000 AXPZ20 KNHC 171603 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Thu Oct 17 2019 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 1545 UTC. ...SPECIAL FEATURES... Low pressure of 1010 mb is centered near 10N126W drifting northwest. Latest satellite imagery reveals that this is fairly small system, with a prominent banding feature that coils around the center, except in the SW quadrant. The imagery shows scattered moderate to isolated strong convection within 90 nm of the center in the NW semicircle and within 60 nm of the center in the SE semicircle. Similar convection is within 60 nm of 10N123.5W. Strong winds are within 60 nm of the center in the northern semicircle, with wave heights to 9 ft. This low is forecast to move little over the next couple of days, while it has a medium chance of becoming a tropical cyclone. Beyond 48 hours, global models indicate little overall motion with this low. Please refer to the latest NHC Tropical Weather Outlook under AWIPS/WMO headers MIATWOEP/ABPZ20 for more information. Heavy Rainfall Event for southern Mexico: Moderate to fresh strong southwesterly monsoonal flow under a very moist and unstable atmosphere will continue to advect abundant moisture over southern Mexico through Sat. As a result, heavy rainfall is possible over portions of southern Mexico from Chiapas to Jalisco. These rains could cause flooding and mudslides, especially in mountainous areas. Strong gusty winds are possible in and near showers and thunderstorms. Please monitor products from your local or national meteorological service for more details on this event. ...TROPICAL WAVES... The axis of a tropical wave is near 119W from 03N to 18N, moving westward at about 10 kt. Scattered moderate convection is noted east of the wave within 30 nm of 10N118W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from along the coast of Colombia to across northern Costa Rica and to 11N86W to 17N96W to 14N108W to low pressure near 14N114W 1010 mb to 11N121W to low pressure near 10N126W 1010 mb to 10N131W to 10N140W. Scattered moderate isolated strong convection is within 240 nm south and 180 nm north of the trough between 98W and 104W. Scattered moderate convection is within 180 nm south of the trough between 105W and 113W, also within 60 nm south of the trough between 87W and 89W and within 60 nm north of the trough between 130W and 135W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please read the Special Features section for more details about a heavy rainfall event over southern Mexico. Moderate to fresh SW monsoonal flow and wave heights of 6-8 ft will remain to the south of the monsoon trough in the Gulf of Tehuantepec zone and vicinity through the end of the week. Elsewhere, a ridge will build through the week across the Baja California offshore waters producing mainly a moderate NW to N wind flow. A set of large northwest well will propagate into the Baja California Norte offshore waters by the end of the week with wave heights reaching a range of 10-14 ft, spreading southeastward reaching the Revillagigedo Islands by Sat night and continuing through Sun night. This swell will gradually decay early next week. Looking ahead, the pressure gradient across the Gulf of California region will tighten early next week as high pressure west of the area shifts northeastward. This will allow for northwest flow to freshen, with locally strong flow expected in the northern and central Gulf. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Mainly gentle to moderate southwest to west winds and wave heights in the 4-6 ft range will continue through Fri. Southwest swell will begin to propagate into the southern waters on Fri. The swell will spread northward across the forecast waters through the upcoming weekend. REMAINDER OF THE AREA... High pressure ridging dominates mainly the waters north of 19N and west of about 120W. Overnight scatterometer data indicated mainly gentle to moderate trades across this area under the ridge. Just to the south of the ridge, a trough is over the far western water roughly along 139W from 11N to 17N. This trough will drift westward with an area of fresh to strong trades and wave heights of 8 ft. The trough will shift west of 140W tonight. The Special Features low pressure system is nearly stationary along the monsoon trough near 10N126W. Please read the Special Features section above for more information about this low pressure system. A large set of long-period northwest swell has propagated into the northwest forecast waters, with wave heights of 8-10 ft located to the northwest of a line from 32N128W to 27N140W. Wave model guidance indicate that this swell will reach from near 27N115W to 20N128W and to 13N140W by late Fri night, with higher wave heights in the range of 11-14 ft north of 28N between 118W and 128W, and to north of a line from 24N114W to 15N125W to 12N140W by early Sat, with wave heights of 8-11 ft and wave heights to 14 ft north of 26N between 118W and 126W at that time. The swell is forecast to slowly decay from northwest to southeast by the end of the upcoming weekend and into early next week. $$ Aguirre