000 AXPZ20 KNHC 061605 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...GALE WARNING... The latest surface observations show gale-force winds in the offshore zone of Nicaragua and NW Costa Rica. The sea heights range from 15 feet to 18 feet in that region. The wind speeds will reach a peak of 40 knots later this morning, and then they will diminish gradually, to less than gale-force, by Saturday morning around sunrise. Please read the High Seas Forecast, MIAHSFEP2/FZPN03 KNHC, for more details. ..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough passes through Honduras near 13N88W, to 17N100W, to a 1007 mb low pressure center that is near 17N108W, to 09N125W, to a 1009 mb low pressure center that is near 12N136W, beyond 10N140W. Convective precipitation: scattered to numerous strong within 120 nm to the south of the monsoon trough between 92W and 95W. Widely scattered moderate to isolated strong elsewhere within 90 nm to the north of the monsoon trough, and within 210 nm to the south of the monsoon trough, between 88W and 97W. Scattered moderate to isolated strong from 08N to 11N between 99W and 103W. Isolated moderate to locally strong within 120 nm to the south of the monsoon trough between 110W and 118W , and within 60 nm to the north of the monsoon trough between 113W and 117W. Isolated moderate to locally strong within 150 nm of the 1007 mb low pressure center that is near 17N108w, in the western quadrant. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... The broad cyclonic circulation, that is constituting a Central American Gyre, is causing an atypical NW to N gap wind event in the Gulf of Tehuantepec. The gap winds of the Gulf of Tehuantepec will diminish gradually, as the Central American Gyre weakens. The wind speeds will be at less than advisory levels by Saturday afternoon. The gradient that is between low pressure along the Baja California Peninsula and high pressure to the west of 120W will support gentle to moderate N to NW winds through early Sunday. The sea heights during that period will range from 5 to 7 feet. NW swell will support seas of 8 to 10 ft N of 25N and W of Baja through Tuesday morning. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Scattered to numerous strong rainshowers are in the offshore zones from El Salvador to Guatemala to Mexico. This precipitation is related to the Central American Gyre. The latest wind observations that are in the offshore zone of Nicaragua and NW Costa Rica gale-force winds, and sea heights that are reaching 18 feet. The wind speeds may reach 40 knots during the afternoon and evening of today. The wind speeds are forecast to diminish to less than gale-force by tonight/early on Saturday. Long period cross-equatorial SW swell is generating sea heights ranging from 8 to 11 feet in the waters from Panama to Costa Rica, which will start to subside tonight. The large seas will create dangerous breaking surf along the coast in these areas. The monsoonal flow will continue to support copious amounts of rain between northern Costa Rica and Guatemala and Mexico into the weekend. It is possible that this extremely heavy rainfall may produce life-threatening flash floods 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 weak cold front that is in the NW forecast waters passes through 30N138W to 27N140W. Sea heights of 8 to 9 ft are to the west of the front. The front is forecast to dissipate tonight. The sea heights are forecast to subside by late Saturday morning. Long period SW swell is maintaining sea heights that are greater than 8 feet in the entire discussion area from 06N to 18N between 79W and 117W. 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. $$ mt