000 AXPZ20 KNHC 110952 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 952 UTC Tue Apr 11 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. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning...Strong high pressure building southwestward over SE Mexico will tighten the pressure gradient over the Isthmus of Tehuantepec early on Wednesday continuing through Thursday afternoon. Strong northerly winds are forecast to begin late tonight and early Wednesday, then quickly increase to minimal gale force briefly on Wednesday morning, with gale conditions developing again on Wednesday night into Thursday morning. Expect seas to build to 10 to 12 ft downstream of the gulf waters near 14.5N95.5W on Wednesday and Thursday mornings. The pressure gradient will relax slightly Thursday afternoon with fresh to strong northerly flow pulsing thereafter through Saturday. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The intertropical convergence zone axis extends from 07N93W to 04N106W to 04N125W where it is disrupted by an embedded surface trough, then resumes from 04N129W to 01N140W. Widely scattered moderate convection is within an area bounded by 11N120W to 10N113W to 04N108W to 04N126W to 10N124W to 11N120W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A surface ridge extends from NW to SE across the offshore waters to the W of 104W. Moderate to locally fresh anticyclonic winds are observed along the Pacific coast of Baja, with long period NW swell contributing to combined seas of 6 to 8 ft. The pressure gradient will tighten late tonight into early Wednesday with NW flow W of Baja California Norte increasing to fresh to strong. The strengthening winds along with fresh NW Swell will help to build seas to 7 to 10 ft. These conditions will persist through Friday before diminishing slightly into the weekend. In the Gulf of California, moderate NW flow will become variable at light to gentle speeds through the day. These conditions will then prevail through the week and into the upcoming weekend with seas mainly 2 ft or less, except 2 to 4 ft across the southern gulf through tonight. In the Gulf of Tehuantepec, see the special features section above for details on an upcoming gale force gap wind event. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... In the Gulf of Papagayo, fresh to locally strong nocturnal drainage winds are expected through the week and into the upcoming weekend. The most significant winds are expected on Wednesday night when seas will also build to 9 ft downstream of the gulf waters near 10.5N87.5W. In the Gulf of Panama, moderate to fresh nocturnal northerly flow is expected during the overnight hours through the remainder of the week and into the upcoming weekend, with seas building to 5 to 7 ft downstream of the gulf waters near 06.5N80W. Elsewhere, light to gentle winds and combined seas of 3 to 6 ft will prevail for the next several days. REMAINDER OF THE AREA... A cold front extends into the NW portion from 30N138W to 29N140W from a parent 1003 mb low pressure system N of the area near 37N132W. Gale force SW winds ahead of the front have shifted N of 32N while fresh to strong SW winds are still present from 30N to 32N, and 20 kt or less S of 30N. Seas up to 8 to 10 ft in NW swell are propagating into the NW corner. The front will weaken as it continues eastward, temporarily stalling tonight before moving again Wednesday and Wednesday night as another front arrives SE of 30N140W. Another set of NW swell with seas of 8 to 12 ft will arrive behind the next front Wednesday through Thursday, decaying thereafter. Elsewhere, a ridge extends from 1023 mb high pressure near 29N128W to the SE to near 16N110W. Recent scatterometer data showed fresh to strong trades across the W central waters where seas are 9 to 10 ft, with surrounding moderate to fresh trades and 8 to 9 ft seas elsewhere SW of the ridge. Similar conditions are expected to prevail through the remainder of the week into the upcoming weekend. $$ LEWITSKY