000 AXPZ20 KNHC 200916 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 916 UTC Tue Jun 20 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 0900 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 09N75W to 12N95W to 09N120W. The intertropical convergence zone axis extends from 09N120W to 07N130W to 04N140W. Scattered moderate convection is from 04N to 10N between 83W and 88W. Scattered moderate and isolated strong convection is N of 14N between 94W and 96W, including the Gulf of Tehuantepec, from 09N to 11N between 105W and 117W, and from 07N to 10N between 124W and 135W. Broad and elongated surface low pressure is forecast to continue for a couple more days across most of Central America and Eastern Mexico under a diffluent upper ridge, with locally heavy rains expected near the large clusters of thunderstorms. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A NW to SE trough along the Baja California Peninsula will extend southward while drifting SW-W through the week. A weak surface low will develop along the trough near 21N115W Wed evening, moving to 17N120W Thu evening, then gradually dissipating through Fri. NW swell of 6 to 8 ft will reach the offshore waters of Baja California Norte later today and will linger through the week, before decaying this coming weekend. In the Gulf of California, moderate SE flow expected across the southern waters today, with these conditions spreading N to along 30N on Wed and Thu. Guidance is hinting at a fresh SE breeze across the gulf waters to the N of 30N late Thu. The pressure gradient will then relax supporting light southerly winds during the weekend. In the Gulf of Tehuantepec, fresh northerly drainage winds are expected through the morning with seas up to 8 ft. Drainage winds are only forecast to reach moderate at best thereafter. SW swell of 5 to 8 ft S of 14N will gradually subside through the end of the week. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gentle to moderate SW to W winds are expected across the entire forecast area through Wed, then the pressure gradient will gradually relax with a gentle SW breeze continuing through Sat night. Long period S swell in the form of 5 to 8 ft seas currently across the area will subside through the day, with seas less than 8 ft everywhere by Wed afternoon. REMAINDER OF THE AREA... A nearly stationary surface high is centered just N of the area near 34N136W with moderate to fresh flow observed across the waters W of a line from 32N120W to 18N140W, with gentle to moderate trades elsewhere. An amplifying surface trough extending S-SW from the southern tip of the Baja California Peninsula, is forecast to shift SW-W through mid week with a surface low developing near 21N115W Wed evening, moving to 17N120W Thu evening, then gradually dissipating through Fri. Northerly swell of 6 to 9 ft is propagating across the NW waters and will linger through mid week before being reinforced by a new set of northerly swell which will build seas to 10 to 14 ft N of 28N Thu through Fri. These seas will then decay into the upcoming weekend. An area of 6 to 9 ft seas primarily due to SW swell are observed across the tropical waters to the S of 14N, except 3 to 6 ft seas are forecast to the lee of the Galapagos Islands. These seas are already subsiding from the N, and are forecast at 5 to 7 ft by late Thu. $$ Lewitsky