000 AXPZ20 KNHC 210848 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Tue Mar 21 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 0600 UTC surface analysis and satellite imagery through 0830 UTC. ...SPECIAL FEATURES... A ship identified as ZCDG4 reported north winds of 30-40 kt across the Gulf of Tehuantepec near 0600 UTC with 10 ft seas. Gale force winds in this region are forecast to diminish later this morning, however near gale force winds are expected through tonight. Winds then will further diminish to fresh to strong continuing to Thursday night as a nearly stationary center of high pressure in the Gulf of Mexico enhances drainage flow across the Isthmus of Tehuantepec into the eastern Pacific Ocean. Northerly swell generated by this gap wind event continues to propagate southward mixing with swell generated in the Gulf of Papagayo region as well as with cross equatorial southwest swell. This is resulting in combined seas of up to 9 ft in waters from from 03N to 13N between 91W and 104W. Seas will begin to gradually subside tonight. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The ITCZ extends from 05N87W to 02N101W to 03N110W, then resumes at 03N116W to 06N130W. Scattered moderate convection is noted within 240 nm north of axis between 92W and 107W. A trough stretches from 09N110W to 02N113W. Scattered moderate convection is from 02N to 09N between 107W and 115W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the Special Features section for information on the Gulf of Tehuantepec gap wind event. A 1020 mb high pressure centered near 24N120W will maintain gentle to fresh northwest winds across the offshore waters west of Baja California through Wednesday evening with seas of 4 to 6 ft. A cold front is expected to push into northern Baja California by Wednesday night. A tight pressure gradient will result between the front and high pressure building behind it, thus supporting fresh to strong NW winds off the Baja California coast Wednesday night through early Friday morning. Seas off Baja California will build to 8-10 ft during that period. Winds will also increase across the north and central Gulf of California with the frontal passage Wednesday night through Thursday, and across the southern Gulf of California Thursday afternoon through early Friday morning. Currently, marine guidance suggests SW-W winds of 20-30 kt and building seas of 5- 6 ft across the northern Gulf of California, and NW winds of 20- 25 kt and seas of 6-7 ft across the remainder of the Gulf. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... High pressure will prevail over the northwest Caribbean and Gulf of Mexico, which will allow for the continuation of fresh to strong gap winds across the Gulf of Papagayo through Friday with seas to 8 ft. Fresh to strong northerly winds are also expected in the Gulf of Panama and downwind to about 05N with seas less than 8 ft today and Wednesday. Otherwise, light to gentle winds and combined seas of 3-5 ft are expected to continue the next several days elsewhere. REMAINDER OF THE AREA... High pressure of 1020 mb located near 24N120W will remain nearly stationary over the next 24 hours. A cold front extends from 30N128W to beyond 23N140W. This front will reach from 30N121W to 24N130W tonight, and from 30N116W to 21N130W Wednesday evening, then continue eastward into the northern Baja California peninsula and the northern Gulf of California. Seas will build to 8-11 ft across the NW waters in the wake of this front by Tuesday evening. A third cold front is forecast to reach the northwest forecast waters early Friday morning, briefly producing fresh to strong winds N of 29N and building seas to 12 ft by Friday evening. $$ NR