000 AXPZ20 KNHC 222208 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Sun Apr 22 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 1800 UTC surface analysis and satellite imagery through 2045 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 09.5N73W TO 09.5N76W TO 06N97W. The ITCZ continues from 06N97W TO 08N107W TO 05N126W to beyond 06N140W. Scattered moderate TO strong convection is present from 04N TO 09N BETWEEN 77W AND 85W...within 120 nm N AND 150 nm S OF the trough between 85W AND 97W...from 08N TO 13.5N between 107W AND 117W...and within 180 nm N and 150 nm S of the ITCZ W of 117W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Moderate NW winds with seas of 5 to 7 ft currently prevail across the offshore waters of Baja California as ridging from the NW and lower pressure over the SW United States and NW Mexico combine to maintain a modest pressure gradient over the area. Winds W of the peninsula will gradually diminish through Tue as the high to the NW weakens and lower pressure over the SW United States and NW Mexico fills and shifts east. However, new NW swell moving into the region today will help to maintain seas in the 5-7 ft range through Monday, except around 8 ft to the N through W of Isla Guadelupe. Winds and seas will then diminish very slightly Mon night through Wed. Light to gentle variable winds prevail throughout the Gulf of California, and are expected to persist through Wed as the high gradually weakens and the area of low pressure weakens and moves east. W across the Gulf of Tehuantepec region have become light and variable this afternoon. Another cold front moving across the NW Gulf of Mexico today and tonight will induce the next mild gap wind event over the Gulf of Tehuantepec Mon through Thu. A small plume of N to NE winds will be intermittent across the immediate Gulf waters, and will be strongest during nocturnal drainage flow. Gales are not expected during this event. 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 between nightfall and mid morning to 20-25 kt across and downstream of the Gulf of Papagayo through at least Tue night with seas peaking each episode between 6 and 8 ft. Winds over the Gulf will be lighter on Wed and Thu as high pres N of the Caribbean weakens. Gulf of Panama: Gentle to moderate N to NE winds with seas of 3 to 6 ft in SW swell prevail across the Gulf of Panama and offshore of Panama and Colombia to 250 nm this afternoon. Active convection continues across the region today from 04N TO 09N E of 85W, with thunderstorms producing strong gusty winds and rough seas. A surface trough extending W across Panama and Costa Rica, then WSW to 06N97W is acting as a focus for the convection. Winds across the Gulf will remain gentle to moderate tonight through Thu, while farther offshore and SW, gentle to moderate SW winds will prevail Sun through Thu. Corresponding seas will generally run between 4 and 6 ft. Elsewhere, mainly light to gentle winds are expected S of 08N through Thu. Cross-equatorial swell will mix with residual swell downwind from Papagayo through Wed, 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, then rebuild to between 5 and 7 ft on Mon and Tue as another round of SW swell arrive. REMAINDER OF THE AREA... Strong high pressure centered well offshore of Northern California has begun to weaken and shift NE today, as a new cold front approaches 140W from the NW. The high continues to ridge 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 NE trades N of the ITCZ generally between 08N and 22N W of 125W through tonight. The combination of these winds, NW swell and SW swell will support combined seas of 8 to 10 ft over these waters. Active convection continues across this trade wind belt this afternoon as a deep layered trough just to the NW is maintaining unstable conditions aloft. The area of 8 ft seas will gradually shrink in coverage through Tue as the ridge to the N weakens. A cold front will reach the far NW corner of the discussion area Tue morning, preceded by the next pulse of NW swell. The front is not expected to move beyond 28N137W by Wed afternoon, with N to NE winds of 20-25 kt prevailing across the far NW waters. Seas in excess of 8 ft will only impact the NW waters during this time. A new pulse of SW swell is moving into the equatorial waters W of 100W this afternoon, and will spread NE towards the offshore waters through Tue. This cross-equatorial swell will combine with NW swell to create an even larger area of 7 to 9 foot seas W of 81W through Tue, and reach as far N as 06N. $$ Stripling