000 AXPZ20 KNHC 250337 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Fri Nov 25 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 0000 UTC surface analysis and satellite imagery through 0300 UTC. ...SPECIAL FEATURES... Otto has weakened to a tropical storm over NW Costa Rica. The center should emerge into the Eastern Pacific waters in the next few hours. At 25/0300 UTC, Otto is centered near 10.9N 85.6W or about 18 nm/30 km N of Liberia, Costa Rica moving west or 265 degrees at 11 kt. Estimated minimum central pressure is 990 mb. Maximum sustained wind speed has decreased to 60 kt with gusts to 75 kt. On the forecast track, the center of Otto should move across northwestern Costa Rica and into the eastern North Pacific Ocean during the next few hours, then move away from the Central American coast on Friday. Some additional slow weakening is forecast during the next 48 hours. Please see the latest NHC advisory under AWIPS/WMO headers MIATCMAT1/WTNT21 KNHC for more details. Gulf of Tehuantepec Gale Warning: A ridge across eastern and SE Mexico is tightening the pressure gradient across the Isthmus of Tehuantepec. This is supporting strong to minimal gale force northerly winds in the Gulf of Tehuantepec with seas up to 13 ft. These winds are forecast to further increase to 40 kt Friday night through Saturday night. At that time...the ridge will be reinforced by a stronger high pressure building across Texas and eastern Mexico. Seas will eventually build to 15-16 ft with the strongest winds. Please see the latest High Seas Forecast product under AWIPS/WMO headers HSFEP2/FZPN03 KNHC for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N83W to 08N92W. The Intertropical Convergence Zone axis extends from 08N92W to 09N110W to 10N120W to 11N140W. Scattered moderate convection is from 08N to 14N between 120W and 125W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... High pressure across the U.S. Rocky Mountain region combined with elongated inverted surface troughing over northwest Mexico is supporting fresh to strong northerly winds over the northern and central Gulf of California. Seas are expected to build to 8 ft N of 29N tonight. Some of these winds will surge through passages across northern Baja California. A cold front will move across the area this weekend. Winds will increase to near gale force in the Gulf of California north of 29.5N Saturday night through early Sunday both ahead of and behind a pre-frontal trough, with winds diminishing by Sunday afternoon. Winds will increase again Sunday night into early Monday with the actual frontal passage, diminishing Monday afternoon. A set of long period NW swell is propagating across the offshore waters of the west coast of the Baja California Peninsula with combined seas of 8-11 ft. This swell event will reach the Revillagigedo Islands by Friday afternoon with seas of 8 ft covering the waters W of 112W. Additional pulses of NW swell will continue to affect the offshore forecast waters during the upcoming weekend. A strong cold front will move toward Baja California Norte Sunday night into early Monday bringing fresh to strong northwest winds behind it and large seas of 10 to 14 ft. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... See the special features section above for details on approaching Tropical Cyclone Otto. Fresh to strong W-NW winds are expected from 10N to 11N E of 86W, including the Gulf of Papagayo tonight. Otto is forecast to move across forecast zone PMZ113 tonight through Fri night. Elsewhere, light to moderate northwest to north flow and combined seas of 3 to 5 ft prevail north of the monsoon trough, with moderate to locally fresh southwest flow and combined seas of 3 to 5 ft south of the monsoon trough. Little change is forecast through the upcoming weekend and into early next week outside of the influence of Otto, except for seas building slightly to 4 to 6 ft by early Saturday. REMAINDER OF THE AREA... A strong ridge dominates the N waters. The pressure gradient between the ridge and lower pressure in the vicinity of the ITCZ continues to support a large area of 20 to 30 kt trades across the west-central waters. These winds combined with primarily northwest swell are producing seas of 8 to 12 ft. Little change in this pattern and marine conditions is expected through the upcoming weekend. A cold front is forecast to reach 30N by Fri evening and extends from 30N128W to 27N138W by Friday night. The front will move eastward across the N waters on Saturday while dissipating. $$ GR