000 AXPZ20 KNHC 140917 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Thu Sep 14 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 0600 UTC surface analysis and satellite imagery through 0930 UTC. ...SPECIAL FEATURES... Tropical Storm Max is centered at 16.6N 100.5W 998 mb at 0900 UTC SEP 14, moving E-NE or 070 DEG at 6 KT. The maximum sustained winds are 55 kt with gusts to 65 kt. Scattered strong convection is currently noted within 180 nm SE and 75 nm NW semicircles of Max. Max is forecast to move inland over Mexico tonight. Locally heavy rains are expected to spread inland with the system. These rains may cause life-threatening flash floods and mudslides. For additional information refer to NHC forecast advisories under WMO/AWIPS headers WTPZ21 KNHC/MIATCMEP1. Tropical Depression 15-E is centered at 15.3N 122.2W at 0900 UTC Sep 14, moving WNW or 285 degrees at 04 knots. The minimum central pressure is estimated 1005 mb. The maximum sustained winds are 30 kt with gusts to 40 kt mainly over the N semicircle. Scattered moderate isolated strong convection is currently observed within 210 nm over the NW semicircle of the depression. Although the depression is experiencing upper level wind shear, it is forecast to strengthen to a tropical storm in about 36 hours and continue westward maintaining tropical storm strength through the upcoming weekend. For additional information refer to NHC forecast advisories under WMO/AWIPS headers WTPZ25 KNHC/MIATCMEP5. A 1007 mb surface low is analyzed along the monsoon trough near 16.5N 109.5W, and is accompanied by scattered moderate isolated strong convection within 120 nm either side of a line from 17.5N107W to 13N115W. The pressure gradient will support minimal gale force 25 to 35 kt southwesterly flow within 150 nm over the SE semicircle today, with seas of 10 TO 15 FT. A band of strong southerly winds is also observed elsewhere within 90 nm either side of a line from 16.5N107W to 11N113W, with 8 to 12 ft seas. This low is forecast to move N to near 18N110W tonight, and near 19N109W on Fri night, with favorable environmental conditions for tropical cyclone formation as the area of the gale force winds spread out to 90 nm over the SE and 30 nm over the NW semicircles. At the least, mariners should expect strong to near gale force cyclonic winds, large seas, and a large area of thunderstorms to reach near the entrance to the Gulf of California on Sat. ...TROPICAL WAVES AND TROPICAL LOWS... A 1008 mb low is embedded in the monsoon trough near 11N135W with scattered moderate isolated strong convection observed within 150 nm of the low. INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends NW off the coast of Costa Rica at 11N86W to 14N96W where it loses identity in the cyclonic circulation associated with Tropical Storm Max. The monsoon trough resumes SW of max near 16N112W and continues W through Tropical Depression 15-E, then turns SW through an embedded 1008 mb surface low at 12N135W to beyond 09N140W. Scattered moderate isolated strong convection is noted within 75 nm of 03N79W, and within 90 nm either side of line lines from 07N77W to 10N88W, and from 15N91W to 11N97W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the special features section above for more on Tropical Storm Max, and the gale warning associated with low pres centered near 16.5N109.5W. 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 over the far northern Gulf waters. A W to E orientated ridge will meander from 23N116W to 21N110W through Thu night, then retract W on Fri night as the previously described surface low, or tropical cyclone 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 ahead an approaching tropical low. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate southwesterly monsoonal flow 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 on Fri night. REMAINDER OF THE AREA... Elsewhere, a ridge extends from 32N138W to 23N116W with light to locally moderate anticyclonic flow expected elsewhere N of the monsoon trough and W of 115W through the upcoming weekend. $$ Nelson