New Orleans Evacuates As Gustav Weakens
Posted: (August 31, 2008 02:43 pm)

Hurricane Gustav continues to weaken as it quickly approaches the northern Gulf coast. As of 1:00 pm EDT maximum sustained winds had decreased to 115 mph with some higher gusts.  A HURRICANE WARNING remains in effect from Cameron Louisiana eastward to the Alabama/Florida border and evacuations remain mandatory for the city of New Orleans at this time. 

Plotting the storm......as of 1:00 pm CDT the center of Hurricane Gustav was approximately 270 miles southeast of the mouth of the Mississippi River. It is now moving towards the northwest at 17 mph and should continue this forward motion over the next 24 to 48 hours. However, a dercrease in forward speed is expected soon which could create serious problems farther inland. I'll get into that a little bit more in just a sec. On its current track, Gustav should make landfall some time Monday morning along the coast of Louisana. 

Even though Gustav is a very large storm, Hurricane force winds only extend outward up to 50 miles. Quite honestly, this could end up being the saving grace for the city of New Orleans which was devastated by Hurricane Katrinaonly three years ago. Because of the small area of hurricane force winds within the storm the perfect track has to develop to produce Katrina like damage again. At this time it does not appear that this will happen. Now dont get me wrong here, there will be no escaping the Tropical Storm Force winds in the Big Easy which is home to about 200,000 people. And this will still cause some damage to signs, roofs, shrubs, trees and mobile homes. But the extent of the damage produced from Tropical Storm Force winds compared to Hurricane Force winds is significantly less. So wind damage should be kept down to a minimum in New Orleans if the storm continues on its current projected path.

The image below shows how far the Tropical Storm Force winds and Hurricane Force winds extend outward from the center of circulation. Notice how small the area of hurricane force winds is. The second image (below) is the current forecasted track from the NHC. Notice how close the eye is expected to make landfall in proximity to the city of New Orleans. This is going to be a very close call.





The big problem is going to be the tremendous storm surge and flooding. In order to pin point the specifics on that we have to ask the question....... where does the right front quadrant of the storm make landfall?
 
The right front quadrant of the storm is typically the strongest part of the hurricane because it combines the storms forward speed with the speed of the winds swirling around it.  So as i mentioned earlier this morning, if the hurricane has 120 mph sustained winds during the time of landfall and it is moving at 20 mph, the northeast quadrant will more than likely see wind gusts to 140 mph....minimum. Those kinds of winds will produce a storm surge of 15 to 20 feet above normal tide levels. Not to mention the 20 to 25 foot waves crashing on top of that.  These conditions are expected just to the east of where the center of circulation comes onshore. Right now that does appear to be a direct hit for New Orleans.

Some of the levee's are still not completely restored from Katrina three years ago. Hence the reasoning for the mandatory evacuations. So this is where all the problems are going to stem from. Not necessarily the winds but the surge and flooding. Remember Katrina......it wasn't the winds that devastated the city, it was the flooding. Lets all hope and pray that this does not happen again.

Ok, earlier I mentioned how the forward speed of Gustav is expected to slow down by Tuesday morning and how that may create problems for locatioins further inland. These problems would be in the form of flooding across Mississippi and Arkansas. Heavy rains could fall over the same areas for an extended period of time should this storm slow down. It may also interact with the tail end of a cold front which could enhance the rainfall even more for a time. Allof this spells trouble from southwestern Mississippi northward to southern Arkansas where forecasted rainfall totals of over 13 inches spread out across this region. Below is a look at the predicted rainfall amounts from Gustav.

I will have another update this evening.

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