188 AXPZ20 KNHC 180909 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Wed Dec 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 0845 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: An ASCAT pass from 0322 UTC last night indicated strong to near gale-force gap winds ongoing in the Gulf of Tehuantepec region. These winds are forecast to reach gale-force tonight and continue through late Sat night. A a cold front is forecast to move across the Gulf of Mexico tightening the pressure gradient. Please see the latest NWS High Seas Forecast issued by the National Hurricane Center at website: https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from northern Colombia to Panama to 08N83W to 06N88W to 07N92W, where it transitions to the ITCZ and continues to 07N102W to 07N112W to 08N123W. A trough extends from 10N125W to 05N125W. The ITCZ resumes west of this trough at 07N126W and to beyond 07N140W. Scattered moderate convection is within 30 nm south of the ITCZ between 105W and 109W and between 126W and 131W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... High pressure of 1027 mb is analyzed west-northwest of Baja California Norte near 32N129W. A ridge extends from the high east-southeastward across the Baja Peninsula. The related gradient is allowing for generally moderate to fresh northwest to north winds to continue across the waters north of Cabo San Lazaro along with 5 to 8 ft seas in northwest swell, except for higher seas of 7 to 11 ft west of Baja California Norte. In the Gulf of California, winds are moderate to fresh in speeds and northwest in direction with seas 2 to 4 ft. Strong to near gale- force northerly winds are in the Gulf of Tehuantepec region along with seas to 8 ft. Light to gentle winds and moderate seas in mixed swell prevail across the southwestern Mexican offshore zones. For the forecast, the gradient related to the previously mentioned high pressure will allow for gentle to moderate northwest to north winds to be over the offshore waters N of Cabo San Lazaro through this morning, then be at light to gentle speeds through Fri night. These winds are forecast to increase to moderate to fresh speeds afterward during the weekend. A new set of northwest swell is forecast to approach Baja California this afternoon before subsiding during Thu morning. Fresh to strong northwest winds in the central Gulf of California will diminish some to fresh speeds tonight,to mostly moderate speeds from Thu to Sat night and to light to gentle speeds Sun and Sun night. Strong to near gale- force gap winds ongoing in the Gulf of Tehuantepec region are forecast to reach gale-force tonight and continue through late Sat night. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Fresh northeast winds are pulsing to strong speeds in the Gulf of Papagayo region generally driven by the gradient associated to high pressure that extends into the northwestern Caribbean Sea from the Gulf of Mexico. Moderate to fresh northerly winds are pulsing in the Gulf of Panama, where seas are 4 to 6 ft. Elsewhere south of the monsoon trough and between Ecuador and the Galapagos, southerly winds are light to gentle and seas are 4 to 6 ft in a south to southwest swell. For the forecast, fresh to strong northeast winds will continue to pulse in the Papagayo region through the next few days along with moderate seas. Moderate northerly winds pulsing to fresh speeds will continue in the Gulf of Panama through Sun. Gentle to moderate winds between Ecuador and the Galapagos Islands will continue through Fri, then mainly gentle speeds will prevail afterward. ...REMAINDER OF THE AREA... High pressure of 1027 mb is analyzed near 32N129W. A ridge extends southeastward from this high across the subtropical waters, which is supporting moderate to fresh northeast winds west of the Baja Peninsula offshores along with seas to around 8 ft reaching to near 120W. The gradient between the ridge and relatively lower pressure found to its south is sustaining fresh to strong trades over the tropical waters west of about 123W, where seas are in the 8 to 11 ft range. A surface trough that is analyzed along 125W from 05N to 10N has helped to sustain the fresh to strong winds as where noted in an ASCAT satellite data pass from yesterday. Satellite imagery shows scattered showers and isolated thunderstorms from 04N to 06N between 124W and 126W. Moderate to fresh trades are elsewhere south of the ITCZ and north of the ITCZ west of 120W. For the forecast, mostly fresh northeast to east winds and seas to 11 ft will be present west of about 123W through Thu as the gradient in place fluctuates little. The aforementioned trough will continue westward though Thu while losing its identity. The fresh to strong winds near will diminish to mostly fresh speeds on Thu. A cold front is expected to approach 30N140W tonight, preceded by fresh to strong southerly winds. The leading edge of a large set of northwest swell is forecast to outrun the front reaching from near 30N132W to 23N140W by Wed night. Seas with this swell are expected to be of 8 to 10 ft. A reinforcing cold front will briefly skirt the northwest forecast waters Fri night into Sat while weakening. Yet another cold front may approach 30N140W on Mon, preceded by fresh to strong southwest to west winds, and like the previous one have the leading edge of a large set of northwest out ahead of it. Latest wave model guidance from the GFS depicts seas to about 20 ft near 30N and west of 135W on Mon. $$ Aguirre