000 AXPZ20 KNHC 230917 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 917 UTC Wed Nov 23 2016 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... Hurricane Otto in the southwest Caribbean Sea near 10.9N 80.4W at 23/0900 UTC or about 161 nm east-northeast of Limon, Costa Rica or about 209 nm east-southeast of Bluefields, Nicaragua moving west-northwest at 4 kt. Maximum sustained wind speed is 65 kt with gusts to 80 kt. Estimated minimum central pressure is 988 mb. The official forecast calls for Otto to move across Central America near or along the border of Costa Rica and Nicaragua Thursday and Thursday night, emerging into the Pacific Ocean near the Gulf of Papagayo late Thursday night into Friday. A tropical storm warning is now in effect for zone PMZ113, and tropical storm conditions are possible in PMZ111 and PMZ115. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMAT1/WTNT21 KNHC for more details. Gulf of Tehuantepec gale warning: Fresh to strong northerly winds will diminish briefly this afternoon, then will increase back to fresh to strong levels this evening before reaching gale force late tonight as the pressure gradient tightens due to strengthening high pressure ridging over eastern Mexico. Gales are then expected to persist through Saturday night. The strongest winds are expected during the overnight and early morning hours. Seas will build to up to 14 ft during the strongest winds. Fresh to strong northerly flow will then gradually diminish through the day Sunday into Sunday night. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 09N83W to 06N93W. The intertropical convergence zone axis extends from 06N93W to 08N115W to low pressure near 10N130W to 11N140W. Scattered moderate and isolated strong convection is from 08N to 16N between 115W and 129W. Scattered moderate convection is from 10N to 12N west of 137W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... High pressure building in over the U.S. Rockies will cause winds to increase to fresh to strong out of the northwest over the Gulf of California west of 110W late tonight into early Thursday, diminishing by early Friday as the pressure gradient weakens. These winds are expected to seep through the northern passages of the peninsula into the Pacific waters west of the peninsula Thursday and Thursday night. Seas will build to up to 7 to 9 ft in the northern Gulf of California. Otherwise, moderate to fresh northerly winds will persist west of the peninsula across the open Pacific waters. Northwest swell to the west of Baja California are decaying with combined seas of 5 to 8 ft, the highest to the south near the Revillagigedo Islands. A tight pressure gradient will setup offshore of southern California which will increase northerly winds to fresh to strong just to the north of the discussion area. These winds will send fresh northerly swell of 7 to 9 ft into the area this afternoon. Seas will continue to build to 8 to 12 ft Thursday through Friday as a new set of northwest swell arrives behind a remnant frontal boundary. That swell will then decay Friday into Friday night. Yet another, and stronger cold front will approach from the northwest on Saturday, moving across the area during the remainder of the weekend. Northwest swells will arrive with this front, building seas to 9 to 13 ft Sunday and Sunday night. Meanwhile, southwest winds in the northern Gulf of California will increase to fresh to strong Saturday night, then will become west-southwest Sunday night, increasing to fresh to near gale force. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... In the Gulf of Papagayo, moderate to fresh drainage flow will diminish later this morning. See the special features section above for information on tropical cyclone Otto. Mariners planning to transit through the Panama Canal are also urged to monitor Otto, currently in the southwest Caribbean Sea. Elsewhere, gentle to moderate winds and combined seas of 3 to 5 ft prevail on either side of the monsoon trough. Little change is forecast through the end of the week and into the upcoming weekend. REMAINDER OF THE AREA... A decaying frontal boundary is approaching 30N140W with a new set of northwest swell behind it, up to 8 to 11 ft. Relatively strong high pressure ridging is punching across this boundary and extending across the waters north of the ITCZ from northwest to southeast. This ridging combined with surface troughing and 1011 mb low pressure embedded in the ITCZ near 10N130W is resulting in a tight pressure gradient across the west-central waters, where fresh to strong trades prevail. These winds combined with decaying northwest swell are producing combined seas of 9 to 12 ft. Little change in this pattern and the marine conditions is expected through the remainder of the week and the upcoming weekend, with the trades persisting and multiple reinforcing sets of northwest swell propagating into the area. $$ LEWITSKY