000 AXPZ20 KNHC 091513 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1500 UTC Sat Jun 9 2018 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 1500 UTC. ...SPECIAL FEATURES... Hurricane Aletta centered near 16.4N 113.1W at /1500 UTC or 190 nm SW of Socorro Island moving WNW at 5 kt. Estimated minimum central pressure is 973 mb. Maximum sustained wind speed is 85 kt with gusts to 95 kt. Numerous moderate to strong convection is within 60 nm of the center. Scattered moderate isolated strong convection is noted elsewhere from 10N to 20N between 109W and 115W. Aletta continues to be impacted by southerly vertical shear. The system will weaken rapidly with the combination of strong vertical shear, cooler sea surface temperatures, and dry air entrainment. The latest forecast has Aletta weakening to a tropical storm later tonight and a tropical depression Monday morning. Please refer to the latest NHC Forecast Advisory under WMO/AWIPS headers WTPZ22/MIATCMEP2, and the NE Pacific High Seas Forecast under WMO/AWIPS headers FZPN03/MIAHSFEP2 for the latest information on this system. Low pressure is centered near 11.5N101W. Numerous moderate scattered strong convection was noted within 90 nm se semicircle of the low center. Scattered moderate isolated strong convection was noted elsewhere from 07N to 17N between 95W and 105W. Environmental conditions are favorable for this system to develop into a tropical cyclone this weekend. Since winds are expected to reach gale force in 24 hours, a gale warning remains in effect. There is a high potential for this low to develop into a tropical cyclone during the next two days, and this warning may be changed to a tropical cyclone warning. Please refer to the latest NHC Tropical Weather Outlook under header ABPZ20/MIATWOEP for the latest potential for development on this system. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 11N85W to low pres near 11.5N101W. It resumes from 10N116W to 07N130W. The ITCZ extends from 07N130W to 05N140W. Scattered moderate isolated strong convection was noted from 05N to 08N east of 85W. Scattered moderate isolated strong convection was noted from 11N to 14N between 89W and 94W. Scattered moderate isolated strong convection was noted within 90 nm south and 30 nm north of the monsoon trough between 116W and 128W. Scattered moderate isolated strong convection was noted within 60 nm of the ITCZ west of 135W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See above for more on Hurricane Aletta, as well as a gale warning associated with a broad area of low pressure, which has the potential for tropical development this weekend. Elsewhere, a broad ridge W of the area will support moderate to fresh NW winds west of the Baja Peninsula through the weekend. A pulse of NW swell prevails west of northern Baja California, with seas greater than 8 ft. This swell will merge with swell generated by Hurricane Aletta west of the Baja Peninsula generating confused seas greater than 8 ft that will persist into early next week, possibly becoming reinforced next week by the developing special feature low pressure system. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Fresh east winds will continue across and downstream of the Gulf of Papagayo through the period, becoming fresh to strong Sat night. The monsoon trough will meander across the forecast waters near 10N. REMAINDER OF THE AREA... The surface ridge extending across northern waters will slowly shift westward the next few days. Fresh trades will continue across the tropics to the south of the ridge. NW to N swell from strong northerly winds along the coast of California continues to support seas to 9 ft within an area bounded by 23N131W to 30N124W to 30N119W to 23N112W to 23N131W. This swell will combine with swell generated from Hurricane Aletta this weekend. Long period cross- equatorial SW swell is also propagating across the forecast waters. The swells will combine the next couple of days, with seas greater than 8 ft covering much of the forecast waters south of 25N and west of 95W by Sunday in mixed swell. $$ AL