000 AXPZ20 KNHC 262155 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Thu Oct 26 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 1800 UTC surface analysis and satellite imagery through 2145 UTC. ...SPECIAL FEATURES... Possible Tropical Cyclone Formation: A surface low is analyzed near 10N88W and is estimated at 1007 mb. Scattered moderate isolated strong convection is observed within 120 nm over the N quadrant and within 270 nm over the s semicircle of the low center. This low is forecast to move northwestward through the upcoming weekend, with environmental conditions favorable for tropical cyclone formation. The forecast is for near gale force winds, and 8 to 12 ft seas, within 180 nm of the low center on Sat. Heavy rainfall is expected across Costa Rica, Nicaragua, Honduras, and Guatemala over the next few days. Gulf of Tehuantepec Gale Warning: Winds have diminished below gale force with near gale force northerly winds currently in and downstream of the gulf waters forecast to gradually diminish to 20 kt or less early Fri. The resultant large NE swell continues to propagate S and mix with long period cross-equatorial southerly swell, as well as long-period NW swell, with a plume of seas 12 ft or greater currently along 06N between 94W and 102W. These seas should subside to a max of 9 ft by sunrise Fri. Strong N winds will resume in the Gulf of Tehuantepec on Fri night, and increase to minimal gale force around mid morning on Sat, with gale conditions then persisting through Sun morning. Heavy Surf Conditions: Seas of 8 to 9 ft, with 20 to 24 second wave period, are forecast to reach the Pacific coast of the Baja Peninsula on Sat night and reach the Pacific coast of Mexico as far S as 17N on Sun night. Refractive swell at 15 to 17 seconds will arrive across the southern Gulf of California on Sun. This powerful surf energy may produce dangerous near shore conditions including rip currents and beach erosion. INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends W from the Pacific coast of Costa Rica at 11N86W through an embedded 1007 mb surface low at 10N88W to 08N100W, then the monsoon trough turns NW to 11N109W, then wiggles SW through a 1010 mb surface low embedded in the trough at 08.5N134W to beyond 08N140W. Scattered moderate isolated strong convection is observed within 210 nm either side of a line from 07N85W to 10N96W, within 150 nm either side of a line from 14N102W to 08N117W, and within 120 nm either side of a line from 12N126W to 07N138W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Heavy Surf Conditions: please refer to the special features section above for information on heavy seas arriving this upcoming weekend. Gulf of Tehuantepec: please refer to the special features section above for information on a strong gale event. Gulf of California: Light and variable winds expected through late Fri, then a moderate NW breeze is forecast through Sat night. Light and variable winds expected on Sun becoming a moderate S breeze on Mon. A surface ridge extends E across the waters W of the Baja Penisula, with light to gentle anticyclonic winds, except becoming a moderate NW breeze within 180 nm W of the Central and Southern Baja Peninsula on Fri evening. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Possible Tropical Cyclone Formation: please refer to the special features section above for information on a tropical low near 10N88W. Otherwise, moderate southerly winds, and 4 to 6 ft seas, are expected S of 08N through the upcoming weekend. REMAINDER OF THE AREA... A broad ridge dominates the EPAC waters N of 12N W of 115W accompanied by gentle to moderate anticyclonic flow, and combined seas of 5 to 7 ft to the S of 30N and moderate to fresh NE winds N of 30N W of 128w. The pressure gradient will relax on Fri. A new batch of long-period NW swell, in the form of 8 ft seas will arrive at 32N140W early Fri. Expect seas of 8 to 13 ft W of a line from 32N123W to 13N140W midday on Sat, before beginning to subside. $$ Nelson