525 AXPZ20 KNHC 270245 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Wed Sep 27 2023 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 0000 UTC surface analysis and satellite imagery through 0240 UTC. ...TROPICAL WAVES... A tropical wave is entering the eastern Pacific, passing through Panama and Costa Rica north of 05N, along 84W, moving west at 5 to 10 kt. No significant convection is noted near the tropical wave axis at this time. A tropical wave is analyzed along 125W from 04N to 17N, moving W at 10 to 15 kt. Scattered moderate convection is active from 11N to 13N between 123W and 127W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N83W to 10N105W to 09N115W. Segments of the ITCZ extend from 09N115W to 09N122W, and from 06N127W to 09N140W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Earlier scatterometer satellite data along with recent ship observations show fresh to strong northerly winds persisting off Baja California, between high pressure to the northwest and a trough to the east. Yet the extent of fresh to strong NW winds off Baja California is starting to decrease slightly this evening, as the high pressure off southern California erodes ahead of a cold front moving through the northwest Pacific. But even as the winds diminish, wave heights will build off Baja California due to the arrival of long-period NW swell. A recent altimeter pass along with a couple of the ship observations showed combined seas are already 10 to 12 ft mainly off Baja California Norte. Gentle to moderate breezes farther south and in the Gulf of California, with 4 to 6 ft seas in open waters with mixed swell. For the forecast, the fresh to locally strong NW winds will persist off Baja California north of Cabo San Lazaro into early Wed between the high pressure north of the area and the trough over the Gulf of California. But winds will gradually diminish through Fri as the ridge shifts NW. Seas will build 8 to 13 ft in NW swell offshore Baja California through Thu before slowly subsiding Fri through Sat. Farther south, moderate to fresh N gap winds will pulse to strong across the Gulf of Tehuantepec tonight. Looking ahead, expect fresh westerly gap winds over the northern Gulf of California will start Fri afternoon, ahead of an approaching cold front, possibly reaching near-gale force by Sat evening. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Light and variable breezes are evident off northern Central America, north of the monsoon trough. Gentle S to SW breezes are noted farther south, except moderate winds S of 04N. Combined seas are 4 to 5 ft across the region with southerly swell. For the forecast, gentle to moderate winds will prevail to the north of 06N with seas 5 ft or less through Sat night. Gentle to moderate SW winds farther south will increase to moderate mainly south of 05N starting early Thu, before diminishing Fri night. Seas south of 05N will build to 6 to 8 ft in southerly swell beginning Wed and persist through Fri evening. Highest seas to near 9 ft will occur to the SW of the Galapagos. ...REMAINDER OF THE AREA... The remnant low of T.C. Fourteen-E is fully exposed near 13N138W with a pressure estimated to be 1011 mb. An earlier scatterometer satellite data indicated mostly fresh winds are still accompanying the low within 300 nm in the northern semicircle, implying a large area of rough seas of 8 ft there. Farther north, altimeter satellites passes continue to indicate of long- period NW swell crossing 30N and moving into the discussion waters, accompanying a frontal trough approaching 30N. This satellite altimeter data showed that seas were 1 to 3 ft higher than the global wave models, and that this swell is arriving about 6 hours faster than previously forecast. To the south, satellite altimeter data also showed seas to 8 ft crossing the equator between 110W and 120W. This is part of a large area of southwest cross-equatorial southerly swell moving into the waters south of 03N and west of 100W. For the forecast, the remnants of T.C. Fourteen-E will weaken to a trough during the next 24 hours while moving west- southwestward. The frontal trough approaching 30N140W will stall and dissipate north of 28N and west of 135W on Wed. High pressure north of the front will increase the pressure gradient to the west of 125W, and freshen the winds tonight through Thu. Large, long-period NW to N swell will continue to propagate into the waters north of 22N, then cover the area north of a line from Baja California Sur to 10N120W to 10N130N by late Wed. This swell will raise seas to around 14 ft along 29-30N overnight. Meanwhile high pressure will build north of the area in the wake of the frontal trough, supporting fresh to strong trade winds by Wed from 11N to 22N west of 122W, with combined seas building to 13 ft in a mix of NW swell and shorter period NE to E wind waves. Farther south, southerly swell will continue to move across the equator, supporting combined seas of 8 to 9 ft south of 03N and west of 115W by Thu. $$ Christensen