000 AXPZ20 KNHC 280901 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 901 UTC Mon Aug 28 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 0600 UTC surface analysis and satellite imagery through 0830 UTC. ..TROPICAL WAVES... A tropical wave is analyzed to the N of 12N along 103W moving W at 10 kt. Only widely scattered convection is in the immediate vicinity of the tropical wave axis. A tropical wave is analyzed from 12N116W to 21N114W moving W at 10 to 15 kt. Only isolated convection is noted near the tropical wave axis. ..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N75W to low pressure near 09N88W, then resumes from 18N92W to 17N106W to low pressure near 16N113W to 12N124W to 10N140W. Scattered moderate and isolated strong convection is from 02N to 09N to the E of 80W including the Gulf of Panama, and also from 13N to 16N between 105W and 110W. Scattered moderate convection is from 05N to 07N between 91W and 98W, from 08N to 11N between 103W and 110W, and also within 90 nm S of the monsoon trough axis between 125W and 136W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A ridge axis extends from NW of the area to near 22N116W, which supports moderate to locally fresh NW to N flow across the open Pacific waters W of the Baja California Peninsula. A surface trough extends from NW to SE across the Baja California Peninsula and is forecast to meander over the area, moving at times across the Gulf of California through the early part of the week, with weak surface low pressure developing along the central portion. Active convection is present near and offshore of Cabo Corrientes early this morning with scattered moderate to strong found from 17N to 23N between 105W and 108W. This convection developed along the mountains of western Mexico during the evening prior to propagating offshore, and should diminish later this morning. The main feature of concern during the week will be an area of low pressure which is forecast to develop near 16.5N106.5W embedded in the monsoon trough by early Tue. Fresh to locally strong S to SW flow is already present S of the monsoon trough supporting 7 to 9 ft seas. The low is forecast to shift NW passing offshore of Cabo Corrientes Tue evening through early Wed, then to between the Revillagigedo Islands and Cabo San Lucas Wed evening through early Thu, and northward thereafter. At a minimum, fresh to near gale force winds and building seas to greater than 12 ft just offshore will accompany the low, with hazardous winds and seas moving across the entrance to the Gulf of California Wed night, spreading northward thereafter. The official forecast shows a high potential for tropical cyclone development with this low after 48 hours. Meanwhile in the Gulf of Tehuantepec, light offshore nocturnal flow expected this week, with light to gentle onshore flow during the day. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Low pressure is embedded in the monsoon trough near 09N88W with scattered moderate and isolated strong convection within 300 nm in the SE quadrant of the low, with additional convection attempting to develop on the N side. This low is forecast to shift NW-W during the next couple of days before dissipating by mid-week. In the Gulf of Papagayo, moderate E flow will prevail this morning, then again Fri night into early Sat. Otherwise, light and variable flow is expected N of the monsoon trough through the week, while moderate to locally fresh southerly winds are expected S of the monsoon trough. Long period southerly cross-equatorial swell, in the form of 7 to 9 ft seas, mainly across the offshore Pacific waters of Colombia and Ecuador will gradually subside through Tue. REMAINDER OF THE AREA... The remnant low of post-tropical cyclone Kenneth has finally degenerated into a trough extending from 30N138W to 26N135W. A ridge axis noses into the area from 32N132W to 22N116W. The trough will dissipate between 24 and 48 hours while the ridging builds in across the area. This ridging will support mainly moderate to locally fresh trades, and seas of 4 to 7 ft in mixed swell through the week. Meanwhile, moderate to locally fresh southerly monsoonal flow prevails S of the monsoon trough W of 120W, while fresh to locally strong flow prevails between 100W and 120W with seas of 7 to 10 ft. These conditions are forecast to persist through Thu night while low pressure as mentioned above develops and moves NW across the offshore waters of Mexico. Conditions will improve Fri into the upcoming weekend as the low lifts northward and dissipates. $$ Lewitsky