000 AXPZ20 KNHC 180924 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Sun Aug 18 2019 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 0900 UTC. ...SPECIAL FEATURES... A 1010 mb low pressure center is located near 12.5N92W, or about 120 nm south of the coast of Guatemala. Numerous moderate and scattered strong convection is noted within 120 nm in the NW semicircle of the low. Additionally, numerous moderate and scattered strong convection is from 12N to 18N between 94W and 99W. This activity is affecting coastal portions of Chiapas and Oaxaca in Mexico, with heavy rainfall and flash flooding possible. This low is expected to move W-NW through the next couple of days with a medium chance of tropical cyclone formation. Winds and seas are expected to increase and build as the low parallels the coast. Refer to the latest NHC Tropical Weather Outlook under AWIPS/WMO headers MIATWOEP/ABPZ20 KNHC for more information. ...TROPICAL WAVES... A tropical wave axis extends from the coast of El Salvador southward into the eastern Pacific along 88W/89W. This wave is moving W at around 15 kt, but will likely slow down in forward motion over the next couple of days. No significant convection is noted over the eastern Pacific with this wave. A tropical wave axis is located along 104W/105W, moving W at around 10 kt. No significant convection is noted with this wave. A tropical wave axis is located along 119W, moving W at around 5 kt. Numerous moderate and scattered strong convection is noted from 08N to 14N between 113W and 121W. A tropical wave axis is located along 127W/128W, with a 1010 mb low pressure area near 13.5N127W, moving W at around 5 kt. Scattered moderate convection is within 120 nm in the NW quadrant of the low. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 11N86W to low pressure near 12.5N92W to 12N104W to low pressure near 12.5N115W to low pressure near 13N127W to 09N140W. Scattered moderate to strong convection is from 08N to 11N between 93W and 99W. Scattered moderate and isolated strong convection is from 07N to 17N between 107W and 111W, and also from 12N to 14N between 122W and 124W. Scattered moderate convection is from 08N to 10N between 134W and 135W, and also from 14N to 16N between 134W and 136W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please read the Special Features section for more details about the low pressure area south of Guatemala forecast to impact the waters. A weak high pressure ridge extends SE from the north-central Pacific into the Baja California offshore waters, bringing gentle to moderate NW winds to these waters. This ridge will generally remain in place into the middle of the week, with the pressure gradient increasing Monday and Tuesday, supporting NW winds to moderate to fresh offshore of Baja California Norte. A low pressure trough along the Baja California peninsula will support fresh S to SE winds over the northern Gulf early this morning before diminishing. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Please read the Special Features section for more details about the low pressure area south of Guatemala. Offshore winds in the Gulf of Papagayo will pulse at times to fresh through the early part of the week. Southerly swell with seas of 5 to 7 ft offshore of Ecuador and the Galapagos Islands will subside through today, with a new set of long period SW swell arriving by mid-week. Otherwise, mainly moderate winds will prevail, along with seas of 4 to 6 feet. REMAINDER OF THE AREA... A weak ridge extends SE from 1026 mb high pressure near 41N143W. Scatterometer data showed gentle to moderate trades outside of any deep convection, while altimeter passes sampled 4-7 ft seas, except N of 29N between 123W and 131W where seas were up to 8 ft in northerly swell. The swell will subside through today. A weak cold front or pre-frontal trough is forecast to breach SE of 30N140W by the end of the forecast period with a wind shift and building seas to 7 ft behind it. $$ Lewitsky