000 AXPZ20 KNHC 130930 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Wed Sep 13 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 Depression 15-E centered at 14.9N 119.4W at 0900 UTC moving W or 270 degrees at 08 knots. The minimum central pressure is estimated 1004 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 later today 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 1008 mb surface low is analyzed along the monsoon trough at 15N103W and is accompanied by scattered moderate isolated strong convection within 150 nm over the SE and within 90 nm over the NW semicircles of the center. Environmental conditions are favorable for this system to strengthen to a tropical cyclone as it moves northward and inland Mexico near 18N late tonight or early Thu. Regardless of development, locally heavy rains are expected to spread inland over SW Mexico and could cause life-threatening flash floods and mudslides. A 1006 mb surface low is analyzed along the monsoon trough at 15N111W, and is accompanied by scattered moderate isolated strong convection currently within 60 nm either side of a line from 14N110W to 17N114W. Environmental conditions are favorable for this system to strengthen to a tropical cyclone as it moves northward this week across the offshore waters between 105W and 112W. At the least, expect strong to near gale force cyclonic winds, and seas conservatively to 20 ft, 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 W-NW off the coast of Nicaragua at 11N86W to 13N90W through an embedded surface low at 15N103W to a second embedded surface low at 15N111W to Tropical Depression 15- E at 14.9N119.4W, then the monsoon trough turns SW to 11N126W, then W through another embedded surface low at 11N135W, then dips Sw to beyond 09N140W. Scattered moderate isolated strong convection is noted to the N of 06N E of 81W, and elsewhere within 75 nm either side of a line from 13N105W to 08N131W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... 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 as the previously described surface low, or tropical cyclone approaches the southern tip of the Baja Peninsula this weekend. Gulf of California...Light, mostly NW winds expected through Fri with large southerly swells arriving across the southern waters on 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