000 AXPZ20 KNHC 230228 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0228 UTC Sun Oct 22 2017 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 0215 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Storm Warning: High pressure building southward across eastern Mexico in the wake of a cold front will help tighten the pressure gradient over the area. In response to the tighter pressure gradient, fresh to strong northerly flow will funnel through the Chivela pass into the Gulf of Tehuantepec starting tonight. Winds will further increase to gale force by early Monday morning as the cold front moves through the western Gulf of Mexico. Model guidance has been consistency indicating 50 kt winds at 10-m with stronger winds aloft. With the due northerly trajectory N of the area in the SW Gulf of Mexico, and the relatively warm waters in the Gulf of Tehuantepec area the ingredients are present for ample mixing. Thus, the gale warning has been upgraded to a storm warning at 48 hours. Seas will easily build to up to 17 to 20 ft by midweek, if not higher. The storm force winds should diminish Wednesday evening, with gale force winds then persisting into early Thursday morning before diminishing to fresh to strong for the remainder of Thursday, then to 20 kt or less by Friday. ...TROPICAL WAVES... The axis of a tropical wave the was in the vicinity of 102W/103W has become diffuse and difficult to track, with any leftover convection having become widely isolated. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N84W to 08N103W to 09N120W. The intertropical convergence zone axis extends from 09N120W to 07N130W to 08N140W. Scattered moderate and isolated strong convection is from 10N to 12N between 112W and 124W, and also from 06N to 11N W of 132W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the special features section above for information on a developing storm event in the Gulf of Tehuantepec. Recent ship observations in the Baja California offshore waters indicate that seas continue to subside, currently in the range of 7 to 10 ft. NW flow has also diminished to moderate. The seas will continue to gradually subside to less than 8 ft off Baja California Sur and within 200 nm of the coast of Baja California Norte through late Monday. Looking ahead, gentle breezes associated with a weak pressure pattern along with slight to moderate seas will prevail by late week. High pressure over the Great Basin region of the western United States has strengthened winds over the Gulf of California. Fresh to strong winds are expected to continue through Tuesday, before diminishing as the area of high pressure shifts eastward and the pressure gradient weakens. Winds will be the strongest tonight through Monday when seas will peak around 8 ft. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gentle to moderate winds will prevail over the forecast area through early Monday, increasing to moderate to fresh S of the monsoon trough by Monday afternoon. NW swell originating from the Gulf of Tehuantepec will propagate into the offshore waters of Guatemala and El Salvador by the middle of the week. REMAINDER OF THE AREA... A set of large NW swell with seas near 11 ft will continue to propagate SE while gradually subsiding. A new reinforcing set of NW swell will arrive at 30N140W on Monday, however peak seas will be less than the previous set. Seas will then subside, to less than 8 ft, by mid week with tranquil marine conditions expected by the end of the week. $$ Lewitsky