000 AXPZ20 KNHC 211024 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Wed Aug 21 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 0845 UTC. ...SPECIAL FEATURES... A 1007 MB low pressure system is located near 14.5N104.5W, or about 250 nm south of Manzanillo, Mexico. This area of low pressure is embedded within a large area of cyclonic winds that cover the area between 96W and 112W. A large area of showers and thunderstorms associated with this broad circulation continues tonight, with a cluster of strong thunderstorms persisting near the low. and suggesting that it is slowly becoming better organized. Environmental conditions are favorable for further development, and tropical cyclone is expected to form within the next 48 hours. Global models suggest that gale force winds will develop by Thu afternoon associated with this low. Currently, numerous moderate and scattered strong convection is located within 180 nm across the NW and 120 nm across the SE semicircles, while scattered moderate to strong convection is elsewhere from 06.5N to 18N between 94W and 118W. The low is expected to move WNW at 10 to 15 kt through 24 hours, running parallel and several hundred miles offshore the coast of central Mexico, and then turn more NW and offshore of Baja California. This system could still produce locally heavy rainfall leading to flash flooding across the coastal states of Mexico from Oaxaca to Jalisco over the next couple of days. Refer to the latest NHC High Seas Forecast under AWIPS/WMO headers MIAHSFEP2/FZPN03 KNHC for more details on the forecast of this low. ...TROPICAL WAVES... A tropical wave extends from the eastern Bay of Campeche S-SE across far southeast Mexico and Guatemala to near 07N89W. Scattered to numerous moderate to strong convection is occurring ahead of this wave from 10N to the Mexican coast between 93W and 100W, while scattered moderate isolated strong convection is elsewhere behind the wave from 05.5N TO 10N between 81W AND 93W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N73W TO 08N80W TO 11.5N91W to low pressure near 14.5N104.5W to 11.5N110W to 16.5N120W to low pressure near 16N123.5W to near 12N139W. Scattered strong convection is noted from 03N to 08.5N E of 79.5W. Scattered moderate to strong convection is within 120 nm either side of the trough between 130W and 140W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section for more details about the low pressure area offshore of Manzanillo. The pressure gradient between high pressure northwest of the area and low pressure across the northern Gulf of California is producing fresh to locally strong NW winds offshore of Baja California N of 25N this morning, and is expected to continue today before retreating to the NW late this afternoon and evening. This will maintain seas of 5-7 ft in mixed NW to N swell. Low pressure over the U.S. Great Basin will induce fresh to strong SE to S winds over middle and north portions of the Gulf of California Wed evening through Fri. A middle to upper level trough extending from the SW Gulf of Mexico WSW across central Mexico has maintained unstable upper level conditions and is supporting ongoing moderate to strong convection across the waters from Cabo Corrientes to the Mazatlan area. This convection is expected to diminish this morning. The trough will remain in place through tonight and is expected to support another round of late afternoon and night time convection across this area again Wed. Overnight scatterometer data showed E to SE winds of 20 kt between the low pressure center S of Manzanillo to the coast between Puerto Angel and Manzanillo. Seas in this region are ranging from 6 to 10 ft. Look from fresh to strong E to SE winds and seas remaining in the 6-9 ft range through Thu as the low moves parallel to the coast. Very active convection also across this area will have the potential for strong wind gusts and frequent lightning. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... A weak pressure gradient is expected to produce 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 today, building seas to 6 to 7 ft late today into Thu. REMAINDER OF THE AREA... A 1022 mb high pressure located near 30N133W 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. The remnants of a low pressure center persist along the monsoon trough near 16N123.5W. fresh winds to around 20 kt surrounding this low are combining with mixed swell across the region to produce seas of 6-8 ft from 15N to 17.5N between 124W and 130W. This low will shift W and weaken through Fri. Elsewhere winds are expected to increase S of the monsoon trough through Thu night, particularly between 105W and 120W, in response to the developing low pressure system offshore of Manzanillo. As the monsoon through continues to lift northward fresh to strong SW monsoonal winds will create wind waves that will combine with SW swell to produce seas of up to 10 ft S of 15N between 100W and 120W through Thursday. Some northerly swell will cross south of 30N to near 25N around 120W Thursday, with seas around 8 feet expected. $$ Stripling