221 AXPZ20 KNHC 280406 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 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 0000 UTC surface analysis and satellite imagery through 0345 UTC. ...SPECIAL FEATURES... Tropical Storm Miriam centered near 14.0N 132.5W at 28/0300 UTC or 1545 miles E 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 on Tuesday. Numerous moderate and scattered strong convection is within 150 nm in the E semicircle and within 90 nm in the W semicircle. Scattered moderate convection is elsewhere from 09N to 17N between 129W and 136W. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCPEP5/WTPZ35 KNHC for more details. Low pressure near 15N110W 1006 mb is moving W with scattered moderate and isolated strong convection within 300 nm in the N semicircle and within 150 nm in the SW quadrant. Associated winds and seas are currently 20 to 25 kt with seas in the range of 8 to 9 ft. The low has a high chance of becoming a tropical cyclone during in less than 24 hours. 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 03N along 87W 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 101W moving W at around 10 to 15 kt. Scattered moderate convection is N of 09N between 97W and 104W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from low pressure over northern Colombia near 09N74W to 08N83W to 09N96W to low pressure near 15.2N110.4W to 10N120W to 12N125W. Scattered moderate and isolated strong convection is from 04N to 10N E of 99W. Scattered moderate convection is from 06N to 13N between 117W and 126W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A ridge extends southeast from a 1037 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 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 1006 mb low pressure near 15.2N110.4W. 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 14N to 23N W of 135W 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 by Tue afternoon. $$ Ramos