(CBS/AP) NEW ORLEANS - Finally reaching hurricane status, the unwieldy and wobbly Isaac bore down on this city Tuesday, offering one of the first tests for a stronger, more fortified levee system built after the catastrophic failures during Hurricane Katrina.
Seven years after that storm transformed this city, the mood was calm as the first wave of rain bands and wind gusts rolled ashore, and these battle-tested residents took the storm in stride, knowing they've been through a lot worse. Isaac looked to make landfall as early as Tuesday as a Category 1 hurricane with winds of at least 74 mph - much lower than the 135 mph winds Katrina packed in 2005.
Many residents along the Gulf Coast opted to ride it out in shelters or at home and officials, while sounding alarm about the dangers of the powerful storm, decided not to call for mass evacuations. Still, there was a threat of storm surge and the possibility of nearly two feet of rain as it slowly trudges inland.
"We don't expect a Katrina-like event, but remember there are things about a Category 1 storm that can kill you," Mayor Mitch Landrieu said, urging people to use common sense and to stay off any streets that may flood.
Isaac became a hurricane Tuesday, a massive storm that reached more than 200 miles from its center, threatening to flood the coasts of four states with storm surge and heavy rains on its way to New Orleans, with surface wind speeds of 75 mph and flight-level winds even stronger, at 110 mph.
Meteorologist Jeff Berardelli of CBS Miami station WFOR-TV reports one factor that delayed Isaac from developing into a hurricane was that dry air to the north of the storm inhibited those stronger flight-level winds from dropping down to the surface.
Weather models indicated that Isaac will slow down when it makes landfall, possibly dropping between 15 inches and 20 inches of rain on a very large area that may include New Orleans, Berardelli reports. Isaac could also cause between 6 feet and 12 feet of storm surge east of the storm's center.
Berardelli notes that the outer bands of rain rotating into Isaac's center pose a tornado threat. Because the tornadoes move extremely fast and are wrapped in rain, they can't be seen coming.
Isaac was centered about 75 miles southeast of the mouth of the Mississippi River at midday and was moving northwest at 10 mph.
In New Orleans, Landrieu insisted the city was ready, CBS News correspondent Byron Pitts reports. When asked about the comfortable and confident stance people have about the storm - and if that's a good place to be - Landrieu said, "I think what they're comfortable and confident in is that, given the level of this storm, that the levees can hold and we're not gonna have a Katrina event."
In Cocodrie, La., the biggest concern was the expected storm surge, CBS News correspondent Manuel Bojorquez reports. Two major flood gates meant to protect this coastal community are still under construction. One of them, the Houma Navigation Canal, won't be complete until next hurricane season. Everyone in the area is under a mandatory evacuation notice.
In Biloxi, Miss., CBS News correspondent Mark Strassmann reports Mississippi's construction standards could place some areas in real trouble. The city faces the northeast quadrant of Isaac, potentially the storm's most powerful and punishing side.
One study by the Insurance Institute for Business Home & Safety rated construction standards in 18 hurricane-prone states, from Maine to Texas. Florida scored high, a 95 out of 100; Louisiana, 73. But Alabama scored 18, and Mississippi scored the lowest - 4 out of 100.
CBS News correspondent Rebecca Jarvis reports Isaac could lead to an increase in gas prices between 5 cents and 10 cents in the next week. More than 40 percent of U.S. refineries are along the Gulf Coast, and about half of them are directly in the storm's path.
Many refineries are either shut down or are considering whether to stop production until the storm passes, Jarvis reports. Gas supplies are already 4 percent lower than normal this year because of the closure of six other refineries earlier this month.
In Tampa, Fla., site of the Republican National Convention, CBS News chief Washington correspondent Bob Schieffer reports that GOP officials are developing response plans in case Isaac takes a turn for the worse.
"The optics of a split-screen of people in peril over here and people at a convention having fun is something they really don't want to face up to," Schieffer said on "CBS This Morning" Tuesday.
Possibilities include canceling more sessions, which was done on Monday when the storm was near Tampa, or only having Mitt Romney address Americans after being named the party's presidential nominee, Schieffer reports.
In Washington, President Obama urged Gulf Coast residents to listen to local authorities, saying in brief remarks at the White House that "now is not the time to tempt fate.
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