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

[Bryce Stone]

I just wanted to comment on the SPC's forcast for today. They got it pretty much right, but I noticed that there were also quite a few tornadoes outside of the moderate risk area (most notably the long-track one in Arkansas). There were also quite a few high wind reports way east of the moderate area. I noticed that they moved the moderate risk area east quite a bit at the end of the day.

Having no in-depth meterological training, I won't criticize the SPC at all. They did a great job on March 12th, 2006. But I think they were a little off on the moderate risk area they were pushing today. Not only that, but with at least 11 dead and 60+ preliminary tornado reports I think today was absolutely a high risk day. I really have no idea why they didn't issue a high risk today.

So, up for discussion, should the moderate risk have been expanded to areas further south and east earlier in the day and why did the SPC not go with a high risk?

[Andy Wehrle]

Honestly I think SPC's decision to hold off on the high risk had a lot to do with Saturday's outflow-dominated garbagefest. Evolution of convection Sunday was highly dependent on the same mesoscale/boundary layer processes that Saturday's was. Sometimes you get it, and sometimes you don't.

The vast majority of the convection across the initial moderate risk area was linear, yet still managed to produce quite a few tornadoes in addition to widespread damaging winds and hail. Despite the possibility of more discrete convection to the south (in southern MO/AR/western TN and KY) that area was left out of the moderate risk early on. I would presume that had something to do with concerns over surface winds not being ideal for intense tornadoes. Obviously something changed or was being overlooked. It might be interesting to compare the short-term low-level wind field model forecasts from immediately before the event with what was actually observed.

[HAltschule]

These LSR's are particularly sad. Many reports include damage swaths more then 1/2 mile wide. This tornado had enormous G2G Shear with it that, at times, was spread out over a very large area. Our thoughts and prayers have to go out to the victims and their families.

0755 PM TORNADO NEWBERN 36.12N 89.27W
04/02/2006 DYER TN AMATEUR RADIO

*** 11 FATAL *** IN THE NAVOO COMMUINITY ALONG HWY 2
HOUSES DESTROYED. POWER KNOCKED OUT. FATALITIES ON BIFFLE
ROAD NEAR JIMMY DEAN PLANT IN NEWBERN. ADDITIONAL
FATALITIES OCCURRED IN THE BOGOTA AREA.
----------------------------------------------------------------------------------------
0843 PM TORNADO 1 W BRADFORD 36.07N 88.84W
04/02/2006 GIBSON TN LAW ENFORCEMENT

*** 8 FATAL, 50 INJ *** FATALITIES OCCURRED IN THE
RUTHERFORD/BRADFORD AREA.

[Brett Adair]

Also, just keep in mind that the daybreak has just broken across this area and I am sure we will be getting some chilling photographs before this is all over with. Could you guys please post news images here if you find them of damage.

[Rich Thompson]

I just wanted to comment on the SPC's forcast for today. They got it pretty much right, but I noticed that there were also quite a few tornadoes outside of the moderate risk area (most notably the long-track one in Arkansas). There were also quite a few high wind reports way east of the moderate area. I noticed that they moved the moderate risk area east quite a bit at the end of the day.

Having no in-depth meterological training, I won't criticize the SPC at all. They did a great job on March 12th, 2006. But I think they were a little off on the moderate risk area they were pushing today. Not only that, but with at least 11 dead and 60+ preliminary tornado reports I think today was absolutely a high risk day. I really have no idea why they didn't issue a high risk today.

So, up for discussion, should the moderate risk have been expanded to areas further south and east earlier in the day and why did the SPC not go with a high risk?
[/b]

Bryce,

I've worked at SPC long enough to not get too upset when folks criticize our forecasts. It seems everyone is an expert *after* the event :P

Anyway, I worked day shift yesterday, so I can comment on that part of the episode. A squall line swept across the majority of the MDT risk area during the early morning hours, leaving the 60+ dewpoints to the S of MO/IL. Still, steep lapse rates were present and the main shortwave trough was expected to pivot over the recovering warm sector in MO during the afternoon, when storm development was anticipated. Low-level shear profiles were modest in the open warm sector through the day (0-1 km SRH AOB 200 m2/s2), while the somewhat stronger shear was located along the warm front where the low levels had yet to destabilize. The MO/IA/IL part of this event was a race between destabilization along the warm front and the transition from a more discrete to linear convective mode.

Farther S, the question was convective initiation. The influence of the mid level trough appeared to extend as far S as nrn AR. There was not much of a low-level focus for initiation there, but afternoon temperatures got warm enough to reduce convective inhibition and allow things like convective rolls and terrain to intitiate isolated storms. The nrn AR environment consisted of strong deep layer shear and large CAPE (near 3000 J/kg for ML parcel), but similar low-level shear to MO and rather large T-Td spreads. Our guess was that the initial storms would mainly be a threat to produce very large hail, which they did. By early-mid afternoon, we noticed that the clouds and early precip across ern AR/wrn TN/wrn KY had held temperatures down, but winds were still backed to more southerly and dewpoints had remained in the mid 60s. We weren't sure how long the backed flow area would hang on after the precip moved away by mid afternoon and the clouds began to erode, but I thought enough of it to go TOR watch and mention the possibility of an increase in the tornado threat toward nern AR.

In retrospect, that favorable area did hold on and shear even improved during the evening, when the tornado threat appeared to peak. In the perfect world I would have issued PDS TOR before any cumulus clouds had formed, but there was just too much uncertainty. The environment was modified on the mesoscale by the early clouds/rain, and that is always going to present a problem for longer range outlooks. I also worked 3 May 99 back in the day, and I promise that *nobody* on this list would have believed a perfect forecast from that morning relying on subtle confluence boundaries, HCRs, a cirrus hole (none of which were resolved until late morning or afternoon), and a poorly forecast speed max!

By the way, the long track supercell cut across the MO bootheel, which was in the extreme srn part of the MDT risk. Why is this considered to be a bad forecast?

[John MacKay]

This day warranted a MDT risk until the long track supercells got going (which were under a conditional probability at the time). I was partly expecting a high risk on the 0100 UTC (there was a hatched 15% tornado probability on that one, an upgrade from the hatched 10%), but I didn't know the specifics of what was going on. The environment in TN seemed to get more favorable after the 0100 UTC outlook for long-track tornadic supercells.

The watches were issued in a timely manner and were generally well placed. This event should have only been a MDT if we take out the supercells in AR, MO, TN (the SLGT seemed warranted with all the factors up in the air). The SPC did a good job overall yesterday, with maybe the possible exception being the 0100 UTC outlook. But then again, I didn't know all of the factors there.

[John Farley]

These LSR's are particularly sad. Many reports include damage swaths more then 1/2 mile wide. This tornado had enormous G2G Shear with it that, at times, was spread out over a very large area. Our thoughts and prayers have to go out to the victims and their families.

0755 PM TORNADO NEWBERN 36.12N 89.27W
04/02/2006 DYER TN AMATEUR RADIO

*** 11 FATAL *** IN THE NAVOO COMMUINITY ALONG HWY 2
HOUSES DESTROYED. POWER KNOCKED OUT. FATALITIES ON BIFFLE
ROAD NEAR JIMMY DEAN PLANT IN NEWBERN. ADDITIONAL
FATALITIES OCCURRED IN THE BOGOTA AREA.
----------------------------------------------------------------------------------------
0843 PM TORNADO 1 W BRADFORD 36.07N 88.84W
04/02/2006 GIBSON TN LAW ENFORCEMENT

*** 8 FATAL, 50 INJ *** FATALITIES OCCURRED IN THE
RUTHERFORD/BRADFORD AREA.
[/b]
I just learned a few minutes ago that the man who was killed in the clothing store in Fairview Heights, IL was the husband of someone with whom I worked for a number of years. Things like this make us realize the terrible human impact of these storms that so fascinate us.

Much less significant, the effects of this storm have been felt over an unusually wide area. We have been in the dark for 18 hours now at my house, and over 100,000 are still without power just in Missouri and Illinois. Because of the widespread straight-line winds, the effect on the power system has been unusually widespread, making it hard to bring in crews from outside because so many areas have been affected. That, of course, is trivial compared to the loss of human life, and the misery that has caused to the loved ones of those who have perished.

[Brett Adair]

http://kfvs12.images.worldnow.com/images/739020_vf.jpg

WHOA....check out the video of this large wedge on the ground that went through Caruthersville, MO.

http://www.kfvs12.com/

[Gabe Garfield]

WHOA....check out the video of this large wedge on the ground that went through Caruthersville, MO.

http://www.kfvs12.com/
[/b]

:o That video is amazing! The supercell structure associated with these tornadoes was tremendous! Absolutely classic! I saw some images from other tornadoes that occurred in Tennessee, and they also had similar structure. Yesterday's supercell structure reminds me somewhat of the supercells of April 26, 1991 in that the cloud bases weren't particularly low and there wasn't a whole lot of scud underneath the cloud base. The tornadoes also seemed to have a very laminar appearance (with the exception of the wedge), which made them particularly photogenic.

As far as damage is concerned, CNN reports a fire department head (in Dyer Co., TN) as saying "There's nothing left but a foundation on some houses." It'll be interesting to see what the damage assessment reveals...it is quite probable that this particular tornado was at least an F4 (barring "sliders"). We shall see...

Gabe

[Jeff Miller]

http://kfvs12.images.worldnow.com/images/739020_vf.jpg

WHOA....check out the video of this large wedge on the ground that went through Caruthersville, MO.

http://www.kfvs12.com/
[/b]

That is an amazing tornado.

Notice something I believe is of extreme interest in the last part of the video, there is what assumes to be a horizontal tube forming out of the main vortex stretching very near what appears to be a satellite tornado and its dust whirl. (2:31). What incredibly complex atmospheric conditions were going on at that time! This video also reminds me of a particular tornado Bobby Prentice caught I believe on April 26, 1991 I believe in was it Red Rock, OK? Same horizontal tube on the left side of the vortex but not so near a satellite tornado! Amazing!

In relation and keeping the conversation on topic, I am quite saddened to hear of the numerous fatalities from this system. I was not anticipating this degree of an outbreak, though I knew a significant episode was likely. Kudos and cheers to the SPC for doing the best they could with all the tools they had at their disposal. It was a tough day and they worked their tail ends off on it, so Rich, thanks for commenting and great job to ya.

[Darren Addy]

Not only that, but with at least 11 dead and 60+ preliminary tornado reports I think today was absolutely a high risk day. I really have no idea why they didn't issue a high risk today.
[/b]

Last number I heard was 23 dead and they may not be through counting yet. I'll let the NWS guys defend themselves here, but it seems to me that whether the area was hatched as a moderate risk or high risk is far less relevant than whether or not the watches and warnings were going up when they needed to be. People on the ground pay no attention to the SPC's convection forecast products. Neither do media outlets. They do announce (and people hopefully pay attention) to watches and warnings. If the watches and warnings are being issued in a timely manner, then loss of life becomes a combination of who is paying attention and chance (population density in the area the tornado decides to track).

Personally, a moderate risk gets my attention. It doesn't have to be "high" for me to think that something significant could happen. But my most people probably aren't getting in the basement unless the sirens go off. And that should have nothing to do with whether the day was listed "high risk" or not.

Darren Addy
Kearney, NE

[Gary Stofer]

Rich
Thanks for commenting on this. Outlooks aside (the general public does not care about outlooks) the watches for the most part were issued in a timely manner by the SPC yesterday with one exception. There were numerous svr and several torn warnings in TN around 3pm yesterday, long before a watch was ever issued. I was just curious if you had any input on why it took so long to get the blue box up for that area of the country yesterday? When you issue a watch, do you just look at the weather to see if it is favorable for svr or do you take into account that storms are already ongoing and severe?
Thanks for your input and hard work.
Gary

[Jeff Snyder]

It's also important to remember the spatial and temporal scales that differentiate convective outlooks, watches, and warnings. Outlooks are not intended to be drawn for individual storms, and neither really are watches (though there have been some very small watches that seem to have been issued based upon propagation of small storm clusters and a supercell pair). If there are only a couple of supercells, I can't imagine coverage would be significant enough to warrant a High risk. Reference back to Probability to Categorical Outlook Conversion (http://www.spc.noaa.gov/misc/SPC_Prob_Conv_Otlk_Change_20060214.html) for the probabilities needed for a high risk.

The supercells were in watch boxes, and were covered under warnings. Yes, there have been smaller enhanced categorical risks (I've seen small high risks), but the storms were already covered in a watch and were warned. Hindsight is always 20/20, and it's good to go back and do a post-analysis, but we've also seen the opposite case this year (PDS watches, high-end MDT risks, only to have trouble squeezing out more than 4-5 tornadoes).

[Kurt Wayne]

Notice something I believe is of extreme interest in the last part of the video, there is what assumes to be a horizontal tube forming out of the main vortex stretching very near what appears to be a satellite tornado and its dust whirl. (2:31). What incredibly complex atmospheric conditions were going on at that time! This video also reminds me of a particular tornado Bobby Prentice caught I believe on April 26, 1991 I believe in was it Red Rock, OK? Same horizontal tube on the left side of the vortex but not so near a satellite tornado! Amazing!
[/b]

Yes, it was the Red Rock tornado. Mr. Prentice was saying "Look at the TUBE, Gene!", obviously to a chase partner. At times, that whirl in the Caruthersville video reminded me of multiple pics/video captures of the killer 1979 Wichita Falls tornado...I think they were both around the same size. Not saying one should flee from a tornado, but I've been to C'ville...nice town, southernmost county seat in Missouri, borders the Mississippi River but without a bridge. NOWHERE TO RUN in any direction east/NE/SE for those who couldn't get below ground level, unlike in the Wichita Falls whirl where there were several exit routes. (Though many lost their lives on those same routes.)

One thing about weather conditions...that Caruthersville storm from other KFVS-TV reports seemed to move almost straight east. I haven't seen sequential radar grabs but I may have seen the storms which either became or came right after the C'ville supercell. Our house is in Bentonville, AR, where the tor of three weeks ago went right over us. The skies above us were almost cloudless but around 1:00 pm yesterday cooking lunch I saw what almost looked like "feeder bands" of small eastward-moving cumulus to my north, right across the Arkansas/Missouri border. At around 4:00pm, when my son was waiting for a ride with his friend to an indoor pool we looked off to the east and I saw the back end of a line of overshooting cloud tops which looked eerily like shots (Brian?) Ensminger of KFSM-TV took of the Twin Oaks (OK)/Bentonville tornadic supercell as it sped east away from him...these supercells appeared to be either in Carroll County (Berryville/Eureka Springs) or farther east in Boone County (Harrison) in Arkansas. Horrifying to see that these storms were far worse. (I think I saw video of a pickup truck atop the roof of a structure in Tennessee...with the stripped-to-the-foundations damage I wouldn't be surprised if we see some F4 ratings, just like the 1979 Wichita Falls storm was). :(

[Jeff Snyder]

I don't have radar grabs from the exact time when the supercell was over Caruthersville, but I do have one from 0200z... The reflecitivity image is almost as classic/textbook is they come for supercells:

Base Reflecitivity Tilt 1 (http://www.tornadocentral.com/now/4-2bref1.png)
SR Velocity Tilt 1 (http://www.tornadocentral.com/now/4-2srv1.png)

[Gabe Garfield]

Based on an aerial survey of the Dyer Co. tornado by WCMTV (based in Memphis), I can see only evidence of high-end F3 damage. Of course, they may not have surveyed the entire path length, so there might be isolated locations of violent tornado damage.

Still no PNS from Memphis...I would expect one soon, though.

Gabe

[Jeff Snyder]

<div class='quotetop'>QUOTE("PAH PNS")</div>
PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE PADUCAH KY
200 PM CDT MON APR 3 2006

...WIDESPREAD THUNDERSTORM WIND DAMAGE REPORTED ACROSS PORTIONS OF
FAR SOUTHWEST INDIANA AND WESTERN KENTUCKY...

EACH COUNTY EMERGENCY MANAGER...ALONG WITH A NATIONAL WEATHER
SERVICE DAMAGE ASSESSMENT TEAM MEMBER...HAD DETERMINED THAT ALL OF
THE DAMAGE WAS DUE TO MICROBURST WINDS ASSOCIATED WITH THE
THUNDERSTORMS. WINDS ACROSS SOUTHWEST INDIANA WERE ESTIMATED TO BE
BETWEEN 60 TO 70 MPH...WHILE WINDS ACROSS PORTIONS OF DAVIESS COUNTY
KENTUCKY WERE ESTIMATED TO BE BETWEEN 80 TO 90 MPH. COUNTY
EMERGENCY MANAGERS STATED THAT THERE WERE NO INDICATIONS OF A
TORNADO.
[/b]
--> http://www.srh.noaa.gov/printable.php?pil=...=20060403191156 (http://www.srh.noaa.gov/printable.php?pil=PNS&sid=PAH&date=20060403191156)

I only post that because there were a few tornado reports in that KPAH CWA. I am interested in seeing something out of the Memphis NWSFO.

In addition, the St. Louis NWSFO performed a very quick damage survey from a tornado in their CWA. Props for their rapid PNS release, as they had it about about 4am, less than 12 hours after the tornado occurred.
<div class='quotetop'>QUOTE("LSX PNS")</div>
NATIONAL WEATHER SERVICE ST LOUIS MO
403 AM CDT MON APR 3 2006

...PRELIMINARY DAMAGE SURVEY FOR APRIL 2 2006 ST. CLAIR COUNTY
ILLINOIS...

PERSONNEL FROM THE NATIONAL WEATHER SERVICE OFFICE IN ST. LOUIS
CONDUCTED A PRELIMINARY SURVEY OF THE DAMAGE THAT OCCURRED OVER
NORTHERN ST. CLAIR COUNTY SUNDAY EVENING, APRIL 2ND. THE DAMAGE
WAS PRODUCED BY A SHORT-LIVED TORNADO.
...
TOTAL LENGTH...7-8 MILES
WIDTH...80-90 YARDS
DAMAGE INTENSITY WAS RATED AT F1
[/b]
--> http://www.srh.noaa.gov/printable.php?pil=...=20060403090302 (http://www.srh.noaa.gov/printable.php?pil=PNS&sid=LSX&date=20060403090302)

[Gabe Garfield]

Strike my previous comments, damage looks extraordinarily severe based on viewing further video from WCM-TV. Click on "Dyer County tornado damage" in the following link, and you'll see what I mean.
Video of Aerial Survey (http://www.wmcstations.com/Global/story.asp?S=4715221)
There appears to be several locations that took at least F4 damage (foundations wiped, only tree stumps left, etc.). Should be *very* interesting to see what rating this tornado achieves.

Gabe

[Jeff Snyder]

Strike my previous comments, damage looks extraordinarily severe based on viewing further video from WCM-TV. Click on "Dyer County tornado damage" in the following link, and you'll see what I mean.
Video of Aerial Survey (http://www.wmcstations.com/Global/story.asp?S=4715221)
There appears to be several locations that took at least F4 damage (foundations wiped, only tree stumps left, etc.). Should be *very* interesting to see what rating this tornado achieves.

Gabe [/b]

With the Dyer Count Tornado Damage link, I concur that it looks F3 to low-end F4. Usually, with the most intense tornadoes (above mid-range F4), you don't often see a whole of debris about, presumably because much of it is centrifuged away. OF course, any damage assessing we do is amatuer, since there's a lot more to it. But from a prelim point, I concur. The damage around 1:10 is interesting.

The second link that page ("Damage summary" or sometihng like that), there is an interesting part around 0:34. I'm not sure if that was a small house or what, but you can see that most of the debris has been carried away from the site. There do appear to be a few trees standing, and that truck being where it is makes me wonder if the winds were really too strong. Overall, I think the video makes me think Manchester, which was an F4.

EDIT: I should note the vehicle near the damage at 0:34 may belong to those people who are standing near the used-to-be-structure, and it's possible that the vehicle was not in the tornado. If it was in the tornado, then, from the fact that it doesn't look like it rolled me and the fact that it's up on its wheels (as vehicles should be LOL), makes me wonder if F4-level winds really were required to do the damage to whatever structure was there.

[Alex Lamers]

Armchair surveying for Dyer Co. gives me these conclusions:

1. (Around 1:55) House with walls completely taken off...debris piled up behind the house. Looks to be trees with branches completely shredded off and some debarked. Given these storms were relatively quick moving, I would expect this to be an F4 as suggested by EF scale laid out damage indicators. Now, obviously the EF Scale is not in effect but I think you can use it as a damage indicator and then adjust to the current Fujita scale. The damage by that house would tend to indicate low end F4 to me.

2. (Around 2:53) Metal Building System (chicken building, something similar?) totally destroyed. EF scale damage indicator for strong F3 damage typically.

Later on and earlier in the clip we see some buildings partially destroyed but with some walls still standing and some trees with branches still affixed so at its strongest it seems like an F4. Obviously I don't think this is the entire tornado path though...and only segmented views.

Gibson Co...

Houses shown are mainly deroofed about DOD6 so looks like mainly F2 damage at the worst on that clip. Awaiting the TN/AR/S MO PNS's...

[Alex Lamers]

New PNS from ILX (Springfield)

NWS SURVEYS ARE STILL ONGOING IN A NUMBER OF AREAS OVER
CENTRAL ILLINOIS. THESE SURVEYS IN COMBINATION WITH EMERGENCY
MANAGER DAMAGE SURVEYS AND SPOTTER/EYE WITNESS SIGHTING
INFORMATION HAS CONFIRMED THE OCCURRENCE OF 12 TORNADOES
...AS THIS TIME.

NOTE THAT THIS IS ONLY PRELIMINARY BEGINNING TORNADO
INFORMATION. AS ADDITIONAL INFORMATION BECOMES
AVAILABLE...LATER UPDATES WILL BE ISSUED.

So 12 tornadoes from that CWA ALONE! Some damage reports up there indicated strong tornadoes. Then you have to consider that there were tornado reports as far north as IA and warnings as far S as MS. I will be interested to see the final results.

---

Now, I'm pretty sure these OBVIOUS supercell signatures had plenty of lead time on them so I'm wondering why I'm seeing statements like this...

"By the time the (tornado) sirens started going off, it was at our back door," Sisk said Monday. "I didn't hear a train sound, I heard a roaring."* She and the children ran into a closet.

"The next thing I knew, everything was falling apart," Sisk said.[/b]

It always seems like, and I'm not discounting the accounts of people who were actually there, that the tornado was at their house before the sirens went off or before a warning was issued. Is it just that everything happens real fast or were the warnings last night really that bad? I was pretty sure they were issuing stuff way out ahead of the storms.

[Greg Stumpf]

By the way, the long track supercell cut across the MO bootheel...[/b]
Hmmm - gotta wonder if we just had another "tri-state" tornado?

[Jeff Miller]

Hmmm - gotta wonder if we just had another "tri-state" tornado?
[/b]

I certainly would concur, Greg as it started in Arkansas, cut across the Missouri bootheel and went well into Tennessee. Crossed three states, I would call it the "Little Tri-State Tornado" - though it certainly isn't little or weak, just in comparison to the one in 1925.

[Greg Stumpf]

I certainly would concur, Greg as it started in Arkansas, cut across the Missouri bootheel and went well into Tennessee. Crossed three states, I would call it the "Little Tri-State Tornado" - though it certainly isn't little or weak, just in comparison to the one in 1925.
[/b]
Well, assuming the storm produced a continuous tornado across that area. I'm not sure that's verified yet.

[Jeff Miller]

Well, assuming the storm produced a continuous tornado across that area. I'm not sure that's verified yet.
[/b]

Looking forward to the surveys on this one for sure to see the verification (or not) of this.

[Kurt Wayne]

The KFVS web site original linked here has a second story "Deadly storms move across the heartland" that does indeed show the time lapse radar, showing it moving from the Caruthersville/North Pemiscot area over north Dyer and north Gibson counties where the greatest loss of life occurred.

It also looks like, given the track on radar, these from the same system that my son and I saw way off to our east. Amazing...the Bentonville area is quite "gun-shy" right now due to the tornadoes of three weeks back...if the folks here had known what was brewing to the east of them, heading east...

We were SO blessed that our own "tor" came through at 10:00 pm rather three-five hours earlier, although what we got was bad enough.

[Alex Lamers]

F2 Tornado in White County AR. PNSLZK.

[Johnnie Gambill]

KAIT-8 news at 5:00 (Jonesboro, AR) reported that they spoke with the team from NWS Memphis - they're going with "at least an F4, possibly F5" in reference to the tornado that affected Marmaduke, AR.

[Alex Lamers]

As if in mockery, my chase target was within 15 miles of an F2 tornado in SE IA. Two others, F1 and F0 from Davenport at this time.

Oh, and does anyone know when the last time we had an F5 in the CONUS was? I would be interested because in my annual beginning of the year forecast I said this looks like the year we will break the F5 drought...we shall see what the survey teams come up with.

[mikegeukes]

F5 Tornadoes of the United States
http://spc.noaa.gov/faq/tornado/f5torns.html

Mike

[Alex Lamers]

F5 Tornadoes of the United States
http://spc.noaa.gov/faq/tornado/f5torns.html

Mike
[/b]

Wow this would be the first in 6 years! :o

[Chris Hayes]

As if in mockery, my chase target was within 15 miles of an F2 tornado in SE IA. Two others, F1 and F0 from Davenport at this time.

Oh, and does anyone know when the last time we had an F5 in the CONUS was? I would be interested because in my annual beginning of the year forecast I said this looks like the year we will break the F5 drought...we shall see what the survey teams come up with.
[/b]

The last "recorded" F5 tornado was the May 3rd, 1999 Moore F5 tornado. There have been some tornados in the past few years in which the NWS was about to rate an F5, but they stuck it at F4. The last one I know of occured on May 4 or 8, 2003. Be interesting to see if Kentuck tornado is rated F5. :o

[mikegeukes]

PRELIMINARY ASSESSMENT
F3 Dyer County TN

I am keeping a log of the surveys on this:
04-02-06 Storm Damage Surveys
http://www.stormtrack.org/forum/index.php?showtopic=10848

Mike

[Alex Lamers]

The last "recorded" F5 tornado was the May 3rd, 1999 Moore F5 tornado. There have been some tornados in the past few years in which the NWS was about to rate an F5, but they stuck it at F4. The last one I know of occured on May 4 or 8, 2003. Be interesting to see if Kentuck tornado is rated F5. :o
[/b]

Actually, KY tornado (only a portion of it) is currently rated an F3. New ratings came out for Gibson and Dyer in TN both F3...with Dyer at 200 MPH. Haywood Co tornado was a very brief but potent F2 tornado (only 3/4 mi long and 30 yds wide).

[Gabe Garfield]

KAIT-8 news at 5:00 (Jonesboro, AR) reported that they spoke with the team from NWS Memphis - they're going with "at least an F4, possibly F5" in reference to the tornado that affected Marmaduke, AR.
[/b]

I would assume that they are reporting the damage in segments if that is the case. Memphis is in charge of the Marmaduke section of the tornado track, and they haven't released anything about that as of yet.

On another note, I'm surprised that the Dyer Co. segment of damage was given only strong F3. There were a number of houses where no outer walls were present after the tornado passed. I suppose construction issues came into play when they rated these particular sites.

Gabe

[Kevin Bowman]

This day warranted a MDT risk until the long track supercells got going (which were under a conditional probability at the time). I was partly expecting a high risk on the 0100 UTC (there was a hatched 15% tornado probability on that one, an upgrade from the hatched 10%), but I didn't know the specifics of what was going on. The environment in TN seemed to get more favorable after the 0100 UTC outlook for long-track tornadic supercells.

The watches were issued in a timely manner and were generally well placed. This event should have only been a MDT if we take out the supercells in AR, MO, TN (the SLGT seemed warranted with all the factors up in the air). The SPC did a good job overall yesterday, with maybe the possible exception being the 0100 UTC outlook. But then again, I didn't know all of the factors there.
[/b]


"THE COMBINATION OF MODERATE INSTABILITY AND 45-55 KT WLY MID-LEVEL
FLOW SUGGEST THE THREAT FOR A FEW SUPERCELLS AND BOWING LINE
SEGMENTS CAPABLE OF DAMAGING WINDS...LARGE HAIL AND A FEW TORNADOES.
THIS SEVERE THREAT WILL LIKELY CONTINUE SUNDAY NIGHT ACROSS THE TN
VALLEY AND NRN PORTIONS OF MS AND AL"

"A HIGH risk area suggests a major severe weather outbreak is expected, with a high concentration of severe weather reports and an enhanced likelihood of extreme severe (i.e., violent tornadoes or very damaging convective wind events occurring across a large area). In a high risk, the potential exists for 20 or more tornadoes, some possibly F2 or stronger, or an extreme derecho potentially causing widespread wind damage and higher end wind gusts (80+ mph) that may result in structural damage"

Mesoscale Discussion 405 issued at 205 had increased tornado threat if storms fired and moved into western Arkansaw.

Mesoscale Discussion 409 issued at 7 had the possibility of "long tracked significant tornadoes"

Even if th SPC had issued a high risk it wouldnt have saved lives, as was mentioned before, there was a watch and warnings. It really dosent matter that there was no PDS watch either for one, the general public usually never learns of the PDS wording anyway, most news casts only report Tornado watch till 12 ect. If anything, the high risk may have been better over illinois and indiana for the squall line not the supercells in Tennessee. The convective outlook shouldnt matter though once a watch is issued, if you are placed under a Tornado Watch, guess what, even if you are under a slight risk, you could still be hit by a tornado and it could even potentially be violent. SPC did a good job IMO.
This is from Watch 132 issued at 325

[Michael Auker]

I would assume that they are reporting the damage in segments if that is the case. Memphis is in charge of the Marmaduke section of the tornado track, and they haven't released anything about that as of yet.

On another note, I'm surprised that the Dyer Co. segment of damage was given only strong F3. There were a number of houses where no outer walls were present after the tornado passed. I suppose construction issues came into play when they rated these particular sites.

Gabe
[/b]
Local NWS offices aren't allowed to rate tornadoes higher than F3...only the official survey team has the authority to give F4 or F5 ratings. Apparently, the team will be visiting Arkansas, Missouri, and Tennessee in the coming days...according to another weather board. Maybe then some will be rated F4 or higher...

[Marc Austin]

The Dyer tornado surely looks to be F4 based on some of the aerial video. I would be very suprised to find it was rated only F3 when the state NWS officials visit the area.

[Rich Thompson]

Rich
Thanks for commenting on this. Outlooks aside (the general public does not care about outlooks) the watches for the most part were issued in a timely manner by the SPC yesterday with one exception. There were numerous svr and several torn warnings in TN around 3pm yesterday, long before a watch was ever issued. I was just curious if you had any input on why it took so long to get the blue box up for that area of the country yesterday? When you issue a watch, do you just look at the weather to see if it is favorable for svr or do you take into account that storms are already ongoing and severe?
Thanks for your input and hard work.
Gary
[/b]

Gary,

That's a fair question. We wrote an MD about the possibility of the small MCS in nrn MS strengthening as it moved into middle TN later in the afternoon:

http://www.spc.noaa.gov/products/md/md0404.html

The storms didn't really intensify, there was additional development NE of the small MCS. We weren't really sure how much the new development would amount to, and then I got tangled up with what I considered to be more important threats in MO/IL/AR with tornado watches 132 and 133 between 3 and 4 pm CDT. Unfortunately, we got behind the TN/KY convection, and it occurred near shift change and at the same time we had other more serious threats. The evening shift did eventually issue a SVR watch, though you can't blame them because it was ramping up as they began their shift.

Rich T.

[Jeff Snyder]

Hmm, from the new PNS from Memphis NWSFO, the tornado was only F3 "through" Caruthersville. That said, before it went through that town:
<div class='quotetop'>QUOTE("MEG PNS")</div>
IN MARMADUKE THE TORNADO REACHED F3 AND POSSIBLE HIGHER
INTENSITIES ALONG WITH WIDTH OF HALF A MILE TO THREE QUARTERS OF A
MILE.
...
IN CARUTHERSVILLE...PRELIMINARY ESTIMATES OF 64 INJURIES...ALTHOUGH
NO FATALITIES. AS THE TORNADO PASSED INTO THE CITY THE WIDTH OF THE
TORNADO WAS HALF TO THREE QUARTERS OF A MILE WIDE AS IT PASSED OVER
I-55. THE TORNADO HAS BEEN RATED AN F3 AS WELL. [/b]

--> http://www.srh.noaa.gov/printable.php?pil=...=20060404022151 (http://www.srh.noaa.gov/printable.php?pil=PNS&sid=MEG&date=20060404022151)

It does sound, from the rest of the description of the tornado as it was near Marmaduke, that the tornado may have been F4. However, the sound of the PNS didn't make it seem like they think F5 is warranted. Just my interpretation.

[Gabe Garfield]

Local NWS offices aren't allowed to rate tornadoes higher than F3...only the official survey team has the authority to give F4 or F5 ratings. Apparently, the team will be visiting Arkansas, Missouri, and Tennessee in the coming days...according to another weather board. Maybe then some will be rated F4 or higher...
[/b]

I didn't know that was the policy...thanks for the info. So, I s'pose that's a bit like when SPC puts an unhatched probability on Day 3 for an expected severe weather outbreak because they can only go so high. It'll be interesting to see what the experts think.

Gabe

[Ronnie Bradley]

F2 Tornado in White County AR. PNSLZK.
[/b]
And that tornado track was roughly 1.5 miles NW and N of my residence! :o
Another near miss for me. The Sept 24 F2 tornado from Rita tracked 1.5 miles to the SW of my residence.
I had to work this weekend but when the supercell rolled through Nrn Searcy, I saw some funnel clouds. The F2 was beyond the horizon (trees and hills N of town...).
Baseball to softball sized hail pelted my grandparents area (Mt. Pisgah; south of Letona) and the hail did major damage to one of our churchmember's vehicle (busted windows). One person [from the Rosebud area] was in ER due to a big hailstone smashing his foot as he tried to make a run to his storm shelter. A mobile home's roof was penetrated by a big hailstone in the Center Hill area.
The LZK NWS page had a picture of the colossal hailstones, with one the size of a plastic Foldgers coffee container (5")!
While at work, someone brought in some hailstones and I held one that was easily baseball size, and I had no doubt in my mind that the said hailstone was bigger than that when it first hit the ground.

[Alex Lamers]

Thanks Michael for pointing that out. I knew that from the Stoughton tornado up here in WI and being around the Wx Service office in August but completely forgot about it. I'm assuming thats what the "F3 OR HIGHER" verbiage is all about. I'm sure they have their opinions. Anyone know how quickly the official survey team responds?

Breaking down what they said in their PNS for possible hints...

NUMEROUS HOUSES DESTROYED...typically associated with F3 or higher, not much light shed on the situation there.

15 RAILROAD CARS WERE LIFTED OFF THE TRACK ANDBLOWN OVER...OK let me say this right here and right now that regardless of the Fujita rating that takes an INCREDIBLE amount of force. Amazing. Now it says that F2 strength winds can push railroad cars over, but those are boxcars. I guess it also depends on the type of railroad car...and the fact it says lifted. Still doesn't shed a lot of light on the situation.

FIVE MILES EAST OF MARMADUKE...2 WELL CONSTRUCTED HOMES WERE FLATTENED AND A NEW CAR THROWN 80 YARDS...this is interesting because they used the words WELL CONSTRUCTED. Both of these things appear to fit well in the F4 description here - "Well-constructed houses leveled; structures with weak foundations blown off some distance; cars thrown and large missiles generated.". Now its interesting they mentioned the distance the car flew too because typically F5 is associated with over 100m or 110 yards. Its very close and I will be intrigued by what they find.

So I'm expecting this to come up to an F4, possibly an F5...back to where we started in the quote :blink:

Anybody know if the official team will be investigating just this tornado or others as well?

[John Farley]

NWS St. Louis has now upgraded the Fairview Heights, IL tornado to F2, and has confirmed a total of 4 tornadoes, 2 F2 and 2 F0. The Hillsboro, IL tornado, rated F2, was on the ground for 20 miles. The 50-60 mph movement of the storms, of course, had the effect of lengthening the tornado tracks, giving even the relatively short-lived Fairview Heights tornado a track around 7 miles long.

EDIT, Tuesday, 10:40 a.m. - Now 5 confirmed, with addition of F1 tornado near Highland, IL. Also, they are indicating a likely tornado in Randolph Co., IL, and are surveying other areas, so additional tornado tracks may be added.

Here at my house in Edwardsville, the power finally came back on this afternoon around 5:20 after being out for nearly 24 hours. It is amazing how dependent we are on electricity for so many things. We had to pitch a fair amount of food, and late this evening the grocery stores were very busy with people replentishing what had to be tossed out. Although I did not see it in the LSRs, local media reported quite a bit of straight-line wind damage around Edwardsville - 6 cars set on fire when a tree fell and dragged power lines onto them, a number of houses and apartment buildings with trees down on them, and at least one building unroofed. A number of large trees went down on a house and power lines a block or so northeast of my house.

[Perry Williams]

The Dyer tornado surely looks to be F4 based on some of the aerial video. I would be very suprised to find it was rated only F3 when the state NWS officials visit the area.
[/b]

I agree......IMO it was a violent tornado.


Thanks Michael for pointing that out. I knew that from the Stoughton tornado up here in WI and being around the Wx Service office in August but completely forgot about it. I'm assuming thats what the "F3 OR HIGHER" verbiage is all about. I'm sure they have their opinions. Anyone know how quickly the official survey team responds?

Breaking down what they said in their PNS for possible hints...

NUMEROUS HOUSES DESTROYED...typically associated with F3 or higher, not much light shed on the situation there.

15 RAILROAD CARS WERE LIFTED OFF THE TRACK ANDBLOWN OVER...OK let me say this right here and right now that regardless of the Fujita rating that takes an INCREDIBLE amount of force. Amazing. Now it says that F2 strength winds can push railroad cars over, but those are boxcars. I guess it also depends on the type of railroad car...and the fact it says lifted. Still doesn't shed a lot of light on the situation.

FIVE MILES EAST OF MARMADUKE...2 WELL CONSTRUCTED HOMES WERE FLATTENED AND A NEW CAR THROWN 80 YARDS...this is interesting because they used the words WELL CONSTRUCTED. Both of these things appear to fit well in the F4 description here - "Well-constructed houses leveled; structures with weak foundations blown off some distance; cars thrown and large missiles generated.". Now its interesting they mentioned the distance the car flew too because typically F5 is associated with over 100m or 110 yards. Its very close and I will be intrigued by what they find.

So I'm expecting this to come up to an F4, possibly an F5...back to where we started in the quote :blink:

Anybody know if the official team will be investigating just this tornado or others as well?
[/b]

Alex, since there were over two dozen fatalities, I fully expect a NOAA Natural Disaster Survey team to conduct an extensive analysis of the entire event.

I haven't seen any images or aerial video from the Marmaduke area, but it sounds as if this violent tornado was close to F5 intensity at its peak. IMO both the Dyer and Gibson killer tornadoes were of F4 intensity (based upon video I've seen online tonight and on CNN yesterday afternoon).

[Terry L. Schenk]

Interesting set of parameters that existed in W TN as the storms were moving into that area. A couple of screen shots from the SPC Mesoanalysis page show why the storms were so strong. Take a look at the Significant Tornado (8) and Craven (130)parameters! YIKES!

Terry L. Schenk[attachmentid=77][attachmentid=78]

[Sam Shamburger]

Although this is my personal opinion, and is based on a quick analysis of rather poor quality radar snippets that have lots of range folding and dealiasing errors, it appears the Marmaduke/Caruthersville/Newburn supercell produced multiple tornadoes and not one long-track tri-state tornado.

Based on loops of SRV data, it appears the mesocyclone/tornado that went through Marmaduke occluded as it approached the Missouri border, and a new meso formed SE of Leonard, AR. This new mesocylone tracked just south of Kennett, MO, continued through Caruthersville, MO, then occluded and curved into southern Lake County, TN and dissipated. A new mesocyclone formed along I-155 & the Mississippi River and tracked eastward across northern Dyer County, TN, through Newbern, and into northwestern Gibson County. Then this mesocyclone occluded, and a new meso formed approximately SW of Rutherford, TN, and tracked eastward through Bradford.

Again, my quick analysis could easily be incorrect, since I've just glanced over the poor quality radar data I have from the event. However, with even hints of mesocyclone occlusions, it looks like this was not one super long-track tri-state tornado. It will take closer analysis of radar data, extensive aerial surveys, and gathering of eyewitness and stormchaser accounts to determine the true number of tornadoes with this supercell. Regardless of the number of tornadoes that are finally determined, this was a historical supercell in my book.

[George Tincher]

Guys, watching the same video you have watched and looking at some of the same photos you have seen, I have to agree with what most of you are saying that there is AT LEAST some minimal F4 level damage visible.

Now, how does this work when they have to bring in the expert team? If the NWS cannot assign any rating above an F3, then wouldn't it make sense for them to assign a preliminary rating of F3 (that's all these current ratings are...preliminary), then call the expert team and tell them to come have a look see?

This kind of seems to me what the NWS survey teams are indicating. They are saying "we know it's at least F3", but hinting it could be stronger. They may just keep the "preliminary" rating in place and turn it over to the team of experts to make the final call. As such, I expect to see at least one (and possibly more) of the tornadoes bumped up to F4. Could one of them be an F5? I suppose that's possible. But I haven't personally seen any photographic or video evidence to back that up, so I can't say. I did see a few homes that appeared to be swept away, but unless I am physically there and seeing how well constructed and anchored those structures are, then there is just no way to be sure.

Either way, regardless of whether these are upper end F3, F4 or F5, several of yesterday evening's tornadoes were absolute beasts that resulted in heavy loss of life and immense damage. As such, they were all very significant and will be remembered as such by those who lived through them, those who lost family and friends or those who witnessed them.

[Jeff Snyder]

MEG has put up lots of damage pictures from the tornadoes in their CWA. You can check them out at http://www.srh.noaa.gov/meg/events/April2006/index.htm

From those pics, I haven't really seen anything that I'd call definitive F5 damage. There are some houses that are completely destroyed, but, in almost all of those cases, the debris is laying nearby. Some of the pictures (such as http://www.srh.noaa.gov/meg/events/April20...eb/P4030031.jpg (http://www.srh.noaa.gov/meg/events/April2006/images/ar/web/P4030031.jpg) ) look a lot like the damage from the Manchester SD tornado. In addition, a few pictures below that image on the MEG page remind me of the Spencer SD F4. Of course, we don't know if the worst possible damage is contained in those pics. Some of the pics look impressive, in terms of the amount of debris, but then you can see what looks like mobile homes in the background with only a roof or outer walls missing (F2-F3).

[Glen Romine]

I thought the same things as Jeff. I don't see any evidence beyond F3 in the images posted to the site so far. You might think the most impressive damage images they found would be on the site - but maybe there is more that they haven't had time to upload yet. Certainly a lot of destruction - but nothing that appears to clearly be in the devastating category.

In the pic above that Jeff mentioned - I noted the trees are pushed over - but even small branches still intact. This makes me think the home may have slid off a poor foundation attachment. The debris pieces are large and in close quarters with each other.

Glen

[Alex Lamers]

An incredible 20 tornadoes in the ILX (Central Illinois) CWA as of right now and 6 in the Davenport CWA which makes the total 26 and not even in the strong tornado outbreak zone yet. Wow!

[Eric Treece]

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.

[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.
[/b]

The Marmaduke tornado in the Marmaduke/Caruthersville/Newbern "family" is now being called a "strong F3". (http://www.commercialappeal.com/mca/midsouth_news/article/0,1426,MCA_1497_4596256,00.html)

(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 (http://www.bentonville.k12.ar.us/tornado/) 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. :)
[/b]

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).
[/b]
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.