000 AXPZ20 KNHC 181619 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1610 UTC Fri Nov 18 2016 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 1200 UTC surface analysis and satellite imagery through 1515 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec gale warning: A locally tight pressure gradient across southern Mexico continues to support fresh to strong northerly winds across the Gulf of Tehuantepec this morning. This gradient will very temporarily weaken this afternoon, allowing for winds to briefly diminish to near 20 kt. High pressure is then forecast to surge down along eastern Mexico toward the area behind the strongest cold front yet of the season moving across the Gulf of Mexico. Northerly winds will rapidly blast to gale force this evening, then will reach to 40-45 kt Saturday night. Model guidance continues to suggest that minimal storm force conditions are briefly possible Saturday evening. Associated seas will build to around 20 ft by late Saturday night. Winds will diminish below gale force by Tuesday morning, with another gale force wind event expected later next week. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N83W TO 08N97W TO 11N114W TO 08N129W. The ITCZ extends from 08N129W to 10.5N140W. Scattered moderate to strong convection is noted within 120 nm south of the axis east of 87W, and within 90 nm N and 210 nm S of axis between 89W and 123W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the special features section for information on the gale warning in the Gulf of Tehuantepec. Moderate N to NE winds are observed north of 22N across the Pacific waters of Baja California this morning and are expected to veer more northeasterly and diminish slightly this afternoon through Saturday. A strong pulse of NW swell is moving through the region today and will peak this morning then gradually fade tonight through Sunday morning before the next large NW swell event moves into the region Sun through Mon. Overnight altimeter data suggested seas in the 8-11 ft range across the waters and are likely the peak of this current pulse of swell. Gulf of California: Moderate to locally fresh northwest winds have spread southward through most of the basin to Tepentu and Las Islas de San Jose and San Francisco this morning. Sea through the south portion of the basin have built to 4-6 ft. These winds will generally persist today and tonight, then diminish somewhat on Saturday. Expect light and variable winds on Sunday. Winds will become southerly and increase to fresh to strong on Sunday night, north of 29N east of troughing which will develop ahead of an approaching cold front. That front will move across the northern gulf during the day Monday. Winds will shift to northerly and gradually increase back to moderate to fresh through Tuesday night. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Moderate offshore winds are expected across the Gulf of Papagayo during the overnight hours through Saturday night. A persistent cyclonic circulation in the western Caribbean Sea will combine with strengthening high pressure ridging over Central America thereafter, which will increase the nocturnal drainage flow to fresh to strong into early next week. Elsewhere, light to gentle northerly winds and combined seas of 3 to 6 ft are occurring north of the monsoon trough, which continues to meander from east to west along about 09N, while moderate to locally fresh southwest flow is observed south of the monsoon trough, with combined seas of 4 to 7 ft primarily in long-period southwest swell. Little change is forecast through the upcoming weekend. REMAINDER OF THE AREA... Moderate to large northwest swells is moving through the regional waters this morning, producing seas of 6 to 10 ft north of the monsoon trough and ITCZ. This swell will decay from northwest to southeast, however, and a new reinforcing pulse of northwest swell is already reaching 30N140W this morning. This pulse of NW swell is in association with the next cold front which will breach 30N140W in the next few hours. Associated winds of 20 kt or greater should remain just north of 30N. The front will extend from 30N131W to 25N137W, becoming stationary to 23N140W by late tonight, then from 30N126W to 25N132W by late Saturday night. The set of northwest swell will continue to propagate across the waters through the remainder of the weekend and into early next week, with seas up to 15 ft skirting across 30N. High pressure ridging will build in behind the front, resulting in a tight pressure gradient across the west-central waters north of the ITCZ Sunday through early next week. Trades will increase to fresh to strong, and the northwest swell will mix with fresh northeast wind waves to produce combined seas of 8 to 11 ft. $$ Stripling