000 AXPZ20 KNHC 281605 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1402 UTC Fri Jun 28 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 1510 UTC. ...SPECIAL FEATURES... Tropical Storm Alvin centered near 19.0N 117.7W at 28/1500 UTC moving NW at 13 kt. Estimated minimum central pressure is 999 mb. Maximum sustained wind speed is 55 kt with gusts to 65 kt. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP1/WTPZ21 KNHC for more details. Scattered moderate convection is present in the NE semicircle within 180 nm of the center. Steady weakening is forecast, with Alvin expected to become a remnant low by Saturday night and dissipate by Sunday. See the latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP1/WTPZ21 KNHC for more details. Gulf of Tehuantepec Gale Warning: High pressure over Mexico combined with a tropical wave passing south of Tehuantepec is causing a Gulf of Tehuantepec gap wind event. Minimal N to NE gale conditions are expected to continue through Sat night then slowly diminish Sun and Mon. Peak seas are expected to reach around 16 ft today. Please read the latest High Seas Forecast issued by the National Hurricane Center under AWIPS/WMO headers FZPN03 KNHC/HSFEP2 or at website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for details. A tropical wave has an axis extending from 02N97W to 11N97W, moving W around 10 kt. Scattered moderate and isolated strong convection is found from 06N to 11N between 93W and 102W. Environmental conditions are expected to be conducive for the development of this system over the next several days, and a tropical depression is likely to form late this weekend or early next week while the disturbance moves W to WNW well away from the coast of Mexico. This system has a medium chance of becoming a tropical depression during the next 48 hours and a high chance of becoming a tropical depression during the next 5 days. ...TROPICAL WAVES... A tropical wave has an axis extending from 07N89W to 16N89W, moving W around 15 kt. Scattered moderate and isolated strong convection is found from 06N to 10N between 84W and 91W. A tropical wave with an axis extending from 04N136W to 14N135W is moving W around 10 kt. Scattered moderate and isolated strong convection is seen from 06N to 10N between 132W and 137W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N77W to 09N87W to 08N98W to 06N109W, then resumes from 12N114W to 09N121W. The ITCZ continues from 09N121W to 08N131W, then resumes from 08N137W to beyond 07N140W. Numerous moderate and scattered strong convection is seen within 90 NM of 06N79W. Scattered moderate and isolated strong convection is observed elsewhere within 210 nm either side of the monsoon trough E of 99W. Scattered moderate and isolated strong convection is present from 04N to 13N between 99W and 111W. Scattered moderate and isolated strong convection is taking place 06N TO 11N W OF 115W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section for more details about the Gulf of Tehuantepec Gale Warning. Quiescent conditions are expected for the next several days over the Gulf of California. Tropical Storm Alvin is expected to not significantly impact the Mexican offshore zones, with moderate to fresh NW to N winds west of Cabo Corrientes and Baja California through at least Mon night. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... A tight north to south pressure gradient across Central America is causing a significant Gulf of Papagayo gap wind event. Fresh to strong NE winds are expected to extend from the coast of Central America to 95W through Sat, then diminish by Sat night as the pressure gradient relaxes. The extended length of this plume of offshore winds extending from the Papagayo area will generate a broad zone of seas 7 to 10 ft through Sat that will combine with N swell from Tehuantepec to produce a large area of high seas between 90W and 100W through Sun. Moderate offshore winds will prevail north of the monsoon trough, with moderate S- SW winds south of the trough axis the next few days. New S to SW long- period swell will reach the equator beginning on Sun and produce rough waves. REMAINDER OF THE AREA... Please see the Special Features section for more details about Tropical Storm Alvin. A broad weak ridge extends from high pressure NNW of the area. Gentle to moderate trades prevail south of the ridge. Seas are mainly running 5 to 8 ft in mixed northerly and southerly swell. Overall high pressure will continue for several more days. Trades will strengthen slightly in the W central waters this weekend into early next week, with seas building to between 8 and 10 ft. SW and SE swell along the equator will gradually decay. $$ CAM