000 AXPZ20 KNHC 191557 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 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 1200 UTC surface analysis and satellite imagery through 1445 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 11N76W TO 10N80W TO 14N95W TO 09.5N125W. The ITCZ extends from 09.5N125W TO low pres near 10N129.5W 1009 MB TO 07N140W. Scattered moderate and isolated strong convection is from 04N TO 09N between 77W AND 91W. Scattered moderate to strong convection is within 60 NM N and 270 NM S of trough between 87W AND 125W, and within 120 NM OF ITCZ from 125W TO 140W. An elongated low pressure circulation continues this morning from the southeast Gulf of Mexico across the Yucatan Peninsula and Central America to the eastern Pacific waters near 11N92W. This large circulation is forecast to move WNW across the Gulf of Mexico through the early part of the week, while the southern portion drifts westward towards the Gulf of Tehuantepec. Locally heavy rains are expected near large clusters of TSTMs over portions of Central America and eastern Mexico during that time and may lead to flash flooding and landslides due to near saturated soils. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of Tehuantepec: Fresh northerly drainage winds are expected late tonight, and again on Tue night. Periods of active convection associated with the elongated low pressure across Central America will produce heavy rains along the coastal zones and waters from Manzanillo to Tehuantepec during the next 48 hours. 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 by 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 southerly swell currently across the offshore waters S of 17N will begin to tonight, with seas subsiding to 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 S swell, in the form of 6 to 9 ft seas, will begin to subside tonight, 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 S 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 NW of the area near 33N140W. A ridge axis extends from the high to the SE to near 16N122W. 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. $$ Stripling