New Orleans to Pensacola at high risk from Katrina

By: Dr. Jeff Masters , 4:05 PM GMT on August 27, 2005

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The Hurricane Hunters measured a central pressure of 949 mb at 11:14am EDT, up from the cental pressure of 941 mb measured at 7:07am EDT. Concentric eyewalls with diameters of 13 and 40 nm were reported, satellite images show that the eye has filled in with clouds and the cloud top temperatures have warmed. These observations indicate that an eyewall replacement cycle has begun. This was expected, since the 7:07am Hurricane Huneter report indicated that the eye diameter had shrunk to 9 nm, about the smallest diameter one gets before an eyewall replacement cycle begins.

The maximum winds may fall below 115 mph while Katrina undergoes this eyewall replacement cycle, as the inner eyewall collapses and a new outer eyewall forms. This would make Katrina a strong Category 2 storm, and indeed the maximum winds seen so far by the Hurricane Hunters were only 87 knots (100 mph) at 10,000 feet. This is a temporary affliction, since Katrina is in nearly ideal conditions for strengthening, and is expected to reach Category 4 status by Sunday. The convection and outflow are starting to look better on the north side of the hurricane, and Katrina should have a more symmetrical shape typical of Category 4 hurricanes by Sunday. As seen in the cumulative wind image below, Katrina has increased markedly in size the past 12 hours, and will deliver a widespread damaging blow wherever she comes ashore.



The favorable intensification conditions for Katrina are expected to last up until landfall, when some increase in shear may occur. Intensification forecasts are highly unreliable, though, and it would be no surprise if Katrina were a Category 2, 3, or 4 landfall. The track forecast is getting more believable, as Katrina's westerly motion shows that it has begun it recurvature, pretty much where NHC and the models were predicting. A landfall between New Orleans and Pensacola is on track for Monday morning or afternoon. I expect a Category 3 storm at landfall.

I'd hate to be an Emergency Management official in New Orleans right now. Katrina is pretty much following the NHC forecast, and appears likely to pass VERY close to New Orleans. I'm surprised they haven't ordered an evacuation of the city yet. While the odds of a catastrophic hit that would completely flood the city of New Orleans are probably 10%, that is way too high in my opinion to justify leaving the people in the city. If I lived in the city, I would evacuate NOW! There is a very good reason that the Coroner's office in New Orleans keeps 10,000 body bags on hand. The risks are too great from this storm, and a weekend away from the city would be nice anyway, right? GO! New Orleans needs a full 72 hours to evacuate, and landfall is already less than 72 hours away. Get out now and beat the rush. You're not going to have to go to work or school on Monday anyway. If an evacuation is ordered, not everyone who wants to get out may be able to do so--particularly the 60,000 poor people with no cars.

Dr. Jeff Masters

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231. Weatherwatcher007
5:54 PM GMT on August 27, 2005
In this link you can clearly see that the second eyewall is forming and is becoming predominant and a burst of extreme convection is wrapping around it.

Link
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230. StormJunkie
5:58 PM GMT on August 27, 2005
With a storm this size it would be bad either way if the evey is within 40 miles of NO. Either the lake has water pushed over the levees from storm surge or the rain and wind push the water in to the city.
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229. Selu
1:00 PM CDT on August 27, 2005
wxfan...isthere a model plot that shows the GDFL shift back to the west?
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228. Selu
12:55 PM CDT on August 27, 2005
Wow, Unlabeled...I've never heard of such. My prayers will be with those kids. Entering college as a new freshman is hard enough...potentially carrying the trauma of a huge, devastating hurricane with you as you attempt to make your way through strange freshman territory is going to be so difficult for those kids.

USM will not lock down, but they will wait until the last minute to cancel classes. My guess is that most of the kids have already left Hattiesburg and Gulf Coast USMs.
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227. HurricaneParty
12:50 PM CDT on August 27, 2005
Good site about Doughnuts

Click Here
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226. StormJunkie
5:56 PM GMT on August 27, 2005
Hugo was a doughnout. 145 mph winds came in Charleston, SC 70+ mile an hour winds still in Ashville.
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225. wxfan
5:57 PM GMT on August 27, 2005
New GFDL shifts back west. The eastward movement of the models over the last 12 hours may have been a fluke.
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224. hookedontropics
5:56 PM GMT on August 27, 2005
Thanks Storm Junkie, Do I make sense when I say that (as crazy as that sounds?
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223. Hawkeyewx
12:55 PM CDT on August 27, 2005
It is noteworthy that both the 12z GFS and GFDL have again shifted westward and both now take the eye of Katrina over or just west of New Orleans while still moving toward the north or north-northwest.
Member Since: July 5, 2005 Posts: 2 Comments: 1923
222. nola
11:53 AM CST on August 27, 2005
hooked on tropics - you are correct. NO will fare much better is we are on the west side. Southerly winds will fill the lake, northerly winds will empty it.
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221. wxfan
5:55 PM GMT on August 27, 2005
It is DEFINITELY going just South of the next forecast point. NOT GOOD for NOLA and points west.

http://www.ssd.noaa.gov/PS/TROP/DATA/RT/float-vis-loop.html
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220. hookedontropics
5:55 PM GMT on August 27, 2005
Lefty, my brother lives off of exit 126.

This storm's size is growing significantly right now
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219. StormJunkie
5:52 PM GMT on August 27, 2005
Hooked- This is the post you were talking about I thin

PLEASE READ IF YOU DO NOT KNOW WHAT A NO DIRECT HIT WOULD MEAN.



flooding map of NO

Results of Direct Hit on NO
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218. pseabury
5:54 PM GMT on August 27, 2005
Hey Lefty...DC for me right now...Isabelle was a nightmare with the power outages up here. NOLA is still my home though, and I'm gonna hate to see her go, which she will in my lifetime.....hopefully just not this time.
Member Since: May 28, 2005 Posts: 0 Comments: 3
217. leftyy420
5:53 PM GMT on August 27, 2005
hey i live just north of you in fredericksburg,va
Member Since: August 24, 2005 Posts: 35 Comments: 1987
216. hookedontropics
5:51 PM GMT on August 27, 2005
We were 250 miles from Isabel's landfall in Richmond, VA. We had power out for a week. You have to do west out of harms way with this storm.
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215. boiredfish
5:48 PM GMT on August 27, 2005
This thing's approaching 86 and still no closer to crossing 25.

It's gonna suck if people in sw/sc La. have to evacuate. Guess they'd have to go clear to west Texas to find a hotel room.

The eyewall cycle is amazing to watch.....

Member Since: July 8, 2005 Posts: 0 Comments: 442
214. leftyy420
5:49 PM GMT on August 27, 2005
a doughnut cyclone is a cyclone where the eye wall is large about 30-40 miels and the storm is really round with little if any feeder bands. also the eye wall is so strong she can be an intense storm 165 mph wind sor higher and fight off the centricle forces that cause a smaller eyed storm to go into eye wall cycles. this means she could mantain that intensity at cat 5 for some time likley all the way to the landfall


to the guy in mobile good job than man. call ur neigbors and make sure they are ready
Member Since: August 24, 2005 Posts: 35 Comments: 1987
213. hookedontropics
5:49 PM GMT on August 27, 2005
There was a post on here yesterday with a link of NO and how it sits below sea level. It is my understanding from reading this, as crazy as this sounds, it would actually be better to get a north wind instead of a south wind. The water can only be pushed into NO with a north wind.
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212. StormJunkie
5:49 PM GMT on August 27, 2005
Doughnut equals a reall strong wide eye 40 miles+. The worst of a storm spread over about an 80 to 160 mile wide area.
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211. Hawkeyewx
12:48 PM CDT on August 27, 2005
Sorry, but I guess the Isabelle pic link I gave you may not work because I am not allowed a large enough data transfer.
Member Since: July 5, 2005 Posts: 2 Comments: 1923
210. HurricaneGuru
5:48 PM GMT on August 27, 2005
Call a CAT 5 more appropriately a SUPERCAT 5
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209. Selu
12:45 PM CDT on August 27, 2005
Look for both USM campuses to announce closure by Sunday. Both the Gulf Coast and Hattiesburg campuses. They are moving toward it now. (I've seen this before, and the next update will be either tonight or tomorrow morning, to call off classes until Wednesday at both campuses.)

http://www.usm.edu/gulfcoast/severe_weather.html
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208. Unlabled
5:49 PM GMT on August 27, 2005
Loyola jsut cancelled classes:

Due to the approach of Hurricane Katrina, Loyola University New Orleans will be closed on Monday, August 29 and Tuesday, August 30. All student activities this weekend are cancelled including Swamp Stomp. Students who can do so are encouraged to implement their personal evacuation plans. The Residence Halls will remain open, with meal service, for those resident students who are unable to leave. Loyola facilities will not be a shelter for non-resident students or the community. Students who plan to come to New Orleans should delay their travel plans until the university re-opens.

THe Hurricane Emergency Preparedness Team will continue to monitor the storm and issue updates as necessary.
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207. leftyy420
5:47 PM GMT on August 27, 2005
becaue with a non doughnut cyclone she could be stringer but with the eye wall cycle she would possible not be as strong as she could be at landfall. a doughnut cyclone will have intense winds with no way of weakening as long as the conditions remained favorable. if she is becoming a doughnut she will more than likley be a mod cat 5 at landfall. we will see. adv out she is still a cat 3 155mph winds. erie that was what isabelle was with the same pressure prior to her doughnut genesis. she than had max winds of 145kts for 5 days
Member Since: August 24, 2005 Posts: 35 Comments: 1987
206. AnonymousBystander
5:49 PM GMT on August 27, 2005
http://www.ssd.noaa.gov/PS/TROP/DATA/RT/float-ir4-loop.html

Look at the last few frames.

This thing is EXPLODING
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205. JaxAdjuster
5:45 PM GMT on August 27, 2005
what is a donut storm? I am assuming that means an inner and outer eye. What's up with that?
204. StormJunkie
5:46 PM GMT on August 27, 2005
Something real bad Carb. Kinda like a really strong super typhoon.
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203. hookedontropics
5:47 PM GMT on August 27, 2005
She has grown significantly in the past two hours.
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202. LoneGunman
5:46 PM GMT on August 27, 2005
Can someone explain what a doughnut hurricane is?
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201. mobilegirl
5:40 PM GMT on August 27, 2005
We live in Midtown Mobile - approx 5 miles from the top of the bay - 15 miles inland. Stayed through Ivan, the house across the street was untouched in Frederick.

If in fact we're entering a cycle of increased activity, either scientists are going to have to get a better handle on storm tracking, or they're going to have to pave 10 lanes of I-10 / I-65.

If I lived in New Orleans, I'd feel differently - but the whole gulf coast evacuation thing is getting a bit tired... even though it shouldn't.
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200. Unlabled
5:46 PM GMT on August 27, 2005
actually Selu.. Loyola goes on campus lock down and no one is allowed to leave... Once we go into lock down thats it and they are stuck on campus and are put in the sports complex...

They do not have enough buses or other Transportation to get those kids to the Superdome...

Loyola also has not cancelled classes for Monday yet... Good grief...
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199. Hawkeyewx
12:33 PM CDT on August 27, 2005
Here is a link to a great satellite pic of the Isabelle doughnut.

Link

One possible good sign for the US coast is the fact that many of the models are forecasting Katrina to be moving nne around landfall. That would indicate the southwesterly mid to upper level winds would reach Katrina before landfall and would be able to inflict some shear. As Steve says in his newest blog entry, Camille was able to hit land at max intensity because the southwesterly shearing winds had not yet reached it and the storm was still moving nnw at landfall.
Member Since: July 5, 2005 Posts: 2 Comments: 1923
198. Selu
12:43 PM CDT on August 27, 2005
Unlabeled. Certainly the students who don't have a way out will shelter at the Superdome with others who can't get out.

Question is, will the Superdome be able to weather a Cat 4 or Cat 5 Hurricane? What about UNO Lakefront Arena?

I hope that the kids who don't have vehicles can catch rides with friends who do.

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197. caymanray
5:42 PM GMT on August 27, 2005
Why would a doughnut be worse than a storm with a compact concentric eye other than a wider swath of wind damage?
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196. EZMonster
5:37 PM GMT on August 27, 2005
From Hurricane Hunter's vortex observations 30 min ago:

OUTER EYE ON RADAR 50 NM DIA OPEN SE.
INNER EYE 40% COVERAGE SSW - SE
195. mobile0504
5:39 PM GMT on August 27, 2005
lefty- I am always prepared during the whole hurricane season, I not stupid, but alot of people in this area have been told latley this year and last to prepare, evac. and that mobile was to take the direct hit. I think that everyone just assumes that we will not take a hit or be affected because of the storms hitting to the east of us.I am actually worried for the people of my community not taking this seriously, and I thought that if a watch was posted maybe they would. I promise you I am very up on all storms every year and know just what to do.
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194. Carbo04
5:43 PM GMT on August 27, 2005
'There is no such thing as Cat 6.......156 and higher is a cat 5......lol'


I know, I was meaning what is Cat. 6 by StormTop terms?
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193. Unlabled
5:42 PM GMT on August 27, 2005
Jeff. has voluntary EVAC... 1nce lower parishes go through Jefferson Parish, he wants Jeff parish residents leaving AFTER that.

Orleans parish is silent.
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192. weatherboyfsu
5:42 PM GMT on August 27, 2005
There is no such thing as Cat 6.......156 and higher is a cat 5......lol
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191. Selu
12:42 PM CDT on August 27, 2005
Watch i-55 and I-59 go contraflow by five o'clock today. Governor of Mississippi has to approve it--I hope he will.
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190. Selu
12:41 PM CDT on August 27, 2005
If they don't evacuate Jefferson Parish RIGHT NOW, many people will NOT GET OUT.
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189. leftyy420
5:41 PM GMT on August 27, 2005
i really believ we are seeing a doughnut cyclone in genesis alot more than i did an hr ago omg this will be a storm to remeebr
Member Since: August 24, 2005 Posts: 35 Comments: 1987
188. isobar5
5:40 PM GMT on August 27, 2005
If this model run is current it would show a little shift east would it not?
http://www.skeetobiteweather.com/imagelinkbeta.asp?image=AL122005
Don't get me wrong I think everyone on the North Gulf should not let their guard down.
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187. Unlabled
5:36 PM GMT on August 27, 2005
If this hurricane does not turn soon New Orleans will be in the NE quadrant of this beast and it truly might turn into a catastrophe.

I am still very worried about the incoming freshmen at Loyola and Tulane... their parents just dropped them off and now have no way of Evacuating.

Loyola's plan is to hold them up in their sports complex but I am afraid that it will not hold up in the face of a strong CAT 4 +
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186. StormJunkie
5:40 PM GMT on August 27, 2005
NOLA OFFICIALS ON TWC.
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185. Carbo04
5:40 PM GMT on August 27, 2005
lol, Cat 6. How strong is that? Like 210?
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184. leftyy420
5:39 PM GMT on August 27, 2005
she now has very deepconvection to the north and east wrapping around the second eye. she looks like she will be ready to stregthen in the next 3 hrs. she is really getting better organised really fast
Member Since: August 24, 2005 Posts: 35 Comments: 1987
183. StormJunkie
5:37 PM GMT on August 27, 2005
CARB- Only StormTop can use that term. That is what he said. I laughed at him when he coined the CAT 6. That was the same time about four days ago when he said Pass Christian was in for it.
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182. weatherboyfsu
5:36 PM GMT on August 27, 2005
I think anyone that has friends well inland that can go ahead and leave should do that....what the heck....go on and go visit especially if shes hot......lol....just playing.....you can always come back as soon as katrina makes up her mind......i think I'd rather be safe then sorry......
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181. Dragoon
5:38 PM GMT on August 27, 2005
The new recon report shows that if anything the outer eyewall is becoming LARGER.. and it is slowly beginning to disintegrate and take over the inner eyewall.. with a 40% coverage noted (meaning it no longer even qualifies as the "inner eyewall"
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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