000 AXPZ20 KNHC 191556 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Mon Dec 19 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 1500 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec...A storm warning has been issued for the Gulf of Tehuantepec with the morning forecast package. A strong surface ridge in the wake of a stationary front across the Western Gulf of Mexico will provide a strong pressure gradient across the Isthmus of Tehuantepec, which is forecast to result in the first storm gap wind event of the 2016-2017 season. At present, winds are likely reaching gale force. Coatzacoalcos, on the north side of Isthmus of Tehuantepec is currently reporting sustained N winds of 40 kt, while Ixtepec in the state of Oaxaca is reporting sustained N winds of 25 kt. Currently, the GEFS probabilities indicate 100 percent of gale force winds in and downstream of the Gulf of Tehuantepec while the GFS Model is forecasting northerly winds of 47-48 KT this evening through early Tuesday morning. So, the decision was made and a storm warning has been issued. Marine guidance also indicates that the gale force winds will persist through Friday. Seas are forecast to build to 18-20 ft with the strongest winds, particularly on early Tuesday. Of note, the monthly distribution of the Tehuantepec events shows that the largest number of gale force events occurs in December. Storm- force events occurs most often in January. Gulf of California...A gale warning is in effect for the Gulf of California. Strong high pressure centered over the Great Basin north of the area will allow winds to reach gale force around 1800 UTC today over the far northern Gulf of California. Seas will build as high as 10 ft N of 29.5N. Winds over the far northern Gulf will diminish below gale force tonight as the high pressure shifts east. But fresh to strong northwest winds will persist across the entire Gulf of California Tuesday before diminishing from north to south by Tuesday night. Seas will reach near 8 ft between Los Cabos and Cabo Corrientes on Wednesday due in part to northerly swell from the Gulf of California. By Wednesday night, NW-N winds in the 20-25 kt range are expected between Los Cabos and Las Marias Islands with seas building to 9 ft. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 07N77W to 06N85W to 07N97W. The ITCZ continues from 07N97W to 10N120W, then resumes at 09N124W to beyond 06N140W. Scattered moderate convection is located within 30 nm of the ITCZ between 102W and 106W, and from 08N to 10N between 117W and 125W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A storm warning has been issued for the Gulf of Tehuantepec and gale warning is in effect for the northern Gulf of California. Please, see Special Features section above for details. Moderate to fresh northerly flow persists over the waters off Baja California today, with seas of 6 to 8 ft based on an altimeter pass. Elsewhere offshore of Mexico, and outside of the Gulf of Tehuantepec and Gulf of California, gentle to moderate breezes and 3 to 5 ft seas will persist. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Fresh to strong northeast winds are expected to pulse from the Gulf of Papagayo to the Gulf of Fonseca during the overnight and early morning hours through Wednesday morning, with the assistance of the nocturnal drainage flow. Seas should build to 10-11 ft west of 90W. Northeast swell will merge with the Gulf of Tehuantepec gap wind event to provide a large area of 8-12 ft seas from 08N to 13N to 107W Tuesday morning, and from 05N to 13N to 110W on Wednesday morning. Northerly moderate to fresh breezes will pulse across the Gulf of Panama through the end of the week. REMAINDER OF THE AREA... A 1034 mb high pressure is centered north of the area near 35N133W supporting a broad area of fresh to strong northeast to east winds over much of the forecast waters north of 07N and west of 125W. Farther east, a surface trough extends from 08N122W to 15N121W. The trough will drifts northwest into the ridge through the next couple of days. The tighter pressure gradient on the north side of this system will enhance the area of northeast winds through mid week. Seas to 11 ft are noted, per altimeter data, within the area of these fresh to strong winds. The high pressure is forecast to move SE while slightly weaken. As a result, the aerial coverage of fresh to strong winds will decrease by Wednesday. $$ GR