Gustav Update. Bottom line: Run Away Now.

Posted by Greg Laden on August 30, 2008
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Gustav’s eye has passed over western Cuba, and remained a category four hurricane the entire time. One gust in Cuba, where Gustav mainly affected the tobacco growing region, as clocked at 204 miles per hour. Miles. Not kilometers. The storm has caused considerable damage there (source).

Here is the salient information regarding the current forecast:

1) Confidence about Gustav’s path has increased and the following may, while it should be read with the usual caveats as to error, is thought to be more accurate than typical.

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2) The intensity estimate has much less certainty. There are wind sheer effects that will reduce the hurricane’s strength, and there is some VERY warm water over which it shall cross over the next several hours. Later, the storm will move over other areas of relatively cool water. Most likely, the storm will make immediate landfall at Category Four strength.

3) Given the angle of approach to the northern gulf in relation to the shape of the coast around the Delta, there are numerous different scenarios that are at this point impossible to narrow down. The more oblique the angle the more rainfall may be brought ashore. Plus, the exact forward speed of the storm … which determines how long tropical force winds affect the coast and how long storm bands bring rain inland …. will ultimately determine much of the storm’s effects. There is very little certainty regarding this aspect of the storm, and the HPC is saying nothing about this at this time.

There is a mandatory evacuation in New Orleans at this time.

You may remember that when Katrina, a mere Category Three storm, came shore, it was said (by some) that the storm itself had little to do with destruction of New Orleans. Rather, New Orleans was severely damaged by a flood. As though that flood was not the outcome of the storm.

So let’s get this straight now. A hurricane coming ashore does three things …. each of these three things is part of the hurricane.

i) strong winds blow;

ii) lots of rain may fall, causing flooding and general wetness; and

iii) a storm surge, caused by low pressure and the winds can raise the ocean and bring it along the ‘dry land’ in some cases quite some distance.

A hurricane is made of these three things. The effects of Katrina in New Orleans was mainly flooding, in parts of Mississippi mainly storm surge and wind. As far as Gustav is concerned, we will have to see.

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Comments

  1. #1 daenku32
    August 30, 2008

    I just wonder if the levee is going to hold. They have been so busily rebuilding the city, it might have been all in vain.

  2. #2 Ana
    August 30, 2008

    OF COURSE it’s in vain, daenku32 – just a matter of time – it’s a city built on swampland. People need to move. Not gonna get any better.

  3. #3 Stephanie Z
    August 31, 2008

    Built on swampland next to lots of very warm water, which is also important. Giant engineering projects can only do so much to keep the water out when storms keep dumping water in behind them.

  4. #4 Left_Wing_Fox
    August 31, 2008

    Talk to the Dutch about living below sea level. They seem to be handling it quite well. However, that’s Europe. America seems to have lost it’s will to perform these sorts of public works projects.

    New Orleans is going nowhere. Period. The economic confluence of the Mississippi and the Gulf make the city far too important economically to be anything less than a major city. As a nation, we can either buck up, and put the money and man-hours into a public works project our grandchildren will be proud of, or we let it slide into America’s Calcutta, the tombstone on America’s relevance in the world.

  5. #5 Who Cares
    August 31, 2008

    Well we Dutch don’t get category 2+ hurricanes.
    What hit the Netherlands in 1953 barely broke category 1 (11 to 12 beaufort). And it broke through because of a combination of lack of maintenance, the amplification of the storm surge due to the Dover strait bottleneck and the bottlenecks created around by (at that time) open areas between the province Zeeland. The result a storm surge in the range of 15-18 feet (4.5-5.5m) on top of the tide. Which is about as high or a bit higher then they predict for Louisiana when Gustav gets there.

  6. #6 greg laden
    August 31, 2008

    This is complex. Normal tides in the North Atlantic are much larger than normal tides in the Gulf of Mexico. So, on one hand, the dikes need to be equipped for greater changes in sea level, but on the other hand, you can get much larger storm surges in the north Atlantic, theoretically. The Dutch have the will to make the dikes work because almost the entire country is protected by the dikes. The corporations working in the gulf have their assets as protected as they can be. The richer neighborhoods in the general vicinity of N.O. are on higher ground, yes? I don’t know the area that well, but I’ve heard this. The poor and some of the commercial districts in N.O. are of no major concern to the rest of the United States, seemingly.

    So yes, that the Dutch can “do it” and the Americans “can’t” because the Dutch are doing it right and the Americans are doing it wrong could be true. Or maybe not.