000 AXPZ20 KNHC 060322 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Fri Jan 6 2017 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 0000 UTC surface analysis and satellite imagery through 0300 UTC. ...SPECIAL FEATURES... A gale warning is in effect for the Gulf of Tehuantepec. A storm warning will likely be issued with the 0600 UTC forecast package. So far, the strongest Gulf of Tehuantepec gap wind event of the 2016-1017 season will be induced by a cold front forecast to move across the Gulf of Mexico Friday through Saturday. Northerly winds at 20-30 kt will begin to surge into the Tehuantepec area early Saturday morning, then winds will quickly increase to gale force by early Saturday afternoon, with seas building to 10-11 ft. Winds will further increase to 40-45 kt by Saturday evening with wave heights of 16-17 ft. Model guidance continues to indicate winds reaching storm force (50-60 kt) by Saturday night, with seas building up to 24-25 ft. On Sunday, a 1036 mb high pressure center over eastern Mexico will produce a very strong pressure gradient across the Isthmus of Tehuantepec forcing a very strong and broad Gulf of Tehuantepec gap wind event. Looking ahead, winds are forecast to diminish below storm force Sunday night, but gale force winds are expected to persist across the Tehuantepec region through Tuesday. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from a 1009 MB low pressure near 05N89W to a 1008 mb low pressure near 06N106W to a third 1008 mb low pressure near 07N117W to 06N123W. The intertropical convergence zone axis continues from 06N123W to 07N130W to 08N140W. No significant convection. Latest visible satellite imagery comfirmed the presence of the three lows along the monsoon trough. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A weak 1018 mb high pressure persists west of the Baja California peninsula near 25N126W, and is helping to produce gentle to moderate northwest winds across the Pacific waters off the coast of Baja California, with seas in the 3 to 5 ft range based on an altimeter pass. The pressure gradient will tighten slightly offshore of Baja California Sur tonight into early Friday, allowing for moderate to locally fresh northwest flow. The high pressure will move NE in about 24 hours as a low pressure system approaches to the NW corner of the forecast area. In the Gulf of California, moderate to locally fresh NW winds are expected on Friday. Then, winds will increase to 20-25 kt across the southern portion of the Gulf by Friday night with seas of 4-5 ft. These winds will spread south beyond the entrance of the Gulf early Saturday morning. These marine conditions will persist through early Sunday morning. Elsewhere between Cabo Corrientes and the Tehuantepec region, light to gentle breezes and seas in the 3 to 5 ft range, primarily in northwest swell, will prevail over the next several days. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Winds are forecast to also increase in the Gulfs of Papagayo and Fonseca late Saturday night into Sunday morning, with the strongest winds of 25-30 kt in and downstream of the Gulf of Papagayo. These winds could reach near gale force by late Sunday into Monday as strong high pressure builds southward across the western Caribbean and interior Central America in the wake of the Gulf of Mexico/Caribbean Sea cold front. In the Gulf of Panama, fresh nocturnal northerly flow is expected through Sunday night. Winds will further increase to 20-25 kt on Monday as strong winds funnel from the SW Caribbean into the Gulf of Panama. At that time, a strong high pressure ridge will be covering the western half of the Caribbean Sea. These gap wind events, along with a possible storm force wind event in the Gulf of Tehuantepec, will generate a very large area of 8 ft seas or greater that will eventually extend from Tehuantepec and Papagayo regions southward to near 4N-5N and westward to near 110W by early Monday. Elsewhere, light to moderate south to southwest winds will prevail south of the monsoon trough region, with seas 5 ft or less through the upcoming weekend. REMAINDER OF THE AREA... A weak cold front is over the far northwest waters and extends from 30N134W to 26N140W followed by gentle to moderate winds and seas up to 11 ft in NW swell. The front is attached to a 1004 mb low pressure system located NW of the forecast area near 36N144W. A reinforcing cold front, associated with the same low pressure will move across the NW waters on Friday. Southwest winds just ahead of the frontal boundary will increase to 20-25 kt, with combined seas of 7 to 9 ft. Moderate to fresh southwesterly flow winds continue to affect the NW waters on Saturday due to the broad circulation of the low pressure system. A stronger cold front will reach the NW by Saturday evening. Expect fresh to strong SW-W winds ahead and behind the front, particularly N of 25N W of 128W. The most recent scatterometer data shows an area of moderate to fresh trade winds roughly from 10N-16N W of 115W due to the pressure gradient between the aforementioned high pressure and lower pressure in the vicinity of the ITCZ. $$ GR