000 AXPZ20 KNHC 200407 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Sat Oct 20 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 0600 UTC surface analysis and satellite imagery through 0345 UTC. ...SPECIAL FEATURES... Tropical Storm Vicente is centered near 13.7N 92.5W or about 115 miles W of Puerto San Jose Guatemala at 20/0300 UTC drifting W- NW at 3 kt. Estimated minimum central pressure is 1005 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Scattered moderate isolated strong convection is observed within 90 nm SE of the center. An increase in forward speed and a turn toward the west is expected tonight, followed by a turn toward the southwest on Saturday. On the forecast track, the center of Vicente should gradually move away from the coasts of Guatemala and southeastern Mexico tonight and tomorrow. Vicente will contribute to abundant and persistent tropical moisture along the coasts of Guatemala and El Salvador, with precipitation guidance suggesting 5 to 10 inches of rain, with local amounts to 15 inches, are possible across portions of El Salvador and southern Guatemala, and 3 to 6 inches with local amounts to 10 inches near the Pacific coast of southeastern Mexico through the middle of next week. This rainfall could produce life- threatening flash flooding and landslides within mountainous terrain. Refer to the latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP3/WTPZ23 KNHC for additional details. A surface low pressure is centered near 15N104W, or a few hundred miles S-SW of Zihuatanejo, Mexico, and is estimated at 1007 mb. Currently numerous strong convection is observed within 60 nm SE of the center. Scattered moderate to strong convection is noted in bands elsewhere within 150 nm NE and 180 nm SW semicircles of center. Environmental conditions are favorable for tropical development and the low moves W-NW, and later north across the offshore waters of central Mexico. Refer to the latest East Pacific Tropical Weather Outlook under AWIPS/WMO header MIATWOEP/ABPZ20 KNHC for additional details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends northwest off the Caribbean coast of Colombia at 10N76W to the Pacific coast of El Salvador at 14N89W then loses identity in the cyclonic circulation associated with tropical cyclone Vicente. The monsoon trough resumes W of Vicente at 13N95W, and continues NW through the surface low at 15N104W, then turns SW through 13N106W to 10N1117W where scatterometer winds indicate a transition to an ITCZ, which then continues W to 10N130W to beyond 12N140W. Scattered moderate isolated strong convection is observed within 60 nm of the coast from 81W to 87W, within 90 nm either side of a line from 15N93W to 16N99W to 19N109W. Isolated moderate to strong convection is noted within 120 nm either side of a line from 11N115W to 10N123W, and from 11N131W to 08N137 to 08N140W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the Special Features paragraph for details on Tropical Cyclone Vicente and a surface low with high chances of becoming a tropical cyclone later today or tomorrow. A surface ridge will meander across the offshore waters from 23N117W to 21N106W through Mon. Gentle northwest to north flow is expected north of 20N west of 110W through early Tue. The pressure gradient is then forecast to tighten supporting moderate northerly flow west of the Baja California Peninsula during the middle of next week as large southerly swell propagates north through the waters w of Baja. Gulf of California: Light, mostly northerly flow is expected through the middle of next week when large southerly swell will reach the southern approach to the gulf waters. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gentle to moderate southwesterly to westerly monsoonal flow will dominate the offshore waters through Sat night. Fresh southwest winds are expected to develop south of 05N east of 90W on Sat night through Sun night with seas to 9 ft. REMAINDER OF THE AREA... See the Special Features paragraph for details on a surface low with high chances of becoming a tropical cyclone later today or tomorrow. Elsewhere, a surface ridge will meander from near 30N135W to 23N117W through the upcoming weekend. Fresh winds, and 7 to 9 ft seas, are observed across the tropical waters from 13N to 19N W of 133W. These conditions will shift w of the area on Sun night. $$ Nelson