000 AXPZ20 KNHC 131602 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Tue Mar 13 2018 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 1545 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: Strong high pressure is building over the western Gulf of Mexico behind a cold front, with associated cooler and drier air pushing through the Chivela Pass into the Gulf of Tehuantepec. A tight pres gradient has set up over southeastern Mexico as a result of the strong high pres. Notherly gale force force winds in the range of 30-35 kt began late yesterday in the afternoon hours, and are continuing along with seas of 10-14 ft. These gale conditions will persist through late Wed, then diminish below gale force as the strong weakens and shifts eastward. Seas will gradually subside through early on Thu as the area of gale force winds shrinks in coverage. Please see the latest Pacific Ocean High Seas Forecast product under AWIPS/WMO headers HSFEP2/FZPN03 KNHC, for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough axis extends from 07N77W to 06N90W to 04N98W. ITCZ axis begins at 04N98W and continues top 04N110W to 04N124W to 03N140W. Scattered strong convection is within 120 nm S of the trough axis E of 78W. Scattered moderate isolated strong is within 90 nm S of the trough axis between 82W and 85W, and also within 60 nm N of the axis between 80W and 82W. Scattered moderate convection is S of the trough axis within 30 nm of a line from 07N85W to 05N88W, and also within 90 nm N of the axis between 100W and 104W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section for details on an ongoing Gulf of Tehuantepec gale event. High pressure centered near 28N121W is maintaining generally moderate northwesterly winds across the region, except for moderate to fresh winds off the coast of Baja California Sur from Cabo San Lazaro to Punta Eugenia. Seas are 5 to 7 ft off the coast of Baja California and 3 to 5 ft in the Gulf of California. Winds and seas will diminish through tonight and into early Wed as the high pressure shifts eastward and weakens ahead of a cold front that is along a position from near 32N124W to 24N130W. The front will push across Baja California Norte and the northern Gulf of California by Wed evening. Strong westerly gap winds are possible over northern Baja California into the Gulf of California Wed night, then diminish as the front moves farther southward and weakens. Long period NW swell in excess of 8 ft will move into the waters off Baja California beginning Wed following the front. The swell will propagate to the waters of Baja California Sur by late Thu before decaying below 8 ft. Winds and seas will continue to diminish into Fri as high pressure builds over the region. Beyond 48 hours, southwest winds will increase and another round of NW will move into the region ahead of another cold front moving west across the region. Strong westerly gap winds are again possible into the northern Gulf of California Fri night into Sat as the front moves through the region. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Over Gulf of Papagayo, high pressure ridging over the Caribbean will cause moderate to fresh winds to pulse over the Gulf of Papagayo through Tue. Winds will increase back to fresh to strong early Tue night and through Fri night as the pressure gradient re- strengthens in response to high pressure building southeastward over the Caribbean from the Gulf of Mexico. Over the Gulf of Panama, gentle to moderate winds will prevail through mid week, increasing to moderate to fresh thereafter. Seas are expected to be in the range of 4 and 6 ft as moderate cross- equatorial SW swell propagates through these waters, building the seas 5 to 7 ft Thu and Fri as the winds also increase. Elsewhere, expect gentle to moderate winds and 4 to 6 ft seas to prevail, except seas of 8 to 11 ft in northerly swells generated from a gale force gap wind event in the Gulf of Tehuantepec, which will propagate into the Guatemala offshore waters tonight through Tue night. REMAINDER OF THE AREA... A cold front extending from near 32N124W to 24N124W will shift eastward across the waters north of 20N through tonight into early Wed. A few showers and thunderstorms are active along the front currently north of 24N. Strong westerly winds behind the front N of 29N are diminishing. NW swell is propagating into the region behind the front, with seas in excess of 8 ft and reaching 10-15 ft N of N of 28N W of 130W. These seas will subside somewhat through late today, but swell in excess of 8 ft will encompass most of the region west of 120W through mid week. Farther to the south, long period NW swell from 07N to 10N between 125W and 135W will decay by early this afternoon. $$ Aguirre