000 AXPZ20 KNHC 270905 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 639 UTC Wed Sep 27 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 09N76W to 10N82W to 16N91W to 1007 mb low pressure centered just SW of the Gulf of Tehuantepec near 15N96W, to 13N103W to 14N118W to 1008 mb low pressure centered near 13N122W to 11N129W to beyond 11N140W. Scattered moderate and isolated strong convection is observed from 11N to 15N between 117W and 123W. Scattered moderate convection is seen within 90 nm either side of a line from 13N87W to 06N93W, from 11N to 13N between 111W and 115W and along and up to 120 nm south of the trough axis between 123W and 130W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Remnant low pressure of Pilar is hovering just to the SE of Cabo San Lucas. The weak pressure gradient between the low and monsoon trough to the south and southeast is only generating light to gentle winds between the southern tip of Baja and the Gulf of Tehuantepec. The low may limp along today near Cabo San Lucas before it dissipates tonight. Low pressure south of the Gulf of Tehuantepec is producing fresh winds over the southern quadrant of the low, with associated active convection as noted in the monsoon trough section above. This area of low pressure is expected to persist south of the Gulf of Tehuantepec through late week. Elsewhere, a weak pressure pattern over the Mexican offshore waters north of 20N will promote gentle to moderate breezes on both sides of Baja through late week. Strong high pressure building over the Gulf of Mexico north of the area will produce a pulse of fresh to strong gap winds into the Gulf of Tehuantepec Fri night into early Sat. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... An active monsoon trough currently passes over Central America from Guatemala to Panama. The trough will remain close enough to the coast, either inland or just offshore, to produce active convection over the coastal waters the next few days. Moderate SW to W winds are expected south of the trough through Sun. Lighter trade winds are expected north of the rough axis. Long period SE to S swell will maintain 5 to 6 ft seas west of Ecuador and south of the Equator during the next few days. Broad low pressure developing over Central America will cause monsoonal winds to surge to fresh to strong speeds west of Costa Rica by Sunday night or Monday. REMAINDER OF THE AREA... Fresh to strong winds are indicated by the latest satellite- derived wind data within 120 nm in the southeast and within 60 nm in the northwest semicircles of low pressure currently embedded within the monsoon trough near 13N122W. Active convection associated with this low is noted in the monsoon trough section above. Monsoonal SW winds will remain fresh to strong across this general area for the next day or two, before diminishing. Otherwise, weak high pressure centered just NW of the area ridges southeast to near 20N120W. The relatively weak pressure gradient between this area of high pressure and the monsoon trough is producing mainly light to moderate trade winds W of 120W. The high will strengthen by the end of the weak as low pressure currently weakening the high moves east. This will cause winds in this area to become light to moderate. Long period SW swell from the Southern Hemisphere could cause seas to build above 8 ft south of 05N between 100W and 140W by the middle of next week. $$ CAM