern and central waters through Wed, with seas rapidly building to the range of 12 to 18 ft NW of a line from 30N128W to 16N140W by early Tue afternoon. The leading edge of the 8 ft seas is expected to reach the Revillagigedo Islands by early on Thu. $$ GR