000 AXPZ20 KNHC 180916 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 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 0600 UTC surface analysis and satellite imagery through 0900 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A ridge across SE Mexico will continue to support nocturnal minimal gale force winds in the Gulf of Tehuantepec through Thu morning. Lulls below gale force are likely each afternoon. Large seas up to 14 ft will build during the strongest winds, with resultant NE swell propagating downstream away from the source region each night. Northerly winds will pulse at fresh to strong, mainly at night, thereafter. Cold Front: A strong cold front extends from 30N137W to 25N140W. Gale force southerly winds were expected ahead of the front, but a scatterometer pass over the area at 0544 UTC showed a large area of 30 kt winds, as expected, but none at 35 kt, so the warning for gale force winds ahead of the cold front has been discontinued. Nevertheless, strong winds and large NW swell will affect the NW part of the forecast area as the front moves east today. Seas will build to 17 ft behind the front this evening, then continue to propagate across the waters W of 120W through early Wed morning. Please read 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 08N83W to 04N93W. The ITCZ continues from 04N93W to 02N101W to 03N107W to 01N113W to 06N140W. Scattered moderate showers are noted within 30 nm of the convergence axis east of 94W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please read the Special Features section for more details about the Gale Warning in the Gulf of Tehuantepec. Gulf of California: A weak pressure pattern will prevail through Tue with light variable winds, and seas generally 2 ft or less. A decaying cold front will approach the northern Gulf Tue night, producing S to SW winds in the 15 to 20 kt range through Wed night, with seas building to 4 to 6 ft. Moderate NW winds will persist off the Baja California peninsula through Tue night. NW swell associated with a dying cold front will build seas to 8-11 ft. Swell will reach the Revillagigedo Islands on Thu, with seas of around 8 ft. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: High pres across Central America will continue to support strong winds in the Gulf of Papagayo through tonight, with fresh to strong winds thereafter. Winds will be greatest during the overnight and early morning hours with the assistance of nocturnal drainage flow. Seas will build to 9-11 ft during the strongest winds. Gulf of Panama: Fresh northerly winds will prevail in the Gulf of Panama at night through Fri night. Elsewhere, mainly gentle to moderate NE to E winds and 3-5 ft seas will prevail the next several days, except for 5-7 ft SW swell which will affect the waters between Ecuador and the Galapagos Islands through the early part of the week. REMAINDER OF THE AREA... A broad ridge extends across the northern waters to just beyond the Revillagigedo Islands. The pressure gradient between the ridge and the ITCZ supports moderate to occasionally fresh trade winds mainly S of 20N to the ITCZ. Altimeter data shows a large swath of 7 ft seas across the region. High pressure will build by the middle of the week behind a cold front moving across the northern waters, increasing trades S of 20N to the ITCZ, and allowing seas to build to 8-10 ft combined with long period NW swell. Another cold front will approach 30N140W towards the end of the week with more large long period NW swell. $$ Mundell