Dec. 10-11 Severe Weather

[andyhb]

I highly doubt it will come close to challenging the Tri-State tornado, as bad at is. I'm wondering if he's talking more about recent history, which would be Joplin (158 deaths).

Which would still be horrific.

Right now the official toll from the tornado is at least 36 (20+ in Mayfield, 4 in the Princeton area, and 12 in Muhlenberg County including Bremen).

[CryHavoc]

14 minutes ago, CheeselandSkies said:

There's also Joplin...

but yeah. These are death counts you never want to see in the NEXRAD area (only happened three times before, all within 26 days in 2011); that mean either something went horribly wrong with the warning system/public response, the tornado was extremely, extremely strong, or both.

I think given the scale we're looking at, I would be surprised if this tornado killed fewer.

Likely a maxed out EF4+ tornado that hit half a dozen towns and several factories.  It's the worst case scenario especially in December where people really aren't even paying attention to severe weather.  Most of the people hit by a tornado would have been much more worried about a heavy snow or ice storm than a tornado on 12/10 of any given year.

[Hoosier]

Although certainly trivial in comparison to what happened farther south, the tornado that was confirmed in the LOT cwa was noteworthy because of the month.  On a more local level, it is the latest in a year that a tornado has occurred in Lake county IN (previous latest was November 13) and the first DJF tornado on record for Lake county IN.

Here is more info from the event page that LOT put together:

 

Tornadoes during the month of December in the NWS Chicago County Warning Area are exceptionally rare.  Roughly 99.6% of all tornadoes in our area occur outside the month of December, and rough math suggests December tornadoes occur about once every 20 years. Additionally, the Cedar Lake to Crown Point tornado was...

• The first December tornado since 12/4/1973, and only the 4th tornado to occur during the month of December
• The latest tornado on record in a calendar year. The other three happened on 12/3/1955, 12/8/1966, and 12/4/1973. 

 

Severe weather is also exceptionally rare during the month of December. Since 1950, there have only been 9 days during which severe weather was reported in the month of December (roughly 0.7% of all 1220 severe weather days). December 10, 2021 is also the 6th latest day on which severe weather was reported in our forecast area behind 12/23/2007, 12/23/2015, 12/24/1965, 12/27/2008, and 12/28/1982. 

[CheeselandSkies]

7 minutes ago, Hoosier said:

Although certainly trivial in comparison to what happened farther south, the tornado that was confirmed in the LOT cwa was noteworthy because of the month.  On a more local level, it is the latest in a year that a tornado has occurred in Lake county IN (previous latest was November 13) and the first DJF tornado on record for Lake county IN.

Here is more info from the event page that LOT put together:

 

Tornadoes during the month of December in the NWS Chicago County Warning Area are exceptionally rare.  Roughly 99.6% of all tornadoes in our area occur outside the month of December, and rough math suggests December tornadoes occur about once every 20 years. Additionally, the Cedar Lake to Crown Point tornado was...

• The first December tornado since 12/4/1973, and only the 4th tornado to occur during the month of December
• The latest tornado on record in a calendar year. The other three happened on 12/3/1955, 12/8/1966, and 12/4/1973. 

 

Severe weather is also exceptionally rare during the month of December. Since 1950, there have only been 9 days during which severe weather was reported in the month of December (roughly 0.7% of all 1220 severe weather days). December 10, 2021 is also the 6th latest day on which severe weather was reported in our forecast area behind 12/23/2007, 12/23/2015, 12/24/1965, 12/27/2008, and 12/28/1982. 

 

Guessing all the 12/1/18 had to be in the Lincoln/St. Louis CWAs, then? Still, not terribly far off.

[Hoosier]

22 minutes ago, CheeselandSkies said:

 

Guessing all the 12/1/18 had to be in the Lincoln/St. Louis CWAs, then? Still, not terribly far off.

Yeah.  Came close to happening in LOT.

[Witness Protection Program]

1 hour ago, andyhb said:

I highly doubt it will come close to challenging the Tri-State tornado, as bad at is. I'm wondering if he's talking more about recent history, which would be Joplin (158 deaths).

Which would still be horrific.

Right now the official toll from the tornado is at least 36 (20+ in Mayfield, 4 in the Princeton area, and 12 in Muhlenberg County including Bremen).

It seems like usually the actual count doesn't get much higher than after the first day or so, because so many of the missing end up being found elsewhere with relatives, etc.  But, I'm skeptical that will be the case this time, considering the scale, poor quality of construction, etc.  How long will it take to get enough cadaver dogs to check all these sites and the large surrounding thick woodlands and farms, given how so many places were hit?

https://www.kentucky.com/news/state/kentucky/article256528791.html

It sounds like they expect that the current count of 40 survivors out of the 110 workers in the candle factory won't go much higher.  At least 40 more killed in the rest of the state so far.  

https://www.cnn.com/us/live-news/tornado-damage-kentucky-tennessee-12-12-21/index.html

Today the KY gov. said the list of the missing just in Dawson Springs is 8 pages long.  All these hard hit little settlements may start to add up.

I have no idea what the final count will be or records or whatever, but as of now I'd be shocked if the toll doesn't go well over 100 in KY.

 

[WhirlingWx]

1 minute ago, Witness Protection Program said:

Today the KY gov. said the list of the missing just in Dawson Springs is 8 pages long. 

Are you serious? I thought that was for all of Western KY...

[Witness Protection Program]

Yep, just Dawson Springs.  Said in interviews yesterday.  Quote is in the CNN link above.

Elsewhere:

 

 

[Amped]

20 minutes ago, TexMexWx said:

Are you serious? I thought that was for all of Western KY...

Joplin had like 800 missing at one point.  It's hard getting people accounted for after something like this.

[dan11295]

1 minute ago, Amped said:

Joplin had like 800 missing at one point.  It's hard getting people accounted for after something like this.

I am sure many of the missing are with relatives, etc. It can take a few days to track everyone down/confirm they are OK.

AFAIK only 11 deaths have been reported in Dawson Springs so far. It would be very fortunate if it remains that low. Town has ~2500 people and took a direct hit.

 

[Hoosier]

Here is the NWS Paducah page for this event.  Sounds like they are bringing in the best people to assist with the damage survey.

Watch this space:

https://www.weather.gov/pah/December-10th-11th-2021-Tornado

 

[WeatherMonger]

ILX found damage from a 4th tornado

 

[andyhb]

$800,000 house reduced to a slab in Bremen KY.

[andyhb]

Large industrial buildings flattened or even swept away in Dawson Springs KY. The list just goes on and on and on.

[MidwestChaser]

I would be very surprised if this isn't EF-5. This doesn't look like previous instances of houses swept away yet trees are still there; this is complete destruction.

[Witness Protection Program]

Nevermind, I found it.  Looks like they had a lower level built into the hill.

[andyhb]

Devastation in the Cambridge Springs area on the western shore of Kentucky Lake.

[WaryWarren]

Before/after of the Mayfield Consumer Products ("candle factory") building.

[Moderately Unstable]

I post this at my own peril (cue the comparisons of images to the scale), but https://www.spc.noaa.gov/efscale/ef-scale.html

There's your degrees of damage scale. Wondering what wind is needed to cause X damage? There's your link. 

For a single family home: https://www.spc.noaa.gov/efscale/2.html

-Slabbed home bounds are expected to require 200 mph winds. BUT, and this is IMPORTANT for everyone on here: the lower bound is *165* mph (that is not an EF5, which begins at 200). 

For a warehouse: https://www.spc.noaa.gov/efscale/23.html

-Complete destruction does NOT require an EF-5. Note: industrial buildings tend to fare WORSE than well built homes in a tornado. They are large, typically presenting a large and flat surface area orthogonal to the wind direction, and have vast, cavernous interiors. Translation: an industrial building being torn apart is actually less indicative of an EF-5 than a masonry structure, well built home, or similar. 

 

-Structural deformation of a high or mid rise building, generally correlates to a case-closed EF 5 designation. Such as the Mercy medical center in Joplin. 

-Hardwood trees debark at an expected wind speed of 143, (low EF 3). 

 

-For an institutional building like the Grays county courthouse, https://www.spc.noaa.gov/efscale/20.html I would suggest that the DOD is 10, corresponding to a windspeed of 148 (EF3) ranging from 127 (EF2) to 172 (EF4). Other areas on path have worse damage. But that's high profile. 

Quoting from: https://www.weather.gov/ama/damagesurveys , bolding mine:

Quote

Let’s look at an example to help tie everything together.  For an interactive demonstration, this link will be very helpful: http://www.spc.noaa.gov/efscale/ef-scale.html.  A tornado strikes a house, causing the entire roof to be blown off, but all the walls remain standing.  The survey team will first assign a damage indicator of 2 since this is a one- or two-family residence.  The description of the damage corresponds best to a degree of damage of 6 (http://www.spc.noaa.gov/efscale/2.html).  After careful inspection of the construction quality, it is observed that the ceiling joust was fastened with rafter clips to exterior walls, which meets code.  Therefore, the survey team assigns an expected wind speed of 122 mph.  Based on this wind speed, the team assigns the tornado a rating of EF-2 with winds between 111-135 mph.

 

To translate, the survey team needs to evaluate (in a lot more detail than we can with photos), HOW the homes were built, and how they were fastened to their foundations. Did they meet code? What did the radar presentation look like at the time the tornado was over the structure? What did people in the building(s) experience as the tornado went through? How were things fastened together? How long were tornadic winds impacting the structure?   They'll also look for office buildings of mid-range height (I doubt there's any high rise buildings on the path of this tornado). The key to those is looking for structural deformation. E.g. well built concrete and steel buildings that have BENT out of shape. Note: the water tower that collapsed DOES NOT qualify for that. It's a freestanding structure, and the deformation seen is almost certainly a result of impact with the ground and being tossed around along the ground, while presumably filled with water versus the wind itself bending the steel. And therein lies the difference.  Ever dropped a full plastic water bottle on the ground (or a metal one) from height? It breaks, right? How about an empty one? Does that break? Nope. If you blow your water bottle with a leaf blower does it deform? Also no, but it probably would blast away into your neighbors yard and make them think you're pretty weird. My point, the bent steel of the water tower is due to the collapse, not the wind. But, if the team finds actual steel in a building bent by the wind, that's different. 

//

 

For more (albeit old reading): https://training.weather.gov/wdtd/courses/EF-scale/lesson2/FinalNWSF-scaleAssessmentGuide.pdf

This is prior to the switch to the EF scale but the explanations still apply...

From that, bolding mine:

P.30: "Giving a tornado an F5 rating is probably more contentious than it should be; in general, more scrutiny is given to an F5 rating than to an F4 rating. In fact, the reluctance to give tornadoes an F5 rating might well cause some events to be rated F4 that might well have been deserving of the highest rating. In effect, proposing an F5 rating focuses so much attention on the issue that storm survey teams will be hesitant to rate an event at that level unless they find the strongest possible evidence. Most F5-rated tornadoes have hit populated areas; a tornado passing through open country is unlikely to be given the highest rating. In the event a tornado hits a populated area, survey teams can be under some substantial pressure to make an assessment before they have had time to give the issue the careful consideration it deserves. Formally, by the Fujita scale criteria, F5 damage to a frame home not only leaves no interior walls standing, but the debris from the home is swept away, leaving essentially a bare foundation. This sort of “incredible” destruction is as total as it is possible to be; it leaves essentially nothing of the home but a slab or an empty foundation. This criterion would seem to be relatively easy to evaluate but for a number of complicating factors. As always, the structural integrity of the home prior to being hit is a critical element. When distinguishing F5 damage from lesser intensity storms, the attachments along the load path are potential weak points. As already noted, further complicating the issue is the question of the duration of the tornadic winds. The 27 May 1997 tornado that hit Jarrell, Texas, left a number of homes in a particular subdivision with nothing left but empty slabs (Fig. 27).

Even the debris was blown far away, making the F5 rating an apparently easy decision. However, a post-event survey by structural engineers revealed that there was some variability in the attachments. Some homes were rather strongly attached to their slab foundations, whereas others were not. Beyond that, however, an important question became the duration of the strong winds – this was a large, relatively slow-moving tornado (the damage path was estimated to be roughly 3/4 mile wide, moving at 5-10 mph). At the observed speed, homes would experience damaging winds for 5-10 minutes. Not only would the damaging winds have more time to put structures under stress, but the long duration would be more likely to sweep away the debris than if the tornadic windspeeds been of lesser duration. Moreover, this subdivision was relatively isolated, surrounded by mostly open country. In the case of the tornado that hit the Oklahoma City, Oklahoma, metropolitan area on 3 May 1999, some of the F5-rated damage occurred in the suburb of Moore, Oklahoma. In this case, the tornado moved in from other populated areas, and its debris load was already substantial as it entered Moore. The result (Fig. 28) was large piles of rubble remaining on empty slab foundations. The tornado damage path was about 1/2 mile wide at this point and the tornado was moving around 35 mph. The damaging winds would last only about a minute in such a storm, and if debris from a particular home was swept away, other debris would fall in its place. In fact, that is just what was observed during a post-storm survey – the debris left in a particular location in the F5-rated damage area in Moore did not come from that location, but arrived from areas hit previously by the tornado. Hence, the absence of slabs swept clean of debris could not be taken as evidence of intensity levels below that of F5."

 

So, the duration of tornadic wind matters too. Here, we have a 1/2-3/4 mile wide tornado. Calculating the amount of time it would be impacting a structure matters when calculating the wind speeds. 

 

Note, with respect to slabbed homes, an *EF-3* can slab an *un* anchored home. 

 

Overall, while I continue to believe this is a low end EF-5 tornado based on the totality of images across various communities, radar data, and environmental parameters,  it is NOT as "case closed" as some on here (and on twitter) have made it out to be (and that's why this is a process). Also, with respect to myriad comments of "oh gosh I've never seen this", mostly on twitter--yes you have. And you said the same thing after Moore, Joplin (etc) if you were old enough to be following those events when they occurred. Or Tuscaloosa, Bassfield, Philadelphia (MI) etc. This is not the strongest tornado ever recorded. Period. You've got El Reno (an "EF3" but with measured 300+ mph winds and 2.6 mile width with various sub vortices the size of "regular" tornadoes traveling in trochoidal oscillation), the Moore twisters, obviously Joplin, and many others, that, FWIW, had this degree of damage or WORSE. The length of path, time of year, fatality count, and overall significance of this/these tornado(es) is/are historic, and that will be true regardless of whether it is an EF-4, or EF-5. But, it is not the worst damage most of us have seen. It's BAD--no question. But we don't need to over-dramatize it. We've seen the pictures. What's left is for the experts to physically review the places in those pictures in detail, and determine if those slabbed homes would've blown apart with EF3-EF4 winds, or if that would've required that 200mph wind to do that damage. We can't know that from any picture or video, because that information comes from the blueprints and related original construction documents of the home or structure or at least close physical analysis of the debris to find the relevant joints and fasteners (which, I shouldn't have to specify, we don't have access to). 

 

On the other hand, there's also a semi, non-scientific empirical relationship between number of fatalities and EF rating. Generally, the "worst" and most fatal tornadoes are EF-5s. That's because despite the best possible warnings, which this storm did have, at the end of the day, EF-5 tornadoes are in some residences or structures not survivable. If you don't have the right underground structure to protect you, you will die, even in a well built house, and with prior knowledge that the tornado is approaching and having taken appropriate actions (covering yourself with pillows or other materials in an interior room on the lowest floor). Stand in front of a jet engine at takeoff thrust with a pile of wood beams, nails, bricks, cars, etc between you and it: you wouldn't fare so well. If your home gets blown away, you're in that environment.

Of course, being a nighttime, December, tornado, didn't help. That is not the fault of the NWS, or TV mets though, as I've seen tossed around a bit (also mainly on Twitter). They did their job. Have you seen the videos of people driving on the highway, in broad daylight, a quarter mile from a giant wedge tornado? I sure have. You think they were expert chasers or mets that knew the direction the tornado was moving and that it definitely wouldn't hit them? I don't. Have you watched your friends and coworkers ignore tornado warnings (and obviously severe thunderstorm warnings) that are ringing their phone? I have. So have you. Even when the warning says a tornado is on the ground? Yep. People continue along as though nothing is happening. At the end of the day, meteorologists can only warn so much. If people choose to ignore every possible warning, including WEAs, not much more can be done after that. People act (not just wrt tornadoes but in general), when they make a personal connection between information and an imaginable threat to themselves. If someone can't imagine themselves actually being hit by a tornado, and, killed, they won't take action to protect themselves. Fear drives safety behaviors in this case. Fear takes understanding of the threat, and recognition that, yes, it can happen to you. 

 

The link I left for the old training doc contains a plethora of helpful information that can inform you about all that goes into damage assessments, both scientifically and with respect to the psychology of a public wanting answers. Things I didn't copy over but are include good explanations for HOW things are damaged during tornadoes (through both wind action and projectile action), and basically any other question you can think of that you want answered regarding tornadoes and damage assessments (that IS the (old) training doc after all).

 

 

[largetornado]

8 dead, 8 missing at candle factory. Not 70 dead like early estimates per AP and candle factory spokesman

[andyhb]

Uhhh, yikes.

[andyhb]

59 minutes ago, Moderately Unstable said:

Overall, while I continue to believe this is a low end EF-5 tornado based on the totality of images across various communities, radar data, and environmental parameters,  it is NOT as "case closed" as some on here (and on twitter) have made it out to be (and that's why this is a process). Also, with respect to myriad comments of "oh gosh I've never seen this", mostly on twitter--yes you have. And you said the same thing after Moore, Joplin (etc) if you were old enough to be following those events when they occurred. Or Tuscaloosa, Bassfield, Philadelphia (MI) etc. This is not the strongest tornado ever recorded. Period. You've got El Reno (an "EF3" but with measured 300+ mph winds and 2.6 mile width with various sub vortices the size of "regular" tornadoes traveling in trochoidal oscillation), the Moore twisters, obviously Joplin, and many others, that, FWIW, had this degree of damage or WORSE. The length of path, time of year, fatality count, and overall significance of this/these tornado(es) is/are historic, and that will be true regardless of whether it is an EF-4, or EF-5. But, it is not the worst damage most of us have seen. It's BAD--no question. But we don't need to over-dramatize it. We've seen the pictures. What's left is for the experts to physically review the places in those pictures in detail, and determine if those slabbed homes would've blown apart with EF3-EF4 winds, or if that would've required that 200mph wind to do that damage. We can't know that from any picture or video, because that information comes from the blueprints and related original construction documents of the home or structure or at least close physical analysis of the debris to find the relevant joints and fasteners (which, I shouldn't have to specify, we don't have access to).

This is a bunch of silliness, tbh.

Most of us around here that have been for awhile have scrutinized all of the tornadoes you've mentioned here and more, and trust me when I say that there are comparisons between all of these going on.

This one is bad, very bad. The damage with this across a very large area is just about unprecedented aside from tornadoes like Hackleburg, and there are many, many locations with houses that have been completely demolished or swept away. Enough to be compared pretty easily with tornadoes like the ones you've mentioned. The VROT/TDS signatures were up there with tornadoes like El Reno 2011, Vilonia, etc. I'm pretty sure most are aware of the DIs and their limitations, otherwise there wouldn't be this much discussion. As far as December tornadoes go, this one is unprecedented, and this is coming from someone who has been watching these things for over 20 years now. There is really no need for a condescending essay like this.

[Stebo]

1 hour ago, Moderately Unstable said:

I post this at my own peril (cue the comparisons of images to the scale), but https://www.spc.noaa.gov/efscale/ef-scale.html

There's your degrees of damage scale. Wondering what wind is needed to cause X damage? There's your link. 

For a single family home: https://www.spc.noaa.gov/efscale/2.html

-Slabbed home bounds are expected to require 200 mph winds. BUT, and this is IMPORTANT for everyone on here: the lower bound is *165* mph (that is not an EF5, which begins at 200). 

For a warehouse: https://www.spc.noaa.gov/efscale/23.html

-Complete destruction does NOT require an EF-5. Note: industrial buildings tend to fare WORSE than well built homes in a tornado. They are large, typically presenting a large and flat surface area orthogonal to the wind direction, and have vast, cavernous interiors. Translation: an industrial building being torn apart is actually less indicative of an EF-5 than a masonry structure, well built home, or similar. 

 

-Structural deformation of a high or mid rise building, generally correlates to a case-closed EF 5 designation. Such as the Mercy medical center in Joplin. 

-Hardwood trees debark at an expected wind speed of 143, (low EF 3). 

 

-For an institutional building like the Grays county courthouse, https://www.spc.noaa.gov/efscale/20.html I would suggest that the DOD is 10, corresponding to a windspeed of 148 (EF3) ranging from 127 (EF2) to 172 (EF4). Other areas on path have worse damage. But that's high profile. 

Quoting from: https://www.weather.gov/ama/damagesurveys , bolding mine:

 

To translate, the survey team needs to evaluate (in a lot more detail than we can with photos), HOW the homes were built, and how they were fastened to their foundations. Did they meet code? What did the radar presentation look like at the time the tornado was over the structure? What did people in the building(s) experience as the tornado went through? How were things fastened together? How long were tornadic winds impacting the structure?   They'll also look for office buildings of mid-range height (I doubt there's any high rise buildings on the path of this tornado). The key to those is looking for structural deformation. E.g. well built concrete and steel buildings that have BENT out of shape. Note: the water tower that collapsed DOES NOT qualify for that. It's a freestanding structure, and the deformation seen is almost certainly a result of impact with the ground and being tossed around along the ground, while presumably filled with water versus the wind itself bending the steel. And therein lies the difference.  Ever dropped a full plastic water bottle on the ground (or a metal one) from height? It breaks, right? How about an empty one? Does that break? Nope. If you blow your water bottle with a leaf blower does it deform? Also no, but it probably would blast away into your neighbors yard and make them think you're pretty weird. My point, the bent steel of the water tower is due to the collapse, not the wind. But, if the team finds actual steel in a building bent by the wind, that's different. 

//

 

For more (albeit old reading): https://training.weather.gov/wdtd/courses/EF-scale/lesson2/FinalNWSF-scaleAssessmentGuide.pdf

This is prior to the switch to the EF scale but the explanations still apply...

From that, bolding mine:

P.30: "Giving a tornado an F5 rating is probably more contentious than it should be; in general, more scrutiny is given to an F5 rating than to an F4 rating. In fact, the reluctance to give tornadoes an F5 rating might well cause some events to be rated F4 that might well have been deserving of the highest rating. In effect, proposing an F5 rating focuses so much attention on the issue that storm survey teams will be hesitant to rate an event at that level unless they find the strongest possible evidence. Most F5-rated tornadoes have hit populated areas; a tornado passing through open country is unlikely to be given the highest rating. In the event a tornado hits a populated area, survey teams can be under some substantial pressure to make an assessment before they have had time to give the issue the careful consideration it deserves. Formally, by the Fujita scale criteria, F5 damage to a frame home not only leaves no interior walls standing, but the debris from the home is swept away, leaving essentially a bare foundation. This sort of “incredible” destruction is as total as it is possible to be; it leaves essentially nothing of the home but a slab or an empty foundation. This criterion would seem to be relatively easy to evaluate but for a number of complicating factors. As always, the structural integrity of the home prior to being hit is a critical element. When distinguishing F5 damage from lesser intensity storms, the attachments along the load path are potential weak points. As already noted, further complicating the issue is the question of the duration of the tornadic winds. The 27 May 1997 tornado that hit Jarrell, Texas, left a number of homes in a particular subdivision with nothing left but empty slabs (Fig. 27).

Even the debris was blown far away, making the F5 rating an apparently easy decision. However, a post-event survey by structural engineers revealed that there was some variability in the attachments. Some homes were rather strongly attached to their slab foundations, whereas others were not. Beyond that, however, an important question became the duration of the strong winds – this was a large, relatively slow-moving tornado (the damage path was estimated to be roughly 3/4 mile wide, moving at 5-10 mph). At the observed speed, homes would experience damaging winds for 5-10 minutes. Not only would the damaging winds have more time to put structures under stress, but the long duration would be more likely to sweep away the debris than if the tornadic windspeeds been of lesser duration. Moreover, this subdivision was relatively isolated, surrounded by mostly open country. In the case of the tornado that hit the Oklahoma City, Oklahoma, metropolitan area on 3 May 1999, some of the F5-rated damage occurred in the suburb of Moore, Oklahoma. In this case, the tornado moved in from other populated areas, and its debris load was already substantial as it entered Moore. The result (Fig. 28) was large piles of rubble remaining on empty slab foundations. The tornado damage path was about 1/2 mile wide at this point and the tornado was moving around 35 mph. The damaging winds would last only about a minute in such a storm, and if debris from a particular home was swept away, other debris would fall in its place. In fact, that is just what was observed during a post-storm survey – the debris left in a particular location in the F5-rated damage area in Moore did not come from that location, but arrived from areas hit previously by the tornado. Hence, the absence of slabs swept clean of debris could not be taken as evidence of intensity levels below that of F5."

 

So, the duration of tornadic wind matters too. Here, we have a 1/2-3/4 mile wide tornado. Calculating the amount of time it would be impacting a structure matters when calculating the wind speeds. 

 

Note, with respect to slabbed homes, an *EF-3* can slab an *un* anchored home. 

 

Overall, while I continue to believe this is a low end EF-5 tornado based on the totality of images across various communities, radar data, and environmental parameters,  it is NOT as "case closed" as some on here (and on twitter) have made it out to be (and that's why this is a process). Also, with respect to myriad comments of "oh gosh I've never seen this", mostly on twitter--yes you have. And you said the same thing after Moore, Joplin (etc) if you were old enough to be following those events when they occurred. Or Tuscaloosa, Bassfield, Philadelphia (MI) etc. This is not the strongest tornado ever recorded. Period. You've got El Reno (an "EF3" but with measured 300+ mph winds and 2.6 mile width with various sub vortices the size of "regular" tornadoes traveling in trochoidal oscillation), the Moore twisters, obviously Joplin, and many others, that, FWIW, had this degree of damage or WORSE. The length of path, time of year, fatality count, and overall significance of this/these tornado(es) is/are historic, and that will be true regardless of whether it is an EF-4, or EF-5. But, it is not the worst damage most of us have seen. It's BAD--no question. But we don't need to over-dramatize it. We've seen the pictures. What's left is for the experts to physically review the places in those pictures in detail, and determine if those slabbed homes would've blown apart with EF3-EF4 winds, or if that would've required that 200mph wind to do that damage. We can't know that from any picture or video, because that information comes from the blueprints and related original construction documents of the home or structure or at least close physical analysis of the debris to find the relevant joints and fasteners (which, I shouldn't have to specify, we don't have access to). 

 

On the other hand, there's also a semi, non-scientific empirical relationship between number of fatalities and EF rating. Generally, the "worst" and most fatal tornadoes are EF-5s. That's because despite the best possible warnings, which this storm did have, at the end of the day, EF-5 tornadoes are in some residences or structures not survivable. If you don't have the right underground structure to protect you, you will die, even in a well built house, and with prior knowledge that the tornado is approaching and having taken appropriate actions (covering yourself with pillows or other materials in an interior room on the lowest floor). Stand in front of a jet engine at takeoff thrust with a pile of wood beams, nails, bricks, cars, etc between you and it: you wouldn't fare so well. If your home gets blown away, you're in that environment.

Of course, being a nighttime, December, tornado, didn't help. That is not the fault of the NWS, or TV mets though, as I've seen tossed around a bit (also mainly on Twitter). They did their job. Have you seen the videos of people driving on the highway, in broad daylight, a quarter mile from a giant wedge tornado? I sure have. You think they were expert chasers or mets that knew the direction the tornado was moving and that it definitely wouldn't hit them? I don't. Have you watched your friends and coworkers ignore tornado warnings (and obviously severe thunderstorm warnings) that are ringing their phone? I have. So have you. Even when the warning says a tornado is on the ground? Yep. People continue along as though nothing is happening. At the end of the day, meteorologists can only warn so much. If people choose to ignore every possible warning, including WEAs, not much more can be done after that. People act (not just wrt tornadoes but in general), when they make a personal connection between information and an imaginable threat to themselves. If someone can't imagine themselves actually being hit by a tornado, and, killed, they won't take action to protect themselves. Fear drives safety behaviors in this case. Fear takes understanding of the threat, and recognition that, yes, it can happen to you. 

 

The link I left for the old training doc contains a plethora of helpful information that can inform you about all that goes into damage assessments, both scientifically and with respect to the psychology of a public wanting answers. Things I didn't copy over but are include good explanations for HOW things are damaged during tornadoes (through both wind action and projectile action), and basically any other question you can think of that you want answered regarding tornadoes and damage assessments (that IS the (old) training doc after all).

 

 

You can't say that everything is lower bound though. It doesn't work like that either. Even if these cases have lower bounds everything isn't going to be a lower bound. 

[WxBlue]

 

11 minutes ago, andyhb said:

This is a bunch of silliness, tbh.

Most of us around here that have been for awhile have scrutinized all of the tornadoes you've mentioned here and more, and trust me when I say that there are comparisons between all of these going on.

This one is bad, very bad. The damage with this across a very large area is just about unprecedented aside from tornadoes like Hackleburg, and there are many, many locations with houses that have been completely demolished or swept away. Enough to be compared pretty easily with tornadoes like the ones you've mentioned. The VROT/TDS signatures were up there with tornadoes like El Reno 2011, Vilonia, etc. I'm pretty sure most are aware of the DIs and their limitations, otherwise there wouldn't be this much discussion. As far as December tornadoes go, this one is unprecedented, and this is coming from someone who has been watching these things for over 20 years now. There is really no need for a condescending essay like this.

I will agree with this. I did a tornado re-analysis GIS project for my employer over the summer and that involved looking at a lot of damage pictures. This tornado had the intensity similar to Smithville (MS) and the lengthily swath of violent damage (EF4+) similar to Hackleburg (AL). Some of scenes also reminded me of Joplin, too. I don't think we should be sugarcoating how bad and extreme this tornado was regardless of the time of month. This was simply a top-tier tornado and I strongly believe we'll get epic survey results once we get everything put together.

[Buckeye05]

1 hour ago, Moderately Unstable said:

I post this at my own peril (cue the comparisons of images to the scale), but https://www.spc.noaa.gov/efscale/ef-scale.html

There's your degrees of damage scale. Wondering what wind is needed to cause X damage? There's your link. 

For a single family home: https://www.spc.noaa.gov/efscale/2.html

-Slabbed home bounds are expected to require 200 mph winds. BUT, and this is IMPORTANT for everyone on here: the lower bound is *165* mph (that is not an EF5, which begins at 200). 

For a warehouse: https://www.spc.noaa.gov/efscale/23.html

-Complete destruction does NOT require an EF-5. Note: industrial buildings tend to fare WORSE than well built homes in a tornado. They are large, typically presenting a large and flat surface area orthogonal to the wind direction, and have vast, cavernous interiors. Translation: an industrial building being torn apart is actually less indicative of an EF-5 than a masonry structure, well built home, or similar. 

 

-Structural deformation of a high or mid rise building, generally correlates to a case-closed EF 5 designation. Such as the Mercy medical center in Joplin. 

-Hardwood trees debark at an expected wind speed of 143, (low EF 3). 

 

-For an institutional building like the Grays county courthouse, https://www.spc.noaa.gov/efscale/20.html I would suggest that the DOD is 10, corresponding to a windspeed of 148 (EF3) ranging from 127 (EF2) to 172 (EF4). Other areas on path have worse damage. But that's high profile. 

Quoting from: https://www.weather.gov/ama/damagesurveys , bolding mine:

 

To translate, the survey team needs to evaluate (in a lot more detail than we can with photos), HOW the homes were built, and how they were fastened to their foundations. Did they meet code? What did the radar presentation look like at the time the tornado was over the structure? What did people in the building(s) experience as the tornado went through? How were things fastened together? How long were tornadic winds impacting the structure?   They'll also look for office buildings of mid-range height (I doubt there's any high rise buildings on the path of this tornado). The key to those is looking for structural deformation. E.g. well built concrete and steel buildings that have BENT out of shape. Note: the water tower that collapsed DOES NOT qualify for that. It's a freestanding structure, and the deformation seen is almost certainly a result of impact with the ground and being tossed around along the ground, while presumably filled with water versus the wind itself bending the steel. And therein lies the difference.  Ever dropped a full plastic water bottle on the ground (or a metal one) from height? It breaks, right? How about an empty one? Does that break? Nope. If you blow your water bottle with a leaf blower does it deform? Also no, but it probably would blast away into your neighbors yard and make them think you're pretty weird. My point, the bent steel of the water tower is due to the collapse, not the wind. But, if the team finds actual steel in a building bent by the wind, that's different. 

//

 

For more (albeit old reading): https://training.weather.gov/wdtd/courses/EF-scale/lesson2/FinalNWSF-scaleAssessmentGuide.pdf

This is prior to the switch to the EF scale but the explanations still apply...

From that, bolding mine:

P.30: "Giving a tornado an F5 rating is probably more contentious than it should be; in general, more scrutiny is given to an F5 rating than to an F4 rating. In fact, the reluctance to give tornadoes an F5 rating might well cause some events to be rated F4 that might well have been deserving of the highest rating. In effect, proposing an F5 rating focuses so much attention on the issue that storm survey teams will be hesitant to rate an event at that level unless they find the strongest possible evidence. Most F5-rated tornadoes have hit populated areas; a tornado passing through open country is unlikely to be given the highest rating. In the event a tornado hits a populated area, survey teams can be under some substantial pressure to make an assessment before they have had time to give the issue the careful consideration it deserves. Formally, by the Fujita scale criteria, F5 damage to a frame home not only leaves no interior walls standing, but the debris from the home is swept away, leaving essentially a bare foundation. This sort of “incredible” destruction is as total as it is possible to be; it leaves essentially nothing of the home but a slab or an empty foundation. This criterion would seem to be relatively easy to evaluate but for a number of complicating factors. As always, the structural integrity of the home prior to being hit is a critical element. When distinguishing F5 damage from lesser intensity storms, the attachments along the load path are potential weak points. As already noted, further complicating the issue is the question of the duration of the tornadic winds. The 27 May 1997 tornado that hit Jarrell, Texas, left a number of homes in a particular subdivision with nothing left but empty slabs (Fig. 27).

Even the debris was blown far away, making the F5 rating an apparently easy decision. However, a post-event survey by structural engineers revealed that there was some variability in the attachments. Some homes were rather strongly attached to their slab foundations, whereas others were not. Beyond that, however, an important question became the duration of the strong winds – this was a large, relatively slow-moving tornado (the damage path was estimated to be roughly 3/4 mile wide, moving at 5-10 mph). At the observed speed, homes would experience damaging winds for 5-10 minutes. Not only would the damaging winds have more time to put structures under stress, but the long duration would be more likely to sweep away the debris than if the tornadic windspeeds been of lesser duration. Moreover, this subdivision was relatively isolated, surrounded by mostly open country. In the case of the tornado that hit the Oklahoma City, Oklahoma, metropolitan area on 3 May 1999, some of the F5-rated damage occurred in the suburb of Moore, Oklahoma. In this case, the tornado moved in from other populated areas, and its debris load was already substantial as it entered Moore. The result (Fig. 28) was large piles of rubble remaining on empty slab foundations. The tornado damage path was about 1/2 mile wide at this point and the tornado was moving around 35 mph. The damaging winds would last only about a minute in such a storm, and if debris from a particular home was swept away, other debris would fall in its place. In fact, that is just what was observed during a post-storm survey – the debris left in a particular location in the F5-rated damage area in Moore did not come from that location, but arrived from areas hit previously by the tornado. Hence, the absence of slabs swept clean of debris could not be taken as evidence of intensity levels below that of F5."

 

So, the duration of tornadic wind matters too. Here, we have a 1/2-3/4 mile wide tornado. Calculating the amount of time it would be impacting a structure matters when calculating the wind speeds. 

 

Note, with respect to slabbed homes, an *EF-3* can slab an *un* anchored home. 

 

Overall, while I continue to believe this is a low end EF-5 tornado based on the totality of images across various communities, radar data, and environmental parameters,  it is NOT as "case closed" as some on here (and on twitter) have made it out to be (and that's why this is a process). Also, with respect to myriad comments of "oh gosh I've never seen this", mostly on twitter--yes you have. And you said the same thing after Moore, Joplin (etc) if you were old enough to be following those events when they occurred. Or Tuscaloosa, Bassfield, Philadelphia (MI) etc. This is not the strongest tornado ever recorded. Period. You've got El Reno (an "EF3" but with measured 300+ mph winds and 2.6 mile width with various sub vortices the size of "regular" tornadoes traveling in trochoidal oscillation), the Moore twisters, obviously Joplin, and many others, that, FWIW, had this degree of damage or WORSE. The length of path, time of year, fatality count, and overall significance of this/these tornado(es) is/are historic, and that will be true regardless of whether it is an EF-4, or EF-5. But, it is not the worst damage most of us have seen. It's BAD--no question. But we don't need to over-dramatize it. We've seen the pictures. What's left is for the experts to physically review the places in those pictures in detail, and determine if those slabbed homes would've blown apart with EF3-EF4 winds, or if that would've required that 200mph wind to do that damage. We can't know that from any picture or video, because that information comes from the blueprints and related original construction documents of the home or structure or at least close physical analysis of the debris to find the relevant joints and fasteners (which, I shouldn't have to specify, we don't have access to). 

 

On the other hand, there's also a semi, non-scientific empirical relationship between number of fatalities and EF rating. Generally, the "worst" and most fatal tornadoes are EF-5s. That's because despite the best possible warnings, which this storm did have, at the end of the day, EF-5 tornadoes are in some residences or structures not survivable. If you don't have the right underground structure to protect you, you will die, even in a well built house, and with prior knowledge that the tornado is approaching and having taken appropriate actions (covering yourself with pillows or other materials in an interior room on the lowest floor). Stand in front of a jet engine at takeoff thrust with a pile of wood beams, nails, bricks, cars, etc between you and it: you wouldn't fare so well. If your home gets blown away, you're in that environment.

Of course, being a nighttime, December, tornado, didn't help. That is not the fault of the NWS, or TV mets though, as I've seen tossed around a bit (also mainly on Twitter). They did their job. Have you seen the videos of people driving on the highway, in broad daylight, a quarter mile from a giant wedge tornado? I sure have. You think they were expert chasers or mets that knew the direction the tornado was moving and that it definitely wouldn't hit them? I don't. Have you watched your friends and coworkers ignore tornado warnings (and obviously severe thunderstorm warnings) that are ringing their phone? I have. So have you. Even when the warning says a tornado is on the ground? Yep. People continue along as though nothing is happening. At the end of the day, meteorologists can only warn so much. If people choose to ignore every possible warning, including WEAs, not much more can be done after that. People act (not just wrt tornadoes but in general), when they make a personal connection between information and an imaginable threat to themselves. If someone can't imagine themselves actually being hit by a tornado, and, killed, they won't take action to protect themselves. Fear drives safety behaviors in this case. Fear takes understanding of the threat, and recognition that, yes, it can happen to you. 

 

The link I left for the old training doc contains a plethora of helpful information that can inform you about all that goes into damage assessments, both scientifically and with respect to the psychology of a public wanting answers. Things I didn't copy over but are include good explanations for HOW things are damaged during tornadoes (through both wind action and projectile action), and basically any other question you can think of that you want answered regarding tornadoes and damage assessments (that IS the (old) training doc after all).

 

 

This is a bunch of overly-dismissive ridiculousness. You aren't saying anything people aren't already aware of. People at this point know how rating damage based on structural integrity and the overall context works. 

[Moderately Unstable]

Right--so my point was not that the event wasn't bad, nor was I even saying it wasn't an EF5. I also wasn't trying to come off as condescending. I'm not sure who exactly I was being condescending towards, particularly on this forum, but I digress. 

I found a couple of useful links, I shared them, and I copied and emphasized some of what was written. I'm not entirely sure how well they are known, that was why I posted them in the first place. Yes, some people do know that, others don't. 

My main "point" in the essay, is to wait for the survey results. Given that Paducah has already been out, and has assigned a range between 158 and 206, they (for whatever reason), are not in the unequivocal camp. That gives a range of 6 mph for EF5, and, 35 for EF4. That's preliminary, but, that's why I wrote the post. 

[andyhb]

But why would you go through such an effort to tell everybody that "they've already seen this" when in reality this tornado is cut above many others?

[Moderately Unstable]

Fair point. Partly because of what I have been reading on twitter. Perhaps I mis-worded what I meant, but that basically was more of this is not conceptually something no one has seen. I didn't mean it was something that had been seen in December, for this path length (etc etc). Those things are all valid. I meant, from a pure damage standpoint, we have seen damage similar to this before. It is very high end, yes. But when I read twitter posts that exclaim (and I'm not talking about the folks that are actually in person taking photos), that this has never been seen, that's what I meant. I've seen this with strong hurricanes and other severe weather a bunch. Every massive high end event is *the* worst event, rather than, a very very bad event amongst other very very bad events. Which is fine if it is the worst event in that context, but that's a high bar to clear, and one that hasn't yet been officially proven (even though yes, the images are bad). 

[HillsdaleMIWeather]

1 hour ago, largetornado said:

8 dead, 8 missing at candle factory. Not 70 dead like early estimates per AP and candle factory spokesman

Sadly they still think the statewide total will probs end up at around 100, but it's better than the likely 200 total if all the people in the factory had died like they originally thought 

[hlcater]

highly detailed satellite data from sections of the tornado track is being uploaded. I suggest all of you go take a look as its seriously some next level stuff. This was an EF5.

https://trvatlas.maps.arcgis.com/apps/webappviewer/index.html?id=8ff3ff4ef7184e16a54d68a51e56ed60&fbclid=IwAR3dMATGbmNjgaU4C0OKjF9ntq2PfLQGpxzE3mzvLTgexbR1nSZME3sUngA