000 AXPZ20 KNHC 032200 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Sat Sep 03 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. ...SPECIAL FEATURE... A broad area of low pressure embedded within the monsoon trough is analyzed with a mean center near 16N103W, with an estimated pressure of 1007 mb at 1800 UTC. Scattered moderate isolated strong convection is currently observed along the monsoon trough and this low within the area from 11N to 17N between 91W and 113W. Although this convection is disorganized, atmospheric and oceanic conditions continue to be favorable for rapid intensification, and this low has a high potential for tropical cyclone development over the next 5 days as it tracks n-nw reaching low confidence forecast positions near 17N105W on Sun, near 18N106W on Mon, near 22N111W on Tue and moving inland near the Baja Peninsula near 28N113W on Wed. Fresh to strong southwesterly flow...with 6-9 ft seas...is currently observed se of the low and monsoon trough axis within 120 nm either side of a line from 16N101W to 11N108W. There is much uncertainty in these forecast positions as the low is currently very disorganized. The pressure gradient is expected to tighten tonight with strong to near gale cyclonic winds developing near the low center. The gradient should continue to tighten, and gale force winds are forecast within 90 nm of the low...or tropical cyclone center... early Sun. Due to the close proximity to the Pacific coast of Mexico, these winds, and the resultant high seas and surf, will reach the Pacific coast of Mexico between 100W and 105W on Sun. These conditions will shift northward along the mainland Mexican coast reaching the southern tip of the Baja Peninsula on Tue night, while spreading n across the southern Gulf of California on Tue reaching the center gulf waters on Wed. Thunderstorms are already observed along the Pacific coast of Mexico from 90W to 100W. The associated convection will likely increase as the system intensifies, and result in high rainfall accumulations along the coast, and possible mudslides near elevated terrain. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends w-nw from the Pacific coast of Costa Rica at 10N85W, through the embedded 1007 mb low pressure center estimated at 16N103W, then turns sw through a 1011 mb low pressure near 13N120W, then continues sw through a 1010 mb low pressure at 11N137W to beyond 10.5N140W. Except as mentioned in the special features section, only one other area of convection is observed, along the w segment of the monsoon trough from 08N to 14N between 126W and 140W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See special features section above for the discussion on a tropical low, or tropical cyclone, that is developing in the vicinity of 16N103W, and forecast to tracking initially northward, then northwestward through the offshore waters through the middle of next week. Otherwise, a sub-tropical ridge axis extending se just to the w of the offshore waters, will maintain moderate to fresh nw flow, with 4 to 7 ft combined seas, across the waters along the Pacific coast of Baja through Mon, then conditions will begin deteriorate from the s as the tropical low...or cyclone... continues n. Light and variable winds are forecast elsewhere in the offshore waters s of the Gulf of California and n of the cyclonic winds associated with the tropical low. A thermal trough will meander over the Baja Peninsula, and across the northern Gulf of California where a weak low pressure is expected to develop during the early daylight hours during the next few days. This will maintain light and variable flow across the Gulf of California through Mon, except increasing to fresh sw flow between 30N and 31N tonight, and moderate to fresh southerly flow is expected in the same area on Sun night. As mentioned, winds and seas conditions are anticipated to deteriorate across the southern Gulf of California beginning on Mon night, and then spread n across the entire gulf waters on Tue and Wed. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gentle to locally moderate winds and 3 to 5 ft seas expected elsewhere n of 03N, and moderate southerly flow and 3 to 5 ft seas forecast s of 03N through the period. REMAINDER OF THE AREA... Except as previously mentioned in the special features section, a quasi-stationary surface ridge extending from near 32N138W to near 17N121W will shift slightly sw over the next few days. Moderate ne flow will continue through early next week s of the ridge and n of the monsoon trough, with combined seas of 4 to 7 ft. The gradient should relax some late in the weekend. An ill-defined tropical low currently near 13N120W is drifting n, but expected to lose identity in the monsoon trough on Sun. Moderate to fresh sw flow, and 5 to 7 ft combined seas, is expected to continue s of the monsoon trough into next week. $$ Nelson