000 AXPZ20 KNHC 051605 RRA TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Mon Dec 05 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 1545 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The Monsoon Trough axis extends from 09N107W to 08N116W to 08N122W where scatterometer winds indicate the ITCZ begins and extends to 08N131W to beyond 09N140W. Scattered moderate convection is seen within 120 nm north of the ITCZ between 124W and 130W, within 60 nm north of the trough between 112W and 115W, and within 30 nm of the ITCZ between 132W and 138W. Scattered moderate convection is noted from 03N to 07N between 77W and 79W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of California: Gentle se flow north of 29N this morning will increase to a moderate breeze this afternoon from a tightening of the pressure gradient between high pressure ridging west of Baja California and the climatological low pressure over the the far northern portion of the gulf. These winds are forecast to change little through Tuesday night. The next cold front is expected to move southeast across the northern gulf waters on Wednesday followed by fresh to locally strong northwest flow Wednesday night into Thursday. Light and variable winds are forecast across the gulf waters south of 29N through Wednesday, then becoming a strong northwest breeze behind the cold front Wednesday night into Thursday. Seas are expected to build to 5 to 7 ft with these winds. Gentle to moderate northerly winds are occurring to the west of 105W, with seas of 4 to 6 ft in northwest swell, except for higher lingering seas of 6 to 8 ft north of 19N. These seas will subside to 5 to 7 ft by Tuesday afternoon, with seas of 8 to 9 ft in decaying northwest swell continuing north of about 26N. A surface trough is analyzed from 17N101W to 13N102W to 10N104W. This trough is underneath a very pronounced and active sub- tropical jet stream branch that stretches from the deep central tropical Pacific northeastward to over the central portion of Mexico. Waves of upper level energy are riding along this jet stream branch, and are helping to initiate clusters of convection along and near the trough. Latest satellite imagery shows scattered moderate convection within 30 nm of the trough from 14N to 16N, and within 30 nm of 10N104W. This activity is moving to the northeast near 15 kt. The trough is forecast to gradually translate eastward while becoming less defined during the next 48 hours. Gulf of Tehuantepec: The next surge of strong northerly winds is expected to infiltrate the gulf late Thursday afternoon, and gradually strengthen to minimal gale force late Thursdaty night as strong high pressure ridges southward along the Sierra Madre Oriental mountains along eastern Mexico. These gale conditions will continue well beyond the discussion time frame through early on Sunday. Combined seas are expected to build to about 20 ft downstream of the Gulf of Tehuantepec near 14.5N95.5W on Friday. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Moderate to locally fresh nocturnal ene winds are expected to begin again late Tue night with a strong drainage event expected on Friday night. light to gentle northerly winds, except for light and variable winds to the east of 97W are present elsewhere north of the monsoon trough, with seas in the 4 to 6 ft range. A gentle to moderate southwest flow is observed to the south of the monsoon trough, with seas in the 5 to 6 ft in long-period southwest swell. REMAINDER OF THE AREA... A high pressure center of 1025 mb at 35N136W extends a ridge southeastward to 32N134W to 24N123W to near 17N114W. High pressure covers the area north of 17N west of 114W. The pressure gradient between the high and lower pressure near the monsoon trough is producing fresh northeast to east trade winds from 10N to 24N west of 135W, and from 10N to 17N between 116W and 135W with combined seas 8 to 10 ft primarily in a northwest swell. The 1025 mb high is forecast to shift east-southeast to near 33N130W by early on Tuesday as low pressure system and its associated frontal system well west of the discussion area tracks to the north-northeast. With this taking place, the current pressure gradient responsible for the aforementioned fresh northeast to east winds will weaken allowing for these winds to become mostly moderate east trades with locally fresh winds on Tuesday. The 8 to 10 ft combined seas will continue on the subsiding trend through Wednesday as the northerly swell energy dissipates. Only a small area of 8 to 9 ft seas is forecast to remain in the far northeast section of the area west of northern Baja California Norte by Wednesday. $$ Aguirre