Tropical Storm Isaac Poses Significant Storm Surge Threat to the Northern Gulf Coast, Aug. 27, 2012

Tropical Issac Surface Wind Field

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Miami, Florida—(ENEWSPF)—August 27, 2012 – Update 10 a.m. CDT (1500 UTC). The National Hurricane Center is reporting that Tropical Storm Isaac is moving west-northwestward over the eastern Gulf of Mexico and poses significant storm surge threat to the northern Gulf Coast. Isaac is located 26.1n, 85.3west about 250 miles (400 km) south of Apalachiocola, Florida, and about 310 miles (500 km) southeast of the mouth of the Mississippi River with maximum sustained winds of 65 mph (100 km/h). Present movement is northwest or 305 degrees at 14 mph (22km/h).

Changes in Watches and Warnings with this Advisory

All tropical storm warnings have been discontinued east and south of Audile River, Florida.

Summary of Watches and Warnings in Effect:

A Hurricane Warning is in Effect for:

East of Morgan City, Louisiana to Destin, Florida, including Metropolitan New Orleans, Lake Pontchartrain, and Lake Maurepas.

A Hurricane Watch is in Effect for:

Intracoastal City to Morgan City, Louisiana.

A Tropical Storm Warning is in Effect for:

East of Destin, Florida to the Aucilla River, and
Intracoastal City to Morgan City, Louisiana.

A Tropical Storm Watch is in Effect for:

East of Sabine Pass to west of Intracoastal City, Louisiana.

A Hurricane Warning means that hurricane conditions are expected somewhere within the warning area. Preparations to protect life and property should be rushed to completion.

A Hurricane Watch means that hurricane conditions are possible within the watch area.

A Tropical Storm Warning means that Tropical Storm conditions are expected somewhere within the warning area within 36 hours.

A Tropical Storm Watch means that Tropical Storm conditions are possible within the watch area, generally within 48 hours.

For storm information specific to your area, including possible inland watches and warnings, please monitor products issued by your local National Weather Service Forecast Office.

Discussion and 48-hour Outlook

At 10 am CDT, (1500 UTC), the center of Tropical Storm Isaac was located near latitude 26.1 north, longitude 85.3 west. Isaac is moving toward the northwest near 14 mph (22 km/h) and this general motion is expected to continue today with a gradual decrease in forward speed. A turn toward the northwest is expected by Tuesday. On the forecast track, the center of Isaac will move over the eastern Gulf of Mexico today and approach the northern gulf coast in the hurricane warning area on Tuesday. Maximum sustained winds are near 65 mph (100 km/h) with higher gusts. Some strengthening is forecast during the next 48 hours and Isaac is expected to become a hurricane before reaching the northern gulf coast.

Tropical Storm force winds extend outward up to 205 miles (335 km) from the center.

The estimated minimum central pressure is 988 mb (29.18 inches).

Hazards Affecting Land

Storm Surge. The combination of a storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters. The water could reach the following depths above ground if the peak surge occurs at the time of high tide:

Southeast Louisiana, Mississippi, and Alabama…6 to 12 ft.,
South-central Louisiana…3 to 6 ft.,
Florida Panhandle…3 to 6 ft., and
Florida west coast including Apalachee Bay…1 to 3 ft.

The deepest water will occur along the immediate coast in areas of onshore flow. 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 Weather Service Office. Near the coast, the surge will be accompanied by large and dangerous waves.

Wind. Tropical Storm conditions are expected to spread northward into the Florida Big Bend area and the Florida Panhandle in the Tropical Storm warning area tonight. Tropical Storm conditions are expected to reach the northern gulf coast in the hurricane warning area later tonight, with hurricane conditions expected on Tuesday.

Rainfall. Isaac is expected to produce additional rain accumulations of 1 to 3 inches over the Florida Peninsula, where isolated maximum storm total amounts of 15 inches are possible. Total rainfall amounts of 6 to 12 inches, with maximum amounts of 18 inches, are possible in southeastern Louisiana, southern Mississippi, southern Alabama and the western Florida Panhandle.

Tornadoes. Isolated tornadoes are possible in central and northern Florida today, and along the northern gulf coast tonight and Tuesday.

Surf. Dangerous surf and rip current conditions will continue to affect the Florida coastline and the Florida Keys during the next day or so, and begin to affect portions of the northern gulf coast later today.

Source: nhc.noaa.gov