000 AXPZ20 KNHC 112150 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1906 UTC Sun Mar 11 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 1800 UTC surface analysis and satellite imagery through 2045 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: Light to moderate onshore winds will prevail through early Mon morning. Strong high pressure ridging will build southward behind a strong cold front along the Sierra Madre Oriental of eastern Mexico and over the western Gulf of Mexico tonight through Mon night, then remain in place through mid week. Winds will abruptly become northerly, then rapidly increase to fresh to strong over the Gulf of Tehuantepec by late Mon morning. Winds will continue to increase to gale force late Mon afternoon and peak around 45 kt Mon night into early Tue. Gale force winds will likely diminish by midday Thu, with brief lulls below gale force also possible during the afternoon hours Tue and Wed. Seas will peak in the 15 to 17 ft range Mon night or Tue morning. This latest gap wind event will finally wind down by Thu evening. 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 08N84W to 05N94W. The ITCZ axis continues from 05N94W to 04N109W to 02N120W to beyond 07N140W. Scattered moderate and isolated strong convection is noted within 90 nm of the ITCZ axis between 103W and 116W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section for information on the Gulf of Tehuantepec developing gale warning. High pressure measuring 1019 mb is centered near 26.5N119W. The high ridges SE across the open waters W of the Baja California peninsula. The high will maintain 15 and 20 kt NW to N winds tonight through Tue. The high will weaken and dissipate by Wed as a decaying cold front approaches. Long period NW swell generated by winds behind the front will cause seas to build to between 6 and 8 ft W of 110W Wed through Thu. Gulf of California: High pres just NW of the offshore zones is generating moderate NW winds over the central and southern Gulf. Winds will become fresh to locally strong over the waters S of 26N this evening through Mon afternoon, especially near Cabo San Lucas. The pressure gradient across the region will weaken Tue night through Thu, which will allow winds to diminish to between gentle and moderate. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... High pressure ridging over the Caribbean from the SW Atlc is weakening but is still causing moderate to fresh winds to pulse over the Gulf of Papagayo tonight through Tue. Winds over the Gulf will increase back to fresh to strong at night as the pressure gradient restrengthens in response to high pressure building SE over the Caribbean from the Gulf of Mexico Tue night through Thu night, peaking near 30 kt early Thu morning. Over the Gulf of Panama, gentle to moderate winds will prevail through Wed, increasing to moderate to fresh thereafter. Seas are expected to run between 4 and 6 ft as moderate cross-equatorial SW swell continue to arrive. Elsewhere, expect gentle to moderate winds and 4 to 7 ft seas to prevail. REMAINDER OF THE AREA... A busy weather pattern remains in place across the NW and N central waters. A cold front curves SW from 1014 mb low pressure centered just S of Los Angeles, California near 33N119.5W to 31N118W to 30N118W, then continues as a weakening cold front to 28N121W. Another weakening cold front extends S from 32N129W to 29N129W to 25N129W. The plume of tropical moisture heading NE from near the Hawaiian Islands has been diminishing in depth and extent, so the coverage of convection in this area has been decreasing. Scattered moderate convection is present along and up to 90 nm E of the westernmost weakening cold front S of 28N. A stronger cold front is entering the NW corner of the discussion area. An area of fresh to strong winds accompanies the front N of 27N. This area of winds will diminish and lift to the N of 30N by Mon night. Large NW swell will also accompany the boundary, reaching as high as 14 to 16 ft by Mon evening. The front will weaken as it moves across the waters N of 24N and W of 125W. A weaker cold front will introduce a round of reinforcing NW swell Wed night and Thu. Mixed swell are generating an area of seas measuring close to 8 ft generally between 06N and 10N W of 125W. This area of seas will gradually propagate westward and eventually merge with a larger area of NW swell generated by the stronger cold front mentioned in the previous paragraph on Tue. $$ CAM