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katrina downgraded to cat III at landfall - mgc - 01-01-2006 08:57 PM

The wind observation at Michoud was three hours before CPA. How many hurricanes have their wind max that far out. The Katrina report was poor. Does the SFMR work well close to land?...MGC

katrina downgraded to cat III at landfall - soonermeteor - 01-01-2006 11:53 PM

Official pressure with the Catagory 3 winds is now only 2 millibars higher, at 920. This means that Katrina remains stronger than Catagory 5 Andrew.

The other thing is they want us to believe that it was still the same strength when it hit miss, becuase they didn't change how it was downgraded to a cat 3 by the time it made it to the Miss coastline. It crossed shallow water and land, and didn't lose any strength after apparently falling apart before it even made the coast line.

katrina downgraded to cat III at landfall - Coriolis - 01-02-2006 11:10 PM

MGC - The answer to your question about the SFMR - it depends on what you mean close to land. If you mean (as an example) 50 ft offshore then the answer is no. The waters there are shallow, thus you would not have as much sea foam than you would 2 miles offshore.

Soonermeteor - With the exception of your first to sentences - the rest of your last post is a little inaccurate. The landfall intensity in LA was estimated to be 110kts and 105 kt in Mississippi. The NHC did see if fact, that there was a weakening between the landfalls. Also the first landfall is landfall only technically, most of the circulation was still over water until final landfall.

Yes, you were correct, Katrina had a lower pressure than Andrew. The problem is that most people (who don't understand hurricanes) they fail to realize is that what really matters is the pressure gradient, not the pressure.

katrina downgraded to cat III at landfall - CoryPa77 - 01-03-2006 02:09 PM

The NHC didn't upgrade Andrew to a CAT 5 based on the damage they saw. Andrew was a Cat 4 for 10 years before they changed it. Back in the early 90's they used a lower % of the flight level winds to estimate the ground level winds. Sometime later, with more research, they found the ground level winds were about 90% of flight level winds which raised Andew to a Category 5 hurricane.

If you look at NO, there was no roof damage to *most* buildings (I know the Superdome got it), but I remember seeing shingles being blown off by helicopters when they would pick people from the roofs. The hurricane didn't even blow them off! Some windows were blown out from rocks off of buildings roofs being blown into them.

I believe the storm surge was so bad in that area because the slope of the ground in that region is very small to begin with and I think that the storm surge is more dependant on what the storm was just before coming ashore than what it is when it comes ashore. Katrina was a Cat 5 just off shore and it brought similar surge.

katrina downgraded to cat III at landfall - soonermeteor - 01-03-2006 04:21 PM

^ You can't base Katrina's strength off of the wind damage New Orleans. New Orleans barely got the west side of the eyewall, no where near the right front quadrent where the strongest winds typically are. Even when Katrina was listed as a Cat 4, New Orleans only got sustained winds of a Cat 2 strength.

If the strength of Hurricane Katrina was updated for Miss, then that answers my question. They had originally said it was 125 mph, but as I said, if they downgraded Katrina to 125 at the LA Bayou, then they would have to update the Miss winds.

In regards to pressure: the point is that the NHC and everyone else wants to base the intensity of the storm off the lowest recorded pressure, i.e. why wilma is now considered the strongest hurricane ever in the altantic basin. There needs to be some sort of revamp when it comes to catagories, becuase like i said, Katrina goes down in the record books as more intense than Andrew, yet only a catagory 3.

Yes, the strength of the storm surge is not connected directly to the strength of a storm especially at landfall. Katrina's, and Rita's storm surge for that matter, were so great becuase they sat in the center of the Gulf with pressures around 900 mb, which brought all that gulf water into the coast when they made landfall. However, a storm still has to have strength to continue to bring that storm surge into the coast, regardless of the slope of the sea bottom.

Quote:The NHC didn't upgrade Andrew to a CAT 5 based on the damage they saw.

Fujita would disagree with you.