my research on Katrinas final hours

[Jim Cantore]

I've looked into this constantly for weeks now and I believe that Katrina weakened to a four sooner then they thought, which is 2am on the 29th.

My reasons to back it up are that first she had been takeing on small amounts of dry air since about 10:30am on the 28th (water vapor confirms)

Second, this quote from the 11pm discussion on the 28th

THERE ARE CONFLICTING SIGNALS REGARDING THE INTENSITY OF KATRINA.
THE NOAA AIRCRAFT NEAR 00Z REPORTED A PEAK FLIGHT LEVEL WIND OF 155
KT...WHICH WOULD NORMALLY CORRESPOND TO 140 KT AT THE SURFACE. THE
PRESSURE REMAINS EXTREMELY LOW...904 MB AT LAST REPORT. ON THE
OTHER HAND...THE STEPPED-FREQUENCY MICROWAVE RADIOMETER...OR
SFMR...SUGGESTED WINDS WERE IN THE 120-130 KT RANGE...AND LIMITED
DROPSONDE DATA ALSO SUGGESTED SOMETHING A LITTLE BELOW 140 KT.
THERE ARE ENOUGH QUESTIONS ABOUT THE PERFORMANCE OF THE SFMR AT
THESE SPEEDS FOR ME TO STICK WITH THE STANDARD 90 PERCENT
ADJUSTMENT FOR NOW.

Third For a Hurricane with a rapidly expanding pressure field it's pressure rose pretty fast from 905-913mb in a four hour span between 10pm-2am.

Fourth, Satelitte shows RAPID erosion of its south and west side and the collapsing of its inner eyewall, which began before 2am

I believe it dropped to a 4 at about 10pm-midnight but I also think it had enough of an eyewall left that it came ashore in Buras as a boarderline 3/4 maybe 130-140mph and if that buoy in Southwest Pass didnt float away its likely the winds would have measured that strong in my opinion.

As for Mississippi I believe that the original 125mph is about correct, maybe 130, see I believe Katrina was about to, if not starting to re-strengthen, look as she went inland that south and west side began to re-fire.

Is there any logic to my theory guys, and please, be brutal if needed

[Audrey2Katrina]

No need for any brutality at all... sound reasoning... and even the met who made the advisory was clearly uncertain.

BTW, who was the one who wrote that advisory you cited--just out of curiosity?

A2K

[Jim Cantore]

that was the 11pm discussion written by Forcaster James Franklin

[Jim Cantore]

And heres a WV from 11:45 CDT on August 28th that shows the dry air already getting into Katrina

http://smg.photobucket.com/albums/v308/Generation7Mako/?action=view&current=678679.jpg

[Audrey2Katrina]

mmmm... perhaps; but she still looks mighty impressive in that pic.

A2K

[Jim Cantore]

Theres no doubt, However a storm can weaken without falling apart, my belief was the weakening was slower

I went in origionally trying to prove she came in at 140-145mph and that a drop to 125mph was obserd, but I went and found nothing but dead ends.

Then I found a bunch of things that I posted above and got the Idea that the weakening may have been slower but longer, although I do believe she came in at about 135mph.

[wxmann_91]

There is no doubt that weakening commenced at around 18Z, but of course hindsight is 20-20.

Closer examination showed the western edge of the storm straight verticle as opposed to the roundness you see usually, due to a restriction of outflow. Then, as evening began, it began an ERC, just as clearly in loops southwesterly shear impinged on its western semicircle. The dry air continued to penetrate the outer rain bands, evidenced by IR loops, throughout the evening and that night.

However, the next morning, a new burst of convection appeared in Katrina, and in fact, QG enhancedment could've finally begun to cancel out the negative effects of shear, and as well, the ERC could've been finishing. I personally believe that is why Katrina weakened little as it crossed the swampy (that in itself would've had little effect) marshlands of Plaquemines.

[Jim Cantore]

Same effect as the everglades, the swampy terrain acts as sort of a life support.

[wxmann_91]

Theres no doubt, However a storm can weaken without falling apart, my belief was the weakening was slower

I went in origionally trying to prove she came in at 140-145mph and that a drop to 125mph was obserd, but I went and found nothing but dead ends.

Then I found a bunch of things that I posted above and got the Idea that the weakening may have been slower but longer, although I do believe she came in at about 135mph.

Actually I believe the weakening from 18Z the 28th to ~12Z the 29th was quite rapid, but she leveled off as she made landfall.

[Jim Cantore]

the time when her pressure went from 905 to 913 was the time of most rapid weakening most likely

[Javlin]

Also someone in one of the pass threads posted an sst map with Katrina's arrival there was a little warm spot from Burras to the Pass.In that same map you could see where Ortt mentioned that @ one point Katrina might have dropped even lower if she had traveled maybe 50-100 miles further W.We all know if that had occurred New Orleans would not exist anymore with Katrina coming in on the W side.

[wxwatcher91]

I think if Katrina were given 12 more hours, she wouldve made landfall near 145 maybe even 150mph. as she was making landfall, she was looking consistently better on satellite. her west side began to fill in a bit more and she was pushing out a lot of the dry air.