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ZCZC MIATCPAT4 ALL TTAA00 KNHC DDHHMM BULLETIN Hurricane Harvey Advisory Number 18 NWS National Hurricane Center Miami FL AL092017 400 PM CDT Thu Aug 24 2017 ...HARVEY HEADED TOWARD THE TEXAS COAST... ...LIFE-THREATENING AND DEVASTATING FLOODING EXPECTED NEAR THE COAST DUE TO HEAVY RAINFALL AND STORM SURGE... SUMMARY OF 400 PM CDT...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...24.7N 93.9W ABOUT 305 MI...490 KM SE OF CORPUS CHRISTI TEXAS ABOUT 300 MI...480 KM SSE OF PORT OCONNOR TEXAS MAXIMUM SUSTAINED WINDS...85 MPH...140 KM/H PRESENT MOVEMENT...NNW OR 330 DEGREES AT 10 MPH...17 KM/H MINIMUM CENTRAL PRESSURE...976 MB...28.82 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: The Hurricane Warning has been extended northeast of Matagorda to Sargent Texas. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Storm Surge Warning is in effect for... * Port Mansfield to High Island Texas A Storm Surge Watch is in effect for... * South of Port Mansfield Texas to the Mouth of the Rio Grande A Hurricane Warning is in effect for... * Port Mansfield to Sargent Texas A Tropical Storm Warning is in effect for... * North of Sargent to High Island Texas * South of Port Mansfield Texas to the Mouth of the Rio Grande A Hurricane Watch is in effect for... * South of Port Mansfield Texas to the Mouth of the Rio Grande A Tropical Storm Watch is in effect for... * South of the Mouth of the Rio Grande to Boca de Catan Mexico A Storm Surge Warning means there is a danger of life-threatening inundation, from rising water moving inland from the coastline, during the next 36 hours in the indicated locations. For a depiction of areas at risk, please see the National Weather Service Storm Surge Watch/Warning Graphic, available at hurricanes.gov. This is a life-threatening situation. Persons located within these areas should take all necessary actions to protect life and property from rising water and the potential for other dangerous conditions. Promptly follow evacuation and other instructions from local officials. A Hurricane Warning means that hurricane conditions are expected somewhere within the warning area. A warning is typically issued 36 hours before the anticipated first occurrence of tropical-storm- force winds, conditions that make outside preparations difficult or dangerous. Preparations to protect life and property should be rushed to completion. A Storm Surge Watch means there is a possibility of life- threatening inundation, from rising water moving inland from the coastline, in the indicated locations during the next 48 hours. A Hurricane Watch means that hurricane conditions are possible within the watch area. In addition, interests in southwestern Louisiana should continue to monitor the progress of this system. For storm information specific to your area in the United States, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office. For storm information specific to your area outside the United States, please monitor products issued by your national meteorological service. DISCUSSION AND 48-HOUR OUTLOOK ------------------------------ At 400 PM CDT (2100 UTC), the eye of Hurricane Harvey was located near latitude 24.7 North, longitude 93.9 West. Harvey is moving toward the north-northwest near 10 mph (17 km/h). A turn toward the northwest is expected this evening, and Harvey's forward speed is forecast to slow down during the next couple of days. On the forecast track, Harvey will approach the middle Texas coast on Friday and make landfall Friday night or early Saturday. Harvey is then likely to stall near or just inland of the middle Texas coast through the weekend. Maximum sustained winds are near 85 mph (140 km/h) with higher gusts. Strengthening is forecast, and Harvey is expected to become a major hurricane by Friday before it reaches the middle Texas coast. Hurricane-force winds extend outward up to 25 miles (35 km) from the center, and tropical-storm-force winds extend outward up to 90 miles (150 km). The minimum central pressure based on dropsonde data released by a NOAA Hurricane Hunter aircraft is 976 mb (28.82 inches). HAZARDS AFFECTING LAND ---------------------- RAINFALL: Harvey is expected to produce total rain accumulations of 15 to 25 inches and isolated maximum amounts of 35 inches over the middle and upper Texas coast through next Wednesday. During the same time period Harvey is expected to produce total rain accumulations of 7 to 15 inches in far south Texas and the Texas Hill Country over through central and southwest Louisiana, with accumulations of up to 7 inches extending into other parts of Texas and the lower Mississippi Valley. Rainfall from Harvey may cause devastating and life-threatening flooding. STORM SURGE: The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. The water is expected to reach the following heights above ground if the peak surge occurs at the time of high tide... N Entrance Padre Island Natl Seashore to Sargent...6 to 12 ft Sargent to Jamaica Beach...5 to 8 ft Port Mansfield to N Entrance Padre Island Natl Seashore...5 to 7 ft Jamaica Beach to High Island...2 to 4 ft Mouth of the Rio Grande to Port Mansfield...2 to 4 ft High Island to Morgan City...1 to 3 ft The deepest water will occur along the immediate coast near and to the northeast of the landfall location, where the surge will be accompanied by large and destructive waves. Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances. For information specific to your area, please see products issued by your local National Weather Service forecast office. WIND: Hurricane conditions are likely within the hurricane warning area late Friday or Friday night, with tropical storm conditions expected to first reach the coast in the hurricane warning area Friday. SURF: Swells generated by Harvey are likely to affect the Texas, Louisiana, and northeast Mexico coasts by Friday. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. NEXT ADVISORY ------------- Next intermediate advisory at 700 PM CDT. Next complete advisory at 1000 PM CDT. $$ Forecaster Berg NNNN