000 AXPZ20 KNHC 131606 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 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 1200 UTC surface analysis and satellite imagery through 1430 UTC. ...SPECIAL FEATURES... Recently developed Tropical Depression 16-E near 16.2N 101.7W 1006 mb at 1500 UTC SEP 13 moving NNE or 025 DEG at 4 KT. Scattered moderate to strong convection is observed within 180 nm across the E semicircle and 120 nm across the SW and W quadrants. The depression is forecast to move slowly NE this afternoon and tonight and then turn more ENE tonight and enter the coastline near Acapulco shortly after sunrise Thu. Although winds may reach near tropical storm force as the depression moves ashore Thu, and seas will be high and confused, the main impact of this system will be the locally heavy rains expected to spread inland over SW Mexico with and behind it. 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 14.9N 120.6W 1005 mb at 1500 UTC SEP 13 moving W or 270 DEG at 8 KT. The maximum sustained winds are 30 kt with gusts to 40 kt mainly over the NW semicircle. Convection has increased near this depression with Scattered to numerous moderate to strong observed within 180 nm W and 120 nm across the E semicircles. Upper level wind shear has been inhibiting intensification of the depression during the past 24 hours but is forecast to diminish slightly and should allow it to strengthen into a Tropical Storm within 36-48 hours. This system will continuing moving generally westward and maintain tropical storm strength through the upcoming weekend. For additional information refer to NHC forecast advisories under WMO/AWIPS headers WTPZ25 KNHC/MIATCMEP5. A 1009 mb surface low is analyzed along the monsoon trough at 15N111W, and is accompanied by scattered moderate to strong convection within 180 nm W and 120 nm across the E semicircles. 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 15 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 1009 mb low is embedded in the monsoon trough near 11N136W with scattered moderate to strong convection observed within 90 NM S AND 180 NM SW QUADRANTS. INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 11N76W TO 10N81W TO TROPICAL DEPRESSION SIXTEEN-E NEAR 16.2N 101.7W TO LOW PRES 15N111W TO TROPICAL DEPRESSION 15-E AT 14.9N 120.6W TO 10.5N128W TO LOW PRES NEAR 10.5N136W TO BEYOND 09N140W. SCATTERED MODERATE TO STRONG FROM 05N TO 09N E OF 86W...AND ELSEWHERE WITHIN 90 NM N AND 270 NM S OF TROUGH BETWEEN 88W AND 113W...AND WITHIN 90 NM N AND 120 NM S OF TROUGH BETWEEN 122W AND 138W. ...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 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 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. $$ Stripling