000 AXPZ20 KNHC 282136 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1854 UTC Fri Dec 28 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. .INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extend from Colombia near 04N77W to 05N90W to 04N95W. The ITCZ continues from 04N95W to 07N110W to 05N125W to beyond 04N140W. Scattered moderate convection is noted from 05N to 09N between 120W and 128W. Similar convection is from 09N to 12N between 112W and 115W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A tight pressure gradient between 1033 mb high pressure located northwest of the area near 37N132W, and lower pressure over the SW of United States is supporting moderate to fresh NW winds off Baja California north of Punta Eugenia, with gentle to moderate breezes elsewhere off the Baja California coast. NW swell of 10 to 13 ft is accompanying the winds based on latest altimeter data. The pressure gradient will weaken later today allowing the winds to diminish. The NW swell will gradually subside to 8 to 9 ft on Sat, before subsiding below 8 ft through Sun. Looking ahead, while there will be little change in the regional pattern, another group of NW swell to 8-9 ft will reach the waters around Guadalupe Island early next week. Gulf of California: Building high pressure over the Great Basin of United States will support fresh to strong NW winds and building seas across the entire length of the Gulf by Sat night. Winds will begin to increase across the northern Gulf of California tonight, reaching the central part of the Gulf by Sat morning, and the southern Gulf by late Sat. Seas are forecast to be in the 6-8 ft range, with the highest seas from 29N to 30N. The strong winds and associated seas will diminish on Sun as the high pressure weakens and shifts eastward. Looking ahead, this pattern will repeat early next week, with pulses of strong northerly winds returning to the northern Gulf of California late Mon and Tue. Gulf of Tehuantepec: Overnight drainage flow will bring a fresh to strong pulse of northerly gap winds into the Gulf of Tehuantepec Sat night, followed by another fresh to strong pulse Sun night. Looking ahead, a strong gap wind event is expected late next week. Currently, marine guidance suggests winds reaching strong gale force (40-45 kt) with building seas of 16-18 ft. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Fresh to strong NE to E winds are expected across the area through Wed. The winds will be greatest during the overnight and early morning hours, with the assistance of the nocturnal drainage flow, and some added enhancement from the easterly gradient flow from the SW Caribbean. Seas are forecast to build to 8-10 ft while winds peak near gale force mainly at night. Gulf of Panama: Moderate to fresh N winds are expected through Wed, with seas generally in the 4 to 6 ft range. Elsewhere, gentle to moderate NE winds will prevail N of 08N, while gentle to moderate southerly winds are expected S of 08N through Tue. REMAINDER OF THE AREA... A ridge extends from a 1033 mb high pressure system centered near 37N132W across the forecast waters to beyond the Revillagigedo Islands. Recent scatterometer passes indicated a broad area of fresh to strong trade winds farther south in the tropics west of 110W, supported by the strong ridge. Altimeter satellite data indicated seas of 8 to 11 ft over much of the area north of the ITCZ and west of 120W. Long period NW swell is responsible for most of this, although there is a secondary component of short period wave due to trade winds mainly south of 20N and west of 130W. The aerial extent of the trades will increase on Sun as a strong high pressure of 1034 mb persists N of the forecast area. Global models indicate a strong cold-core upper disturbance will dig into the base of a mid/upper level trough early next week, supporting development of a sharp surface trough or even weak low pressure along the ITCZ near 120W by mid week. This will likely enhance the trade winds north of the ITCZ and west of 120W, with near gale conditions possible on the northern end of the surface trough from 10N to 15N between 115W and 120W. $$ GR