000 AXPZ20 KNHC 191605 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Fri Apr 19 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 1545 UTC. ...SPECIAL FEATURES... ...Strong April Gap Wind Event... Gulf of Tehunatepec Gale Warning: The gale force winds have begun to funnel through the Chivela pass and out across the Gulf of Tehuantepec as of 12Z this morning. As the pressure gradient tightens further over southeastern Mexico late tonight, expect for the present north to northeast 30-40 kt gale force winds to increase to 35-45 kt along with waveheights peaking at about 18 ft. The gradient will slacken just a little by early Sat afternoon allowing for the gale force winds to diminish to just under minimal gale force, however, a pulse of minimal gale force winds is expected Sat night before the gradient begins to slacken as high pressure over the western Gulf of Mexico weakens while shifting eastward. Winds over the Gulf of Tehuantepec will response by diminishing to just below gale force early on Sun, then become light and variable during Sun afternoon. Seas in the Gulf of Tehuantepec will lower to below 8 ft on Sun afternoon. The leading edge of the 8 ft seas that will propagate dowmstream from the Gulf will reach near 06N between 98W and 105W by early Sun, and subside to less than 8 ft on Sun afternoon. Please read the Pacific High Seas Forecast under the AWIPS header MIAHSFEP2 and under the WMO header FZPN03 KNHC for more specific marine details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A trough extends from 09N84W to 08N93W to 08N103W, where scatterometer data from last night indicated the ITCZ begins and continues to 06N110W to 05N121W to 05N130W and to beyond the area at 03N140W. Scattered moderate to isolated strong convection is within 240 nm south of the trough between 83W and 89W, and also within 180 nm south of the trough between 94W and 98W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... The pressure gradient associated with a northwest to southeast oriented high pressure over these waters is allowing for gentle to moderate northwest winds to continue to the west of Baja California. The waveheights in these waters are in the 6-8 ft range and will change little through the weekend. A set of northwest swell producing seas of 7-9 ft is expected to propagate into the far northeastern part of the area late Sun night into Mon. Gulf of California: Fresh to strong southwest winds will begin over much of the far northern Gulf of California early on Sat, before diminishing on Sat afternoon and beginning again Sat night into early Sun, diminish Sun afternoon, pulse again on Sun night before diminishing early on Mon. Gulf of Tehuantepec: Please read the Special Features section above for a recently started strong gale force wind gap event. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Moderate to fresh NE to E winds will pulse at night, increasing to fresh to strong Sat evening as the pressure gradient tightens from southern Mexico to Costa Rica. Strong winds downstream will reach 09N and 91W on Sun morning with waveheights peaking to 8 ft. Fresh to strong winds will continue to pulse every night through Tue, however seas are expected to be below 8 ft. Gulf of Panama: Mainly variable light to northeast moderate winds are expected through early next week. Light to moderate wind speeds will prevail elsewhere across the waters west of Ecuador through Tue night. The sea heights will remain in the range from 6 to 7 ft, in SW swell through midweek. REMAINDER OF THE AREA... A high pressure ridge enters the area through 32N135W and reaches southeastward to 24N123W and to near 18N115W. The pressure gradient between the ridge and lower pressure in the subtropics and tropics will result in moderate to fresh northeast to east trades over the area from 08N to 13N W of about 137W. This area of strong trades will expand eastward through the Sun, with waveheights peaking to around 9 ft, but may briefly reach 10 ft at times. The surface trough, that earlier was a long a position from near 05N131W to 01N137 was not identifiable at the surface at 12Z. A surface trough will develop along a position from 07N117W to 05N123W to 02N126W per model boundary layer and surface moisture convergence over the weekend. Expect for showers and thunderstorms to be scattered to possibly numerous near this trough. $$ Aguirre