302 AXPZ20 KNHC 150909 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Tue Dec 15 2020 Tropical Weather Discussion for the eastern Pacific Ocean from the Equator to 32N, east of 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 0900 UTC. ...SPECIAL FEATURES... Gulf of Tehunatepec Gale Warning: A ridge along the eastern slopes of the Sierra Madre Mountains in Mexico and across the western Gulf of Mexico behind a cold front currently supports minimal gale force winds in the Tehuantepec region. A recent scatterometer pass provided observations of northerly winds in the 30 to 35 kt range over the Gulf of Tehuantepec and downwind to 14N. Seas are expected to build to 12 ft. This will be a short-lived gap wind event as winds will quickly diminish well below gale-force by this morning. A second gap wind event is expected in the Tehuantepec area Wed night through Thu night as another cold front moves across the Gulf of Mexico. Marine guidance suggests gale-force winds of 35 to 40 kt and building seas of up to 12-13 ft with this second gale event. Please, read the latest NWS High Seas Forecast issued by the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from a 1009 mb low pressure over northern Colombia near 10N74W to 06N80W to 07N95W to 1011 mb low pressure near 07N103W to 07N111W. The ITCZ continues from 07N111W to 08N125W to beyond 07N140W. Scattered moderate convection is noted from 07N to 10N between 98W and 103W, from 08N to 10N between 117W and 121W. Similar convection can be found from 11N to 14N between 106W and 113W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A Gale Warning remains in effect for the Tehuantepec region. Please, see the Special Features section for more details. A ridge dominates the offshore forecast waters of Baja California. The pressure gradient between the ridge and lower pressures over mainland Mexico is resulting in fresh to locally strong NW winds N of 28N E of 121W. Long period NW swell is currently propagating across the waters N of Cabo San Lazaro with seas building up to 12-13 ft. This swell event will reach the Revillagigedo Islands today. Gulf of California: Mainly moderate to fresh NW-N winds will prevail in the Gulf of California during the forecast period with the exception of fresh to locally strong winds on Wed. Seas will remain under 8 ft. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Moderate to fresh NE-E winds will prevail in the Papagayo region over the next few days with seas of 4-6 ft. Winds are expected to increase to fresh to strong Thu night through Sat night as high pressure builds over the western Caribbean. Gentle to moderate northerly winds are forecast in the Gulf of Panama, pulsing to 20 kt Thu and Fri nights as the tradewinds over the south-central Caribbean strengthens some. Elsewhere, gentle to moderate winds will prevail S of the monsoon trough with mainly gentle winds N of it. REMAINDER OF THE AREA... High pressure of 1028 mb located near 34N129W extends a ridge SE across the northern forecast waters to near the Revillagigedo Islands. The pressure gradient between the ridge and lower pressures in the vicinity of the ITCZ will continue to support a large area of fresh to locally strong trade winds, particularly from 10N to 21N W of 125W. Seas are in the 8 to 11 ft range within the area of the trades due to a combination of wind waves and NW swell. These winds will persist over the next 48 hours as high pressure remains in place. A weak low pressure of 1011 mb is analyzed along the monsoon trough near 07N103W. Scatterometer data confirmed the presence of this system, forecast to move westward with little change over the next 48-72 hours. Long period NW swell dominate most of the waters N of 10N and W of 115W early this morning. Sea heights of 10-13 ft are noted per altimeter data W of Baja California norte to about 125W. Additional pulses of NW swell will reach 30N140W today, and again on Thu night. Swell of 8 ft or greater seas will dominate most of the waters N of 10N W of 110W through at least Wed night. $$ GR