000 AXPZ20 KNHC 190925 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Thu Apr 19 2018 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 0900 UTC. ...SPECIAL FEATURES... A gale warning continues for the Gulf of Tehuantepec. A cold front entering the Gulf of Mexico will usher in high pressure over the northern Gulf of Mexico tonight and Fri. This will tighten the pressure gradient across the Isthmus of Tehuantepec and funnel very strong winds over the Gulf of Tehuantepec. N winds will peak at minimal gale force tonight and Fri morning and produce 10 to 14 ft wind-driven seas to as far downstream as 10N100W. Winds will diminish by Saturday afternoon, and seas will subside below 8 ft. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 06N77W to 07N96W. The ITCZ continues from 07N96W to 07N120W to 05N130W to 06N140W. A large area of active convection is associated with the ITCZ. Scattered moderate and isolated strong convection is present from 07N to 12N between 109W and 115W, and within 75 nm either side of the ITCZ axis between 122W and 132W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Moderate NW to N winds and seas of 6-7 ft are evident in the offshore waters. Seas will subside today as the NW swell fades. A cold front will reach northern Baja California later today, then weaken as it moves SSE through Fri. Moderate NW to N winds over the waters W of Baja California will freshen behind the front tonight and Fri as a tight pressure gradient develops between a ridge building in behind the front over the northern waters and lower pressure over the SW CONUS and NW Mexico. NW swell following the front will cause seas to build along the length of the peninsula. Moderate NW winds over the Gulf of California will strengthen on Fri and become fresh to locally strong over the central Gulf. Winds will subside over the Gulf Sat and Sun as the high weakens slightly and the area of low pressure fills. See the special features section for details concerning the gale force winds expected for the Gulf of Tehuantepec tonight and Fri morning. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Pulsing strong nocturnal NE to E winds are expected across and downstream of the Gulf of Papagayo through Sun night. Gulf of Panama: Fresh northerly winds and seas of 6 to 7 ft are expected across the Gulf of Panama today. Winds will become moderate Fri through Sun, with seas generally running between 4 and 6 ft. Elsewhere, light to gentle winds are expected through Mon as a weak surface through meanders west of Panama and Colombia. Seas will subside from 5- 7 ft to 3- 5 ft by Sun as long period SW swell from the Southern Hemisphere decays. The cross-equatorial swell will mix with residual swell from Papagayo through Fri, and increase seas to 5-7 ft S of 10N. REMAINDER OF THE AREA... High pressure centered northwest of the forecast area ridges SE across the northern forecast waters to near the Revillagigedo Islands. The ridge will weaken some during the next 24 hours, but be reinforced by stronger high pressure building in behind a dissipating cold front Fri and Sat. Cross equatorial SW swell moving into southern forecast waters will dominate the waters S of 10N between 95W and 120W today. Seas will subside to 8 ft or less across most of the area W of 120W by midday Fri. Another round of SW swell could cause waters near the equator to build to 8 ft or above by early next week. $$ Mundell