8/18 Wisconsin tornadoes

[Jeff Snyder]

Prelim damage assessment from MKX NWSFO has the Stoughton tornado as a 1/2-mile wide, 12-15 mile long F3...

--> http://kamala.cod.edu/offs/KMKX/0508191745.nous43.html

No mention of the QRT that's dispatched for tornado damage assessment that appears to be of the violent nature (F4-F5).

[Sam Sagnella]

--Wisconsin--
Brown County-
6NE Wrightstown: 1 mile path / 100 yds wide / F0

Columbia County-
4.5NNE Lodi: .1 mile path / 50 yds wide / F0

Dane County- 1 dead, 21 injured
2N Oregon: 17 mile path / 880 yds wide / High F3 (~200mph) :2.6SSW Rockdale

Grant County into Richland County-
Muscoda: F0/F1 :1N Orion

Iowa County-
2.5ENE Avoca: .1 mile path / 50 yds wide / F0

Iowa County into Sauk County-
1.8NNE Clyde: 6.5 mile path / 100 yds wide / F1 :4.5NE Clyde

Jefferson County-
5W Fort Atkinson: .5 mile path / 50 yds wide / F0 :4.8W Fort Atkinson
5W Fort Atkinson: .7 mile path / 50 yds wide / F1 :4W Fort Atkinson
3.6WSW Fort Atkinson: 1.2 mile path / 50 yds wide / F1 :3WSW Fort Atkinson
1.5SSW Fort Atkinson: 1.4 mile path / 50 yds wide / F1 :1.4SSE Fort Atkinson
3.2SE Fort Atkinson: .2 mile path / 50 yds wide / F0 :3.4SE Fort Atkinson

Manitowic County-
7N Cleveland: 1.5 mile path / 100 yds wide / F1

Marquette County-
1.7NNE Westfield: 5.5 mile path / 100 yds wide / F1 :7.2NNE Westfield

Monroe County-
6E Tomah: 10 mile path / 25 yds wide / F1

Sauk County-
1.5SSW Spring Green: 1.9 mile path / 75 yds wide / F1 :.5ENE Spring Green
1.8W Merrimac: 1 mile path / 75 yds wide / F0 :1WSW Merrimac

Sauk County into Columbia County-
3W Bluff View: 10 mile path / 200 yds wide / F2 :3.2SW Okee

Trempealeau County-
5W Centerville: .03 mile path / 25 yds wide / F0

Vernon County- 1 injured
3.2W Esofea: 1.2 mile path / 25 yds wide / F1 :2W Esofea

Vernon County into Richland County-
5W Viola: 20 mile path / 70 yds wide / Low F2 (100-120mph) :Bloom City

Waupaca County-
2.2SW New London: .3 mile path / 40 yds wide / F0 : 2SW New London

Waushara County-
5SSW Wautoma: 1.5 mile path / 80 yds wide / F0

Winnebago County-
2SW Neenah: .25 mile path / F0


Will update as surveys are completed...

[Scott A. Kampas]

I wouldn't be surprised if the QRT was dispatched. I saw a house explode when the tornado was in its Hesston-like stage and damage that at a hurried glance appeared it might be violent calibre. Here are some shots from locals: http://www.wkowtv.com/index.php/photoviewe...tornado-081805/ (http://www.wkowtv.com/index.php/photoviewer/tornado-081805/)

Scott

[Tim Gonyo]

Seems someone else was on my tornado.. the one that was in Sauk County near Lake Wisconsin. Their pic is on the slideshow here: http://www.wkowtv.com/photoviewer/slidesho...5&currentPic=41 (http://www.wkowtv.com/photoviewer/slideshow.php?directory=tornado-081805&currentPic=41)

Looks really close to the pics in my reports thread... I wonder what road they were on.

[beaudodson]

I wouldn't be shocked if that was upgraded to F4. Time will tell. I did see some very impressive damage images over the past 12 hours.

Certainly was an incredible storm...long tracked Wisconsin Supercell. Looking through the Significant Tornado book one would gather that this is one of the more impressive August outbreaks for Wisconsin.

[Greg Stumpf]

No mention of the QRT that's dispatched for tornado damage assessment that appears to be of the violent nature (F4-F5).
Pretty sure there is no funding for the QRT any more due to the present NWS fiscal situation. I'm on the QRT, along with Don Burgess, and we just discussed this this morning. No calls all year for us. That's not to say they may have called other members (there are 20 in all).

[mikegeukes]

Some research, I did on F3, F4, and F5 tornadoes in Wisconsin for August.

F4 Tornadoes in August: 1950-2004 for Wisconsin:
08-22-64 F4 Ozaukee County, 30 injured.
08-19-68 F4 Marinette County, 2 killed, 3 injured

F3 Tornadoes in August: 1950-2004 for Wisconsin:
08-16-63 F3 Columbia County, 13 injured
08-02-67 F3 Dane County, 2 killed, 5 injured
08-29-92 F3 Washara County, 1 killed, 30 injured
08-23-98 F3 Door County, 2 injured

For some reason, COD text products links to individual text messages, do not stay up for a long period of time, this is why I posted the whole thing

PUBLIC INFORMATION STATEMENT...RESENT NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 438 PM CDT FRI AUG 19 2005

..PRELIMINARY INFORMATION ON THE STOUGHTON TORNADO

SURVEY TEAMS FROM THE NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN OFFICE HAVE MADE A PRELIMINARY DETERMINATION OF THE STRENGTH AND PATH LENGTH OF THE STOUGHTON TORNADO.

THE TORNADO APPEARED TO HAVE FIRST TOUCHED DOWN AT APPROXIMATELY 615 PM CDT IN THE FISH CREEK SUBDIVISION IN THE TOWNSHIP OF DUNN...WEST OF THE TOWN OF DUNN...ABOUT 5 MILES NORTHWEST OF STOUGHTON.

THE TORNADO TRAVELED AN ESTIMATED 12 TO 15 MILES THROUGH STOUGHTON... LIFTING OFF APPROXIMATELY 7 MILES EAST-NORTHEAST OF STOUGHTON.

THE PRELIMINARY FUJITA SCALE RATING IS AN F-3...WITH ESTIMATED WINDS OF UP TO 200 MPH.

THE DAMAGE PATH APPEARED TO BE 1/2 MILE WIDE.
Mike
http://efchasing.blogspot.com/
_________________
I NEED A JOB AND A HOME.

[Alex Lamers]

...UPDATE ON STORM SURVEYS...

DUE TO THE EXTENSIVE AREA THAT HAD TO BE SURVEYED AND THE AMOUNT OF INFORMATION THAT HAS TO BE PROCESSED...FINAL TORNADO STATISTICS WILL NOT BE RELEASED UNTIL SOMETIME SATURDAY AFTERNOON.

...HERE IS WHAT WE KNOW THUS FAR...

DANE COUNTY... THE TORNADO IN THE STOUGHTON AREA WAS RATED AN F3. ONLY ONE TORNADO WAS CONFIRMED AT THIS TIME FOR DANE COUNTY.

JEFFERSON COUNTY... FIVE TORNADOES AROUND THE FORT ATKINSON AREA WERE CONFIRMED.

WALWORTH/RACINE COUNTY... NO TORNADOES WERE VERIFIED.

IOWA...SAUK...COLUMBIA...AND MARQUETTE COUNTIES... STORM SURVEYS ARE STILL ON GOING AT THIS TIME.

$$

When you don't take into account the tornadoes that MKX has not surveyed or completed surveys on yet...we are already around 20 tornadoes which is nearing a daily record which was set on May 8 1988 in the Mother's Day Outbreak (total of 24). That same date holds the record for most tornadoes in Iowa in a day and I believe over 57 tornadoes in all occurred. My facts should be pretty straight on that.

...Alex Lamers...

[Andrea Griffa]

Guys, the images and overall the video of the monster arrived also in Italy television!Crazy and huge tornado.
I can't believe that thre's nota videotape on the web...

Anyone got the video?

[Alex Lamers]

Just totaled it up more thoroughly and based on PNS's so far, this was a 19-tornado day (in Wisconsin only). However, this does not include a definite tornado in Columbia County and a possible/probable one in Sauk Co. Additional tornadoes may be found here and there but for NOW it seems the all time daily record is safe. Nonetheless it was a historic outbreak.

...Alex Lamers...

[Jim Tang]

I know this is a lot to ask, but does anyone have SPC Mesoanalysis Maps from the outbreak (like sig tornado potential, supercell potential, etc.)?

Thanks! :D

[beaudodson]

Top 5 Tornado Days in Wisconsin...
1) May 8 1988 - 24 Tornadoes
2) July 3, 1983 - 22 Tornadoes
3) June 8, 1993 - 18 Tornadoes
3) August 18, 2005 - 18 Tornadoes (preliminary)
5) June 23, 2004 - 17 Tornadoes

The 30 year normal /1971-2000/ for tornadoes in Wisconsin is 21 per year. The year of 1980 had the greatest state total with 43 tornadoes.


NWS

TORNADO OUTBREAK
http://www.crh.noaa.gov/mkx/document/tor/081805.php

[Steven Williams]

We even had a small snippet of TV news here in New Zealand about the Wisconsin tornadoes.

The photos on that link above are interesting.

[John Farley]

Are there statistics available online somewhere on the number of tornadoes this year, by state? (Seems to me there are, but I can't remember where.) Wisconsin has had several smaller outbreaks earlier this year, so I would guess that 1) the record for tornadoes in a year in Wisconsin is in jeopardy, if not already broken, and 2) Wisconsin must account for a large proportion of the tornadoes nationwide this year.

BTW, congratulations Scott and Mark on a great catch of the Stoughton tornado, and thanks, Scott, for posting the link to the pics by locals - a lot of nice shots there!

[Bill Hark]

Here are some more great images of one of the Wisconsin tornadoes. (Stoughton)

http://www.gazetteextra.com/stoughtontornado/index.asp

I love the color of the first few images in the series. Great shots!

Bill Hark

[Andy Wehrle]

Wisconsin has had several smaller outbreaks earlier this year, so I would guess that 1) the record for tornadoes in a year in Wisconsin is in jeopardy, if not already broken

Current tornado count from 8/18 is 28 statewide (17 in the MKX CWA, equal to the statewide count from 6/23/04) http://www.crh.noaa.gov/mkx/document/tor/081805.php

The several cluster outbreaks of weak tornadoes in central Wisconsin in early June totaled about 20-so that would be at least 48 for the year, a new record.

http://www.nislwx.com/forums/viewtopic.php?t=46

[beaudodson]

Well now we know that this has broken the one day record.

COMBINED WITH THE 5 CONFIRMED TORNADOES IN THE NWS GREEN BAY COUNTY
WARNING AREA...AND THE NWS LA CROSSE OFFICE REPORT OF 6 CONFIRMED
TORNADOES IN THE WISCONSIN PORTION OF THEIR COUNTY WARNING AREA...
THIS GIVES A TOTAL OF 28 CONFIRMED TORNADOES ON AUGUST 18TH IN
WISCONSIN.

THIS NUMBER SETS A NEW RECORD FOR THE MOST TORNADOES REPORTED IN ONE
DAY IN THE STATE. THE PREVIOUS RECORD WAS 24 TORNADOES SET ON MAY 8
1988.

NWS - http://iwin.nws.noaa.gov/iwin/wi/public.html

[Andrea Griffa]

Wisconsin has had several smaller outbreaks earlier this year, so I would guess that 1) the record for tornadoes in a year in Wisconsin is in jeopardy, if not already broken

Current tornado count from 8/18 is 28 statewide (17 in the MKX CWA, equal to the statewide count from 6/23/04) http://www.crh.noaa.gov/mkx/document/tor/081805.php

The several cluster outbreaks of weak tornadoes in central Wisconsin in early June totaled about 20-so that would be at least 48 for the year, a new record.

http://www.nislwx.com/forums/viewtopic.php?t=46

Seeing the radar images those tornadic supercells don't seem so much strong from the point of view of reflectivity...It's true that this is not a sign of the strenght of the mesocyclone rotation but I did think to see something like a strong hook echo...I wann say that is pretty uncommon to observe a strong tornadic supercell with a similar hook echo. Besides I don't see a evident isolation of the supercells, typical of the main outbreak supercells.

It could be interesting to see the sounding of those zones but I cant' find it. Maybe it could be a strong minisupercell; Andy, did you observe the elevation of that supercell?

[Alex Lamers]

It was a pretty classic looking supercell in several stages (including near Viola and Stoughton) but frequently the torando became rain wrapped in other areas of S WI, leading to the appearance of poor overall structure. I can say from watching it from left to right across the state that it looked like your classic cyclic supercell from the Plains. There were hook echoes several times but you need to find those locations and also it is helpful to watch the event in its entirety so it is easier to pick out. There was one over Stoughton and one over Viola for sure (Brett Adair posted the smoothed image over Viola on another thread). Based on mean storm track calculations it deviated an average of about 45 degrees right of the mean storm motion. The g2g was nearly always strong across the entire state although it did get muddled in places.

This was an incredible outbreak, especially for a Slight Risk day -- it didn't look too impressive at the start and the instability certaintly wasn't high or extreme (with rain in the morning and clouds too).

...Alex Lamers...

[Jim Tang]

Does anybody have GRLevel3 radar images from the Stoughton/Ft. Atkinson supercell?

Also, I'm still looking for SPC Mesoanalysis Maps from the event. Does anybody know where I could look for them, or does anybody have them, or do I have to wait for a case study by Jon Davies?

Thanks in advance! :D

[Andrew Pritchard]

You might try taking a look in the SPC's Severe T'storms Event archive, they save quite a bit of stuff from the day. Not sure if you can find mesoanalysis info though. Worth a shot though.

[Andy Wehrle]

By the way...I bet this is the first year in recorded history we beat out Illinois' tornado count. Perhaps even Oklahoma's too. Certainly we beat Oklahoma's strong tornado count. :P

Viola area storm:

http://sphs.angeltowns.net/images/storms/2005/GRL3_ARX_10.png

http://sphs.angeltowns.net/images/storms/2005/GRL3_ARX_11.png

http://sphs.angeltowns.net/images/storms/2005/GRL3_ARX_velocity_2.png

http://sphs.angeltowns.net/images/storms/2005/GRL3_ARX_velocity_2_overlay.png

http://sphs.angeltowns.net/images/storms/2005/GRL3_ARX_velocity_3.png

http://sphs.angeltowns.net/images/storms/2005/GRL3_ARX_velocity_4.png

Stoughton storm about 10 minutes before all hell broke loose (little red + is my set "home" location-which is not 100% accurate but is close):

http://sphs.angeltowns.net/images/storms/2005/GRL3_MKX_32.png

http://sphs.angeltowns.net/images/storms/2005/GRL3_MKX_32B.png

http://sphs.angeltowns.net/images/storms/2005/GRL3_MKX_velocity_7.png

I find it kind of ironic that I just had the kind of experience that ignited the interest in tornadoes for many of you-yet for me the interest was already there.

[Scott Olson]

I put together a composite chart based on archived data from OBS/Wind Profiler/NCEP Fronts/etc:

http://img361.imageshack.us/img361/999/aug18wioutbreak0rp.gif (http://imageshack.us)

Kudos to all who got to chase this one, by the time I reliazed the mesoscale setup it was to late.

-Scott Olson

[Jason McIntosh]

I first want to say that it was dissapointing to hear that someone died from this tornado. The man was even in his basement. I was leaving town(Madison) at 3 pm. I was on a trip to Ohio when I heard the news about the outbreak in WI. It figures that the day I leave the best opprotunity arrises. I have to believe there was some divine intervention going on there. I could see the supercell from Gary, IN!! I bet that thing was up around 50,000 ft. If you watch the radar loop of the entire event you can see that the same supercell was responsible for most of the tornadoes from Vernon county to Jefferson county. It was an amazing event. I still wished I was there. :cry:

[Jerry Funfsinn]

I was disappointed I decided not to chase SW Wisconsin on Thursday, even though I watched it unfold all day. The post event "I should have"s were bothering me . But I am gun shy of that part of WI or any part for that matter. Lo and behold I get a call last night from someone I went to high school. He tells me he was in Stoughton on vacation and he filmed the tornado as it passed through and would I like to see it. What the #@!$% are you kidding. Like I always say, the best chases turn out to be the unplanned ones. He has always wanted to see a toenado and this was his first. I'm sure it left an impression.
Here is a link to the video.
http://www.creativejetstream.com/

Jerry Funfsinn

[Brett Adair]

That is NO F-3 torando. You can see the debris falling from the sky on those folks in that video. This video needs to be sent to the Milwaukee NWS if it hasn't been already. I believe that is at least F-4 there.

[Aaron Kennedy]

What does debris falling on people have to do with strength of the tornado?

Aaron

[rdale]

"You can see the debris falling from the sky on those folks in that video."

I missed that section of Fujita's work on classifying storms ;>

Debris can fall from the sky from any sort of tornado, so disregarding the ground survey to add a notch on the scale is not warranted here.

- Rob

[Brett Adair]

Well, that is a good distance away from the tornado. Indicates to me that the updraft is EXTREMELY strong. Also, there are photos from Stoughton of a home where it was completely demosished down to parts of the basement. That leans me more towards and F-4 rating in some locations.

[Aaron Kennedy]

Updraft intensity does not equal tornado intensity....

A house getting blown to bits doesn't neccesarily mean a F4/5 either.

Many factors are factored into determining the F-scale including condition/construction of the house.

Aaron

[mikegeukes]

More information on the F-Scale, also there are many more links.

A Guide to F-Scale Damage Assessment
http://meted.ucar.edu/resource/wcm/ftp/Fin...ssmentGuide.pdf (http://meted.ucar.edu/resource/wcm/ftp/FinalNWSF-scaleAssessmentGuide.pdf)

Mike

[Brett Adair]

I am currently talking with a NWS-MKE meteorologist. He is trying to get the tornado upgraded to F-4 as we speak. I will give you more reasoning as I recieve it.

Edit: Bill thinks that the key is the tornado was nearly stationary at some points in time. He has taken photo's and there are areas of where F-4 damage was reached he said. Also, the entire office found it interesting that debris was strown 60-70 miles away from the tornado at the NWS office. He thinks he has the evidence to get the WCM to get it upgraded to F-4 sometime this week.

[Jeff Snyder]

I am currently talking with a NWS-MKE meteorologist. He is trying to get the tornado upgraded to F-4 as we speak. I will give you more reasoning as I recieve it.

Edit: Bill thinks that the key is the tornado was nearly stationary at some points in time. He has taken photo's and there are areas of where F-4 damage was reached he said. Also, the entire office found it interesting that debris was strown 60-70 miles away from the tornado at the NWS office. He thinks he has the evidence to get the WCM to get it upgraded to F-4 sometime this week.

I still don't know how damage being thrown long distances is any good indicator of tornado strength. If I'm not mistaken, mid and upper-level flow was strong that day, so any debris that made it to the midlevels of the storm would quickly be whisked away downstream. I wish I still had the presentation, but Tim Marschall made a talk a couple of years ago regarding the La Plata tornado. Areas that were preliminarily rated F4-F5 because the "foundations were wiped clean" were later found to be as low as F1-F2 IIRC. Some houses are built very poorly and not attached to the foundation very well (if at all). Again, IIRC, Tim found that some houses were "wiped clean" by winds of only 130-140mph -- he deemed this "sliders". It does NOT always take a lot of wind to demolish a house! I'm not saying that this isn't the case this time, especially if you're getting it from a (seasoned?) NWS met. I just think that some folks see a clean foundation and automatically think F4-F5.

[Glen Romine]

I'd certainly like to see the detailed survey report - describing what damage the team found, and the basis for the assessment. I've seen some images that superficially look F3, nothing that clearly would imply F4, but really there isn't that much available on the net that I've yet seen to make an even somewhat educated guess. As for the possibility of an upgrade to F4, I thought that power was removed from local NWS offices and only a QRT can assign F4 or greater intensity. maybe someone more in the know can comment further.

Glen

[Andy Wehrle]

From my observations, many of the houses in the Williams Drive neighborhood where the worst damage was observed are well-built frame houses. So are the ones in my neighborhood, where the fatality occurred. This tornado was quite capricious, even by tornado standards. On the north end of my neighborhood (north of Skaalen Road) most of the houses are still standing, some with all or part of the roof missing, some with very little damage at all. Two are completely razed to the foundation, and one is missing the entire second story with the first story intact (the Orlofske's house, where the fatality occured).

I think topography may have played a role in the damage here. Many of the houses in my neighborhood are built into the side of a hill (so they appear as 2-story from the bottom of the hill and 1-story from the top). Much of the hill is densely covered by trees. I believe several houses (including mine) were sheltered from the worst winds because of their position in relation to the hillside and trees. The houses that were completely destroyed were located such that they were fully exposed to the wind.

The pattern of damage (flattened house next to relatively intact house) is also consistent with a multiple-vortex tornado. I believe the "ambient" tornado circulation was relatively weak, perhaps F1-low F2, but it contained imbedded intense suction vorticies that produced the F3/possibly F4 damage.

My house was either in the edge of the tornadic circulation or in an inflow jet. Either way it was very close- <50 yards.

[Robert Dewey]

I thought the F-scale was primarily a damage scale, and then an estimated strength is assigned based upon the damage. Over time, houses will continue to be built stronger and better - so what exactly is the "norm" when comparing damage? It would seem that over time, tornado ratings would be skewed given the change in housing materials, construction methods, etc..

I guess there should be some "norm" as to what a strong framed house is, and that "norm" should remain the same for years to come. This means that tornadoes which were rated in the 1970's may have actually been weaker when compared to today's standards, or then again - maybe tornadoes today are rated too weak compared to the "norm" that was used years and years ago... Just some food for thought.

Honestly, I think that the WI tornado, based on Andy's description, would probably be very high-end F3, or more likely an F4. A tornado which occured in MI during the July 2, 1997 outbreak generated an F3 rating, and didn't do nearly as much damage - perhaps that one was rated too strong?

[Jeff Snyder]

Just a reminder that most tornadoes only produce "max damage" over a very small part of their lifetime/track. For example, the "average" F3 tornado only produces F3 damage over a very small part of their track. I think the Moore/Bridgecreek OK 5-3-99 F5 only produced F5 damage over well less than 1% of the total area affected by the tornado. All you need is a single structure that was deemed to be "F5-level" damage for the entire tornado to receive an F5 rating, regardless of it's "strength" over the rest of its track.

It's been noted that the Fujita scale was mathematically developed so that F12 = mach 1. Now, I'd REALLY like to know if Fujita developed the F-scale based on a derivation of probable damage from particular wind speeds, or a derivation of the probably wind speed for given damage. It's generally understood that the F-scale is a DAMAGE scale, as Rob noted. However, if that were the case, then "structural engineering" wouldn't matter, since a flattened house is a flattened house. However, the fact that we've begun to realize that not all houses are built equally implies that probable wind speeds are being incorporated in damage assessment, and thus the F-scale isn't an entirely damage-based scale. Well, maybe it is, but the refinement of the scale strongly relies on an examination of the type and degree of damage relative to wind speeds.

[Alex Lamers]

I am currently talking with a NWS-MKE meteorologist. He is trying to get the tornado upgraded to F-4 as we speak. I will give you more reasoning as I recieve it.

Edit: Bill thinks that the key is the tornado was nearly stationary at some points in time. He has taken photo's and there are areas of where F-4 damage was reached he said. Also, the entire office found it interesting that debris was strown 60-70 miles away from the tornado at the NWS office. He thinks he has the evidence to get the WCM to get it upgraded to F-4 sometime this week.

The Fujita Scale has its limitations and there is the over/under 1 rule that from what the tornado is ruled it could THEORETICALLY be one rating higher or lower. So under that rule of thumb, this tornado could be anywhere from F2 to F4. Second, you need to consider building construction and other factors that you cannot merely determine from a photograph. Although the damage looked bad (and it was for sure) "armchair surveying" typically isn't too accurate although it can be an interesting challenge if you are a little bored or intrigued.

In this particular case, and any case for that matter, you cannot judge the intensity of a tornado based on debris being lofted miles away. Surely it takes a strong updraft, but there are no conlcusive studies (at least that I am aware of) that suggest that you can measure intensity by that factor, nor is it common practice to use such information in NWS Storm Surveys despite how interesting it is.

Now on to the actual point at hand...F4 or not? Bill has said...while there is evidence of...and I am placing this in quotes due to the subjectiveness of the Fujita scale..."F4-type damage", it is not sufficient enough or conclusive enough to classify the Stoughton tornado as an F4 at this time, hence the F3 rating that you see on the Public Information Statement which is accurate based on current information. Reports from eyewitnesses said that the tornado was moving relatively slow over Stoughton. The exact figures are not available for you yet but lets just say that several minutes of exposure to 200 mph winds would cause "F4-type damage" but this is not necessarily indicative of an F4 tornado. The quoted information is not necessarily accurate in the sense that the high-end F3 rating seems plausible.

As you all may imagine, the process of evaluating double-digit tornadoes spread across a CWA is not a quick and easy process. I know you are all eager for information, and the office is working to get the information out as quickly as possible for all interested parties. As far as detailed damage assessments and county maps, those will be out within the week...no promises on exact timing.

Hope this helps clear up some issues...

Alex Lamers/Bill Borghoff
WFO MKX

[nickgrillo]

I thought the F-scale was primarily a damage scale, and then an estimated strength is assigned based upon the damage. Over time, houses will continue to be built stronger and better - so what exactly is the "norm" when comparing damage? It would seem that over time, tornado ratings would be skewed given the change in housing materials, construction methods, etc..

I guess there should be some "norm" as to what a strong framed house is, and that "norm" should remain the same for years to come. This means that tornadoes which were rated in the 1970's may have actually been weaker when compared to today's standards, or then again - maybe tornadoes today are rated too weak compared to the "norm" that was used years and years ago... Just some food for thought.

Honestly, I think that the WI tornado, based on Andy's description, would probably be very high-end F3, or more likely an F4. A tornado which occured in MI during the July 2, 1997 outbreak generated an F3 rating, and didn't do nearly as much damage - perhaps that one was rated too strong?

Yeah, and that thought comes to mind when reviewing alot of climotology. Taking a look at MI's climo data, there hasn't been a violent (F4/F5) for nearly 30 years... What explains that? Prior to 1977, there were violent tornadoes pretty often -- with two F5's occuring in the same decade. Then, as the years progressed, you'd see weaker and weaker ratings. There hasn't been a single tornado rated higher then F2 for nearly 10 years...

Is that the case? Obviously, houses are built much stronger then they were 30 years ago, so if a tornado was rated F4 based on demolished houses in 1975, then what would it be rated today?

[mikegeukes]

Getting off-topic somewhat.
The Fujita scale came about in 1971, 1980 the NWS started to verify warnings, in fact looking at Storm Data, the F-Scale started to appear
in the early 80's in Storm Data. The Super Outbreak in Storm Data, gives no F-Scale Rating.

From: A Guide to F-Scale Damage Assessment

The Fujita scale became the standard for estimating the intensity of tornadoes in the mid-1970s.

Along with this windspeed scale, Fujita included a description of the damage associated with each category – those in Table 1 are taken from the original reference (Fujita 1971).

In addition, Fujita used a set of damage photographs (Fig. 2) to illustrate the intensity categories. With the introduction of these materials, it became possible for someone surveying the damage from a tornado to estimate the F-scale (implying an estimate of the range of windspeeds).

Further, using newspaper accounts and photographs, it became possible to assign an F-scale to historical events, a project which was undertaken by the National Severe Storms Forecast Center (NSSFC), with the support of the Nuclear Regulatory Agency in 1976. Students were hired to do the necessary research into old newspapers and other accounts of storms.They assigned an F-scale rating to as many historical events as possible based mostly on newspaper accounts and photographs.

In 1973, the official authority for doing Storm Data passed from the state
climatologists to the NWS offices. From the late 1970s to the present, it has been expected that all tornadoes that become part of the Storm Data record will have an F-scale number assigned to them, as well as estimates of the path length and width.

Moreover, the actual application of the Fujita scale has been complicated by the frequent absence of standard structures by which the intensity could be estimated.

When a tornado passes through open country (or through vegetation for which no reliable standards exist) during some or all of its path, there is no obvious way to apply the standards developed by Fujita’s work for those segments of the path.

Therefore, it becomes challenging to know what the windspeeds were. Further, the F scale estimate applies to the entire event, whereas the rating is based on what might only be a single point of the worst damage. Of course, Fujita recognized that a tornado damage path can be complex in terms of the variation in damage along it.

For Michigan, since 1990, for F3 and higher tornadoes occurred on the following dates: 09/14/90, 03/27/91, 05/28/91, 06/21/96, and 07/02/97

Mike

[Scott Currens]

Nick Grillo wrote:

Obviously, houses are built much stronger then they were 30 years ago, so if a tornado was rated F4 based on demolished houses in 1975, then what would it be rated today?

Are homes really built stronger today? I don't have any facts to back this up, but I think builders cut more corners now than ever.

Shane have you seen a change in the quality of new home construction?

[Gabe Garfield]

Are homes really built stronger today? I don't have any facts to back this up, but I think builders cut more corners now than ever.


Good point, Scott. One of my good friends was a house framer about a year ago, and he told me that house constuction is terrible these days. In fact, he told me a story about some home builders who built the house an entire foot off of specifications. They had to make some major adjustments to even make the house look somewhat presentable. A house is as only good as those who built it.

I also wanted to say that the existence of a strong updraft is at least qualitatively an indicator of tornado intensity. If you think about it, a strong updraft would lead to strong evacuation of air mass. This evacuation of airmass would cause the development of a strong low pressure center, which would in turn create a strong horizontal pressure gradient. Finally, a strong horizontal pressure gradient would lead to strong horizontal winds (i.e. winds that cause the damage at the surface).

Just the mere fact that the Stoughton tornado was able to loft debris to such incredible heights (reaching 500 mb? :shock: ) suggests that it was at least a "strong" class tornado. IMO, I think the Stoughton tornado was at some point capable of producing violent class tornado damage. The damage survey apparently hasn't produced any compelling evidence that this was the case, however. But, as Jeff pointed out, tornadoes generally produce extreme damage in relatively localized areas, so it is possible that this tornado was violent, but wasn't hitting anything at the moment.

Gabe

[John Farley]

Even after some downward revision in the preliminary number of tornadoes for August 18 (from 28 to 24), the total number of tornadoes in Wisconsin for 2005, now standing at 54, easily breaks the old record for number of tornadoes in a year. A public information statement providing details on this can be found at:

http://kamala.cod.edu/wi/latest.nous43.KMKX.html

As many tornadoes as there have been this month, there were (as of today) even more in June of this year.

[Aaron Kennedy]

Gotta disagree with you Gabe....


I also wanted to say that the existence of a strong updraft is at least qualitatively an indicator of tornado intensity.

Studies have shown that updraft intensity actually decreases around the time of tornadogenesis. This makes sense considering the mesocyclone is typically going through occlusion. The occlusion cuts off the updraft, weakening it... often (for cyclic supercells), a new UD develops ahead of the surging RFD to the southeast of the primary circulation.

Aaron

[Shane Adams]

Also, there are photos from Stoughton of a home where it was completely demosished down to parts of the basement. That leans me more towards and F-4 rating in some locations.

Don't get your hopes up. The 6-12-04 Mulvane, KS tornado completely leveled a two-story home and removed two walls from the basement, and still wasn't upgraded to F4 from F3 (which several chasers believe is a mistake). Apparently, you'll need debarked trees to confirm an upgrade from F3 to F4; leveled houses and cars thrown hundreds of yards aren't enough. I can understand the house construction making a difference...but a car is a car.

[Shane Adams]

Shane have you seen a change in the quality of new home construction?

I've only been around newly-built homes a few years, so I can't make a comparison to older homes. However I can confirm that the builders we follow DO attach the frame to the foundation. I'm fairly certain all new homes are built that way (secured to foundation), at least in Norman.

[Joe Nield]

Are homes really built stronger today? I don't have any facts to back this up, but I think builders cut more corners now than ever.

I would venture to say absolutely not. I think home construction quality probably peaked sometime in the mid 20th century, although I, too, have no facts to back that up.

A subdivision has been gradually being constructed across the street from my parents' house for the last 10 or 12 years. They seriously throw these houses up in a few weeks. I call them tornado fodder.

[Joe Nield]

I'm fairly certain all new homes are built that way (secured to foundation), at least in Norman.

I was assisting a symposium on the Fujita scale at the AMS conference in Long Beach, CA back in 2003 when Tim Marshall gave a presentation on construction quality concerns as they relate to the F-scale. He found that, even in the hardest hit areas in Moore, the same corners were being cut at an alarming rate among new homes being constructed.

Apparently lessons learned are no match for dollars saved in the short term.

[Gabe Garfield]

Studies have shown that updraft intensity actually decreases around the time of tornadogenesis. This makes sense considering the mesocyclone is typically going through occlusion. The occlusion cuts off the updraft, weakening it... often (for cyclic supercells), a new UD develops ahead of the surging RFD to the southeast of the primary circulation.

I guess I should do better to define what I mean by "updraft". When I say updraft, I'm not referring to the updraft of the entire storm, but rather, the upward motion in a tornado itself.

Anecdotally speaking, I can't possibly imagine that the upward motion in the Andover, KS tornado (in the vicinity of the developing tornado) was greater before tornadogenesis than after. If you watch the video when it was hitting the Golden Spur mobile home park, cloud elements rise from near the surface and hit the ambient cloud base in just around 1 second (which indicates an extremely strong updraft).

More scientifically speaking, the presence of a downdraft does not preclude the presence of a stronger updraft. Rasmussen et al. hypothesize that a positively buoyant rear-flank downdraft will return to the center of circulation when it hits the ground. Thus, it will actually enhance the updraft in the vicinity of the developing tornado (as well as tighten the circulation which will also lead to a stronger updraft).

Gabe

[Bob Hartig]

Now, I'd REALLY like to know if Fujita developed the F-scale based on a derivation of probable damage from particular wind speeds, or a derivation of the probably wind speed for given damage.

That kind of expresses my own question: What exactly was Fujita after when he developed his scale? From what I've read, I doubt he was concerned primarily with rating damage for its own sake--otherwise, why even bother to assign a range of wind speeds to different points on the F scale? As somebody has pointed out, a flattened house is a flattened house. If, however, his primary concern was to extrapolate tornado intensity from the damage, then correlating damage to wind speeds makes perfect sense. And of course, that's exactly what the Fujita scale does.

Obviously a lot of complications and nuances have emerged with the F-scale, and it's interesting to see these things getting hashed out in this format and elsewhere. But in the midst of all that, I think it would pay to consider the good doctor's raison d'etre for conceiving his scale. He hoped to provide some measuring stick, however rough, for determining tornado intensity. I wonder whether Fujita himself would agree that his scale is purely a damage rating, or whether that isn't a rather dogmatic stance toward a tool he devised in order to estimate tornado wind speeds. In other word, actual intensity is the thing, not the damage it causes, which is subject to all the caprices of home construction (including lack of any construction at all in the open prairie). So maybe it's just as legitimate to refer to "F4 winds" even when F4 damage isn't present as it is to assign an F2 rating when F4 damage has occurred. If wind speed/intensity is in fact the heart of the matter, then more than just damage probably needs to be factored in when assigning an F Scale rating. After all, we do have Doppler radar.

My two cents as an interested non-expert.

[Glen Romine]

The obsession wit the exact wind range given in the Fujita Scale I think is what most seeking to revise it are trying to get away from. Fujita stepped in to fill a needed void - namely trying to get a feel for the frequency of violent tornadoes relative to the seemingly more common weaker tornadoes - but not having any real way to quantify that. Some of his early survey work was of atmoic bomb blasts - and trying to understand the damage patterns it created. Of course Fujita was hoping to get a feel for the likely strength of the tornadic winds that would be required to cause the amount of damage observed. After all - there was no real way to measure them in those days - so the only real information you had to work with with the width, length, and extent of damage caused by a tornado. A weakness of this method is that you can't practically place every possible structure in a wind tunnel and expose it to the same conditions in a tornado and see what it really takes to cause the structure to fail by x amount. He had no hard data to base his estimates on - they were just a ballpark estimate given the knowledge available at the time. Much has since been learned that suggests Fujita's estimates were probably too high, even in the most pristine cases (well built home exposed to tornadic winds with no debris loading).

Several questions quickly pop to mind. What about the duration of time exposed to various wind speed intensities? Will exposure to 210 mph winds for 1.5 seconds cause more damage than 180 mph winds for 60 seconds? How do you quantify the affects of debris loading on structure failure? What about home design/construction impacts the degree of home failure? What about once the first structure fails - and then the debris from that starts impacting the next structure downstream? Any doubts that a home being pelted with flying 2x4's won't fail faster and more extensively than one impacted by air alone, regardless of the wind speed?

Considering the case at hand, It is known that most modern homes first fail by the garage doors blowing inward - and I'd bet that the neighborhood in Stoughton featured 3-car garages on every home - a common requirement in affluent Wisconson neighborhoods. Most of these homes will also have basements - so the structure is only attached along the outside edge of the home. You can easily find examples of F4 tornadoes in say Kansas where a home with a basement has the subfloor blown away - exposing the entire basement. I haven't seen one example of this from the Stoughton WI tornado - so you are then reliant on the sub floor attachment being equivalent to a slab if you want to call removal of interior walls, but not the subfloor as F4.

Regardless, returning to the discussion on Fujita scale, it is a damage scale - not a wind scale, regardless of what we hope to gain from it at the end of the day in terms of understanding of the frequency of extreme winds. Even if you had an exact wind measurement from the Stoughton tornado and it gave you a wind speed at ground level of 210 mph, it would be wrong to classify the tornado as an F4 if no damage equivalent to the F4 classification was found. Why, you undoubtedly ask? Because the entire climatology we currently have is based on the damage estimates - and if you change how tornadoes are classified to a new standard, such as measured wind speed, then you just made the entire tornado database worthless because it now no longer has consistent classification. Of course the system is severely flawed - nobody is questioning that, but it is the system we currently have in place, so like it or not it is what it is. Really, it is vastly better than the system we had before - which was none at all.

Glen

[Scott Olson]

Regardless, returning to the discussion on Fujita scale, it is a damage scale - not a wind scale, regardless of what we hope to gain from it at the end of the day in terms of understanding of the frequency of extreme winds. Even if you had an exact wind measurement from the Stoughton tornado and it gave you a wind speed at ground level of 210 mph, it would be wrong to classify the tornado as an F4 if no damage equivalent to the F4 classification was found. Why, you undoubtedly ask? Because the entire climatology we currently have is based on the damage estimates - and if you change how tornadoes are classified to a new standard, such as measured wind speed, then you just made the entire tornado database worthless because it now no longer has consistent classification. Of course the system is severely flawed - nobody is questioning that, but it is the system we currently have in place, so like it or not it is what it is. Really, it is vastly better than the system we had before - which was none at all.

Glen
I certainly don't agree that our climo database would become useless. While the system for classification has been consistent the actual rating hasn't been. It's become more accurate but is quite a subjective system. Observed wind speeds and DOW recorded wind sppeds HAVE been consistent in all but a case or two with the cooresponding wind speed associated with the Fujita scale. It seems that some damage assessments have been attaching a wind-speed as well as a Fujita rating. Just because it's all we have doesn't mean we shouldn't discuss it or even work to improve it. I support an ehnaced Fujita scale that cooreleates damage/wind speed more accurately.

[Aaron Kennedy]

I think the original poster was trying to relate the storm scale updraft to tornado intensity hence my comments... we're obviously talking about seperate entities Gabe ;)

Aaron

[Glen Romine]

I certainly don't agree that our climo database would become useless.

Well, I guess we are all welcome to our personal opinions, but good science doesn't allow you to change the methodology of classification midstream, even for one data point. This would be akin to throwing out the data points that don't fit with your idea, but here we are adding data points to the side we want to have them in. Sure, it would be nice to know how frequently tornadoes having winds speeds greater than x speed occur over a given interval of time (for a number of reasons) - but again we only have a handful of measurements - many of which remotely sensed and NOT at the ground. Photogrammetry methods of wind speed estimation have clearly shown the horizontal wind speeds are not uniform with height in a tornado - so at what height do you decide is corect for classifying tornado intensity? Just about any method you can come up with there is going to be problems. Subjectiveness is difficult to avoid, but that was part of the reason for the formation of the QRT to try and preserve at least the high end classifications.

Someday a better system will undoubtedly come along - but for now we have a decent estimate of how often a tornado will cause x amount of damage, and would benfit from letting go of the idea of a wind intensity climatology anytime in the near future.

[Scott Olson]

I certainly don't agree that our climo database would become useless.

Well, I guess we are all welcome to our personal opinions, but good science doesn't allow you to change the methodology of classification midstream, even for one data point. This would be akin to throwing out the data points that don't fit with your idea, but here we are adding data points to the side we want to have them in. Sure, it would be nice to know how frequently tornadoes having winds speeds greater than x speed occur over a given interval of time (for a number of reasons) - but again we only have a handful of measurements - many of which remotely sensed and NOT at the ground. Photogrammetry methods of wind speed estimation have clearly shown the horizontal wind speeds are not uniform with height in a tornado - so at what height do you decide is corect for classifying tornado intensity? Just about any method you can come up with there is going to be problems. Subjectiveness is difficult to avoid, but that was part of the reason for the formation of the QRT to try and preserve at least the high end classifications.

Someday a better system will undoubtedly come along - but for now we have a decent estimate of how often a tornado will cause x amount of damage, and would benfit from letting go of the idea of a wind intensity climatology anytime in the near future.

I think good science requires us to refine methodology as technology and knowledge permits. As for height, 10m seems to be a well accepted standard but I totally acknowledge that any reduction formula is problematic and similar problems arise. As for the QRT from what I understand the QRT isn't even funded anymore.

-Scott.

[Justin Turcotte]

Our pre-Fujita scale tornado climo was developed to satisfy the needs of the Nuclear Regulatory Commission. More or less to develop a some sort of threat assessment for nuclear power plants. Aruably the most significant flaw with the F-scale is the lack of damage markers along the full extent of the tornado path. This is particularly problematic in the Plains where "well-built" structures are scarce. In my opinion it is impossible to develop a threat assessment without quantifying this bias. I hope to have this completed as a portion of my MS thesis this winter. Here is a data sample from 1950-2001 for the Norman CWA. In some CWAs the probable number of "potential" F2+ intensity tornadoes is nearly five fold higher than current records indicate. Just beacuse some county in the TX Panhandle doesn't have a high frequency of strong tornadoes based on current climo doesn't make it a prime location for a power plant, missile silo, oil refinery, or other critical infrastructure.

Back to the Stoughton tornado... On some news video I saw some houses almost leveled. The homes still had partial walls standing indicating F3 damage (and giving some indication the home was built reasonably well). If a house is completely reduced to the foundation then it deserves an F4 rating. I havn't seen an image of a home with this type of damge from the event just yet.

http://snrs.unl.edu/amet898/turcotte/misc/cwaplots/Norman.jpg

[Andy Wehrle]

Video up:

http://sphs.angeltowns.net/movies/August_1..._18_tornado.wmv (http://sphs.angeltowns.net/movies/August_18_tornado.wmv)

Caution: Do not ATTEMPT to view on dial-up or otherwise slow connection.

BTW, my home barometer measured 29.28" (about 991 mb) at about 11 PM on Thursday night. That's some low pressure system considering this is August and not April or November. And who says there aren't dynamic systems in the summer?

[Alex Lamers]

For those of you interested in the tornadoes and tornado count for the state of Wisconsin, the MKX PNS has been updated...

NEW TORNADOES AND INDIVIDUAL TORNADO INFO...
http://kamala.cod.edu/offs/KMKX/0508242019.nous43.html

RECORDS AND OVERALL COUNT...
http://kamala.cod.edu/offs/KMKX/0508242052.nous43.html

We are now at 26 tornadoes for the event after finding two more tornadoes...one in Eastern Dane and one more in Southern Jefferson. In addition the Stoughton tornado track was extended east into Far Southwest Jefferson County, although only F1 damage was noted in Jefferson County segment of track.

...Alex Lamers...