000 AXPZ20 KNHC 040349 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Wed Oct 4 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 0000 UTC surface analysis and satellite imagery through 0230 UTC. ...SPECIAL FEATURES... Low pressure of 1004 mb is located south of the Gulf of Tehuantepec near 14N95W. Scattered moderate and isolated strong convection was noted within 150 nm in the W semicircle of the system and elsewhere from 11N to 16N between 95W and 99W. Environmental conditions are expected to be conducive for some additional development over the next couple of days while the system moves slowly westward. The latest Tropical Weather Outlook gives this low pressure a medium chance of formation through 48 hours and a high chance within the next 5 days. Please refer to the latest Tropical Weather Outlook for more information on the potential for development of this low. ..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 14N92W to 1004 mb low pres near 14N95W to 13N110W to 1010 mb low pres near 13N125W to 12N140W. Scattered to strong convection is from 14N to 17N between 102W and 106W. Scattered moderate convection was noted within 120-180 nm either side of the monsoon trough axis between 123W and 129W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See Special Features above for more details on low pressure south of the Gulf of Tehuantepec. The combination of winds associated with the developing low pressure and long period SW swell of 20 to 22 seconds will generate a large area of seas of 8 to 12 ft or possibly higher S of 13N between 95W and 130W by late Wednesday. This swell will reach the offshore waters of Mexico, south of Cabo Corrientes late Wednesday into Thursday. 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 propagating into the waters west of Baja California Norte, will subside to 7 to 8 ft tonight and 6 to 7 ft Wednesday. 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 clusters of moderate to strong 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 250 nm off the coast from Nicaragua to Guatemala by Wednesday. As low pressure develops in the western Caribbean Sea late Wednesday and Thursday, winds and seas will increase across the offshore waters of Panama and Costa Rica to 20 to 25 kt and 9 to 12 ft. The arrival of cross- equatorial long period SW swell will aid in enhancing seas in the area. The potential exists for dangerous breaking surf along the coast of Costa Rica and Panama. The dangerous surf may extend into the Gulf of papagayo by late Thursday and Friday. Cross equatorial SW swell, with periods of 20 to 22 seconds will begin to reach the waters between Ecuador and the Galapagos Islands tonight, building seas to 7 to 8 ft by Wednesday night. REMAINDER OF THE AREA... High pressure of 1024 mb centered N of the area near 34N140W with an associated ridge extending southeast to near 22N120W. 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. Northerly swell propagating into the northern waters has built seas 8 to 9 ft over this area as far south as 26N/27N between 120W and 130W. Seas associated to this swell are forecast to subside below 8 ft by early Wednesday. $$ Cobb