National Hurricane Center's Tropical Weather Discussion

Eastern Pacific Ocean

197 AXPZ20 KNHC 172211 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Wed Oct 17 2018 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 2115 UTC. ...SPECIAL FEATURE... Satellite-derived winds and surface observations indicate that an elongated low pressure system is about 90 nm south of Guatemala. Although associated shower and thunderstorm activity is currently disorganized, environmental conditions are expected to be conducive for additional development, and a tropical depression or a tropical storm is likely to form during the next day or two. The system is forecast to moves generally toward the west-northwest near or just offshore the coast of southern Mexico. See the East Pacific Tropical Weather Outlook under AWIPS/WMO header MIATWOEP/ABPZ20 KNHC for further details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends 09N83W to low pres near 12N92W to 12N112W to 08N120W to 10N130W to 10N140W. Scattered moderate convection is within 180 nm south of the monsoon trough E of 95W. Scattered moderate isolated strong convection is N of 11N between 95W and 100W, and from 06N to 12N W of 127W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... The remnants of Tropical Depression Tara located near 20N106W are generating scattered showers within 90 nm of Las Tres Marias Islands. A relaxed pressure gradient between low pressure along western Mexico and surface ridging extending to just west of the Revillagigedo Islands will maintain gentle to moderate NW winds over the offshore forecast waters W of Baja California through early Monday. Seas over the region during this period will range between 4-6 ft, increasing to 7 ft for the southern offshores of Baja late on Sun. Moderate to fresh NW winds with seas to 5 ft are forecast for the Gulf of California through Sat, decreasing to light to gentle winds the reminder weekend into Tue next week. A current gap wind event in the Gulf of Tehuantepec, with winds to 25 kt as per latest scatterometer data, is forecast to merge with the area of low pressure located south of Guatemala on Thu evening. See the Special Features section for further details. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Fresh to locally strong SW monsoonal flow will prevail for the offshore waters of Nicaragua and Guatemala through Fri with seas to 11 ft. Near gale force winds are expected on Thu evening over portions of the Guatemala offshores as a low pressure/possible tropical cyclone deepens west of the area. Active showers and thunderstorms associated with this area of low pressure are expected to continue across much of Central America and the adjacent Pacific coastal waters, spreading well inland the next few days. REMAINDER OF THE AREA... A dissipating stationary front extending from 30N136W to 24N140W will vanish by early Thu. Long period NW swell behind the front will cause seas to build to between 8 and 9 ft generally N of 15N and W of 132W. $$ NR