000 AXPZ20 KNHC 212124 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1931 UTC Wed Jun 21 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 11N86W to a 1008 mb low pressure near 12N94W to 10N110W to 09N127W. The ITCZ continues from 09N127W to beyond 08N140W. Scattered moderate convection is within 120 nm S of the monsoon trough between 107W and 114W. An area of showers, with embedded tstms, is noted from 04N to 10N between 80W and 89W in a southwesterly wind flow. This convective activity is affecting parts of Panama. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Moderate to locally fresh northerly flow is noted off Baja California Norte between a trough over the peninsula and a ridge that covers the remainder of the northern forecast waters. This pattern is also supporting moderate to locally fresh southerly winds over the Gulf of California south of 30N. Expect moderate to fresh southerly winds across the northern Gulf of California tonight through Thursday night, and then again on Sunday. Northerly swell of 8 to 9 ft continues to propagate across parts of forecast zones PMZ011 and PMZ013. This will persist through Friday. A developing trough just west of the southern Baja California Peninsula is producing mainly light to gentle winds across the waters from 15N to 25N between 110W and 120W. This trough will move west through Thursday, enhancing southerly flow near Los Cabos and across much of the Gulf of California into Saturday when the gradient relaxes. This trough could be the reflection of an upper-level low currently spinning near 22N117W. A band of moisture is forecast to persist along the east coast of the Gulf of California over the next 24-48 hours supporting some shower and tstm activity. Farther south, a weak low level circulation is noted along the monsoon trough near 11N86W. This low will move across the Gulf of Tehuantepec supporting moderate to locally fresh east to southeast winds off the coasts of Chiapas and Oaxaca Friday and Saturday. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gentle to moderate southwest to west winds are expected across the entire forecast area the rest of today, then the pressure gradient will gradually relax with a gentle southwest breeze continuing through Sunday night. Long period SW swell of 6-7 ft will gradually decay to 5-6 ft by Thursday night, and to 4-5 ft on Friday. REMAINDER OF THE AREA... A ridge dominates most of the waters north of the ITCZ/Monsoon Trough. Scatterometer and altimeter passes continue to indicate an area of moderate to fresh winds and seas of 8 to 10 ft roughly north of 20N and west of 120W. The ridge will shift west as the above mentioned trough also drifts west. A broad and weak low pressure is forecast to develop along the trough axis near 20N118W by tonight. Northerly swell will continue to propagate across the waters north of 20N, building seas up to 11 ft through Friday night. Seas will gradually subside, from east to west, across the north waters on Saturday. $$ GR