000 AXPZ20 KNHC 021507 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1505 UTC Mon Oct 2 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 1400 UTC. ..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 08N80W to 13N88W to 1006 mb low pres near 13N94W to 13N110W to 1008 mb low pres near 12N130W to 1008 mb low pres near 11N139W. Scattered moderate and isolated strong convection are within 180 nm of the monsoon trough axis E of 93W. Numerous moderate to strong convection are from 09N to 15N between 93W and 102W. Scattered moderate convection is within 210 nm S of the monsoon trough axis between 102W and 120W, and within 120 nm of either side of the monsoon trough axis W of 125W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gap winds will pulse to fresh to locally strong over the Gulf of Tehuantepec during the overnight and early morning hours tonight into Tuesday as a ridge persists across the western Gulf of Mexico and the eastern slopes of the Sierra Madre Mountains. Winds and seas will increase across the Gulf of Tehuantepec area Wednesday night through Friday night as an area of low pressure strengthens a couple hundred miles south of southeastern Mexico. Environmental conditions are expected to be conducive for gradual development of this low over the next few days while the system moves slowly west-northwestward. The combination of winds associated with the low and long period SW swell, will generate an expanding area of seas of 8 to 12 ft or possibly higher offshore Mexico S of 20N Thursday and beyond. Elsewhere, a ridge dominates the waters west of the Baja California Peninsula producing gentle to moderate northerly winds and seas of 4 to 5 ft. Northerly swell are propagating into the waters west of Baja California Norte, with seas of 7 to 9 ft offshore Baja California Norte prevailing through Tuesday. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... An active monsoon trough is currently across parts of Central America and adjacent waters with widespread convection. The trough will remain close enough to the coast, either inland or just offshore, to produce additional active convection over portions of Central America as well as the adjacent coastal waters during the next few days, with locally heavy rain possible. Fresh to strong SW to W winds and seas of 8 to 11 ft are expected to affect the waters beyond 200 nm off the coast from Nicaragua to Guatemala through Wednesday. Winds and seas will also increase across the offshore waters of Panama and Costa Rica Wednesday night and Thursday. The arrival of long period SW swell early Thursday will help build seas even more, reaching 8 to 12 ft and locally higher offshore central America into the early parts of next weekend. Cross equatorial SW swell, with periods of 20 to 22 seconds are forecast to reach the waters between Ecuador and the Galapagos Islands Tuesday night, building seas to 7 to 8 ft by Wednesday night, shifting north of the area by late Friday. REMAINDER OF THE AREA... High pressure of 1026 mb centered N of the area near 38N139W has a ridge axis that extends southeastward to near 18N118W. The pressure gradient between this area of high pressure and the monsoon trough is supporting moderate to fresh NE winds N of 15N W of 130W. The pressure gradient between the area of high pressure and low pressure over the SW United States and NW Mexico is producing fresh to strong N winds north of 29N between 123W and 126W. Associated northerly swell propagating into the northern waters has built seas 8 to 11 ft over this area as far south as 26N between 119W and 131W. Winds over this area will decrease through tonight, with associated swell 8 ft or higher subsiding below 8 ft by early Wednesday. Fresh SW winds to the south of the monsoon trough and low pressure along the trough is helping generate 8 ft seas from 08N to 12N and west of 132W today. These seas are expected to subside below 8 ft late tonight. Cross equatorial southerly swell will spread across the waters south of 02N between 105W and 135W by Tuesday, with seas building to 8 to 10 ft. This swell 8 ft or greater will reach as far north as 12N E of 135W by Thursday morning. $$ Latto