000 AXPZ20 KNHC 121557 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Tue Mar 12 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 1200 UTC surface analysis and satellite imagery through 1400 UTC. ...SPECIAL FEATURES... Gale Warning: A 1005 mb low pressure center of 1005 mb between Isla San martin and the coast of Baja California Norte near Campo La Chorera has shifted NE during the past several hours and is expected to move inland later this morning. Overnight scatterometer data showed winds to around 30 kt occurring within 60 nm of the low in the west semicircle, and are assumed to be slowly diminishing this morning. Seas across this area and extending beyond 200 nm from shore are running 9-15 ft in a mixture of NW swell and NW wind swell. 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 09N83W to 04.5N88W. The ITCZ extends from 04.5N88W to 04.5N105W TO 03.5N118W to beyond 04.5N140W. Scattered moderate isolated strong convection is seen within 180 nm north of the ITCZ between 91W and 122W. Scattered moderate to strong convection is seen within 210 nm north of the ITCZ between 125W and 140W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A mid-latitude low pressure system has moved from offshore of the coast of California, southeastward and unusually far south, to along the coast of Baja California Norte, as described above. An associated cold front has swept south and southeastward and extends from the northern Gulf of California southward and crosses the peninsula to the south of Bahia de Concepcion, then continues southwest to 20N114W to the tropics near 13N134W. High pressure to the northwest of the front is producing sufficient pressure gradient for fresh to strong N to NW winds behind the front and extending well beyond 120W. Seas across this area are 10-15 ft in NW swell. The associated low center will move eastward across northern Baja California this morning, while the associated cold front shifts east and southeastward through the entire Baja peninsula, and will begin to gradually weaken. Fresh to locally strong northerly winds are expected over the waters between Las Marias Islands and Los Cabos following passage of the cold front this afternoon and evening. A set of large long- period northwest swell will propagate across the forecast waters in the wake of the front and begin to reach the Revillagigedo Islands tonight and through the rest of the week. This will produce hazardous surf conditions along the coast of Baja California. Looking ahead, high pressure building over the Great Basin will support strong northwest winds across the Gulf of California by late Thu. Farther south, a cold front moving through the western Gulf of Mexico will result in near gale-force gap winds through the Gulf of Tehuantepec by late Fri. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... A modest ridge prevail across the SW North Atlantic and eastern Gulf of Mexico, and is producing a fairly tight pressure gradient over Central America and the Caribbean Sea. This pattern will continue to support fresh to strong northeast winds pulsing across the Gulf of Papagayo region through Wed night. Winds will be strongest during the overnight and early morning hours with the assistance of nocturnal drainage flow. Expect seas to peak at 9 or 10 ft downstream associated with each nocturnal peak in winds through the next 24 hours. These winds are forecast to diminish on Fri. Fresh to strong north to northeast gap winds over the Gulf of Panama will pulse again tonight, then diminish to moderate to fresh winds pulsing at night over this area through Fri. Elsewhere, gentle to moderate winds with mixed swell will persist through Fri. REMAINDER OF THE AREA... Strong high pressure ridging is building east-southeast across the waters in the wake of the previously described low and cold front. Overnight Ascat data revealed a large area of fresh to strong north to northeast winds over the waters roughly north of 06N and west of 125W. Latest altimeter data showed seas to 14 ft over the outer waters north of 19N east of 130W and to 13 ft north of 19N west of 130W. west of 135W. The gradient between the strong high pressure and the cold front is resulting in fresh to strong northwest winds over waters north of 25N and east of 125W along with seas of 11 to 14 ft in northwest swell. This area of winds and large seas will shrink through tonight, and is forecast to be confined to north of 29N and east of 124W by late tonight. Further south, the building ridge will support an expanding area of fresh to strong trade winds from about 05N to 20N today, then from about 08N to 14N and west of 125W tonight through early Thu. Wed. Seas in this region will build to around 12 ft with a mix of longer period northwest swell and shorter period northeast wind waves. The large northwest swell will gradually decay as it moves through the region, but seas of 8 to 10 ft will dominate the waters west of 110W through Fri. $$ Stripling