000 AXPZ20 KNHC 162150 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Fri Jun 16 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 1800 UTC surface analysis and satellite imagery through 2145 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends WNW from 11N86W to 14N101W to 08N120W where scatterometer winds indicate that the ITCZ forms, and then extends SW to beyond 06N140W. Scattered moderate isolated strong convection is observed over and to the S of the monsoon trough within 150 nm either side of a line from 05N78W to 13N100W to 10N117W, and along the ITCZ within 120 nm of 06N138W. Broad low pressure is forecast to continue for a couple of days across most of Central America and Eastern Mexico. Additionally, a large area of disturbed weather has formed over the W Caribbean with favorable conditions for gradual development as it tracks NW across the Yucatan Peninsula this weekend, and into the southern and central Gulf of Mexico early next week. Locally heavy rainfall accumulations are possible as large clusters of tstms develop. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A nw to se orientated ridge will meander across the EPAC waters well to the W of the offshore zones through Wed night, while a NW to SE orientated trough will meander across the Baja Peninsula and Gulf of California. A gentle to locally moderate NW breeze is forecast across the offshore waters W of 112W through late Sun,then the NW flow will increase to a moderate NW breeze through late Mon, with these conditions continuing to the W of 114W on Tue and Wed as a N to S trough develops along 112W. Strong northerly drainage winds are expected in the Gulf of Tehuantepec on Mon night into Tue. Large SW swell is forecast across the waters S of 14N beginning on Sun night. Light and variable winds expected elsewhere across the open Pacific waters through early Sat when a moderate W breeze will develop, and continue through Sun before diminishing. Large NW swell will propagate S and reach near 30N120W on Tue, and near 27N120W on Wed. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... A moderate SW to W breeze expected across the entire forecast area through Wed night. Long period SW swell will build seas to 9 ft across the waters S of 02N by late Sat, and across the entire offshore waters by late Sun. These seas will begin to subside on Sun night, with seas less than 8 ft by late Wed. REMAINDER OF THE AREA... A surface high near 32N136W will shift N of 32N tonight leaving a ridge extending SE to near 11N113W. This ridge will shift W over the upcoming weekend, terminating near 11N127W on Tue as broad low pressure develops along 115W to the N of the monsoon trough. A consensus of model guidance suggests that a surface low will develop near 18N115W during the middle of next week. In the meantime, moderate to fresh anticylonic flow is forecast across the discussion area through Sun, with seas of 7 to 9 ft to the NE of the ridge between about 120W and 125W. Fresh trades across the tropics to the SW of the ridge will support an area of 6 to 8 ft seas from 07N to 12N to the W of 136W through late Sat. An area of 6 to 8 ft seas, primarily due to SW swell, is a observed from 07N to 12N between 102W and 108W. These seas will subside below 8 ft late tonight as a batch of cross equatorial southwesterly swell, in the form of 7 to 9 ft seas, spreads N across the equator between 95W and 110W. Expect 7 to 9 ft seas across the tropics to the E of 120W on Sat through Mon before beginning to subside on Mon night into Tue. Expect 4 to 6 ft seas to the lee of the Galapagos Islands. These southerly swell should subside to less than 8 ft by late Wed. $$ Nelson