000 AXPZ20 KNHC 210358 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 208 UTC Sat Apr 21 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 0000 UTC surface analysis and satellite imagery through 0245 UTC. ...SPECIAL FEATURES... Northerly winds across and downstream of the Gulf of Tehuantepec continue to gradually diminish, but will remain in the 20 to 30 kt range overnight as nocturnal drainage flow augments the winds. Seas are slowly subsiding and are now down to 8-11 ft. Winds will begin to more rapidly diminish in areal coverage after sunrise. Supporting high pressure across the southern U.S. behind a stalled cold front over the northern Gulf of Mexico is shifting slowly eastward, and is allowing the pressure gradient across the Isthmus of Tehuantepec to continue weakening. Winds will become light and variable and seas will subside below 8 ft by Sat evening. Another cold front entering the NW Gulf of Mexico could induce the next gap wind event over the Gulf of Tehuantepec Mon through Thu. Gales are not expected during this event. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 07N77W to 06N86W to 05N113W. The ITCZ continues from 05N113W TO 05N125W to beyond 06N140W. Scattered moderate and isolated strong convection is present from 05N to 07N between 86W and 91W, and from 05N to 09N between 105W and 112W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Fresh NW winds and seas of 5 to 8 ft prevail across the offshore waters of Baja California as a tight pressure gradient exists between a ridge building in from the NW and lower pressure over the SW United States and NW Mexico. NW swell following a front that swept through the area last night will maintain seas at 5-8 ft tonight. Winds and seas W of the peninsula will then diminish Sat through Mon as the high to the NW weakens. Moderate NW winds prevail over the N Gulf of California, while fresh NW winds are observed through the central Gulf. Winds will subside over the Gulf Sat and Sun as the high weakens slightly and the area of low pressure moves east. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Fresh NE to E winds across the region are expected to pulse from nightfall through morning to 20-25 kt across and downstream of the Gulf of Papagayo through at least Tue night with seas peaking each night between 7 and 9 ft. Gulf of Panama: Fresh northerly winds and seas of 5 to 7 ft in SW swell prevail across the Gulf of Panama and offshore of Panama and Colombia to 250 nm today. Very active convection has been developing at night along the coast of Colombia. More convection could produce strong gusty winds and very rough seas to near 8 ft later tonight. Northerly winds will become gentle to moderate Sat through Sun across the Gulf of Panama, while farther offshore and SW, gentle to moderate SW winds will develop. Seas will generally run between 4 and 6 ft. Elsewhere, mainly light to gentle winds are expected S of 06N through Tue. Cross-equatorial swell will mix with residual swell downwind from Papagayo through Tue, and maintain seas in this area between 5 and 7 ft. Elsewhere seas will subside to 3-5 ft by Sun as long period SW swell from the Southern Hemisphere decay. REMAINDER OF THE AREA... Strong high pressure is centered W of California near 140W. The high ridges SE across the northern forecast waters to near the Revillagigedo Islands. The pressure gradient between the ITCZ and the high to the north will support fresh to strong NE trades N of the ITCZ generally between 05N and 20N W of 125W through Saturday. The combination of these winds, NW swell and SW swell will support combined seas of 8 to 11 ft over these waters into Saturday, expanding N to 30N by Sunday as NW swell propagates into the northern waters. The NW swell will begin to decay below 8 ft Sunday night before becoming reinforced by another pulse of NW swell by Monday night. Cross equatorial SW swell moving into the southern forecast waters continue to decay and seas have subsided to 8 ft or less near the equator. Another round of SW swell could cause waters near the equator to build to 8 ft or above on Mon or Tue. $$ CAM