000 AXPZ20 KNHC 182057 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2016 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 1800 UTC surface analysis and satellite imagery through 2030 UTC. ...SPECIAL FEATURES... A 1008 mb low pressure center is located about 150 nm SW of the Guatemala/Mexico border, near 12N92W. The center is drifting WNW at less than 5 kt. Numerous moderate and scattered strong convection is located within about 240 nm of all quadrants. Heavy rainfall is occurring in areas along the coasts of El Salvador, Guatemala, and Chiapas. This low has a medium chance of tropical formation as it moves slowly WNW through Tuesday. Heavy rainfall and the potential for flash flooding is expected across portions of Guatemala, Chiapas, and Oaxaca over the next couple of days. Winds and seas should gradually increase as the low tracks parallel to 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 along 108W, moving west around 5 kt. Scattered moderate convection is located from 08N to 16N between 107W and 113W. A tropical wave axis is located along 121W, moving W around 10 kt. Late morning scatterometer data as well as recent satellite imagery indicated that low pressure has organized near 12N119W, with pressure of 1008 mb. Numerous moderate and scattered strong convection from 08N to 14N between 116W and 124W. Fresh westerly winds are occurring within about 240 nm SW semicircle of this low. There is a low chance of tropical formation from this tropical wave and associated low pressure over the next couple of days, and winds and seas may gradually increase as it continues moving W around 10 kt. A tropical wave is along 130W, moving W at 5 to 10 kt. Although the low pressure center associated with this wave has diminished today, scattered moderate convection continues from 13N to 17N between 127W and 131W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 08N76W to 10N86W to low pres near 12N92W to low pres near 12N119W to 15N130W. Scattered moderate convection is noted from 07N to 13N between 96W and 106W and from 08N to 14N between 113W and 116W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section for more details about the low pressure area south of Guatemala and approaching the Gulf of Tehuantepec. 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 slowly shift SE into the middle of the week, causing the pressure gradient to increase Monday through early Wednesday. This will support moderate to fresh NW winds offshore of Baja California Norte, becoming fresh to locally strong Tuesday afternoon and evening. A low pressure trough along the Baja California peninsula will support fresh S to SE winds over the northern Gulf this morning before tonight. This trough will redevelop again late Wed into Thu to again produce fresh southerly wind flow across the northern Gulf. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Please see the Special Features section for more details about the low pressure area SW of Guatemala. Winds across the Papagayo region will remain offshore and 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 tonight, with new long period SW swell arriving by mid-week. Otherwise, mainly moderate W to SW winds will prevail S of 10N, along with seas of 4 to 6 feet. REMAINDER OF THE AREA... A weak ridge extends SE from 1023 mb high pressure near 41N143W. Scatterometer data showed gentle to moderate trades outside of any deep convection, while altimeter data sampled 4-7 ft seas. 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. This will force the ridge ahead of it to shift ESE, and gradually tighten the pressure gradient to the south across the tradewind belt. E to NE tradewinds will freshen W of 120W Tue through the end of the week due to this pattern shift. $$ KONARIK