This is the official blog for Bryan Norcross, Hurricane Specialist at The Weather Channel.
By: Bryan Norcross , 3:20 AM GMT on August 30, 2012
I was looking over last night's blog and realize now all of the hazards I didn't list. I was concentrating on the effects in southeast Louisiana, which all came to pass except that Grand Isle seems to have lucked out... or we haven't heard yet.
My rainfall estimates look low... I said up to 20 inches and that much fell just today at Audubon Park in New Orleans. It looks like some areas will get 30 inches of rain or more!
And then there's the unrelenting severe weather in Mississippi and some in Alabama as well. I expected heavy rain and wind there, but a band set up near Gulfport and Biloxi and arced up to then north all day. Communities in that channel of storms got pounded. To a somewhat lesser degree the same thing happened near Mobile.
Major storm surge flooding hit the western Mississippi coast and the area east of New Orleans outside the levee. And... another thing I didn't mention, it looks like there will be significant flooding around Lake Ponchartrain as well.
A couple of days ago, I talked about the nightmare scenario of people not evacuating or taking protective measures because Isaac was a disorganized tropical storm. To make it worse, it was a no-show in Key West. Indeed, that happened in Plaquemines Parish. It's incredibly lucky that nobody died when the levee there was topped and the water went up to people's roofs.
No doubt untold tens or hundreds of thousands of people are going to wish they had more batteries and food and other storm supplies since they'll be trapped at home with no power and trees down all around them. Travel isn't going to be possible in many areas for at least a few days due to downed trees and flooding.
Isaac is a monstrous vortex with a tremendous amount of momentum (think a huge, heavy spinning top). Even with the friction of the ground, it's going to take a long time to spin down. Making it even worse, in the Gulf of Mexico the storm had more rain on its back side than its front due to the dry air it was encountering. That is still the case. Hopefully some of that will weaken as the storm moves north, but there is a LOT of the tropical circulation still to come ashore.
The last 20% of a storm like this is always the worst. Trees, bridges, sea walls, levees, and anything else subject to the pounding wind and/or rising water is more likely to fail or be topped at the end of the storm. I'm expecting more and more evacuations and reports of neighborhoods isolated because of the wind, rain, and surge effects of the storm.
I'm hoping for the best... but fearing the worst.
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