Hurricane Isaac Getting Better Organized as it Nears Southeastern Louisiana, Aug. 28, 2012 – UPDATE 4 pm CDT

Hurricane Isaac Surface Wind Field

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Miami, Florida—(ENEWSPF)—August 28, 2012 – UPDATE 4 pm CDT (2100 UTC).  The National Hurricane Center is reporting that Hurricane Isaac getting better organized as it nears southeastern Louisiana, with flooding from storm surge and rainfall expected.  Hurricane Isaac is located 28.7 north, 89.2 west, about 30 miles (45 km) south-southwest of the mouth of the Mississippi River, about 105 miles (170 km) south-southeast of New Orleans, Louisiana.  Maximum sustained winds are 80 mph (130 km/h).  Present movement is northwest or 310 degrees at 8 mph (13 km/h).

Changes in Watches and Warnings with this Advisory

None.

Summary of Watches and Warnings in Effect

A Hurricane Warning is in effect for:

  • East of Morgan City, Louisiana to the Mississippi-Alabama border, 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:

  • The Mississippi-Alabama border to Destin, Florida,  
  • Morgan City to Cameron, Louisiana.

A Tropical Storm Watch is in effect for:

  • East of High Island, Texas to just west of Cameron, 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.

A Tropical Storm Watch means that Tropical Storm conditions are possible within the watch area.

For storm information specific to your area, please monitor products issued by your local National Weather Service Forecast Office.

Discussion and 48-hour Outlook

At 400 pm CDT, (2100 UTC), the center of Hurricane Isaac was located by NOAA Doppler Radars near latitude 28.7 north, longitude 89.2 west. Isaac is moving toward the northwest near 8 mph (13 km/h). A northwestward motion at a slightly slower speed is expected over the next day or two. On the forecast track, the center of Hurricane Isaac should reach the coastline of southeastern Louisiana this evening.

Maximum sustained winds have increased to near 80 mph (130 km/h) with higher gusts. Isaac is a category one hurricane on the Saffir-Simpson Hurricane Wind Scale. Some slight strengthening is possible before Isaac makes landfall. gradual weakening is expected after landfall occurs.

Hurricane-force winds extend outward up to 60 miles (95 km), mainly to the northeast and east of the center. Tropical-storm-force winds extend outward up to 185 miles (295 km). Tropical storm conditions are occurring along the coastal areas of southeastern Louisiana, Mississippi, and Alabama. NOAA Buoy 42040 located east of the mouth of the Mississippi River recently measured sustained winds of 63 mph (100 km/h) and a gust to 83 mph (135 km/h).

The estimated minimum central pressure is 975 mb (28.79 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:

  • Mississippi and southeastern Louisiana…6 to 12 ft.,  
  • Alabama…4 to 8 ft.,  
  • South-central Louisiana…3 to 6 ft.,  
  • Florida Panhandle…3 to 6 ft.,  
  • Apalachee Nay…2 to 4 ft., and
  • Remainder of Florida west coast…1 to 3 ft.

The deepest water will occur along the immediate coast in areas of onshore winds.  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 will continue to spread across the warning area this evening, and Hurricane conditions should spread onshore across southeastern Louisiana during the next few hours. Winds affecting the upper floors of high-rise buildings will be significantly stronger than those near ground level. At about the 30th story, winds would likely be one Saffir-Simpson Category stronger than at the surface.

Rainfall. Isaac is expected to produce total rainfall amounts of 7 to 14 inches, with possible isolated maximum amounts of 20 inches, over much of Louisiana, Southern Mississippi, Southern Alabama, and the extreme Western Florida Panhandle. These rains could result in significant lowland flooding.

Tornadoes.  Tornadoes are possible along the northern Gulf Coast through tonight.

Surf. Dangerous surf and rip current conditions will continue to affect the west coast of Florida and portions of the northern Gulf Coast for the next day or so.

Source: nhc.noaa.gov