Hoosier

Today was about as unstable of a mid-May day here as I can recall.

We'd need to know the helicity to get a close approximation. Just looking at the CAPE and crudely estimating the helicity, I'd say the EHI would be over 15 and possibly approaching 20.

With that shear... wicked

ILX ran a special 18z sounding on 7/13/04: Low level flow isn't that impressive but there's nice veering with height. Also check out the max hail size...I have no idea how that is calculated

Peoria sounding is the closest thing we have. Given the surface obs at the time of the tornado, I'm guessing the thermodynamic environment in northern IL was very similar.

We need a RAOB site in Indiana or Kentucky

Yeah it's harder to get the good shear this far south in summer. Usually you have to rely on some freak meso/microscale interactions to produce strong/violent tornadoes.

Jesus...I knew 8/4 was really unstable but I didn't realize it was that unstable. I wonder what instability is like in that area of the Middle East that often gets dewpoints well into the 80's.

Obviously there are different ways to measure instability but I'm focusing on CAPE. I remember one from IA or NE last year or the year before which had MLCAPE well over 5000 (maybe over 6000). 7/13/04 was another crazy unstable day with SBCAPE over 7000 in IL. Another good one is the Peoria sounding from 8/28/90 with MLCAPE over 5500 (SBCAPE of 7000-8000 IIRC)

That is really impressive.

I won't be surprised if the final number surpasses the total from 1974.

Time makes people forget. Plus there's a little truth in the lake myth, but it gets exaggerated to the point where people think it will prevent something big every time. Cook county had 24 minutes of lead time on 4/21/67, outstanding for that era especially given that the tornado hadn't previously touched down yet in another county. Oak Lawn had about 25,000 people and the tornado damage path was only a couple hundred yards wide at most, but we got unlucky with a lot of people caught in traffic. I've read the damage survey and it seems like the only F4 damage occurred in Oak Lawn...so if that severe damage would've been more widespread or farther northeast, it probably would've been worse. There's been some frightening modeled scenarios about what would happen if a violent tornado tracked through Chicago. The area with rather high population density is much bigger though as you said.

Long post so I'm not quoting the whole thing, but just wait. A mass casualty tornado is inevitable. It's been 20 years since Plainfield and that was only one violent tornado. Given the urban sprawl around there, that would be bad enough, but imagine 2 or 3 violent tornadoes in one day like 1967. It's hard to just pick one metro area in the US and say "this is where the next mega tornado disaster is likely to be" but your area is probably as likely as anybody. At least you have more basements than Alabama, but there's also more people.

Well, my relatives in Tuscaloosa are fine. They are on the north side of town so it missed them. They know someone who works in the ER and I guess there are babies lined up in the hallway with no parents around.

Obviously, but the question is whether one should be forced to have one. That starts to bring a political element into the discussion though.

Technically, but you know how we roll in this subforum.

Survey thread: http://www.americanwx.com/bb/index.php/topic/17853-427-428-tornado-outbreak-damage-assessment-thread/

Hard to even fathom that, but it was hard to fathom 260 yesterday.

What was the infamous line that Gary England told his viewers on 5/3/99...something like "if you don't get underground, you're going to die." If a TV met said that yesterday, there probably would've been a mass exodus out on the streets. In cases like this, there are bad options and there are worse options for the public at large. Unfortunately we had really bad luck yesterday.

Even if some of the tornadoes in 1974 were off by one Fujita category, you're still talking about violent tornadoes from Indiana/Ohio all the way southward into Alabama. We didn't have that yesterday.

Yeah, it's not a great policy for the general public on the whole (especially in highly populated areas), but if you're weather savvy and can evacuate, why not?

If you're gonna dare to say that something could approach 1974, then you should post some solid meteorological reasoning. Almost all of your posts were one or two sentenced and some variation on "I think this could be like 1974." That's not going to win you a lot of support around here.

It will happen again at some point but it could take a long time. Regardless, the death toll with this tornado outbreak is probably as anomalous as Hurricane Katrina. You look at hurricane fatalities on a year by year basis and they have gone down...then you come to 2005. Similar principle with this event.

144 (time-sensitive)

FYI, I posted a general thread in the main forum. http://www.americanwx.com/bb/index.php/topic/17825-april-27-2011-tornado-outbreak/