000 AXPZ20 KNHC 180927 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 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 0600 UTC surface analysis and satellite imagery through 0820 UTC. ...TROPICAL WAVES... A western Caribbean tropical wave is along 80W-81W and extends southward across Panama and into the eastern Pacific waters north of 05N, moving west at 10 kt. Widely scattered clusters of moderate to strong convection are along the coasts of Colombia, Panama, and Costa Rica north of 03W and east of 86W. A tropical wave is along 94W-95W extending from the Isthmus of Tehuantepec southward over the eastern Pacific waters to near 04N, moving westward at 10 kt. Scattered moderate to strong convection is described below, and extends between 90W and 96.5W. A tropical wave is along 111W from 17N to near 06N, moving westward at about 10 kt. Scattered moderate to strong convection is noted within 90 nm of the monsoon trough between 108W and 117W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10.5N74W to 11.5N83W to 09N95W to 10.5N117W to 10n132w, where it transitions to the ITCZ, and continues to 10.5N131W to beyond 10N140W. Scattered moderate isolated strong convection is noted from 03.5N to 10N E of 86W. Scattered moderate to strong convection is noted from 06.5N to 18N between 91W and 105W, and from 08N to 12.5N between 108W and 139W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A broad surface ridge extends southeastward into the region through 30N124W to offshore of Cabo Corrientes near 17N107W. Over the near and offshore waters of the Baja California peninsula, moderate NW winds prevail, except for strong winds along the coast between Punta Eugenia and Cabo San Lazaro. Seas are 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 sough of 20N are 4 ft in long period SW swell. Strong thunderstorms cover much of the nearshore waters of Tehuantepec and Chiapas south to 13N. Recent satellite scatterometer showed light to gentle W to SW winds covering most of the Gulf of California tonight, with an area of moderate westerly gap winds entering the Gulf waters between 24N and 25N. Seas are 1 to 3 ft, except to 4 ft in SW swell across the entrance. For the forecast, the current Pacific ridge will remain in place and fluctuate throughout the week. This pattern will produce moderate to fresh NW to N winds over the near and offshore waters of the Baja California peninsula tonight, gradually weakening this morning through Thu. Expect fresh winds near the coast each evening through night. 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 gaps winds N of 30N each evening and night. ...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 tonight, along about 10N. North of the monsoon trough, moderate or weaker winds are observed, with moderate easterly gap winds flowing across the Papagayo region. Seas are 4-5 ft in SW swell except to 6 ft south through west of the Galapagos Islands. Widely scattered clusters of moderate to strong thunderstorms are within 75 nm of the coasts from Colombia to Costa Ric. Earlier scattered strong convection occurring across the waters of Guatemala and Chiapas has shifted mostly into the Tehuantepec area. 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 across 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 from a 1031 mb high centered near 38N157W extends east-southeastward to 30N124W 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 28N and west of 125W, with strongest from 10N to 18N west of 135W. Seas are 6-8 ft in mixed swell south of 17N west of 133W, and 4-6 ft elsewhere. For the forecast, little overall change is expected over the open Pacific waters for the next several days, as the ridge dominates the region. A weak cold front will sink across 30N east of 130W Wed night and 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 late Wed through Sat, becoming moderate to fresh. Seas will build 6 to 8 ft from 03N to 11N east of 120W during that time. $$ Stripling