158 AXPZ20 KNHC 280951 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Tue Aug 28 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 0600 UTC surface analysis and satellite imagery through 0915 UTC. ...SPECIAL FEATURES... Tropical Storm Miriam centered near 14.0N 133.5W at 28/0900 UTC or 1285 nm ESE of Hilo, Hawaii moving W at 10 kt. Estimated minimum central pressure is 999 mb. Maximum sustained wind speed is 55 kt with gusts to 65 kt. Miriam is forecast to increase in intensity to hurricane strength today. Numerous moderate and scattered strong convection is from 11N to 15N between 132W and 136W. Scattered moderate convection is elsewhere from 10N to 16N between 128W and 138W. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCPEP5/WTPZ35 KNHC for more details. Low pressure near 16N111W 1007 mb is moving W with scattered moderate and isolated strong convection within 210 nm in the NW semicircle and within 90 nm in the SW quadrant. Associated winds and seas are currently 20 to 25 kt with seas in the range of 8 to 10 ft. The low has a high chance of becoming a tropical cyclone during the next two days. A gale warning has been issued beginning at 18 UTC Wed in the event that tropical cyclone formation does not occur by then. ...TROPICAL WAVES... A tropical wave axis is N of 05N along 89W 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 102W moving W at around 10 to 15 kt. Scattered moderate convection is N of 06N between 98W and 104W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from low pressure over northern Colombia near 09N74W to 08N83W to 08N96W to low pressure near 16N111W to 11N120W to 12N126W. Scattered moderate and isolated strong convection is from 04N to 10N E of 100W. Scattered moderate convection is from 08N to 16N between 114W and 124W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A ridge extends southeast from a 1037 mb high pressure near 43N150W 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 to occasionally fresh NW winds funneling along the coast of Baja California Norte through Fri, with seas generally in the 4 to 6 ft range. Winds will diminish on Sat as the pressure gradient weakens. Nocturnal offshore flow in the Gulf of Tehuantepec will pulse to moderate to fresh the next several nights. Otherwise, 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 moderate to fresh. REMAINDER OF THE AREA... Please see special features section above for information on T.S. Miriam, and for possible tropical cyclone development of broad 1007 mb low pressure near 16N111W. 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 16N to 23N W of 137W where the remnants of a surface trough are generating fresh to locally strong NE winds with seas to 9 ft. The associated winds and seas will shift W of the area this afternoon. $$ Ramos