000 AXPZ20 KNHC 151530 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1530 UTC Fri Sep 15 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 1200 UTC surface analysis and satellite imagery through 1530 UTC. ...SPECIAL FEATURES... The center of Tropical Storm Norma at 15/1500 UTC is near 18.7N 109.7W, moving NNW, or 340 degrees at 02 knots. The estimated minimum central pressure is 996 mb. Maximum sustained wind speeds are 55 kt with gusts to 65 kt. Scattered moderate to strong convection was noted within 150 nm of the center. Norma is forecast to gradually strengthen and should become a hurricane tonight or Saturday as the storm moves N. Please read the latest NHC Forecast/Advisory under AWIPS/WMO headers MIATCMEP2/WTPZ22 KNHC for more details. The center of Tropical Depression Fifteen-E at 15/1500 UTC is near 15.9N 125.0W, moving W, or 275 degrees at 04 knots. The estimated minimum central pressure is 1006 mb. The maximum sustained wind speeds are 30 kt with gusts to 40 kt. Scattered moderate isolated strong convection was noted 120 NM in the SW semicircle. The depression may finally strengthen to a tropical storm later today or Saturday. Please read the latest NHC Forecast/Advisory under AWIPS/WMO headers MIATCMEP5/WTPZ25 KNHC for more details. ...TROPICAL WAVES AND TROPICAL LOWS... The remnant low of former T.S. Max was centered near 17N98W with a central pressure of 1010 mb. The remnant low consists of broken to overcast low and mid clouds with embedded shower activity. A 1010 mb low pressure is near 12N133W in the monsoon trough. S to SW winds of 20 to 25 kt are within 180 nm of the SE semicircle with seas to 9 ft. The low is expected to weaken gradually through Saturday with seas subsiding to less than 8 feet by Saturday night. ...Intertropical Convergence Zone/Monsoon Trough... Monsoon trough extends from 10N85W to 10N98W...then resumes from 13N127W to 10N140W. Scattered moderate to strong convection was noted within 180 to 240 NM either side of the trough axis E of 98W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the special features section above for more information on Tropical Storm Norma. A NW to SE oriented trough will meander E to W across the Baja California Peninsula and the Gulf of California with a surface low developing intermittently along the trough axis across the far northern Gulf waters. A northwest to southeast orientated ridge extends from 25N118W to 22N114W will shift W on Fri night as Norma approaches the southern tip of the Baja Peninsula this weekend. Gulf of California...Light and variable winds expected through Fri with large southerly swells arriving across the southern waters late Fri night or early Sat well ahead of Norma. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate southwesterly monsoonal flow is expected through the upcoming weekend with 6 to 8 ft seas primarily due to cross- equatorial swell that is forecast to subside below 8 ft late Friday into Saturday. The monsoon trough has been lifting northward the past few days and will move north of Panama and near the coast of Costa Rica and Nicaragua late Fri...then potentially inland farther north to Guatemala. Abundant moisture converging near the trough will allow for scattered heavy showers and tstms that could produce very heavy rainfall and lead to flash flooding and mudslides across coastal zones and large river discharges early next week. REMAINDER OF THE AREA... A surface ridge extends from a 1022 mb high pressure center that is near 35N140W to 28N136W and 20N133W. Light to locally moderate anticyclonic flow is expected elsewhere N of the monsoon trough and W of 115W through the upcoming weekend. $$ Cobb