000 AXPZ20 KNHC 092138 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Wed Nov 9 2016 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. ...SPECIAL FEATURES... A gale warning is in effect for the Gulf of Tehuantepec. Fresh to strong northerly winds, in the 20-30 kt range, are forecast to surge into the Tehuantepec area over the next several days as a ridge builds and persists across eastern Mexico and the western Gulf of Mexico. Winds are expected to further increase to minimal gale force, with the assistance of the nocturnal drainage flow, tonight through Thursday night. Seas are forecast to build to 11 ft in and downstream of the Gulf. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N85W to 08N90W to 1009 mb low near 11N107.5W to 11N115W, then resumes at 15N117W to a 1011 mb low near 14N122W to 12N126W. The ITCZ axis extends from 12N126W to 10N135W to 09N140W. Scattered moderate convection can be found from 11N to 13N between 122W and 125W, from 10N to 13N between 125W and 130W, and from 11N to 13N between 134W and 136W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A gale warning is in effect for the Gulf of Tehuantepec. Please, see Special Features section for details. For the Gulf of California...moderate to fresh winds are noted across the northern Gulf of California based on scatterometer data, with mainly gentle to moderate winds elsewhere. High pressure building across the U.S. Great Basin and Rocky Mountains will support fresh to strong northwest winds over the northern Gulf this evening through late Thursday. Elsewhere...another set of long period NW swell is reaching the waters W of Baja California. Seas of 8-12 ft will dominate the offshore waters W of 112W by early Thursday morning. This swell event will reach the Revillagigedo Islands by late Thursday. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate to fresh winds are expected in the Gulf of Papagayo during the overnight and early morning hours through the weekend. Elsewhere, light to gentle winds will prevail over the waters north of 10N, with gentle to moderate mainly SW winds S of 10N. Seas of 4 to 6 ft will persist across the region through the end of the week in mixed NW and SW swell. REMAINDER OF THE AREA... A 1021 mb high pres located near 33N129W and extends a ridge to near the Revillagigedo Islands. The pressure gradient between the high and lower press in the vicinity of the ITCZ is resulting in a belt of moderate to fresh trade winds between the ITCZ and about 20N and W of 120W based on scatterometer data. A 1011 low pres near 14N122W is also helping to slightly increase the winds across this area. Another area of low pressure is analyzed near 11N107.5W or about 475 nm south-southwest of Manzanillo, Mexico. This system continues to produce a large area of disorganized showers and thunderstorms. Satellite imagery shows scattered moderate to isolated strong convection from 08.5N to 14.5N between 103W and 111W. Strong upper-level winds currently affecting this system are expected to increase during the next few days, and any development should be slow to occur while the low moves northwestward and then northward at 5 to 10 kt. Long period NW swell, with significant wave heights as high as 16 ft, will continue to propagate SE across the forecast waters over the next several days. The leading edge of this swell event, with wave periods between 20 to 21 seconds, will reach from Los Cabos to the Equator at 135W by tonight. Seas of 8-12 ft will dominate the waters NW of a line from 23N110W to the Equator at 133W on Thursday. Additional pulses of NW swell will reach the NW corner of the forecast region early on Friday as another cold front moves into the discussion area. These sets of large, long period NW swell are associated with powerful storm systems over the north central Pacific. $$ GR