000 AXPZ20 KNHC 170855 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Thu Oct 17 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 0800 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N76W to 08.5N88W to 11N107W to 09.5N115W to low pres 1011 mb near 10.5N128W, then transitions to the ITCZ and continues to beyond 09N140W. Scattered moderate isolated strong convection is noted from 05.5N to 09N between 79W and 85W and from 09N to 14N between 107W and 117W. Scattered moderate to strong convection is noted from 08N to 11N between 124W and 137W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... High pressure of 1022 mb located well W of the the Baja California waters near 28N141W extends a broad ridge southeastward to just south of the Revillagigedo Islands. The pressure gradient between this ridge and a trough over the Gulf of California is supporting moderate NW to N winds over the Baja California waters, where seas are in the 7-10 ft range in NW swell across the waters north of Cabo San Lazaro, and 6-9 ft southward to the Revillagigedo Islands. Moderate to locally fresh SW to W gap winds have developed across north and central portions of the Gulf of California. Seas are 3 ft or less except 3 to 4 ft in the fresh winds across north portions. Another surge of strong northerly gap winds has begun across the Gulf of Tehuantepec tonight, and extends to about 75 nm offshore, where seas are in the 6-9 ft range. Over the rest of the Mexican offshore waters, light to gentle winds and moderate seas 4 to 7 ft prevail. For the forecast, moderate northerly winds across the Baja California waters will weaken modestly this afternoon through the weekend. NW swell moving through the Baja California waters will start to subside today. Low pressure has developed across the northern Gulf of California tonight and will persist through Fri, inducing moderate to fresh SW to W gap winds across the Gulf basin, becoming strong across the north portions Thu night through Fri. A cold front will move southward through Baja Norte Fri afternoon and night and reach central portions of Baja on Sat before dissipating. Gap winds across the Tehuantepec region will increase to fresh to strong speeds tonight through early next week, pulsing to near gale-force each night Thu through Sat. A brief period of gale-force winds is possible across Tehuantepec Sat as northerly winds behind a Gulf of Mexico cold front funnel through the Isthmus of Tehuantepec and accelerate across the Gulf of Tehuantepec waters. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Light to gentle onshore winds prevail north of 09N tonight, north of the monsoon trough. South of the monsoon trough, gentle to moderate SW to W winds prevail. Seas across the area waters are 4-6 ft in SW swell. For the forecast, light to gentle onshore winds are expected north of the monsoon trough through Sat night, as low pressure attempts to organize across the western Caribbean. South of the monsoon trough gentle to moderate SW to W winds are expected today then diminish slightly through early next week, except for moderate S to SW winds south of 04N. Seas across the area waters will slowly subside through Fri as gentle to moderate winds persist, and small NW and SW swell dominates the area waters. New cross-equatorial S swell will enter the regional waters Fri night through Sun night, gradually increasing sea heights. Active convection accompanying a tropical wave across the west and northwest Caribbean will shift westward into the Pacific offshore waters from Costa Rica to Guatemala Fri night through Sun morning. ...REMAINDER OF THE AREA... High pressure of 1022 mb is centered near 28N141W, and extends a ridge east to west across the region. The pressure gradient between this area of high pressure and lower pressure in the vicinity of the ITCZ is supporting fresh to locally strong winds N of the ITCZ to near 20N and W of 125W, where seas are in the 9-12 ft range. Moderate to fresh trade winds are elsewhere south of 23N to the ITCZ, and west of 120W. Seas over these waters are 8-11 ft in NW swell. Light to gentle winds are in the vicinity of the high center, where seas are in the 6-8 ft range in decaying NW swell. Gentle to moderate northerly winds are east of the high center, and west of Baja California, where seas are in the 8-10 ft range in NW swell. Light to gentle winds, and moderate seas are elsewhere N of the monsoon trough. Gentle to moderate winds, and seas of 5-8 ft prevail S of the ITCZ/monsoon trough. For the forecast, the aforementioned high pressure will drift further west today, then collapse tonight as a cold front sinks into the region. The cold front will move into the northern waters tonight and reach near 20N by Sat before dissipating. This will bring a brief period of moderate to fresh NE winds immediately behind the front Fri and Fri night, and moderate NE swell moving into the regional waters. South of the current high pressure, the associated anticyclonic wind flow will dominate the waters north of the ITCZ, producing moderate to fresh trade winds south of 20N and west of 130W through Fri. Moderate to large NW swell spreading across regional waters is currently moving into the tropical Pacific waters west of 120W and will reach 110W tonight. Otherwise, mainly gentle to moderate winds will prevail across the open waters through Thu. New southerly swell will cross the equator Fri through Sat. $$ Stripling