378 AXPZ20 KNHC 271543 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1543 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...SPECIAL FEATURES... Tropical Storm Miriam centered near 13.9N 130.5W at 27/1500 UTC or 1290 nm WSW of The Southern Tip Of Baja California moving W at 12 kt. Estimated minimum central pressure is 999 mb. Maximum sustained wind speed is 55 kt with gusts to 65 kt. Miriam is forecast to become a hurricane tonight. Numerous moderate scattered strong convection is within 90 nm in the NE semicircle and 180 nm in the SW semicircle. See latest NHC forecast/ advisory under AWIPS/WMO headers MIATCPEP5/WTPZ35 KNHC for more details. Low pressure near 13.5N108.5W at 1008 mb is moving W with scattered moderate and isolated strong convection within 210 nm in the NW semicircle. A tropical wave is located just to the W from 03N to 19N along 110W. Associated winds and seas are currently 20 kt or less and less than 8 ft, however the low has a high chance of tropical cyclone formation during the next 24 hours. A gale warning has been issued beginning at 12 UTC Wed in the event that tropical cyclone formation does not occur by then with sufficient model guidance support for such. ...TROPICAL WAVES... A tropical wave axis is N of 02N along 83W moving W at 15 kt. Scattered moderate and isolated strong convection is described in the monsoon trough section below. A tropical wave axis is N of 04N along 97W moving W at around 10 to 15 kt. Associated convection is described in the monsoon trough section below. A tropical wave axis is from 03N to 19N along 111W 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 low pressure over northern Colombia near 09N75W to 06N86W to 13N103W then resumes near 12N111W to 09N122W to 12N127W then resumes near 15N135W to 14N140W. Scattered moderate and isolated strong convection is from 03N to 07N E of 80W, within 180 nm N of the axis between 81W and 102W, from 09N to 11N between 102W and 105W, from 07N to 10N between 112W and 122W, from 18N to 21N W of 137W. Also, scattered moderate to strong convection is from 23N to 27N in the Gulf of California associated with a surface and upper level trough. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A ridge extends southeast from a 1038 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. 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 tonight. REMAINDER OF THE AREA... Please see special features section above for information on T.S. Miriam, and for possible tropical cyclone development of broad 1008 mb low pressure near 13.5N108.5W. 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. The exception will be from 18N to 22N W of 135W where the remnants of a surface trough are shifting W. The associated winds and seas will shift W of the area by Tue afternoon. $$ Lewitsky