000 AXPZ20 KNHC 050350 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Sun Mar 05 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 0000 UTC surface analysis and satellite imagery through 0330 UTC. ...SPECIAL FEATURES... Strong high pressure northeast of the region will support 30-35 KT north to northeast gap winds along a narrow across the Gulf of Tehuantepec through tonight, while a broad swath of 20-30 kt north to northeast encompasses the remainder of the gulf as well as downstream from the gulf to near 12N between 95W and 97W. Seas of 10-14 ft are within the area of gale force winds while seas of 8-12 ft are within the area of 20-30 kt winds. Model guidance is on track in showing these gap winds diminishing through Sunday as strong high pressure ridging extending from the Gulf of Mexico southwest to eastern Mexico slides eastward and the resultant tight pressure over southeastern Mexico and the Isthmus of Mexico slackens. By Sunday evening, residual swell from this event is forecast to be confined well south of the Gulf of Tehuantepec from near 09N to 13N between 93W-110W with seas of around 8 ft primarily in northeast swell. These seas will subside to less than 8 ft by late Sunday night. A pulse of strong northerly flow will push through the Gulf of Tehuantepec on Monday with seas of 8-10 ft. This next round of gap flow will then diminish Monday afternoon with seas lowering to below 8 ft. See the latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFEP2/FZPN03 KNHC for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The ITCZ axis extends from 04N93W to 03N103W to 04N111W to 05N118W. The ITCZ then resumes west of a surface trough analyzed from near 05N121W to 13N118W. Isolated showers and thunderstorms are seen within 60 nm west of the trough axis from 09N to 13N. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A tight pressure gradient associated with strong high pressure that extends from southeast U.S. to the Gulf of Mexico and to eastern Mexico is currently inducing gale force north to northeast winds over portions of the Gulf of Tehuantepec. Please see the special features section for more details. High pressure ridging across the northern and central waters supports gentle to moderate northerly winds offshore Baja California and Mexico waters north of 18N with seas of 4-6 ft. Aside from the Tehuantepec gap winds and large swell from the gap winds between 93W and 105W over the offshore waters, winds south of 18N are gentle to moderate with seas of 5-7 ft. A cold front has quickly pushed southward to along 32N between 136W-140W. This front will move to near 30N by early Sunday afternoon, then weaken as it passes across the northeast waters Sunday evening into Monday. The front will be accompanied by moderate to fresh north to northeast winds. The leading edge of long-period northwest swell producing seas up to 9 ft will follow the front entering the far northern portions of the area north of 29N and west by Sunday evening. This set of northwest swell is forecast to move into the offshore waters of Baja California Norte Monday night into Tuesday, with seas expected to build up to 10 ft. By Tuesday, strong northwest winds will develop over the Gulf of California, with seas building to 8 ft. Another Tehuantepec wind event is forecast to begin early Thursday as strong high pressure surges south-southwest over the Gulf of Mexico and to eastern Mexico in the wake of another cold front that moves across the Gulf of Mexico. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... High pressure north and east of the region will continue to funnel fresh to strong northeast winds through the Gulf of Papagayo and surrounding waters throughout the forecast period. During the late night and early morning hours, the strongest winds are expected as the regional coverage of strong winds expands to include from 08N to 13N and Gulf of Fonseca, and as far west as 92W except to 94W through early Sunday. Seas will build to 8-10 ft within this area as swell propagates westward and merges with large swell propagating from the Gulf of Tehuantepec. Over the Gulf of Panama...north to northeast fresh to strong winds through the gulf tonight will continue into Sunday morning, then pulse again Sunday night into Monday morning. Seas to 8 ft are expected to 8 ft with these winds before subsiding to less than 8 ft on Sunday afternoon. Elsewhere...light to gentle breezes and seas of 4-6 ft will prevail through early next week. REMAINDER OF THE AREA... The combination between high pressure ridging over the northern and central waters and lower pressure in the tropics is producing fresh trades from 05N to 18N, east of 123W which is supporting 8 to 9 ft northeasterly swell west of a line from 16N140W to 12N132W to 07N134W to 05N140W. The trades will decrease the next 24 hours as the high pressure weakens, with seas diminishing below 8 ft by early Sunday afternoon. A surface trough extends from the ITCZ near 04N118W to 12N118W. Isolated showers are within 60 nm of the trough from 09N to 12N. A cold front will cross the northern waters beginning Sunday afternoon. The leading edge of long-period northwest swell producing seas up to 9 ft will follow the front entering the far northern portions of the area north of 29N and west by Sunday evening. This set of northwest swell is forecast to reach farther south to north of a line from 29N116W to 24N125W to 23N132W to 22N140W by Monday evening, with seas expected in the 8-10 ft range at that time. $$ Aguirre