899 AXPZ20 KNHC 270347 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Mon Aug 27 2018 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 0000 UTC surface analysis and satellite imagery through 0245 UTC. ...SPECIAL FEATURES... Tropical Storm Miriam centered near 13.8N 127.9W at 27/0300 UTC or 1160 nm WSW of the southern tip of Baja California moving W at 12 kt. Estimated minimum central pressure is 1001 mb. Maximum sustained wind speed is 45 kt with gusts to 55 kt. Miriam is becoming better organized with numerous moderate to strong convection from 12N to 15N between 125W and 129W. Miriam is expected to become a hurricane by late Monday or early Tuesday as it moves westward. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCPEP5/WTPZ35 KNHC for more details. A tropical wave along 107W has a 1009 mb low associated with it near 11N107W. Rainbands of moderate convection with isolated tstms are from 08N to 16N between 104W and 110W. There is a medium chance that this area of low pressure will develop into a tropical cyclone within the next 48 hours and a high chance of tropical cyclone formation within the next 5 days. Please refer to the latest eastern north Pacific Tropical Weather Outlook for more information. ...TROPICAL WAVES... A tropical wave axis is near 95W N of 05N, moving W at 15 kt. Scattered moderate convection is N of 06N between 93W and 100W. A tropical wave axis is near 107W from 04N to 17N, moving W at 15 kt. Please see above in special features section for more on developing low pressure and the possibility of tropical cyclone development in association to this feature. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 08N78W to 07N94W to 09N101W then resumes near 10N109W to 09N114W to 12N118W then from 15N133W to 13N140W. Scattered moderate convection is from 04N to 10N between 82W and 93W, from 07N to 13N between 110W and 121W. Isolated moderate convection is within 90 NM either side of the monsoon trough W of 132W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A ridge extends southeast from 1039 mb high pressure near 45N148W through NW of the Revillagigedo Islands. The associated pressure gradient between the high and a persistent trough across the Baja California Peninsula will continue to support moderate NW winds funneling along the coast of Baja California Norte through Fri, with seas generally in the 4 to 6 ft range. With low pressure over northern Mexico, light to gentle southerly flow will dominate over the Gulf of California the entire week. In the Gulf of Tehuantepec, nocturnal drainage flow and the passage of a tropical wave will support fresh to strong gap winds tonight into early Mon. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... The monsoon trough will linger along 09N/10N during the next few days. Winds on both sides of the trough axis will generally be light to moderate. The main exception to this will be over the Gulf of Papagayo where nocturnal offshore gap winds will pulse to fresh to strong tonight and Mon night. REMAINDER OF THE AREA... Please see special features section above for information on T.S. Miriam, and for possible tropical cyclone development of broad low pressure associated with a tropical wave near 107W. Elsewhere, the pressure gradient between ridging across the waters north of 20N and the monsoon trough will support moderate to locally fresh trades and 4 to 7 ft seas in mixed swell north of the monsoon trough and west of 120W through the week. $$ Ramos