000 AXPZ20 KNHC 122137 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2016 UTC Sun Jan 12 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: The pressure gradient between high pressure along the eastern slopes of the Sierra Madre Oriental and the equatorial trough is supporting gale force northerly winds across the Gulf of Tehuantepec. Gale force winds will prevail through this evening before winds begin to diminish slightly to around 30 kt. Winds to near gale force will persist across the Tehuantepec region late tonight through Mon night before increasing again to minimal gale force briefly Mon night to Tue morning. Strong to near gale force northerly winds are then forecast to persist across the Tehuantepec area most of the forecast period. Expect seas of 8 to 12 ft with this gap wind event. Gulf of Papagayo Gale Warning: Strong to near gale force daytime winds will continue to blow across the Papagayo region as a strong wind flow in the SW Caribbean funnels through the gap. Winds will increase to minimal gale force during the overnight and early morning hours with the assistance of the nocturnal drainage flow. Seas will build to 8 to 12 ft each late night following the pulse of peak winds. This pattern will continue across Central America through Wed, supporting fresh to strong daytime winds pulsing to minimal gale force each night. The drainage flow will also aid fresh NE to E winds near the Gulf of Fonseca. Please see the latest High Seas Forecast issued by the National Hurricane Center under AWIPS/WMO headers FZPN03 KNHC/HSFEP2 or at website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for further details on these two Gale Warnings. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from near 05N77W to 06N86W to 05N95W. The ITCZ continues from 05N95W to 06N100W to 05N120W to beyond 06N140W. Scattered moderate convection is noted within 120 nm N of the ITCZ between 130W and 138W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see above for more on the latest gale force gap wind event in the Gulf of Tehuantepec. Elsewhere, a surface ridge extends SE across the offshore forecast waters W of Baja California to SE of the Revillagigedo Islands. The pressure gradient between this ridge and a trough over the Gulf of California will support moderate to fresh northerly winds W of Baja California through the forecast period. A set of NW swell is propagating through the waters off Baja California Norte and is forecast to build wave heights of 12 to 14 ft off of Baja California Norte tonight. This swell event will spread southward while subsiding. Seas greater than 8 ft will prevail W of the entire Baja California peninsula by Tue. Elsewhere, variable winds at 10 kt or less generally prevail across the offshore waters from Manzanillo to Puerto Angel, where seas are in the 4-6 ft range in NW swell. Northerly winds will gradually increase to around 15 kt across the Manzanillo area by Mon morning, but otherwise, little significant change is expected in marine conditions across the area for the next few days. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Please see above for more on the upcoming gale force gap wind event in the Gulf of Papagayo. Elsewhere, swell generated in the gap wind areas from Tehuantepec and Papagayo will propagate into the Guatemala and El Salvador offshore waters over the next several days to build seas to 6-8 ft. REMAINDER OF THE AREA... A surface ridge extends across the northern forecast waters from a 1041 mb high pressure located near 41N152W. The pressure gradient between the ridge and lower pressure in the vicinity of the ITCZ to the south of the ridge is producing a large area of fresh to strong trade winds that roughly covers the waters N of the ITCZ to about 28N W of 120W. The most recent altimeter passes indicate seas in the 9 to 12 ft range within this area of winds. These marine conditions are forecast to persist tonight as the strong high pressure prevails NW of the forecast region. The aerial extent and strength of the trades will begin to decrease Mon through Wed as the high pressure starts to weaken and loosens the pressure gradient. Long-period NW swell propagating over the northern waters will spread SE across the forecast area through early next week. Seas associated to this swell event are forecast to peak at 14 or 15 ft over the forecast waters roughly N of 27N between 118W and 130W by this evening. $$ GR