000 AXPZ20 KNHC 211626 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1610 UTC Mon Nov 21 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: Overnight scatterometer data covered a portion of the offshore Gulf of Tehuantepec area, and indicated gale force winds. Global models indicated that windshear the surface were to have peaked at 40-45 kt overnight and diminished slightly to 40 kt after sunrise this morning. Seas across and downstream of the gulf are running 12 to 17 ft this morning. These winds are occurring with high pressure ridging nosing down eastern Mexico behind a strong cold front, which has moved into the Yucatan peninsula. Winds are forecast to diminish below gale force across the Tehuantepec region this afternoon, then will pulse at strong to near gale force tonight through Wednesday morning. Winds are then forecast to increase back to gale force Wednesday night, pulsing to gale force into the upcoming weekend, with the strongest winds anticipated during the overnight and early morning hours. Newly formed Tropical Depression Sixteen in the southwest Caribbean Sea near 11.5N 79.3W at 1500 UTC or about 265 nm east of Bluefields, Nicaragua, and is nearly stationary. Estimated minimum central pressure is 1002 mb. Maximum sustained wind speed is 30 kt with gusts to 40 kt. The NHC forecast calls for the tropical depression to move westward across southern Nicaragua or near northern Costa Rica as a minimal hurricane late Thursday, emerging into the northeast Pacific near the Gulf of Papagayo Friday as a remnant low pressure area. Tropical storm conditions are possible Thursday night and Friday for the Papagayo region, and offshore waters of zone PMZ113, which is within 250 nm of El Salvador to north Costa Rica. Very heavy to torrential rainfall is likely across Nicaragua and Costa Rica during this time period. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMAT1/WTNT21 KNHC for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N80W to 07N91W. The ITCZ extends from 07N91W to 09.5N116W to low pressure near 09N129W to low pressure near 09N131W to beyond 06N140W. Scattered moderate and isolated strong convection is noted within 60 nm N and 120 nm S of the trough between 80W and 86W. Scattered moderate to strong convection is noted within 90 nm N and 180 nm S of the ITCZ between 111W and 132W. ...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, a weakening cold front is approaching Baja California Norte while a small weak low pressure area has developed in the northern Gulf of California. Southerly winds on the southeast side of the low have increased to fresh, but will diminish this afternoon and evening as the front itself moves across the area tonight. Seas of 4-7 ft will prevail there into the early afternoon. Winds will shift to northerly behind the front, and are forecast to increase to fresh to strong across the majority of the gulf waters Thursday into Friday as the pressure gradient across the region tightens. Elsewhere, northwest swell producing seas of 8 to 12 ft is outrunning the aforementioned weakening cold front. This swell will continue to propagate SE toward the Baja California peninsula early this week with high pressure surging in the wake of the front. Seas will gradually decay to less than 8 ft from north to south through Tuesday night. The pressure gradient will then tighten across the region thereafter, with fresh to strong NNW winds developing offshore of Baja California Norte and southern California Wednesday through Thursday, diminishing then through Friday. These winds will send fresh northerly swell into the area, while a new pulse of reinforcing northwest swell for the end of the week building seas back to the 8 to 12 ft range. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... See the special features section for information on newly formed Tropical Depression Sixteen in the southwest Caribbean Sea, which will impact Central America through the week. Across the Gulf of Fonseca, fresh north to northeast winds will diminish to 10 kt or less this afternoon through evening, and then pulse again tonight to 15-20 kt. In the Gulf of Papagayo, strong N to NE winds will continue across the area Tuesday morning, pulsing to around 25 kt late tonight through sunrise Tuesday morning. Seas will build to 7-9 ft during the time of peak winds. In the Gulf of Panama, model guidance is suggesting that the southwesterly monsoon flow will freshen tonight Wednesday, and could reach 20-25 kt depending on the exact path of T.D. Sixteen. Elsewhere, gentle to locally moderate northerly winds, and combined seas of 3 to 6 ft are occurring north of the monsoon trough, which will continue to meander between 07N and 09N through the week. Moderate to fresh southwest flow is observed to the south of the monsoon trough, with combined seas of 4 to 7 ft in long-period southwest swell. Little change is forecast through early next week. REMAINDER OF THE AREA... A cold front extending from 30N116.5W to 26N120W to 18.5N140W will weaken as it continues to move toward the southeast and south. Overnight altimeter data sampled large northwest swell outrunning the front, up to 14 ft along 30N, and generally 9 to12 ft elsewhere W of 120W. These seas will gradually decay through Tuesday. High pressure is surging in behind the front, and ridging combined with an embedded ITCZ surface trough has resulted in fresh to strong trades across the west-central waters. A new cold front will dive southward, weakening as it shifts into the northern waters Tuesday night into Wednesday. This front will bring a new and reinforcing pulse of northwest swell into the area for the remainder of the week, while high pressure ridging continues to force fresh to strong trades across the west-central waters through Friday. $$ Stripling