Isaac reaches hurricane strength

Posted at 1:24 PM, Aug 28, 2012
and last updated 2012-08-28 13:24:48-04

RICHMOND, Va. (WTVR) – Isaac is racing toward the finish line, which will be landfall along the Louisiana and Mississippi Gulf coast states, tonight. Winds are also racing, becoming faster and just surpassing the hurricane intensity threshold at 12:20 p.m. EDT.

As of mid-day Tuesday, Isaac is a Category One hurricane with maximum sustained wind speeds confirmed by Hurricane Hunter aircraft of 75 mph.

A hurricane must have at least 74 mph sustained wind speeds. Isaac held steady at 70 mph sustained wind speeds the first half of Tuesday, but by late Tuesday morning was showing signs of a developing eye-wall. Even though the maximum sustained winds are at 75 mph, higher gusts are occurring.

The National Hurricane Center tropical forecasters expect Isaac to make landfall overnight at hurricane strength as a Category One with winds around 80 mph along southeastern Louisiana and far southern Mississippi. Tropical storm force winds extend out from the center of the storm as far away as 205 miles.

The Air Force Reserve and NOAA Hurricane Hunter Aircraft report the latest minimum central pressure at 12:20 p.m. EDT was 975 mb, or 28.79 inches. The same Aircraft reports Hurricane Isaac’s center location is about 75 miles south-southeast of the mouth of the Mississippi River, or about 160 miles southeast of New Orleans, LA.  Hurricane Isaac is moving northwest at 10 mph, and with t his slow progression, flooding rainfall and coastal surge and wave damage could be significant.

Winds should be around 85 mph as Isaac makes landfall overnight Tuesday into pre-dawn Wednesday, likely not far from New Orleans. Even though the red line takes the center of Isaac very near or directly over New Orleans, it is more important to focus on anywhere within the white outlined cone path because at least tropical storm force conditions will be experienced in that zone.  Tropical storm conditions will overspread the central Gulf coast through this morning, with hurricane conditions by this afternoon. 

Storm surge is still expected to be as high as 12 feet in southeast Louisiana and southern Mississippi. The National Hurricane Center tropical forecasters warn of significant storm surge that could reach the following depths (above ground) if the peak storm surge coincides with the normal high tide along the coast:
Southeast Louisiana and Mississippi: 6 to 12 feet
Alabama: 4 to 8 feet
South-central Louisiana: 3 to 6 feet
Florida Panhandle: 3 to 6 feet
Florida west coast, including Apalachee Bay: 1 to 3 feet

The NHC warns, “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.”

As for expected rainfall, Isaac has been feasting upon the very warm Gulf waters over which it is passing, and will belch the moisture back upon land as Isaac moves slowly inland over the next several days.

CLICK HERE to watch a satellite movie over the past 48 hours of Isaac.
CLICK HERE to keep up with the latest track and live video of Isaac along the Gulf Coast.

As Isaac chugs inland along the Mississippi Valley region, the forecast scenarios computed by tropical models vary widely, but do indicate much-needed rainfall for parts of the U.S. battling one of the worst droughts in our history. In addition, it will carry with it the threat of isolated tornadoes in spiral rain bands as Isaac makes landfall tonight through Wednesday along the central Gulf coast states.

Meteorologist Carrie Rose
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