04/02/2006 DISC: IA/IL/MO/AR/TN

[Kurt Wayne]

If you haven't gone back to the kfvs12.com website in the last day or so, they have added another amateur video of the Caruthersville tornado and some footage from a high school monitoring camera.
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The Marmaduke tornado in the Marmaduke/Caruthersville/Newbern "family" is now being called a "strong F3".

(EDIT: I've not watched the high school video cams yet (we had some doozies here in Bentonville as the local HS has footage of big light poles being blown over and pieces of the indoor practice field roof being blown through the parking lot in our tornado of three weeks ago).

However, this footage Eric refers to seems to be at least twice as long as the first clip, and appears to be being made by a MOM as her son is pleading with her to come inside. It's eerie, because the tornado apparently went right over them (her footage stops as the outer circulation is over the parking lot across the street from their house)...the tornado is directly backlit from the sun and never moves from right to left (or vice versa) so they were apparently facing west as this system moved pretty much straight to the east.

You can see multi-vortex action in the tornado...couldn't tell if the horizontal "tube" is there as the footage occasionally breaks up.)

 

[Bryce Stone]

I just wanted to reiterate that I didn't intend to critize the SPC with my post. In fact, I specifically stated in my original post: "Having no in-depth meterological training, I won't criticize the SPC at all." However, I guess I wasn't clear enough about what I was trying to say. I was simply critiquing science's current ability to forecast tornadoes. There is nothing wrong with post-analysis, and I do not direct it toward the SPC at all. I believe the SPC employs the best scientists that modern meteorology has to offer. When the SPC issues a forecast, most of the storm chasers on Stormtrack seem to concur with that forecast. So my commentary is not directed toward any one entity, but toward the science of tornado forecasting.

As Jeff pointed out, we had a moderate risk for severe storms on two days recently (04/01 and 04/02). In terms of tornado production, one risk underproduced (just a couple of tornadoes) and the other overproduced (many tornadoes, some of which were strong and perhaps violent). To me that says that modern science may be able to accurately predict the location of severe weather days or even a week or more in advance. But I don't feel like science has yet mastered the ability to accurately predict exactly when and where a tornado outbreak will occur. That's all I was trying to say.

I wholeheartedly agree that watches and warnings are much more important for saving human life than outlooks. I completely agree that hindsight is 20/20, and I hate Monday morning quarterbacking. Mankind has came a long way in our ability to predict tornadoes, so here's hoping we will reach our goal of being able to do it consistently and accurately every time.

 

[Rich Thompson]

I just wanted to reiterate that I didn't intend to critize the SPC with my post. In fact, I specifically stated in my original post: "Having no in-depth meterological training, I won't criticize the SPC at all." However, I guess I wasn't clear enough about what I was trying to say. I was simply critiquing science's current ability to forecast tornadoes. There is nothing wrong with post-analysis, and I do not direct it toward the SPC at all. I believe the SPC employs the best scientists that modern meteorology has to offer. When the SPC issues a forecast, most of the storm chasers on Stormtrack seem to concur with that forecast. So my commentary is not directed toward any one entity, but toward the science of tornado forecasting.

As Jeff pointed out, we had a moderate risk for severe storms on two days recently (04/01 and 04/02). In terms of tornado production, one risk underproduced (just a couple of tornadoes) and the other overproduced (many tornadoes, some of which were strong and perhaps violent). To me that says that modern science may be able to accurately predict the location of severe weather days or even a week or more in advance. But I don't feel like science has yet mastered the ability to accurately predict exactly when and where a tornado outbreak will occur. That's all I was trying to say.

I wholeheartedly agree that watches and warnings are much more important for saving human life than outlooks. I completely agree that hindsight is 20/20, and I hate Monday morning quarterbacking. Mankind has came a long way in our ability to predict tornadoes, so here's hoping we will reach our goal of being able to do it consistently and accurately every time.
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Bryce,

My response to your original post was an attempt to explain why we made some of the decisions we made during the day on 4/2. Specifically, I tried to discuss a few of the uncertainties and how they impacted this particular forecast. Many of the more significant tornado episodes can be easily identified as potential supercell days, but more subtle processes eventually enhance the tornado threat. I mentioned 3 May 99 because I'm quite familiar with that event, and it was a fairly recent example of a high impact tornado outbreak that almost nobody saw coming.

The NE AR/ WRN TN tornadoes were (by far) the most serious of the entire severe storm outbreak. How would we view the event if *one* storm didn't happen to form in NE AR? We'll rarely have high confidence in a forecast that hinges on one storm. Our best hope at the present time is to hope we can issue tornado watches for these cases, even if we have an outlook that's not as accurate as we'd like to see when looking back at the event.

Rich T.

 

[Dan Robinson]

Were any of the tornadoes in Illinois and northeastern Missouri associated with mesocyclones? I was surprised to see so many confirmed reports along what we observed to be a solid squall line with strong straight-line winds. Two of the confirmed tornadoes were less than 3 miles from our location in New Berlin, yet we didn't see any classic supercell features, just a solid, tubulent shelf cloud screaming eastward. WxWorx didn't show any persistent nor strong shear markers during this time either. My first assumtion is that these tornadoes were strong gustnadoes - but then does that mean that gustnadoes are officially treated as tornadoes now? For a public standpoint that would make sense as they both can inflict damage.

I guess I'm trying to figure out where all these tornadoes in Illinois and Missouri came from. I'm not disputing them, but if they were gustnadoes I've never seen any offical account stating that.

 

[Scott A. Kampas]

Sunday was a very interesting event across central Illinois and the St. Louis area. There were rotating wall clouds with funnels and tornadoes on the leading edge of the solid line. The line was solid --not a bow/LEWP or any discrete supercells-- with notches and mesocyclones, which were quite deep (extending throughout most of the height of the relatively low-topped storms) at times and many were quite persistent (45 minutes or more).

The circulations on radar coincided with many of the wall clouds, tornadoes, spinups, and gustnadoes that we observed along the I72 corridor. I've never seen tornado or mesocyclone activity like this on the leading of a squall line before. A couple of the rotating wall clouds with funnels looked like any other you would see on the RFB of a classic supercell. Many of the tornadoes themselves generally looked like strong gustnadoes with several having funnels and weakly rotating lowerings above them, but not all. At least one wall cloud was very tight and strongly rotating, but we only got a good glimpse of that one. Another was strongly rotating and looked like any other tornadic wall cloud (it had essentially full tornado condensation at times), except we didn't see it as well and it didn't seem to be as "beefy" or as much lower than the ambient cloud bank as the one near New Berlin (might be the same that you saw Dan). Some of what we first thought were just gustnadoes became visibily connected to cloud circulations, and/or corresponded to larger and stronger actual tornadoes from the damage surveys, and/or coincided with tight circulations on radar.

Scott

EDIT: What was reported as a large tornado moving into Springfield appears to have been several gustnadoes bunched together under a lowering which might have been weakly rotating but I couldn't tell it if it was, and there was no sign of any vertical development to the cloud base or that these were associated with anything going on in the cloud, it was apparently just gustnadoes giving the illusion of a large multi-vortex bowl type tornado.

 

[John Farley]

For the region in which the squall-line-related tornadoes occurred, I think this event was unusual for the NUMBER of tornadoes that it produced, but not for the fact that it produced tornadoes. In fact, I believe I read somewhere (can't recall where now, of course), that around 30-40 percent of tornadoes in IL are associated with linear storms, most often bow-echo type situations. The April 2 system did produce an unusual number of tornadoes, perhaps 30 associated with linear storms in the LSX and ILX CWAs. However, I think it is important to note that the line of storms did evolve into a bow echo around 5:30, with the apex of the bow a little south of where the Fairview Heights tornado occurred. Significantly, the large majority of the tornadoes associated with the squall line occurred to the north of this tornado. To see the evoluation of the line of storms from a straight line into a bow echo, see the reflectivity and velocity radar images at the bottom of this Web page:

http://www.crh.noaa.gov/lsx/?n=april_02_2006

BAMEX and other studies have shown that most tornadoes associated with bow echos occur near or north of the apex of the bow, as nearly all did on Sunday. Tornadoes of this type are most likely to occur in a combination of strong shear and high CAPE, i.e. a situation that, but for strong forcing, would also be favorable for supercells. This link shows a study from the LSX NWS office that illustrates these principles:

http://www.crh.noaa.gov/lsx/science/QLCS/Groups/Group1.php

I have encountered these kinds of situations a couple times chasing, although my only view of the storms Sunday was from the air and behind the line, as I was returning to Edwardsville from a conference in Omaha when these storms occurred. However, I witnessed a brief, weak tornado (which looked like just that, but I didn't believe it at first because it was under the gust front) east of Edwardsville on July 5, 2004, and was in the wrong place to see three such tornadoes that occured in rapid succession when a bow echo overtook a supercell I was chasing on June 13 last year. An area of rotation associated with the July 5 tornado was visible on radar, much as was the case Sunday, and as I recall another brief tornado farther to the southeast also was detected on radar that day.

In summary, I do not think such tornadoes are uncommon, and Sunday's occurred where one would expect them to occur. The only unusual aspect is that there were so many, and perhaps they were stronger than usually occurs in these situations (several F2 tornadoes).

 

[Scott A. Kampas]

BAMEX and other studies have shown that most tornadoes associated with bow echos occur near or north of the apex of the bow, as nearly all did on Sunday. Tornadoes of this type are most likely to occur in a combination of strong shear and high CAPE, i.e. a situation that, but for strong forcing, would also be favorable for supercells. This link shows a study from the LSX NWS office that illustrates these principles:

In summary, I do not think such tornadoes are uncommon, and Sunday's occurred where one would expect them to occur. The only unusual aspect is that there were so many, and perhaps they were stronger than usually occurs in these situations (several F2 tornadoes).
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The point wasn't that tornadoes are uncommon with lines, but that most of those are "spinups" with fairly transitory and shallow if tight couplets (and some reports that make it into the database are mere gustnadoes). Rotating wall clouds (in conjunction --to a lesser degree-- with associated deep, persistent mesocyclones/mesovortices) are fairly uncommon, it seems, but yes there is more research ongoing here. The prolific tornado production with the line from C IL to STL does seem abnormal, and there were many rated strong F1 to F2 from damage surveys (and some decent path widths and lengths too).

Some of the STL metro event was associated with a bowing segment (though not all, some others were cell mergers, for example), but the the Taylorville-Macon circulation, I72 circulations, and Mason-Logan-Tazewell County circulation, among others, were part of a solid line (with some inflow notches).

 

[Walker Ashley]

I've never seen tornado or mesocyclone activity like this on the leading of a squall line before. A couple of the rotating wall clouds with funnels looked like any other you would see on the RFB of a classic supercell. Many of the tornadoes themselves generally looked like strong gustnadoes with several having funnels and weakly rotating lowerings above them, but not all. At least one wall cloud was very tight and strongly rotating, but we only got a good glimpse of that one. Another was strongly rotating and looked like any other tornadic wall cloud (it had essentially full tornado condensation at times), except we didn't see it as well and it didn't seem to be as "beefy" or as much lower than the ambient cloud bank as the one near New Berlin (might be the same that you saw Dan). Some of what we first thought were just gustnadoes became visibily connected to cloud circulations, and/or corresponded to larger and stronger actual tornadoes from the damage surveys, and/or coincided with tight circulations on radar.[/b]

Scott: Do you have pics of these "features" or tornadoes? I have been looking for photo evidence of these tornadoes since Sunday. Thanks!

 

[Scott A. Kampas]

Hi Walker,
I heard you and Gilbert were out and in Springfield. The group I was with does have video and stills of rotating wall clouds, funnels, a couple tornadoes, as well as some spinups and gustnadoes. We probably saw 20 surface circulations altogether, many of what ended up being tornadoes looked like gustnadoes or looked liked gustnadoes initially then became more apparent as something more. I'm working on getting everything together, and can send it to you if you're interested (just PM or email).

A number of other chasers were out and have video and stills as well, including Dan who posted a video with a wall cloud near New Berlin. I've seen the typical turbulent interactions with many a line, but Sunday was interesting in its production of the classic looking WCs and the prolific tornadoes (not just spinups and gustnadoes).

Scott

 

[Bob Schafer]

There is a MUST, MUST SEE vid on the Fox News website:

http://www.foxnews.com/story/0,2933,191016,00.html

From there, click on the VIDEO button just right of the text, and then on "Teen Tapes Twister".

It's incredible.

Gotta get this kid on the forum! He says he's been interested in storms for a long time.