000 AXPZ20 KNHC 230919 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 614 UTC Mon Apr 23 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 0845 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 10N73W to 09N80W to 06N87W to 05N95W. The ITCZ continues from 05N95W to 06N113W to beyond 05N140W. Scattered moderate and isolated strong convection is present from 03N to 10N between 76W and 87W and within an area bounded by 11N109W to 15N116W to 05N131W to 05N108W to 11N109W. Scattered moderate convection is found from 08N to 12N W of 130W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Moderate NW winds and seas of 5 to 7 ft are currently noted 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, NW swell will help to maintain seas in the 5-7 ft range today, except around 8 ft to the N through W of Isla Guadalupe. Winds and seas will then diminish very slightly tonight 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. Winds and seas in the region will gradually increase on Thu and Fri as the ridge from the NW rebuilds. Winds in the vicinity of the Gulf of Tehuantepec are light and variable. However, high pressure building over the NW Gulf behind a cold front will induce the next gap wind event over the Gulf of Tehuantepec tonight through Thu. A small plume of N to NE winds will periodically affect the immediate Gulf waters, and will be strongest during nocturnal drainage flow. This event will be modest with winds peaking at strong speeds and seas peaking at 8 ft or less. 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 7 ft. Winds over the Gulf will be lighter Wed through Fri as high pres N of the Caribbean weakens. Gulf of Panama: Gentle to moderate N to NE winds and seas of 2 to 4 ft are seen across the Gulf of Panama with seas of 3 to 6 ft offshore of Panama and Colombia to 250 nm this morning. Active convection continues across the region this morning near and S of Panama and Costa Rica as well as along the SW coast of Colombia from 03N to 10N between 76W and 87W as showers and thunderstorms produce strong gusty winds and rough seas. A surface trough extending WSW from the border of Panama and Colombia is acting as a focus for the convection. Winds across the Gulf will remain gentle to moderate tonight through Fri, while farther offshore and SW, gentle to moderate SW winds will prevail through Fri. Corresponding seas will generally run between 4 and 6 ft. Elsewhere, mainly light to gentle winds are expected S of 08N through Fri. 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 of 4 to 6 ft will rebuild to between 6 and 8 ft tonight through Wed as another round of SW swell arrive. REMAINDER OF THE AREA... High pressure centered well offshore of Northern California near 37N133W has begun to weaken and shift NE 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 will remain strong enough to support fresh NE trades N of the ITCZ generally between 08N and 22N W of 125W through Thu. The combination of these winds, NW swell and SW swell will support combined seas of 7 to 9 ft over these waters. Active convection continues across this trade wind belt this morning as a deep layered trough extending from near 20N118W to 01N116W maintains unstable conditions aloft. A cold front will reach the far NW corner of the discussion area Tue morning, barely preceded by the next pulse of NW swell. The front will dissipate as it moves beyond 28N137W on Wed as fresh to locally strong winds affect the far NW waters. Seas in excess of 8 ft will only briefly impact the NW waters during this time. A new pulse of SW swell is moving into the equatorial waters W of 100W this morning, Seas of 8 ft or higher will primarily be confined to S of the equator, but the swell will continue spreading NE towards the offshore waters through Wed. This cross- equatorial swell will combine with NW swell to create an even larger area of 7 to 9 foot seas S of 20N and W of 100W Tue through Thu. $$ CAM