000 AXPZ20 KNHC 122036 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Sat Sep 12 2020 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 2000 UTC. ...SPECIAL FEATURES... A 1006 mb low pressure is centered along the monsoon trough near 16N112W. A broad cyclonic circulation is evident around the low in recent scatterometer data, with strong winds in the southern semicircle and moderate to fresh winds over the Revillagigedo Islands in the northern semicircle. Seas are 8-10 ft within the enhanced monsoonal flow south of the monsoon trough. Numerous moderate scattered strong convection is noted west of the low, from 13N to 18N between 112W and 116W. Environmental conditions appear conducive for development, and a tropical depression is likely to form within the next day or so while the system moves west-northwestward away from the coast of Mexico. This system has a high chance of tropical cyclone formation within the next 48 hours. For more information, see the latest eastern North Pacific Tropical Weather Outlook at https://hurricanes.gov. ...TROPICAL WAVES... A tropical wave extends along 90W across Guatemala and El Salvador into the eastern Pacific, moving westward at 10 kt. Scattered moderate convection is noted from 08N to 11N within 120 nm of the wave axis, as well as inland over portions of southern Mexico and Central America. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N76W to 09N82W to 11N95W to 1006 mb low pressure near 16N112W to 1007 mb low pressure near 18N120W to 13N125W to 11N140W. Scattered moderate isolated strong convection is noted within 180 nm of the monsoon trough E of 88W, and within 120 nm of the monsoon trough between 101W and 105W. Scattered moderate convection is occurring within 150 nm south of the monsoon trough between 125W and 130W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section above for more details on the potential for tropical cyclone development associated with low pressure near 16N112W. The low is expected to develop into a tropical depression during the next day or so. Regardless of development, it will increase winds and seas across the outer offshore waters between Cabo San Lazaro and Cabo San Lucas, including near the Revillagigedo Islands. Southerly swell from this system will spread across the Baja California offshore waters through early next week. Recent scatterometer data show gentle to moderate northerly winds over the Baja California waters north of Cabo San Lazaro, with gentle to moderate NW winds in the central Gulf of California. Earlier convection noted near the entrance to the Gulf of California has greatly diminished. Elsewhere, light to gentle winds prevail along the coast of southern Mexico, where a recent altimeter pass indicates seas are 4-6 ft. Modest pulses of moderate to locally fresh northerly gap winds are expected tonight and Sun night over the Gulf of Tehuantepec. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Gentle to moderate S to SW winds persist south of the monsoon trough, which extends across the offshore waters roughly along 10N-11N. Elsewhere, winds remain gentle north of the trough near the coast of Guatemala, El Salvador, and Nicaragua, except for higher gusts in monsoon trough convection. Combined seas remain 4-7 ft in wind waves and background S to SW swell. Gentle to moderate monsoonal flow will prevail over the waters generally S of 10N for the next several days. Combined seas may slightly increase in the waters E of 90W Tue night through Wed as S to SW swell moves across the region. REMAINDER OF THE AREA... Please see the Special Features section above for more details on the potential for tropical cyclone development associated with low pressure near 16N112W. Regardless of development, this system will produce increased winds and seas for the next several days as it moves west-northwestward away from the coast of Mexico. Elsewhere, 1007 mb low pressure near 18N120W is producing scattered moderate convection within 240 nm NW quadrant. Additional development of this system is becoming less likely over the next day or so before it interacts with, and is possibly absorbed by, a larger weather disturbance described in the Special Features section. This system has a low chance of tropical cyclone formation during the next 48 hours. A weak high pressure ridge extends across the NW portion from near 30N131W to 26N140W. South of the ridge, mainly moderate NE trades prevail across the waters north of the monsoon trough, with smaller pockets of fresh winds noted in scatterometer data between 120W and 130W. Combined seas are generally 5-7 ft based on recent altimeter data, possibly peaking around 8 ft within the fresh flow. A broad area of fresh to locally strong monsoonal flow is shown south of the trough between 110W and 125W, with seas generally 6-9 ft in this region. Decaying, long-period S to SW swell lingers across the waters E of 120W, with 7-8 ft combined seas south of the equator. Looking ahead, a new set of southerly swell may move across the southern waters during the early to middle parts of next week. $$ B Reinhart