000 AXPZ20 KNHC 310958 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Mon Dec 31 2018 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 0800 UTC. .INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 10N74W TO 03.5N78W TO 06.5N88W TO 05N92W. The ITCZ continues from 05N92W TO 05N115W to beyond 06.5N140W. Widely scattered moderate isolated strong convection is noted within 90 nm either side of the ITCZ between 107W and 120W, and from 09.5N to 15.5N between 105W and 124W. Scattered moderate to strong convection is noted from 05N to 10N between 128W and 140W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A modest surface ridge extends from the NE Pacific southeastward to near Las Tres Marias tonight, and is maintaining moderate NW to N winds across the offshore waters of Baja California. Fading northerly swell is maintaining seas in the 5-7 ft range. Another pulse of northerly swell will begin to propagate into the waters off Baja California Norte overnight, building seas to 7-10 ft on Mon, and 5-7 ft offshore of Baja California Sur. Seas will then subside through Wed. Gulf of California: A cold front will sweep southward across California and Baja California Norte Tue through late Wed. Associated strong high pressure behind the front will build from the Great Basin of United States southward across the region by midweek, supporting strengthening NWly winds over the Gulf of California Tue through Thu. Strong northerly winds across much of the Gulf by Tue night will spill through the mountain gaps of the Baja Peninsula to produce narrow zones of strong and gusty NE winds across the offshore Pacific waters of Baja California Tue night through late Wed night. Gulf of Tehuantepec: Strong gap northerly winds are expected to return to Tehuantepec late Mon night through Tue night before diminishing Wed and Thu. Another cold front is expected to move across the western Gulf of Mexico Thu, allowing northerly winds to strengthen across Tehuantepec on Thu night, and likely increasing to gale force late Thu night through at least Fri. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Fresh to strong NE to E winds are expected across and downstream of the Gulf of Papagayo through Fri. Winds will peak to around 30 kt during the overnight and early morning hours with the assistance of nocturnal drainage flow. Frequent gusts to gale force are possible Mon night and Tue night within 120 nm of the coast. Moderate to fresh N winds are expected across the Gulf of Panama through Thu, pulsing to strong during the overnight hours and extending well south of the Gulf to near 06N. Elsewhere, gentle to moderate NE winds will prevail N of 08N, while gentle to moderate southerly winds are expected S of 08N. REMAINDER OF THE AREA... High pressure of 1032 mb centered N of the area near 37N135W extends a ridge SE across the forecast waters to near Las Tres Marias, and a broad flat ridge to the south between 120W and 150W. The pressure gradient between this area of high pressure and lower pressure in the vicinity of the ITCZ is supporting a broad area of fresh to strong tradewinds N of the ITCZ to near 23N and W of 113W. The area of high pressure will remain in place N of the area helping to maintain this broad area of fresh to strong trades. Long period NW swell is merging with this tradewind swell to produce seas of 8 to 13 ft over much of the area north of the ITCZ west of 120W. Global models continue to indicate a cold-core upper low will dig southward into the base of a mid/upper level trough between 130W and 135W Tue through Fri, and support the development of a sharp surface trough or even weak low pressure along the ITCZ between 120W and 130W by mid week. This will likely enhance the trade winds north of the ITCZ and west of 120W, with near gale conditions possible over north portions of the surface trough or low. $$ Stripling