000 AXPZ20 KNHC 062202 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2023 UTC Fri Oct 6 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...GALE WARNING... Animated visible satellite imagery shows 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 16 and 18 feet. The wind speeds are peaking 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 12N86W to 17N100W to low pres 1007 mb centered near 14N92.5W to low pres 1008 mb centered near 17N109W to 16N112W to 10N116W to 09N126W to low pres 1010 mb centered near 12N136W to beyond 10N140W. Scattered moderate convection is observed from 10N to 14N between 91W and 196W, from 08N to 11N between 101W and 106W and from 10N to 13N between 112W and 116W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... The broad cyclonic circulation constituting a Central American Gyre is 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. 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 begun to diminish as the Central American Gyre lifts slowly NW. Animated visible satellite imagery shows 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 11N to 12.5N east of 87.5W. Corresponding sea heights in this area are ranging between 16 and 18 feet. The wind speeds are peaking and are forecast to diminish to less than gale force by around sunrise on Saturday morning. Long period cross-equatorial SW swell are generating sea heights ranging from 8 to 12 feet in the waters north of 05N from Panama to Costa Rica. These seas will start to subside tonight as well. The large swell will create dangerous breaking surf along the coast in these areas. The monsoonal flow will continue to support copious rainfall from northern Costa Rica to Guatemala and SE Mexico into the weekend. It is possible that this rainfall will produce more flash flooding and mudslides. REMAINDER OF THE AREA... Gentle to moderate winds prevail to the north of the monsoon trough to 21N, and to the west of 123W. A weakening stationary front over the NW forecast waters passes 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. The sea heights in this area are forecast to subside by late Saturday morning. Long period SW swell are maintaining sea heights greater than 8 feet in the discussion area generally from 05N to 18N east of 119W. The long period swell will decay gradually, and the sea heights that are in this area are expected to subside to less than 8 ft by Sunday morning. $$ CAM