000 AXPZ20 KNHC 102155 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2117 UTC Tue Dec 10 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. ...SPECIAL FEATURES... The next gale force gap wind event is expected to commence across the Gulf of Tehuantepec Wed morning and continue until around midday Thu, as a strong cold front crosses the Gulf of Mexico. Winds over Tehuantepec will abruptly increase to gale force during the morning and are forecasted to peak between 40 and 45 kt Wed afternoon or evening. Expect peak seas Wed evening between 16 and 17 ft downstream of the Gulf. Strong winds Thu evening will gradually taper to fresh by Sat morning as nocturnal drainage flow maintains strong winds over the near shore waters. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 08N78W to 10N110W to 1010 mb low pressure near 07N117W to 08N125W. The intertropical convergence zone continues from 08N125W to beyond 09N140W. Scattered moderate and isolated strong convection is noted from 08N to 10N between 110W and 115W, and from 08N to 10N between 135W and 140W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... 1026 mb high pressure centered near 30N125W is maintaining gentle to moderate northerly flow off the coast of Baja California, depicted well in an earlier scatterometer pass. The scatterometer pass also indicated moderate to gentle winds through the Gulf of California except for south of 25N where fresh N to NE winds were noted. A couple of ship observations corroborated this off Los Cabos as well. A concurrent altimeter pass showed seas of 6 to 8 ft between Baja California Sur and the Revillagigedo Islands, mainly in NW swell. This will diminish through mid week, but seas will build by late Fri as a new round of NW swell moves into the area off Baja California Sur. Elsewhere off southern Mexico outside of the Gulf of Tehuantepec, gentle to moderate flow will persist through mid week. Building high pressure west of the area will allow increasing winds later in the week, especially off Cabo Corrientes. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Fresh NE to E winds will pulse to strong over the Gulf of Papagayo tonight and Wed night. The longest lived winds are expected Wed night through Thu with seas peaking around 8 ft. Elsewhere, gentle to moderate S to SW monsoon flow will persist across the offshore waters of Costa Rica, Panama, Colombia, and Ecuador through Sat night. REMAINDER OF THE AREA... A 1026 mb high pressure center located near 30N125W is supporting tradewinds of 15 to 20 kt across the waters south of 25N and west of 115W. This high pressure will shift slightly south through Tue night and promote a freshening trade wind flow across the region from 22N to the ITCZ and W of 110W. NW swell propagating across the Baja offshore waters will also move into this area overnight to produce seas of 8 to 10 ft. The NW swell will continue to gradually decay through tonight. However, increasing trade winds on the south side of the building high will compensate and keep seas around 8 ft in this area through mid week. A frontal boundary remains stalled over the NW corner of the discussion area near 30N140W. A much stronger frontal system to the NW of this front will also approach this same area and stall Thu. Large NW swell will move out ahead of this next front and propagate into the regional waters beginning early Wed, and cause seas in this area to build through Fri. Seas will eventually peak between 12 and 14 ft Thu night and Fri morning in the far NW portions of the area. This swell will combine with wind waves generated by the fresh to strong trade winds S of 20N Wed night through Thu night. A surface trough propagating W will further tighten the pressure gradient in this area and cause seas to build to between 10 and 14 ft from 10N to 20N W of 130W Fri night and Sat. $$ Christensen