000 AXPZ20 KNHC 191600 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Wed Oct 19 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...SPECIAL FEATURE... A gale warning has been issued for the Gulf of Tehuantepec with the morning forecast package. This gap wind event will be associated with a cold front moving across the western Gulf of Mexico Thursday night through Friday night. Northerly winds at 25-30 kt will begin to surge into the Tehuantepec area late tonight into Thursday morning. Winds are forecast to further increase to minimal gale force by Friday morning with seas building to 9-12 ft by Friday afternoon. This gap wind event is expected to persist during the upcoming weekend. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 14N110W to 1007 mb low pres near 13N113.5W to 10.5N118W to 13N130W to a second low pres of 1008 MB near 12.5N138W to 12N140W. Scattered moderate convection is noted from 10N to 13N between 105W and 111W...and from 10N to 12N between 115W AND 120W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A 1026 mb high pres located N of area near 35N130W extends a ridge SE to near the Revillagigedo Islands at 19N112W. The pressure gradient between the ridge and a trough over western Mexico is resulting in fresh to strong Northerly winds across the waters N of 28N between 120W and 125W with seas of 9 to 11 ft based on an altimeter pass. Moderate to fresh NW to N winds prevail W of Baja California. The combination of these winds and long period NW swell support seas of 8 to 10 ft W of Baja California Norte, and 6 to 8 ft seas W of Baja California Sur. The high pres center will shift SW in about 24 hours and the ridge will weaken through Friday as a cold front approaches the region. The front is expected to stall and weaken near 30N140W by late Friday. The long period swell will subside during the next few days. A new batch of swell of 8 to 9 ft is forecast to arrive offshore Baja California Norte over the weekend. Winds are expected to increase across the northern part of the Gulf of California tonight as high pressure builds across the Great Basin. By Thursday morning...expect NW winds of 20-25 kt and seas of 5-6 ft N of 30N, and NW winds of 15-20 kt with seas of 4-5 ft across the central waters, mainly N of 26N. Moderate to fresh winds are forecast to blow across the Gulf of California or Sea of Cortez by Thursday evening into early Friday morning. Farther south...a gap wind event, reaching minimal gale force, is expected across the Gulf of Tehuantepec. Please, see Special Features section for details. A cluster of moderate to isolated strong convection is N of 13N between 93.5W and 96W, including the Gulf of Tehuantepec. Winds and seas could be higher near thunderstorms. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gentle to moderate southwesterly flow is noted S of 10S, with the exception of moderate to fresh SW winds from 06N-11N between 90W and 97W based on the most recent Ascat pass. Mainly light to gentle winds continue N of 10N. Seas generally range between 5 and 8 ft. A mix of NW and SW swell predominate W of 90W, while SW swell predominate E of 90W. These conditions are forecast to prevail over the next few days. A cluster of moderate to isolated strong convection is also noted from 10N-13.5N between 88W-91W. Winds and seas could be higher near thunderstorms. REMAINDER OF THE AREA... A pair of low pressure systems are observed along the monsoon trough. From E to W, one is near near 13N113.5W. A cluster of moderate convection is within about 60 NM E quadrant of low center. Scattered moderate convection is elsewhere from 11n-13.5N between 112W-115W. An area of fresh to locally strong SW winds to the S of the low center will move in tandem with this feature. Although upper-level winds are only marginally conducive, some development of this system is possible during the next several days while the disturbance drifts northward or northwestward. The second low pres is near 12.5N138W. This system continues to produce disorganized showers and thunderstorms. Satellite imagery shows a cluster of moderate to isolated strong convection E of the low center covering the waters from 11N-13.5N between 134W-138W. Environmental conditions are forecast to become less conducive for development during the next day or so, and significant development of this system appears unlikely while it moves westward at about 10 kt. The pres gradient between the ridge to the N and this low pres is generating an area of fresh to strong winds from 12N to 20N W of 130W with seas of 9-12 ft based on altimeter data. this low is forecast to move west of area in about 48 hours. As a result, winds and seas will diminish across the west-central waters. Currently, seas of 8-11 ft, primarily in NW swell, dominate the forecast region NW of a line from 30N116W to 23N113W to 13N125W to 10N140W. Seas will gradually subside over the next couple of days, but another set of long period NW swell will reach the NW corner by late Friday. Elsewhere, the combination of SW winds S of the monsoon trough and NW swell will support seas of 8-10 ft within an area bounded by a line from 15N110W to 10N94W to 03N105W to 10N121W to 15N110W. In addition, cross-equatorial SW swell of 8-9 ft are propagating NE between 92W and 112W affecting the waters S of the Equator. Seas in this area will subside below 8 ft late Thursday. $$ GR