000 AXPZ20 KNHC 190919 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 919 UTC Mon Jun 19 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 09N74W to 14N94W to 12N105W to 09N123W. The intertropical convergence zone axis extends from 09N123W to 08N140W. Scattered moderate and isolated strong convection is from 06N to 08N between 86W and 92W, within 180 NM in the SW semicircle of a low near 13N92W, from 08N to 11N between 109W and 114W, from 08N to 11N between 120W and 133W, and also from 05N to 08N between 132W and 137W. Low pressure is forecast to move from the Yucatan Peninsula into the Gulf of Mexico through the early part of the week. Locally heavy rains are expected near large clusters of TSTMs over portions of Central America and eastern Mexico during that time. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of Tehuantepec: Fresh to locally strong northerly drainage winds are expected late tonight, and again on Tue night. A NW to SE orientated trough across the Baja California Peninsula is expected to amplify to the S across the offshore waters S of Cabo San Lucas through this afternoon while drifting W, reaching a position from 27N114W to 17N114W by early Wed. A surface low will begin to develop along the trough near 19N115W on Tue night, then move W of the offshore waters to near 17N118W on Wed night. As the low moves westward, it will drag a weakening trough to the W across the offshore waters to the N of 25N on Thu and Fri. Large SW swell currently across the offshore waters S of 17N will begin to subside through the day, with seas less than 8 ft by early Wed. Large NW swell will reach 30N120W on Tue, and spread S to along 25N on Tue night, with little change then expected through Fri night. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... A moderate to locally fresh SW to W breeze is expected across the entire forecast area through the morning, then the pressure gradient will relax with a gentle to moderate SW to W breeze forecast through Fri night. Long period SW swell, in the form of 6 to 9 ft seas, will begin to subside through the day, with seas less than 8 ft everywhere by Wed afternoon. REMAINDER OF THE AREA... An area of 6 to 9 ft seas mainly due to mixed SE and SW swell, will continue to propagate across the waters S of 14N and E of 135W. Expect 3 to 6 ft seas to the lee of the Galapagos Islands. These seas will begin to subside from the N later today, and continue to subside through Fri night. High pressure at 1024 mb is centered just N of the area near 34N139W. A ridge axis extends from the high to the SE to near 17N118W. This ridge will gradually shift westward over the next few days and reach a position to the W of 140W by mid week. An amplifying surface trough extending S from the southern tip of the Baja California Peninsula is forecast to shift W on Tue, with a surface low developing along the trough near 17N118W on Wed. The low should reach near 16N123W on Fri. This will result in the pressure gradient tightening across the subtropics this week, with fresh N winds developing across the waters N of 28N between 124W and 131W by this evening. Accompanying northerly swell will build combined seas to 8 to 12 ft with the highest seas along and N of 30N, with seas of 8 ft or greater reaching across the waters N of 20N by early Tue, lingering through Thu before gradually decaying. $$ Lewitsky