000 AXPZ20 KNHC 070251 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 104 UTC Sat Oct 7 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 0230 UTC. ...GALE WARNING... Animated visible satellite imagery showed winds close to the gale force wind threshold continuing over the offshore zones west of Costa Rica and south of Nicaragua, El Salvador and Guatemala. Corresponding sea heights in this area are ranging between 14 and 16 feet. The wind speeds have peaked and are forecast to diminish to less than gale force by around sunrise on Saturday morning. Please read the High Seas Forecast, MIAHSFEP2/FZPN03 KNHC, for more details. ..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N75W to 08N80W to 12N86W to low pres 1007 mb centered near 13N93W to 16N99W to low pres 1007 mb centered near 17N110W to 13N111W to 09N125W to low pres 1011 mb centered near 13N137W to 11N140W. No significant convection is currently associated with the monsoon trough. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... The broad cyclonic circulation constituting a Central American Gyre is still maintaining an atypical NW to N gap wind event over the Gulf of Tehuantepec. The gap winds over the Gulf of Tehuantepec have begun to diminish as the Central American Gyre weakens slowly and lifts toward the NW. Wind speeds over the Gulf of Tehuantepec will fall to less than advisory levels by Saturday afternoon. The pressure gradient between a low pressure trough along the Sierra Madre Occidental of Mexico and high pressure ridging from 32N131W to near the Revillagigedo Islands will generally support gentle to moderate N to NW winds along the Pacific coast of Baja through Sat night. The sea heights during this time will range from 5 to 7 feet. A fresh round of NW swell will cause seas to build above 8 ft N of 29N on Sunday morning and N of 21N by Tuesday evening. Seas could peak near 12 ft near 30N124W on Monday evening. Winds over the Gulf of California N of 30 N will become locally strong in response to troughing over the Baja Peninsula and building high pressure to the NW. Strong winds could cover the Gulf N of 30N on Monday night in response to building high pressure over the great Basin of the United States. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Convection over the offshore zones from El Salvador to Guatemala has rapidly diminished as the Central American Gyre continues lifting NW. Recent satellite imagery showed winds close to the gale force wind threshold continuing over the offshore zones west of Costa Rica and south of Nicaragua, El Salvador and Guatemala from 10.5N to 11.5N between 87.5W and 90W. Corresponding sea heights in this area are ranging between 14 and 16 feet. The wind speeds have just peaked and are forecast to diminish to less than gale force by sunrise on Saturday morning. Long period cross-equatorial SW swell are maintaining sea heights ranging from 8 to 12 feet in the waters north of 06N from Costa Rica to Guatemala. These seas have begun to subside as well. The large swell are still high enough to create dangerous breaking surf along the coast in these areas. The monsoonal flow is beginning to abate and rainfall over Central America is tapering off. Runoff from the excessive heavy rains that have already fallen could still produce more flash flooding and mudslides. REMAINDER OF THE AREA... Gentle to moderate winds prevail to the north of the monsoon trough to 20N, and to the west of 125W. A weakening stationary front crosses the NW forecast waters from 30N139W to 26N140W. Sea heights of 8 to 9 ft are present near and to the west of the front. The front is forecast to dissipate tonight. Sea heights in this area are forecast to subside by late Saturday morning. Long period SW swell are maintaining sea heights of 8 to 12 feet in the discussion area generally from 06N to 16N east of 117W. The long period swell have already begun to decay. Sea heights in this area will subside to less than 8 ft by Sunday morning. $$ CAM