441 AXPZ20 KNHC 201539 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1302 UTC Tue Aug 20 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...SPECIAL FEATURES... A low pressure system of 1008mb located near 13.5N100W or a couple of hundred miles south of the southern coast of Mexico continues to produce a large area of cloudiness and thunderstorms. Currently, most of the strongest convection associated with this low remains over the offshore forecast waters. A cluster of moderate to strong convection is noted from 14N to 18N between 103W and 107W. Numerous moderate isolated strong convection is seen elsewhere from 10N to 16N between 98W and 105W. Environmental conditions are conducive for development, and a tropical depression is likely to form during the next day or so while the low moves west-northwestward at 10 to 15 kt, parallel to and just offshore of the coast of Mexico. This system could produce heavy rainfall and flash flooding over portions of southeastern Mexico during the next couple of days. The latest Tropical Weather Outlook gives this system a high chance of tropical cyclone formation through 48 hours. A Gale Warning has been issued in association with this system (It is not a tropical cyclone yet) forecast to reach tropical storm force winds in about 48 hours. Farther west, another low pressure system located near 16N122W or more than 900 miles west-southwest of the southern tip of the Baja California peninsula is producing disorganized showers and a few thunderstorms, but mainly on the west side of the low from 15N TO 17N between 123W and 127W. Environmental conditions are expected to become more conducive for development by mid-week, and a tropical depression is likely to form during the next few days while the system moves westward to west-northwestward at about 10 kt. The latest Tropical Weather Outlook gives this system a medium chance of tropical cyclone formation through 48 hours. Latest scatterometer dat indicated winds of 20 to 25 kt within about 90 nm SE semicircle of low center while an altimeter pass provide observations of 10 ft seas near the NE quadrant of the low center. Refer to the latest NHC Tropical Weather Outlook under AWIPS/WMO headers MIATWOEP/ABPZ20 KNHC for more information on both of these lows. ...TROPICAL WAVES... A tropical wave axis is along 115W from 06N to 17N, moving west around 5 kt. Scattered moderate convection is noted from 09N to 15N between 110W and 115W. This wave is expected to be absorbed into the low to its west. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N85W to low pressure near 13.5N100W to 11N110W to another low pressure near 16N122W to a third low pressure near 14.5N131.5W to beyond 11N140W. In addition to convection noted above with the lows near 100W and 122W, and the tropical wave, scattered moderate to isolated strong convection is noted from 05N to 12N between 81W and 90W. Cluster of moderate to strong convection from 06N to 09N between 92W and 95W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section for more details about the low pressure area in the Gulf of Tehuantepec region. High pressure well northwest of the area will promote fresh to locally strong NW winds offshore of Baja California Norte through Wed. Low pressure over the U.S. Great Basin will induce fresh to strong SE to S winds over the Gulf of California Thu and Fri. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... A weak pressure gradient is producing only gentle to moderate winds across the region for the next several days. Long-period cross equatorial SW swell will reach the waters between Ecuador and the Galapagos Islands on Wed, building seas to 6 to 7 ft late Wed into Thu. REMAINDER OF THE AREA... Please see the Special Features section for more details about the low pressure area near 16N122W. A 1007 mb low pressure is centered near 14.5N131.5W, moving west at 5 to 10 kt. Scattered moderate is from 12N to 14N between 129W and 133W. A cluster of moderate to isolated strong convection is noted to the W of the low center from 13N to 15N between 134W and 136W. A 1019 mb high pressure located near 30N128W extends a ridge across the northern forecast waters. This system will remain nearly stationary over the next 48 hours producing mainly gentle to moderate winds N of 20N and W of 110W. The pressure gradient between the ridge and lower pressures in the vicinity of the monsoon trough will result in moderate to fresh trade winds S of 20N. Wind are expected to increase S of the monsoon trough Wed through Thu night, particularly between 105W and 120W. The monsoon trough may lift northward to near 15N as the low pressure system located near Mexico progresses west-northwestward. As the monsoon trough pulls northward, combined SW swell and wind waves south of the trough may produce seas of up to 10 ft. $$ GR