000 AXPZ20 KNHC 041530 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1348 UTC Sun Sep 4 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 1200 UTC surface analysis and satellite imagery through 1445 UTC. ...SPECIAL FEATURE... ...Gale along coast of Mexico... An elongated area of low pressure embedded within the monsoon trough is analyzed with a mean circulation center near 15N106W, with an estimated pressure of 1005 mb at 1200 UTC. Scattered moderate to strong convection is from 11N to 19N between 104W and 110W. There is a high chance of tropical cyclone development over the next 48 hours. Upper-level winds are forecast to become more conducive for development, and a tropical depression is expected to form later today or Monday while the disturbance moves slowly northwestward, parallel to the southwestern coast of Mexico. Regardless of whether or not development occurs, the system is already bringing very heavy rains and gusty winds to southwestern Mexico, and these conditions are likely to continue for the next couple of days. These rains could produce life-threatening flash floods and mud slides, especially in areas of mountainous terrain. please see the Tropical Weather Outlook under AWIPS/WMO Headers MIATWOEP/ABPZ20 KNHC for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N85W 17N100W through a 1005 mb low near 15N106W then along 13N112W 12N127W to 11N140W. Scattered moderate to strong convection is within 120 nm n of trough between 100W and 104W. Scattered moderate to isolated strong convection is within 90 nm north and 210 nm south of trough between 87W and 90W and within 180 nm south of trough between 99W and 104W. Scattered moderate convection is within 150 NM north of trough west of 126W and from 12N to 18N between 99W and 110W. Scattered moderate convection is from 10N to 14N between 125W to beyond 140W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A gale is expected as the 1005 mb low currently near 15N106W moves northwestward to near 18N107W Monday morning. This low is expected to develop into a tropical cyclone in the next 48 hours. See Special Features above. This low will track northwest through the offshore zones through midweek. 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 Tue, except increasing to moderate to fresh southerly flow in the same area on each night. Fresh northerly winds are expected in the Gulf of Tehuantepec late Wed night becoming strong northerly winds Thu morning through Fri. 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 are expected through the period. REMAINDER OF THE AREA... A sub-tropical ridge axis anchored by a 1030 mb high northwest of the discussion area extends southeast through 32N138W to 22N117W. This ridge will persist through Monday night before weakening and retreating northward. This will keep moderate to strong trade winds between the ridge and the monsoon trough through tonight. The ridge will weaken and shift northward when cross equatorial southerly winds will then shift north, keeping moderate to locally strong southerly winds over an area from 10N to 15N west of 120W. $$ PAW