000 AXPZ20 KNHC 201607 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Fri Apr 20 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 1200 UTC surface analysis and satellite imagery through 1515 UTC. ...SPECIAL FEATURES... Minimal gale force winds continue across and downstream of the Gulf of Tehuantepec to near 12.5N96.5W this morning. Winds will further diminish throughout the day and fall below gale force by around noon today and then to 20-25 kt within about 90 nm of the coast by this evening. 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 gradually weaken. Winds will become light and variable and seas will subside below 8 ft by Sat evening. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 07.5N76W TO 05N90W TO 08N106W TO 06N118W. The ITCZ continues from 06N118W TO 07.5N124W to beyond 06.5N140W. Scattered moderate to strong convection is present from 04N TO 07.5N E OF 85W to the coast of Colombia, within 150 nm of the trough between 91W and 109W, and from 05N to 11.5N between 100W and 128W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Fresh to strong NW winds and seas of 5 to 8 ft prevail across the offshore waters of Baja California. The weakening cold front that was crossing Baja California Norte and the adjacent waters has dissipated overnight. Fresh to strong NW winds can be expected over the waters W of Baja California today as a tight pressure gradient sets up between a ridge building in behind the front over the northern waters and lower pressure over the SW United States and NW Mexico. NW swell following the front will maintain seas at 5-8 ft through tonight. Winds and seas W of the peninsula will then diminish Sat through Mon as the high to the N weakens in response to low pres and an attendant cold front approaching from the NW. Moderate NW winds over the Gulf of California will strengthen today and become fresh over the northern and central Gulf. Winds will subside over the Gulf Sat and Sun as the high weakens slightly and the area of low pressure moves east. See the special features section for details concerning the gale force winds affecting the Gulf of Tehuantepec. 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 area expected to pulse at night 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 this morning. Very active convection overnight has become concentrated from 04N TO 07.5N E OF 85W to the coast of Colombia, and is likely producing strong gusty winds and very rough seas to 8 ft or greater this morning. Northerly winds will become moderate today 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 05N 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... A 1029 mb high pressure center was located north of the forecast area near 36N132W. The high ridges SE across the northern forecast waters to near the Revillagigedo Islands. The ridge has been weakened temporarily by cold front that dissipated overnight over the NE waters. The high will be reinforced by stronger high pressure building in behind the dissipated cold front today through Sat. Cross equatorial SW swell moving into the southern forecast waters will affect the waters near the equator between 98W and 120W this morning. Seas will subside to 8 ft or less across most of this area today by this evening. Another round of SW swell could cause waters near the equator to build to 8 ft or above by early next week. The pressure gradient between the ITCZ and building high pressure to the north will support fresh to strong NE trades N of the ITCZ generally between 10N and 15N W of 125W through Saturday. The combination of these winds, NW swell and SW swell will support combined seas of 8 to 12 ft over these waters into Saturday, expanding N to 30N by Sunday as NW swell propagates into the northern waters. The swell will begin to decay below 8 ft Sunday night before becoming reinforced by another pulse of NW swell by Monday night. $$ Stripling