000 AXPZ20 KNHC 231558 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Mon Jan 23 2017 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 1500 UTC. ...SPECIAL FEATURES... High pressure building in behind a cold front that exited the eastern Gulf of Mexico this morning tightened the pressure gradient in the Gulf of Tehuantepec and currently support gale force winds. The high will slide quickly eastward this afternoon while it weakens, which will act to diminish winds below gale force this afternoon. Please see the latest East Pacific high seas forecast under AWIPS/WMO headers HSFEP2/FZPN03 KNHC for further details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The ITCZ extends from 04N91W to 04N109W to 05N140W. No significant convection observed. ...DISCUSSION... ...A series of strong cold fronts has generated a large area of unusually large swell. This swell will continue to affect most of the forecast area through Wednesday... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Fresh to strong southwest winds are observed in the northern Gulf of California ahead of a cold front that has started to enter the Baja California Norte. North to northwest winds of similar magnitude are also within 20 nm off Santiago in Baja California Sur. Winds in these two regions of the Gulf of California will diminish this afternoon, but will pulse again tonight as the front continue to move SE while weakening. Large long period NW swell of 12 to 23 ft generated by gale winds north of the area and behind the front will continue to sweep southeastward into the forecast zones west of 105W through Wednesday. NW winds north of 27N will become fresh to strong this afternoon then subside early Tuesday morning. A strong pressure gradient between high pressure along Mexico and a trough of low pressure off the Jalisco Mexico coast is supporting an area of fresh to strong northwest winds from 18N to 20N between 105W and 107W. These winds will diminish early this afternoon and only long period swell will dominate the 023 offshore zone. Strong winds sustaining the swell event will diminish by Tuesday as the high weakens, with seas decreasing below 12 ft in the offshore Mexico waters Wednesday night. However, seas of 8 to 10 ft will persist west of 96W through the end of the week. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Light to gentle winds will prevail across most of the region through Tuesday. Seas will generally range between 3 and 5 ft until Tuesday, then build about a foot in response to arriving NW swell. REMAINDER OF THE AREA... Scatterometer data from 0330Z shows gales to the west of the front north of 29N between 129W and 137W. Have upgraded the forecast for this area accordingly. Altimeter data shows large NW swell continuing to spreading across the waters with seas greater than 12 ft north of 15N. Seas as high as 24 ft are present near 30N. Large long period swell will continue to sweep southeastward with 8 ft seas reaching the equator this afternoon. Global models agree that the gale force winds over the northern waters that are associated with the cold front will abate during the next 12 hours as attendant low pressure to the west of the Oregon coast weakens. Gales behind the cold front entering Baja California are affecting the northern waters. See the special features section for additional details. Forecast models remain in general agreement in developing an area of low pressure over the western waters near 12N134W on Thursday and Thursday night, but are trending smaller with respect to the size of the system. Nevertheless, a large area of fresh to strong winds will be possible in the vicinity of the low from 12N to 26N W of 120W by Friday morning. $$ Ramos