000 AXPZ20 KNHC 281004 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 711 UTC Sat Oct 28 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 0830 UTC. ...SPECIAL FEATURES... Tropical Storm Selma centered near 13.0N 88.8W 1005 mb, or about 50 nm SSE of San Salvador El Salvador at 28/0900 UTC moving NNE, or 015 degrees at 06 kt. Maximum sustained winds are 35 kt with gusts to 45 kt. Scattered moderate and isolated strong convection is observed from 11.5N to 13.5N between 88W and 93W. Selma is arriving on the coast of El Salvador and will quickly weaken as it moves inland. Selma will dissipate by Sun morning. Heavy rainfall is still possible over El Salvador, southern Guatemala, southern Honduras, western Nicaragua and Costa Rica during the next couple of days. Refer to the latest forecast advisory under WMO/AWIPS headers WTPZ25 KMIA/MIATCMEP5 for additional details. Gulf of Tehuantepec Gale Warning: Strong N winds will develop in the Gulf of Tehuantepec by mid morning today, then increase to minimal gale force this evening, with gale conditions then persisting through Sun morning. Seas will build to 14 ft downstream of the gulf waters near 14.5N95.5W on Sat evening. Near gale force northerly winds will persist through Sun, diminish to strong N to NE winds on Sun night, and finally decrease to less than 20 kt on Mon morning as high pressure over the gulf of Mexico weakens and shifts east. Heavy Surf Conditions: Swells of 8 to 10 ft, with periods of 20 to 24 seconds, are forecast to reach the Pacific coast of the Baja Peninsula tonight, then reach the Pacific coast of Mexico as far S as 19N late Sun night. Refractive swell at 15 to 17 seconds will enter the southern Gulf of California on Sun. The surf energy in these breaking waves may produce dangerous near shore conditions, including rip currents and beach erosion. INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends W from the Pacific coast of Colombia at 09N75W across the Gulf of Panama over Costa Rica to 10N85W. The monsoon trough loses identity in the broad cyclonic circulation in the vicinity of tropical Storm Selma. The monsoon trough resumes SW of Selma at 10N100W and continues W to 08N96W to 08N118W to 12N130W. The ITCZ continues W from 12N130W to 11N135W to beyond 12N140W. Scattered moderate and isolated strong convection is observed east of a line from 02N80W to 10N87W, within 90 nm of a line from 09N93W to 07N109W, and from 13N to 17N between 95W and 102W. Scattered moderate convection is found within 60 nm of a line from 13N114W to 11N121W to 12N132W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Heavy Surf Conditions: please refer to the special features section above for information on heavy seas arriving on the Pacific coast of Mexico this weekend. Gulf of Tehuantepec: please refer to the special features section above for information on the gale event expected to last from this morning through Sunday morning. Gulf of California: A moderate NW breeze is forecast today. Light and variable winds on Sun will become a moderate to locally fresh southerly breeze over the gulf waters N of 28N Mon and Tue. A surface ridge extending SE from 1019 mb high pres centered near 25N130W to near the Revillagigedo Islands will maintain a gentle to moderate NW breeze along the Pacific coast of Baja through Mon night. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Tropical Storm Selma: please refer to the special features section above. Otherwise, moderate SW winds over the region will shift to SW to W and become light as seas across the area are forecast to subside from 5 to 8 ft to 4 to 7 ft by late Sun night. REMAINDER OF THE AREA... A 1019 mb surface high near 25N130W will gradually shift N through Sat with a broad ridge dominating the EPAC waters N of 12N W of 115W and accompanied by gentle to moderate anticyclonic flow. Moderate to locally fresh SE flow will set up across the far NW waters on Sat. Long-period 20 to 24 second NW swell, in the form of 8 to 11 ft seas, has moved into the waters W of 130W and N of 20N. Expect seas of 8 to 13 ft W of a line from 32N118W to 16N125W to 09n140W late Sat, before beginning to subside. However, the swell field in the form of 8 to 11 ft seas, will continue to propagate SE across the waters W of a line from 32N117W to 22N115W to 03N140W on Sun, and across all waters W of 110W on Mon. $$ CAM