000 AXPZ20 KNHC 162205 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Tue Aug 16 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 1800 UTC surface analysis and satellite imagery through 2145 UTC. ...TROPICAL WAVES... A tropical wave is along 98W/99W from 11N to 17N moving westward about 10 kt. latest satellite imagery continues to show very active convection in the form of scattered moderate to isolated strong convection from 10N-16N between 96W-103W, and also within 60 nm of a line from 13.5N94.5W to 15N96.5W. Scattered moderate convection is within 30 nm of a line from 10.5N92W to 13.5N94.5W. This activity is under well pronounced diffluent flow aloft helping to sustain it. Moisture model guidance progs this weather to shift westward through the next 48 hours. A tropical wave is along 106W from 11N to 17N moving westward 10- 15 kt. Latest visible satellite imagery along with an Ascat pass from 1610Z noted an elongated northwest to southwest low pressure circulation with a mean center near 12.5N106W. The surface analysis has a pressure of 1008 mb with this low. The Ascat pass depicted an solid swath of 20-25 kt winds from 08N-12.5N between 103W and 108W. Seas of 6-8 ft are within 60 nm southeast quadrant of the low, while seas to 8 ft in southwest swell are elsewhere within 240 nm se of a line from 15N105W to 09N114w. Scattered moderate to isolated strong convection is observed in association with this system within 180 nm in the southwest semicircle of the the low. Global model guidance suggest that this system will move west-northwestward around the southern periphery of a mid-level ridge over the next couple of days with the possibility of some gradual development. A tropical wave is near 128W from 12N to 20N, with an associated 1010 mb surface low along the wave near 17N128W. Only isolated weak convection is seen within 120 nm of the low and wave from 14N to 20N as mainly dry air aloft prevails over the far western portion of the area n of 14N and west of 127W. The low is forecast to dissipate by the next 24 hours. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N84W to 13N98W to low pressure near 12.5N106W to 11N114W to 13N123W. It resumes at 14N130W to beyond 13N140W. Scattered moderate convection is within 120 nm south of the axis between 121W and 123W, and also between 137W and 140W. ...DISCUSSION... N of 15N E of 120W: A ridge axis extends southeastward into the area from 32N136W 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 extends 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, then are gentle south to southeast from Tehuantepec to Cabo Corrientes as indicated by overnight scatterometer data. Gentle to moderate south to southwest winds prevail south of the monsoon trough, except for the stronger winds related to the tropical wave along 106W with low pressure as mentioned above. Seas are running in the 4 to 6 ft range in southwest swell across much of this area, except for the higher seas associated with the low near 12.5N106W 1008 mb as described above under Tropical Waves. The monsoon trough has lift northward to 13N/14N west of Tehuantepec in response to the tropical wave along 106W. The coverage in 15 to 20 kt winds will expand during the next 24 to 48 hours allowing for combined seas to the south of the monsoon trough to build to 8 to 9 ft seas between 107W and 112W by 48 hours. 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 to fresh during the late night and early morning hours. Southwest cross equatorial swell producing seas to 8 ft are s of a line from 03.4S95W to 02N105W 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 1030 mb centered well north of the discussion area near 40N140W extends a ridge southeastward to near 25N120W. The pressure gradient between this area of high pressure and low pressure within the monsoon trough is producing moderate to fresh trades 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 by Wednesday evening, decaying to less than 8 ft by Friday. $$ Aguirre