000 AXPZ20 KNHC 222122 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1945 UTC Thu Jun 22 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 12N95W to 10N104W to 11N110W to 08N120W to 07N130W to 06N133W. The ITCZ continues from 06N133W to beyond 06N140W. Scattered moderate and isolated strong convection is from 08N to 11N between 111W and 114W, and from 08N to 10N between 114W and 122W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A surface trough is west of Baja California and extends from 29N116W to 21N117W. This is breaking up the usual subtropical ridge in the area, maintaining a fairly light pressure gradient and subsequent wind pattern off the Baja California peninsula, where various ship observations and scatterometer data confirm the presence of light to gentle winds. A recent altimeter pass indicated long period northwest swell with wave height of 8 to 9 ft reaching the western waters of forecast zones PMZ011 and PMZ013. Seas are forecast to subside below 8 ft by early Friday. The trough will dissipate through late Friday, allowing the ridge to build eastward. This will support moderate to occasionally fresh northwest winds along the coast of Baja California through Sunday with building seas of 5 to 7 ft seas. Looking ahead, the pattern will repeat as another weak trough develops off the Baja coast allowing winds to diminish slightly early next week. A recent scatterometer pass also indicates gentle to moderate southerly flow across the southern Gulf of California, and moderate to fresh winds across the central part of the Gulf. moderate to fresh southerly winds are also expected over the northern Gulf through tonight. Farther south, a broad area of low pressure is located near 14.5N94.5W or a few hundred miles south of the Gulf of Tehuantepec. This low is producing disorganized showers and thunderstorms, with satellite imagery showing scattered moderate to isolated strong convection from 13N to 16N between 94W and 96W. Slow development of this system is possible by early next week while it moves west-northwestward parallel to the coast of Mexico. 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 most of the forecast area during the forecast period, with the exception of mainly south winds between Ecuador and the Galapagos Islands, as the pressure gradient remains weak. Long period southwest swell of 5 to 7 ft will gradually decay through the upcoming weekend. REMAINDER OF THE AREA... A ridge dominates most of the waters north of the convergence zone. 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 W of 120W. The ridge will shift west as the above mentioned weak trough drift west, before dissipating by late Friday. Northerly swell will continue to propagate across the waters N of 20N, building seas up to 11-12 ft N of 28N through Friday, as fresh swell moves in around a low pressure system forecsat to move from east to west N of the area. Seas will decay through the upcoming weekend as the low moves NW while weakening. $$ GR