000 AXPZ20 KNHC 182207 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Mon Mar 18 2019 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 2000 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Developing Gale Warning: A high pressure ridge across east and southeast Mexico is supporting strong to near gale force gap winds funneling through the Chivela Pass and across the Gulf of Tehuantepec today. Low pressure has developed along an old cold front that has become stationary across and just north of the Bay of Campeche. Strong to just below gale force winds across the western Bay of Campeche will continue to spill across the Tehuantepec region for the next few days to maintain the strong winds on the Pacific side of the isthmus. Seas are generally 8 to 10 ft presently. Winds will increase or pulse to around 30 kt tonight with gusts to gale force, and then to minimal gale force Tue night through early Wed morning. Seas will build to around 12 ft during these peak winds, and spread seas to 8 ft and higher downstream to near 12N97W each night. Please see the latest High Seas Forecast issued by the National Hurricane Center under AWIPS/WMO headers FZPN03 KNHC/HSFEP2 or at website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for further details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A trough extends from near 08N85W to 06N87W to 03N95W. The ITCZ continues from 03N93W to 01N100W to 02N110W to 04N125W to beyond 06N140W. Scattered moderate to strong convection is noted within 150 nm of the trough between 84W and 94W, and within 120 nm north of the ITCZ between 105W and 110W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section above for more details about the developing Gale Warning in the Gulf of Tehuantepec. Gulf of California: Light to gentle winds prevail across the Gulf as a weak pressure gradient dominates the region. A weakening cold front will approach the northern Gulf late Tue night into Wed. This will result in moderate to fresh S to SW gap winds developing north of 29N that will continue into Wed night. Otherwise, light to moderate winds will prevail across the region through Fri night. Elsewhere, high pressure centered west of Baja California is supporting moderate N to NW winds over the northern waters that will persist through Tue night. NW swell associated with a dying cold front will spread across the area Tue night through Wed night with seas building to 11 ft off Baja California Norte. The NW swell will reach the Revillagigedo Islands by Thu, then gradually decay through late week. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: A strong north-south pressure gradient across Central America has begun to weaken this afternoon but continues to support strong winds offshore gap winds across the Gulf of Papagayo this afternoon, with downstream seas to 9 ft in a mix of SW swell and NE wind waves. Fresh to strong NE to E winds will continue across the Gulf through Fri night, maximizing each night. Gulf of Panama: Fresh northerly winds across the Gulf of Panama today will diminish to moderate to fresh tonight Tue through midweek. Between Ecuador and the Galapagos Islands, 5-7 ft seas in new SW swell will persist through early Wed. Elsewhere, generally light to moderate winds and 3-5 ft seas will prevail for the next several days. REMAINDER OF THE AREA... A strong cold front extends from 30N132W TO 27N133W TO 20.5N140W this afternoon. Overnight scatterometer data showed a broad area of 25-30 kt winds ahead of the front. Winds will diminish slightly tonight as strong southerly winds along and east of the front impact the waters north of 25N as the front moves eastward. Large NW swell behind the front is producing seas to 17 ft across the far NW waters, and will propagate across the region with 8 ft seas reaching to near 120W by Tue night. Elsewhere, 1019 mb high pressure centered near 26N124W is maintaining a broad ridge axis that extends southeast toward the Revillagigedo Islands. The pressure gradient between the ridge and the ITCZ supports moderate to fresh trade winds mainly S of 18N and west of 116W to the ITCZ. Seas across this region are 7- 9 ft with NW and SW swell combining with shorter period NE wind waves. High pressure will build across the far northwest waters Wed and move eastward through Fri night, behind the cold front. The enhanced pressure gradient will result in strong trade winds S of 20N to the ITCZ with seas to 12 ft on Wed in mixed NW and NE swell. Another cold front will approach from the northwest toward the end of the week with more large long period NW swell. $$ Stripling