000 AXPZ20 KNHC 190920 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 326 UTC Wed Apr 19 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 0600 UTC surface analysis and satellite imagery through 0900 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 06N88W to 05N96W to 03N104W. Scattered moderate and isolated strong convection is seen from 05N to 07N between 85W and 95W. The intertropical convergence zone axis stretches from 02N110W to 02N115W to 04N127W to 02N138W. Scattered moderate and isolated strong convection is present from 06N to 11N between 109W and 112W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A surface ridge extends from 1025 mb high pressure centered near 32N128W to near the Revillagigedo Islands at 17N112W. NW winds are increasing to fresh to strong over the offshore waters west of Baja California Norte where the pressure gradient is tight. These winds are generating NW swell and causing seas to build to 8 ft. The fresh to strong winds will spread southward over the offshore waters W-SW of the Baja California Peninsula through Thursday evening to 23.5N as new and stronger high pressure builds SE from N of the area. As a result, combined seas will build to 8-11 ft through early Friday. The pressure gradient will then slacken on Friday and Saturday and allow winds and seas to diminish as a cold front weakens the ridge to the west. Another round of NW swell generated to the lee of the cold front will cause seas to build to between 8 and 10 ft west of Baja California Norte Sunday night through Tuesday. In the Gulf of California south of 29N, gentle to moderate NW winds will become moderate to fresh today through Saturday with late afternoon heating leading to local enhancement of winds. Winds will be light to gentle north of 29N as surface troughing developing over far northern Baja weakens the pressure gradient. Seas will generally be 2 ft or less tonight, then will build to 2-4 ft as winds freshen. In the Gulf of Tehuantepec, moderate to occasionally fresh northerly drainage flow is expected through Friday morning. Gentle to light southerly winds will ensue thereafter until early Sunday. The next significant northerly gap wind event is expected to begin Sunday afternoon as a relatively strong cold front for this time of year pushes south along the Sierra Madre Oriental. Model guidance continues to suggest strong to minimal gale force winds Sunday night through Monday morning. High pressure following behind the front will shift eastward by Tuesday, allowing winds and seas to subside. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... In the Gulf of Papagayo, moderate nocturnal drainage winds will taper off this morning and become light. No significant gap wind events are anticipated through the upcoming weekend. In the Gulf of Panama, mainly light and variable winds are expected this week into the upcoming weekend. Periods of light wind flow from the south will occur during this time frame as low pressure dominates NW Colombia and the adjacent Caribbean. Elsewhere, light to gentle winds and combined seas of 3 to 6 ft in mixing SW and NW swell will prevail through the next several days. REMAINDER OF THE AREA... A 1025 mb surface high centered near 32N128W will strengthen today and tonight. During the past few days the high and associated middle atmospheric ridging has blocked the eastward progress of cold fronts that have stalled and dissipated over the NW waters. Even so, NW swell generated to the W of the fronts are still propagating SE into the discussion waters. Seas of 8 and 12 ft are affecting the NW waters west of a line from 30N130W to 25N135W to 22N140W. This set of NW swell with seas of 8 ft or greater will continue propagating SE and eventually envelop almost all of the waters N of the ITCZ and W of 110W by Friday morning. This large area will decay on Saturday and Sunday. A new set of NW swell will arrive behind a cold front that will decay over the waters just to the west of Baja California Norte this weekend. Southerly winds ahead of the front could become strong over the far NW corner of the discussion area Thursday night and Friday morning. SW swell from the Southern Hemisphere will maintain seas above 8 ft generally south of 01N between 100W and 125W. The swell will decay and allow seas in this area to subside below 8 ft on Friday morning. Otherwise, moderate to fresh trades will prevail SE of the ridging over the W central waters N of the ITCZ and W of 120W through the next several days with little change. Trade wind waves in this area will help support seas of 8 to 9 ft from 07N to 13N between 117W and 132W. This area of 8 ft seas will combine on Thursday evening with the area currently over the NW portion of the discussion area that is spreading SE. $$ cam