000 AXPZ20 KNHC 171002 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Wed Aug 17 2016 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 0830 UTC. ...TROPICAL WAVES... A tropical wave is along 100W from 10N to 17N moving westward near 10 kt. A broad low to middle level wind surge and abundant moisture with and behind this wave continue to produce very active convection across southern Mexico and the Tehuantepec region. Latest satellite imagery shows scattered to locally numerous moderate to strong convection within 150 nm of the Mexican coastline from the Guatemala border to near Mazatlan, and extending well inland. This active weather is expected to continue to shift west and northwestward across southern Mexico during the next 24 hours, where some areas will continue to see very heavy rainfall. The tropical wave is expected to gradually become absorbed with the broad circulation of the wave ahead of it, along 107W, described below. A tropical wave along 107W has evolved into an elongated low pressure of 1007 mb, centered near 13.5N107.5W, moving westward around 10-12 kt. Last satellite imagery showed scattered moderate to strong convection occurring within 150 nm across the SW quadrant of the low, and had decreased in areal coverage the past 6 hours. An overnight ASCAT pass showed southwest winds around 20 kt occurring within 240 nm of the low center across the southwest semicircle, where seas were running 7-9 ft. This low is embedded in an area of abundant tropical moisture and will continue to flare up with active convection during the next 2 days as it shifts more west northwest at 10-15 kt. There is some potential for gradual improved organization of this system and a low chance for tropical cyclone development in the next 48 hours. A tropical wave along 129W-130W with weakening 1011 mb surface low near 16N129W is moving slowly westward around 5 kt. A broad area of moderate to fresh east to northeast winds are found within 240 nm across the NW semicircle of the low, and are producing seas to around 8 ft. Isolated moderate to strong convection continues to flare up on and off across the northern semicircle. The low is expected to open into an inverted trough at the surface today and move westward and cross 140W by early Fri morning. Winds and seas across the northern semicircle will gradually diminish during this time. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from low pres near 10N74W to 10N80W to 13.5N98W to low pres near 13.5N107.5W to 10N120W to low pres near 15.5N109W to beyond 12.5N140W. Scattered moderate to strong convection is noted within 150 nm either side of the trough between 81W and 91W. Widely scattered moderate to strong convection is noted within 120 nm north and 150 nm south of the trough between 109W and 118W, and between 131W and 140W. ...DISCUSSION... N of 15N E of 120W: A ridge axis extends southeastward into the area from 30N140W to near the Revillagigedo Islands. The pressure gradient between the ridge and a surface trough over Baja California is allowing for mainly moderate northwesterly winds over the coastal waters of Baja California Norte, while light to gentle northwest to west winds generally extend from Punta Eugenia to offshore of Cabo Corrientes. Seas continue in the 4 to 6 ft range across this area in mixed NW and SW swell. Light and variable winds prevail inside the Gulf of California. Little change in these overall marine conditions are expected during the next few days, with some increase in each late afternoon and evening along the Baja peninsula due to day time heating. S of 15N E of 120W: Gentle to moderate east to southeast winds generally prevail north of the monsoon trough from the Papagayo area to the Gulf of Tehuantepec area and to near Acapulco, then are gentle south to southeast from Acapulco to Cabo Corrientes. Very active convection described above dominates this region, where heavy rainfall and gusty winds likely accompany strong thunderstorm activity. To the south of the monsoon trough, gentle to moderate south to southwest winds prevail, except for the stronger winds associated with the tropical wave and low along 107W. Seas are running in the 4 to 6 ft range in southwest swell across much of this area, except as described above. The monsoon trough has lifted northward to about 150 nm offshore of the Mexican coast between Puerto Angel and Acapulco, in response to the two tropical waves moving across that area. Southeast winds behind the tropical wave along 100W are expected to increase to around 20 kt across the coastal waters from Puerto Angel to Acapulco this morning and then spread to offshore of Manzanillo by tonight, with seas increasing to 6-8 ft. Otherwise, light to moderate offshore winds will generally prevail across the Papagayo region through the week, except pulsing to 20 kt during the late night and early morning hours with nocturnal drainage flow. Mainly light and variable winds will prevail in the Tehuantepec region through the next 48 hours, except increasing fresh to strong during the late night and early morning hours. Southwest cross equatorial swell producing seas to 8 ft are s of a line from 03.4S96W to 00N104W to the equator at 120W. By 48 hours, this area of swell is forecast to reach westward to 02N126W. W of 120W: High pressure of 1032 mb centered well north of the discussion area near 42N140W extends a ridge southeastward to near 20N122W. The pressure gradient between this area of high pressure and low pressure within the monsoon trough is producing moderate to fresh trades from 25N to the north of the monsoon trough where seas are in the 5 to 7 ft range. Gale force winds off the west coast of the United States will generate a northerly swell that will propagate into the north waters Wednesday, decaying to less than 8 ft by Friday. $$ Stripling