000 AXPZ20 KNHC 070959 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 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 0600 UTC surface analysis and satellite imagery through 0830 UTC. ..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N74.5W TO 08.5N79W TO 16N97W TO 18N107W TO low pres 1007 MB near 11.5N110.5W TO 10N121 TO low pres 1010 MB near 12N136.5W TO 11.5N140W. Scattered moderate isolated strong convection is noted near the trough within 90 nm of the Mexican coast from 96W to 101.5W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... The broad cyclonic circulation constituting a Central American Gyre that has affected the region for the past few days has begun to shift northward across the southern Gulf of Mexico, but is still producing an atypical NW to N gap wind event over the Gulf of Tehuantepec. Overnight ASCAT data showed these northerly gaps winds diminishing to around 15 kt, and are expected to weaken further through around noon today, before winds become light from the south during the afternoon. Elsewhere between Tehuantepec and Cabo Corrientes, light to gently W to SW winds prevail, as the effects of the gyre gradually diminish. Seas across this region are generally 7-9 ft in a mix of cross equatorial swell and SW wind wave generated from the recent large swath of westerly monsoonal winds. Little change in winds is expected here over the weekend, while seas subside modestly to 6-7 ft. The pressure gradient between a low pressure trough along the Sierra Madre Occidentales of Mexico and high pressure ridging from the NE Pacific to just offshore of Baja California Sur will generally support gentle to moderate N to NW winds along the Pacific coast of Baja through tonight. Seas during this time will range from 5 to 7 feet. Winds will weaken slightly on Sunday as a trough of low pressure develop N to S along the length of the Baja Peninsula. A fresh round of NW swell will build seas to above 8 ft N of 26N on Sunday morning and N of 21N by Tuesday evening. Seas could peak near 12 ft near 30N124W on Monday evening. Moderate northwesterly winds across N through central portions of the Gulf of California overnight are building seas 4 to 6 ft, with little change expected through this afternoon before winds and seas diminish tonight. As the trough develops across Baja California Sunday, southerly winds will develop inside the Gulf of California and freshen throughout the day. Global models suggest that strong northerly winds could spread across N portions of the Gulf on Monday evening or 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 diminished significantly during the past 24 hours as the Central American Gyre continues lifting northward across the Yucatan Peninsula and the Gulf of Mexico. Strong SW to W monsoonal winds induced by the gyre from Guatemala to Nicaragua have diminished overnight, and are generally 10-20 kt. Seas remain high, however, and are 8-13 ft in mixed SW cross equatorial swell and SW wind swell, with highest seas offshore of Nicaragua. This mix of swell will continue to generate large and dangerous surf along the area coasts and reefs throughout the weekend as seas gradually subside. As the monsoonal flow continues to abate, associated tropical moisture and rainfall over Central America will continue to taper off. Runoff from the excessive heavy rains of recent day could still produce 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 is just W of the far NW corner of the discussion area, where winds N of 28N and W of 139W are SE at 20-25 kt, and seas 8-10 ft. Seas in this area will subside today as the front drifts W and away from the area. Long period SW swell is maintaining sea of 8 to 10 feet in the discussion area generally from 06N to 16N east of 117W. Seas in this area will subside to less than 8 ft by late Sunday. $$ Stripling