000 AXPZ20 KNHC 182110 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Wed Sep 18 2024 Tropical Weather Discussion for the eastern Pacific Ocean from 03.4S to 30N, east of 120W including the Gulf of California, and from the Equator to 30N, between 120W and 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. ...TROPICAL WAVES... A western Caribbean tropical wave is along 83W. It extends southward across the Costa Rica/Panamanian border to the eastern Pacific waters north of 05N. It is moving westward at 10 kt. Scattered moderate to isolated strong convection is within 120 nm either side of the southern part of the wave from 05 to 08N. A tropical wave is along 96W extending from southeastern Mexico southward over the eastern Pacific waters to near 04N, moving westward at about 10 kt. Scattered moderate to isolated strong convection is within 180 nm west of the wave from 07N to 10N and from 12N to 15N. Similar activity is within 180 nm east of the wave from 10N to 13N. A tropical wave is along 114W from from 05N to 20N, moving westward at 10 to 15 kt. Scattered moderate to isolated strong convection is within 120 nm either side of the wave from 12N to 16N and within 60 nm west of the wave from 14N to 16N. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 08N75W, west-northwestward to across northern Panama, to the central portion of Costa Rica and to 10N85W to 11N98W to 10N110W to 11N117W to 09N129W, where it transitions to the ITCZ and continues to beyond 10N140W. Scattered moderate to isolated strong convection is within 180 nm of the trough between 91W and 93W, and within 60 nm north of the trough between 98W and 102W. Scattered moderate convection is within 180 nm south of the trough between 112W and 119W, between 101W and 105W, also within 120 nm south of the trough between 124W and 129W and within 60 nm north of the trough between 123W and 126W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A broad surface ridge extends southeastward into the region through 30N129W to offshore of Cabo Corrientes near 17N107W. Over the offshore waters of the Baja California peninsula, moderate NW winds prevail. Seas are generally 4 to 6 ft in moderate period swell except 6 to 7 ft in the areas of strong winds. Moderate NW to N winds prevail elsewhere to the south across the Revillagigedo Islands, while moderate NW winds are across the near shore waters from Cabo Corrientes to Manzanillo. Light to gentle NW to W winds cover the remaining waters eastward to Tehuantepec. Seas south of 20N are to 5 ft in long period SW swell E of 105W and in NW swell W of 105W. Scattered showers and thunderstorms moving westward are over the waters SW of the Gulf of Tehuantepec and Chiapas. This activity is present from 11N to 14N between 93W and 103W. Light to gentle S to SW winds are over the northern part of the Gulf of California while gentle SW to W winds are over the southern part of the Gulf, and light and variable winds are over the central portion. Seas are 2 to 4 ft over the Gulf of California, except to 5 ft in SW swell over the entrance to the Gulf. For the forecast, the current Pacific ridge will remain in place and fluctuate throughout the rest of the week. This pattern will maintain moderate to fresh NW to N winds over the offshore waters of the Baja California peninsula, gradually weakening through Thu. Expect fresh winds near the coast each evening through Sat. High pressure will strengthen modestly Fri and Sat to bring a return to moderate to fresh winds. Variable winds less than 15 kt are expected across the Gulf of California, except for pulses of moderate W gap winds across southern portions and fresh SW gap winds N of 30N each evening and night through Thu. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gentle to moderate SW to W winds are occurring south of the monsoon trough. North of the monsoon trough, moderate or weaker winds are observed, with moderate easterly gap winds flowing across the Papagayo region. Seas are 4 to 5 ft in SW swell except to 6 ft south through west of the Galapagos Islands. Increasing scattered to numerous showers and thunderstorms are within 90 to 120 nm of the coasts of Panama, Colombia and southern Costa Rica. For the forecast, gentle to moderate SW to W winds will continue south of the monsoon trough near 10N through tomorrow afternoon, then begin to freshen offshore Thu through Sat. Seas will build to 5 to 7 ft during this time in a mix of SW swell and westerly wind swell. Active weather is expected south of 10N Fri into the weekend. North of 10N, moderate or weaker winds are expected through Thu evening before the monsoon trough begins to lift northward, and winds shift to westerly and gradually increase to gentle to moderate by Sat. Seas will build slightly over the area waters Thu through Sat as a long fetch of westerly winds sets up from offshore to 110W, and generates increasing wind waves moving into the area waters. ...REMAINDER OF THE AREA... Surface ridging extending from a 1030 mb high centered near 38N157W extends east-southeastward to 30N129W to offshore of Cabo Corrientes near 17N107W. The pressure gradient between the ridge and the ITCZ/monsoon trough to the south is forcing moderate to locally fresh NE trades south of about 25N and west of 125W. Seas are 5 to 7 ft in mixed NE and SE swell south of 17N west of 133W, and 4 to 6 ft elsewhere. For the forecast, little overall change is expected over the open Pacific waters for the next several days as the aforementioned ridge dominates the region. A weak cold front that is presently crossing 35N130W will sink southward across 30N east of 130W tonight into early Thu, then push southeastward before dissipating by Fri morning. This will induce a slight decrease in winds during that time period, with winds then increasing slightly Fri through Sat. SW to W monsoonal winds are expected to become well established south of 10N and east of 120W starting tonight through Sat, becoming moderate to fresh. Seas will build to 6 to 8 ft from 03N to 11N east of 120W during that time. $$ Aguirre