000 AXPZ20 KNHC 092153 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2153 UTC Thu Feb 9 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: Strong high pressure will build southward across the eastern coast of Mexico and the western Gulf of Mexico through Thursday night generating a strengthened pressure gradient across the Chivela Pass. This gradient will lead to the development of near gale to gale force N-NE winds beginning late Thursday night and continuing through Friday afternoon. Winds will peak at strong gale force levels...40 kt...and seas are expected to build to 14 ft at peak of highest winds on Friday morning. See latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFEP2/FZPN03 KNHC for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... Surface trough from 03N87W to the equator near 105W. The intertropical convergence zone axis extends from 01S102W to 03S108W to 00S120W. Scattered moderate convection is within 90 nm either side of the surface trough between 90W and 100W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A tight pressure gradient between a trough over the Gulf of California and 1020 mb high pressure farther west near 30N121W has been supporting an area of strong northwest winds through the central Gulf of California since yesterday. The high pressure is weakening, allowing the winds to diminish. A 1740 UTC scatterometer pass showed barely 20 kt winds off Loreto in Baja California Sur. Seas generated from the earlier winds are subsiding as well, with wave heights of 3 to 5 ft subsiding to 2 to 4 ft. The high pressure will shift eastward, allow winds to veer more southerly over the Gulf of California Friday and Saturday. Other than the upcoming gale force winds through the Gulf of Tehuantepec, generally gentle to moderate winds will persist across the region. Seas of 8 to 9 ft due to long period northwest swell will push into the waters off Baja California Norte late Friday, then into the area off Baja California Sur north of Cabo San Lazaro Saturday. Looking ahead, a ridge will build west of the area Sunday as low pressure sets up over northwest Mexico, allowing for strong winds in the far northern Gulf of California and off Baja California Sur, then diminishing Monday. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Strong high pressure is building from the eastern United States through the Gulf of Mexico, supporting strong trade winds over the southwest Caribbean Sea. Along with localized overnight drainage flow, this in turn will be supporting strong gap winds through the Gulf of Papagayo over the next several days, increasing in strength and coverage through early Saturday. A plume of strong winds and 8 to 11 ft seas will reach nearly 600 nm west-southwest of the Gulf of Papagayo. Additional pulses will occur through early next week, but not as strong. Similarly, strong northerly gap winds will pulse through the Gulf of Panama reaching toward the coast of western Panama Friday and Saturday, with a plume of seas of 8 to 11 ft reaching 360 nm to the west- southwest by Saturday. Elsewhere, gentle to moderate winds will persist across the region. REMAINDER OF THE AREA... A cold front is currently analyzed across from 30N130W to 21N140W. Winds have greatly diminished since yesterday near this front as supporting upper dynamics have lifted northeast of the area. Although winds have diminished, large northwest swell from 12 to 15 ft lingers west of the front, with 8 to 12 ft seas in northwest swell within 150 nm east of the front. Scattered showers are likely near the front north of 28N. The front will weaken as it shifts eastward, eventually dissipating in the next 48 hours as it nears the coast of Baja California. The swell will decay below 12 ft tonight, but seas in excess of 8 ft will persist west of 120W into Saturday. $$ CHRISTENSEN