Dallas Tornado Article

[ChrisM]

172 tornadoes in just those two counties over 60 years, that's all that needs to be said. Almost 3 tornadoes/year. "AGW"

[CoastalWx]

It just comes down to this...very simple.

It was an ULL that ejected out of the southern Rockies with an EML/high CAPE environment. Cells developed out ahead of the main squall line and once they hit the boundary..they injested the helicity and went to town..thanks to the high CAPE facilitating. This had nothing to do with climate change, period.

[AtticaFanatica]

I bet there are a lot more EF4 and EF5 tornadoes each year, but they simply do not hit anything at all or anything sufficiently

strong enough to give EF4 or EF5 damage ratings. Regardless of climate change, we are going to see more violent tornadoes

gradually over time as we give them more to hit with expanding infrastructure. You don't have to be a meteorologist to

connect the dots here either. Apply a little bit of logic and reasoning, and you be amazed at what you can figure out!

Agree with this too.

[vortex95]

The biggest, strongest, most monstrous tornado to hit the USA-- exceeding every yardstick to this day-- happened in 1925. If it happened now, would folks have big discussions about how it reflects climate change? By far the most intense hurricane to hit the USA happened in 1935. Same question.

Along the same lines, nothing like the Dust Bowl in the 1930s has occurred since (I realize some of it was due to poor care of the

arable land and such, but to be that dry for so long, the synoptic pattern is by far the main cause) or anything quite like of the

monster storm of Nov 1950 in the East esp for wind (greatest non-tropical cyclone winds for many locations). If wx has got

that extreme, where are the events on this scale now? We've had two "superoutbreaks" of tornadoes since 1950, 1974 and 2011.

Two events like this does not represent a trend. Were there superoutreaks before? Probably, but since tornadoes were no logged

nearly as well before 1950, we don't know for sure. The point is two events (two data points) on the same scale 37 years apart

do no represent a trend. Problem is the logical fallacy that just b/c something extreme occurred "this year", people often think that

"this is how it is going to be from now on". A lot of this is due to how events are portrayed by the media. They often lack proper

historical perspective and the like for such events, which is unfortunate. Case in point, don't we all recall the gloom and doom

forecasts after the 2004 and 2005 ATL hurricane season. and what has happened since? Yes the Atlantic still have been active, but

not a single major hurricane has made landfall in the CONUS since Wilma in 2005...over six year and this is the longest period on

record. Overall global TC activity is way down as well. See here:

http://policlimate.com/tropical/

March 2012: Another record falls... La Nina causes record suppression of global tropical storm numbers ...

The last two calendar years saw a total of 146 global tropical cyclones, the lowest 2-year total in records since at least 1970. In

the past 24-months, including ongoing Southern Hemisphere tropical cyclone activity, there have been a total of 141 global

tropical storms. This is also a record low.

This is amazing given our ability to detect and document TCs has improved greatly in the last couple of decades. Isn't less TCs a good

thing??? Yes, you can spin it as bad since TCs provide 10-15 or the annual rainfall to tropical regions, so perhaps more drought,

but you can't have it all ways! I realize it is more complicated than just using TC count, but the way TCs are portrayed like the end

of the world now when they are destined for landfall, having less overall saves billions of dollars and many lives each year. As I said, this is

a GOOD thing!

[bluewave]

The SPC probably sums things up the best way that we can at this point.

No. Thunderstorms do. The harder question may be, "Will climate change influence tornado occurrence?" The best answer is: We don't know. According to the National Science and Technology Council's Scientific Assessment on Climate Change, "Trends in other extreme weather events that occur at small spatial scales--such as tornadoes, hail, lightning, and dust storms--cannot be determined at the present time due to insufficient evidence." This is because tornadoes are short-fused weather, on the time scale of seconds and minutes, and a space scale of fractions of a mile across. In contrast, climate trends take many years, decades, or millennia, spanning vast areas of the globe. The numerous unknowns dwell in the vast gap between those time and space scales. Climate models cannot resolve tornadoes or individual thunderstorms. They can indicatebroad-scale shifts in three of the four favorable ingredients for severe thunderstorms (moisture, instability and wind shear), but as any severe weather forecaster can attest, having some favorable factors in place doesn't guarantee tornadoes. Our physical understanding indicates mixed signals--some ingredients may increase (instability), while others may decrease (shear), in a warmer world. The other key ingredient (storm-scale lift), and to varying extents moisture, instability and shear, depend mostly on day-to-day patterns, and often, even minute-to-minute local weather. Finally, tornado recordkeeping itself also has been prone to many errors and uncertainties, doesn't exist for most of the world, and even in the U. S., only covers several decades in detailed form.

http://www.spc.noaa.gov/faq/tornado/

[Ian]

172 tornadoes in just those two counties over 60 years, that's all that needs to be said. Almost 3 tornadoes/year. "AGW"

If you look at just Dallas and Tarrant these are the "big" days since 1950

12/14/1971 8

1/17/1996 7

5/3/1979 6

4/25/1994 4

10/21/1994 4

4/16/2002 4

Of course, there are a million ways to break these things down and the record gets generally less and less credible as you head back in time. I think however you cut it for the immediate metro this event is a top-5+ or so in the modern record. But, as with hurricanes it only takes one and if you get 30 EF0 tornadoes it's not necessarily a terrible outbreak.

As a whole it seems most experts don't even want to bring climate change into the discussion of tornado activity as the reliable record is still too small to draw major conclusions on. However, people like Grazulis have stated that a warming climate might mean less in the way of intense tornadoes. See italix:

IMHO, the warming climate is reducing the overall risk to intense tornadoes in the United States, based on total path length of (F3-F4-F5) “intense” across the past 100 years. I have no mechanism, and the credibility of the data would be easy to rip apart… and very hard to defend.

http://dotearth.blogs.nytimes.com/2011/04/29/killer-tornadoes-horrible-and-still-unknowable/

In some ways it makes at least a little logical sense, as you need cold air to interact, though I'm honestly not sure if it's that simple in his idea.

Why it even enters the debate from one -- especially a small -- event is perplexing but I suppose people with agendas peddle them whenever possible. Tornado day counts have remained relatively stable over recent decades as have sig tor days, though on that count they've actually dropped slightly each of the last few decades (have not yet looked at 2011 as data was released after I did the initial count) http://www.ustornadoes.com/2012/03/30/significant-tornado-days-1981-2010/

[vortex95]

I guess it depends how you define "extreme". To me this is not extreme-- it is a noteworthy event, but not an extreme. If this is our definition for "extreme", then we have extremes all the time, all around the nation, every week. Are we confusing "extreme" with "noteworthy"?

In my opinion, legit extremes would be-- for example-- the 2011 tornado season (collectively), the 2005 hurricane season (collectively), the 2011 "Super Outbreak", the May 2011 outbreak (which included the Joplin tornado), the cluster of intense tornadoes (including an F5) that hit Pennsylvania on 31 May 1985 (an example of a regional extreme), etc.

An EF3 in Texas in April? Meh.

"Extreme" so overused as a descriptor for wx these days, it has lost it's meaning. If everything is "extreme" then there no way to put events in proper perspetive. Also, once you are at "extreme", what's the next level?

[HoarfrostHubb]

is all that article needs.

The article should not have even been written IMHO. It is basically writing about a rather off the cuff remark that probably should not have been said in relation to the tornadoes...

Now if Steele had written the article explaining why she thought one particular significant article was related to climate change, or whatever non-"normal" reason, maybe that would be different.

Just another case of media diarhea

[vortex95]

Yeah.

Paul Douglas' post has made the rounds of course but I'm slightly perplexed at least by the opening. Hopefully it was a copy-editor who added it to something they already had and needed to tie to current news.

Tuesday's 13 large, violent tornadoes in the Dallas were a wake-up call for America. With camera-ready smartphones -- it may have been the most-photographed and filmed tornado outbreak in history -- dramatic video that convinced many locals to take the warnings seriously and take cover. Had the Arlington tornado tracked just 19 miles farther east it would have struck downtown Dallas.

http://www.huffingto..._b_1403642.html

One thing that disturbs me about mainstream coverage is that there seems to be little interest by many broadcast/blogging mets to actually get into the details that I think a fair amount of people would do well with knowing. This outbreak was IMO not that close to a worst case scenario for Dallas though looking at the coverage you'd think we just averted a massive disaster.

"Wake up call for America"? I would say Joplin was a wake up call, way more then DFW. More then 100 people killed by a single tornado in the U.S.? That hadn't happened in nearly 58 years.

[vortex95]

I think Hurricane Josh did a good job illustrating extreme tornadic events in the examples he gave in his post listed above. I concur. I also do not think climate change can adequately be applied to mesoscale influenced processes such as tornadoes. As a layperson from what I have read of human induced climate change it would lead to greater extremes in warmth and cold, drought and precip, and more intense hurricanes though not necessarily more frequent numerically.

Mesoscale events like tornandic supercells are far too small in size and brief in period in the big picture to simply connect the dots point A to B and blame climate change. The biggest thing about events like DFW is where tornadic supercells exactly track. A supercell can produce a dozen tornadoes, but if it is out in the middle of nowhere, there is hardly any interest overall. Supercells occur nearly everywhere across the CONUS each year. The law of averages and probabilities dictates that given enough time, there is going to be "the worst case scenario" or close to it (meteotologically), like Joplin. A large violent tornado develops very close to a large city, immediately gets rain wrapped, and maxes in intensity in the populated area. Why is this so hard to accept as happening? I'm not trivilizing how tragic these type of events are of course, but we don't control the wx and currently our technology/understanding does not allow for very precise forecasts for mesoscale events like this.

[andyhb]

"Wake up call for America"? I would say Joplin was a wake up call, way more then DFW. More then 100 people killed by a single tornado in the U.S.? That hadn't happened in nearly 58 years.

Or 4/27. Didn't have a tornado outbreak like that in 37 years.

[vortex95]

It just comes down to this...very simple.

It was an ULL that ejected out of the southern Rockies with an EML/high CAPE environment. Cells developed out ahead of the main squall line and once they hit the boundary..they injested the helicity and went to town..thanks to the high CAPE facilitating. This had nothing to do with climate change, period.

Other things...isolated cells forming ahead of a SQLN...that a red flag for possible tornadic supercells. Storm interacting with a low level boundary? Another red flag. This fits with what we have observed for years. Nothing unusual on why these tornadoes occurred where they did. Just b/c it was in and around a big city, means really nothing meteoroogically. If the right conditions are present, nature does was it does.

[HoarfrostHubb]

If climate change causes more tractor trailers to go flying hundreds of feet in the air and get caught on viral videos, then bring it on

[Riptide]

If climate change causes more tractor trailers to go flying hundreds of feet in the air and get caught on viral videos, then bring it on

This is the kind of rationalism that the world needs.

[andyhb]

Well according to some of these climate change people it will soon be homes flying through the air all the time...

[The_Global_Warmer]

The extremely of an event like this is only one factor to consider for contributing the event itself, or even parts of such event to global warming.

In theory if we could figure out every single process behind this event then we could chart is going back in some fashion compared to the same set of parameters for other events. Once we know with near 100% certainty everything that goes into such event, we can then do high level diagnostics for anomalous parameters.

Example. Northern Hemisphere H500 Heights have been rising for a while.

This is an obvious by product of AGW combined with natural variation. The question you do with this is ask would this set up be the same if this parameter was in in line with the past? How can we know where and when the change has happened and where and when it happens now to give us an average rise from 5585-5590 or so for two decades to higher natural variance, to much higher overall from AGW.

What about SSTs? Water Vapor? Thermal Gradient?

There is a lot of questions that can be proposed for this and they can be next to impossible to answer at this time.

But limited thinking and mockery are not the way to go when it comes to science.

[The_Global_Warmer]

Extreme is irrelevant, except in truely extreme events like the March Heat Wave, the 2003 and 2010 heat waves in Europe, those can be classified under probabilistic events and given a percentage of likely with or without AGW.

what we want to know here with this Tornadic event what is normal given a certain amount of parameters and factors. Then we can determine if and what about AGW could have amplified this situation.

[bluewave]

The extremely of an event like this is only one factor to consider for contributing the event itself, or even parts of such event to global warming.

In theory if we could figure out every single process behind this event then we could chart is going back in some fashion compared to the same set of parameters for other events. Once we know with near 100% certainty everything that goes into such event, we can then do high level diagnostics for anomalous parameters.

Example. Northern Hemisphere H500 Heights have been rising for a while.

This is an obvious by product of AGW combined with natural variation. The question you do with this is ask would this set up be the same if this parameter was in in line with the past? How can we know where and when the change has happened and where and when it happens now to give us an average rise from 5585-5590 or so for two decades to higher natural variance, to much higher overall from AGW.

What about SSTs? Water Vapor? Thermal Gradient?

There is a lot of questions that can be proposed for this and they can be next to impossible to answer at this time.

But limited thinking and mockery are not the way to go when it comes to science.

One study that I have seen suggests that the number of annual severe thunderstorm days would increase

in the US under a warming climate.

http://www.pnas.org/content/104/50/19719.full.pdf

[AtticaFanatica]

My understanding is the peer reviewed work on tornadoes specifically (not the catch-all "extreme weather") is an AGU paper by Diffenbaugh, Trapp, and Brooks. I think they argue CAPE likely increases and vertical shear likely decreases, so changes in tornado occurrence will be difficult to predict. Has there been anything since then?

[AtticaFanatica]

Summary from Harold Brooks of NSSL about current state of climate change impact on tornado occurrence. It reminded me of this thread.

http://www.newscientist.com/article/mg21428637.100-global-warming-heats-up-tornado-debate.html

[JoMo]

Local paper here in Joplin ran a story this weekend on Climate Change and tornadoes.

Howard Bluestein and Kevin Trenberth weigh in.

http://www.joplinglobe.com/local/x157482853/Weather-experts-disagree-on-effect-of-climate-change-severity-of-tornadoes