000 AXPZ20 KNHC 191615 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1610 UTC Sat Nov 19 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 1200 UTC surface analysis and satellite imagery through 1530 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec gale warning: An overnight scatterometer pass indicated northerly flow increasing to gale force, as high pressure ridging surges southward across eastern Mexico tightening the local pressure gradient. Winds are assumed to have increased briefly to near 45 kt prior to sunrise, and currently are easing slightly to around 40 kt. These strong gales are forecast to continue today at around 40 kt and then expected to increase to near storm force tonight into early Sunday once a cold front moves by north of the area across the southwest Gulf of Mexico. Seas will build to 20 to 22 ft late Saturday night into early Sunday. High profile vessels should expect frequent storm force wind gusts tonight, and periods of sustained winds to storm force at elevations above 30 meters. Winds will diminish below gale force Monday afternoon, then will pulse to near gale force during the overnight and early morning hours through Tuesday. Winds are then forecast to increase back to gale force Wed night through the end of the upcoming week. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N85W to 10N105W to low pressure near 09.5N124W. The ITCZ extends from 09.5N124W to 08N130W to 10N140W. Scattered moderate convection is from 07N to 10N between 82W and 96W, and from 07N to 15N between 113W and 127W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the special features section for information on the gale warning in the Gulf of Tehuantepec. In the Gulf of California, overnight scatterometer data indicated fresh to strong northwest to north winds in the central gulf from 25N to 28N, where seas of 5-6 ft are expected. These winds are due to the pressure gradient being tight between inverted troughing which extends up along the eastern coast of the Gulf of California, and sharp high pressure ridging which extends from northwest to southeast across the Baja California Peninsula. These winds are slowly diminishing this morning and are expected to diminish to 20 kt or less by the afternoon. Winds will become southerly and increase to fresh to strong in the northern gulf ahead of an approaching cold front Sun evening and night. That front will move across the area Monday, gradually dissipating across northwest Mexico on Tuesday. Expect fresh to locally strong northwest to north flow again Tuesday night through Wednesday. Elsewhere, northwest swell is decaying with seas currently running around 5 to 8 ft. A cold front will move into the area from the northwest Sunday afternoon and night, with a new pulse of northwest swell outrunning the front and arriving for the latter half of the weekend. Seas will build to 7 to 10 ft Sunday night through Monday night, then will subside thereafter. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... In the Gulf of Papagayo, moderate to locally fresh north to northeast winds occurring overnight through sunrise have begun to diminish slightly this morning and back a bit more northerly. Winds are expected to turn more northwesterly and onshore this afternoon. A persistent cyclonic circulation in the southwestern Caribbean Sea will combine with strengthening high pressure ridging over Central America thereafter, to increase the nocturnal north to northeast drainage flow to fresh to strong into early next week. Elsewhere, light to gentle northerly winds and combined seas of 3 to 5 ft are occurring north of the monsoon trough, which continues to meander from east to west along about 09N, while moderate to locally fresh southwest flow is observed south of the monsoon trough, with combined seas of 3 to 5 ft primarily in long period southwest swell. Little change is forecast through the start of the upcoming week. REMAINDER OF THE AREA... A cold front is sweeping across the northern waters, currently analyzed from 30N129.5W to 23.5N140W. Associated winds greater than 20 kt are found just north of the discussion waters, while northwest swells of 8 to 16 ft, highest along 30N, continue to propagate to the southeast. The front will weaken as it continues across the northern waters, with the swell beginning to outrun the boundary itself. High pressure will quickly build in the wake of the front, which will tighten the pressure gradient, especially across the west- central waters. Trades will then increase to fresh to strong southwest of the ridging late in the weekend through early next week and enhance the east-northeast trade wind flow between 10N and 22N westward of 125W. $$ Stripling