Super Tornadoes

[Shawn Schuman]

Now that's some insane CAPE! We're there any tornadoes on this day? I won't be surprised if there was one or two violent twisters either!

Yes, there was at least one tornado. The sounding is from north-central Bangladesh, about 80 miles north-northwest of Dhaka. Information from that area is sketchy at best, so it's hard to pin down details. There may have been two separate tornadoes along a path of destruction said to be well over 50 miles in length, along with a larger swath of significant straight-line wind damage. Most of the homes are extremely poorly built so it's hard to say how intense the tornadoes were, but there were reports of trees debarked/denuded and mangled, people, livestock and vehicles thrown "long distances," etc.. so it sounds like they were pretty strong. Unfortunately, the death toll was at least 700. The true number may well have been much higher, because there was no official tally and many of the dead were probably buried without being counted. There were also many victims still in critical condition at the area hospitals, and there doesn't appear to have been any follow-up on their condition or whether they'd survived or not.

Because of a combination of occasionally explosive atmospheric conditions and extremely poor housing, Bangladesh is no stranger to catastrophically deadly tornadoes.

 

[DNewman]

Yes, there was at least one tornado. The sounding is from north-central Bangladesh, about 80 miles north-northwest of Dhaka. Information from that area is sketchy at best, so it's hard to pin down details. There may have been two separate tornadoes along a path of destruction said to be well over 50 miles in length, along with a larger swath of significant straight-line wind damage. Most of the homes are extremely poorly built so it's hard to say how intense the tornadoes were, but there were reports of trees debarked/denuded and mangled, people, livestock and vehicles thrown "long distances," etc.. so it sounds like they were pretty strong. Unfortunately, the death toll was at least 700. The true number may well have been much higher, because there was no official tally and many of the dead were probably buried without being counted. There were also many victims still in critical condition at the area hospitals, and there doesn't appear to have been any follow-up on their condition or whether they'd survived or not.

Because of a combination of occasionally explosive atmospheric conditions and extremely poor housing, Bangladesh is no stranger to catastrophically deadly tornadoes.

Wow, and sad at the same time. Thanks for the info. Is there a way to get soundings from the Middle East years back (like in Israel)?

 

[Shawn Schuman]

http://weather.uwyo.edu/upperair/sounding.html

Choose your region and GIF: Skew-T plot. I don't know how far back the archives go for each region/station, but the ones I've used have all covered several decades.

 

[Jeff Duda]

Well, one out of three ain't bad.

Bangladesh/southeast India may very well be the only place on the planet that could ever support an environment that could create such tornadoes. It is ideally placed very near a rich supply of moisture (the Bay of Bengal) with little in the way to suck moisture out of flow coming in from the soutwest-southeast. It is far enough south that it gets very warm there, and has a wonderful source for an EML with the Tibetan Plateau just to the north, thus providing for very steep lapse rates above an extremely warm/moist boundary layer. Getting strong synoptic-scale disturbances is probably pretty hard to do given the low latitude, but given the huge mass of land to the north (from Tibet all the way through Siberia), and thus a source of cold air during transition seasons, it may be possible to get some stronger systems to come through from time to time. The degree of shear I estimated probably would never be realized, however. But if a storm could ingest a well-developed sea-breeze circulation...

 

[Shawn Schuman]

Indeed, I've always been intrigued by the extraordinary conditions that occasionally come together in Bangladesh. Especially the "tornado alley" that extends generally northward from near Dhaka. Information and photos are obviously hard to come by, but some of the photos and accounts that I've seen would suggest violent tornadoes - extensive ground scouring, fairly large trees debarked and denuded, vehicles and people and cattle thrown great distances, etc. That area is certainly no stranger to extraordinarily volatile thermodynamic conditions. The severe weather season tends to be extremely brief, often only lasting the first two or three weeks of April and peaking somewhere around April 12, though several of the most violent and deadly tornadoes have occurred in late April and early-mid May.

I'm not sure where I originally got it from, but this diagram provides a pretty good illustration of how the severe season comes together.

It isn't uncommon to see mid- and upper-level winds in the 40-60 kt range, and I remember seeing a few soundings in that region that looked to have some pretty impressive helicity. I'd hate to see what would happen in the event of a mesoscale accident in the presence of such tremendous instability. There's plenty of nocturnal thunderstorm activity to lay down outflow boundaries, especially in the northern areas.

And here I thought the CAPE in Jarrell (pushing 7,000) on 27 May 1997 was impressive.

 

[DNewman]

http://weather.uwyo.edu/upperair/sounding.html

Choose your region and GIF: Skew-T plot. I don't know how far back the archives go for each region/station, but the ones I've used have all covered several decades.

Ok thanks ill give it a try.

 

[DNewman]

Bangladesh/southeast India may very well be the only place on the planet that could ever support an environment that could create such tornadoes. It is ideally placed very near a rich supply of moisture (the Bay of Bengal) with little in the way to suck moisture out of flow coming in from the soutwest-southeast. It is far enough south that it gets very warm there, and has a wonderful source for an EML with the Tibetan Plateau just to the north, thus providing for very steep lapse rates above an extremely warm/moist boundary layer. Getting strong synoptic-scale disturbances is probably pretty hard to do given the low latitude, but given the huge mass of land to the north (from Tibet all the way through Siberia), and thus a source of cold air during transition seasons, it may be possible to get some stronger systems to come through from time to time. The degree of shear I estimated probably would never be realized, however. But if a storm could ingest a well-developed sea-breeze circulation...

So India would be a nice place to storm chase then if only they had better forecasting!

 

[DNewman]

Indeed, I've always been intrigued by the extraordinary conditions that occasionally come together in Bangladesh. Especially the "tornado alley" that extends generally northward from near Dhaka. Information and photos are obviously hard to come by, but some of the photos and accounts that I've seen would suggest violent tornadoes - extensive ground scouring, fairly large trees debarked and denuded, vehicles and people and cattle thrown great distances, etc. That area is certainly no stranger to extraordinarily volatile thermodynamic conditions. The severe weather season tends to be extremely brief, often only lasting the first two or three weeks of April and peaking somewhere around April 12, though several of the most violent and deadly tornadoes have occurred in late April and early-mid May.

I'm not sure where I originally got it from, but this diagram provides a pretty good illustration of how the severe season comes together.

It isn't uncommon to see mid- and upper-level winds in the 40-60 kt range, and I remember seeing a few soundings in that region that looked to have some pretty impressive helicity. I'd hate to see what would happen in the event of a mesoscale accident in the presence of such tremendous instability. There's plenty of nocturnal thunderstorm activity to lay down outflow boundaries, especially in the northern areas.

And here I thought the CAPE in Jarrell (pushing 7,000) on 27 May 1997 was impressive.

Wow, 7,000j/kg! No wonder that tornado was so extreme in the damage it caused! So if CAPE can get up to 7,000, then is 10,000+ poss? With all that energy an extreme tornado would almost seemingly have to be "super" with all that potential energy built up in the atmosphere!

 

[Dan Robinson]

"Super tornado" is a hyperbolic media-coined term that isn't recognized in storm chasing or science circles. While tornadoes significantly stronger/larger than the current record-holders are theoretically possible, I think that they require conditions beyond what our current atmosphere is capable of. Otherwise we should have at least some climatological/historical record of one.

 

[DNewman]

"Super tornado" is a hyperbolic media-coined term that isn't recognized in storm chasing or science circles. While tornadoes significantly stronger/larger than the current record-holders are theoretically possible, I think that they require conditions beyond what our current atmosphere is capable of. Otherwise we should have at least some climatological/historical record of one.

Not necessarily so, b/c as I quite from someone earlier" if a tree falls in a forest, who will ever hear it" So actually you can't say that we should have some climatological/historical record b/c it could have happened long before our modern technology even began. And never say never b/c weather ceases to follow the rules of science that "man" has made. Also I do know of meteorologists and storm chasers who DO use the term "super tornado" when explaining them and talking about them b/c they recognize their obvious existence.

 

[Mark Ellinwood]

People who are saying 500 mph winds are theoretically possible, you should try doing some calculations with pressure gradient force winds and the like to see what kind of numbers it would take to produce such winds. XKCD actually recently posted in their What If? with what it would take to achieve 500 mph winds on Earth... like a large asteroid or a big volcanic eruption: http://what-if.xkcd.com/66/

In the United States, we get by far the most tornadoes and have recorded tens of thousands of them. Thousands more have been observed elsewhere in the world. It would be a wonder to see a tornado hit 350 mph, let alone 400 or 500 mph.

 

[GPhillips]

A website that has information on Bangladesh tornadoes is at:

http://bangladeshtornadoes.org/

And, it has a lot of nice plots and analyses of historical U.S. tornadoes as well.

 

[MClarkson]

I would think a large broad tornadolike circulation of 5 miles would be possible, even probable over a large enough sample size. A mesocyclone on the ground, as others have said. El Reno was not far removed from this. The 500mph winds however, are a different story. You'd need a large explosive volcano or impact event for natural winds in that range.

 

[Shawn Schuman]

I suppose it depends on how you define a tornado's width, doesn't it? As we've seen most recently with the El Reno tornado, that can be a bit of a thorny question. The 3 May 1999 Mulhall, OK tornado immediately comes to mind as well. If you were to use the diameter of 43 m/s wind gusts as the "width" of the tornado itself, you'd wind up at ~4.3 miles.

While the peak winds measured by the DOW at 30 m AGL in the Mulhall (hereinafter MH) tornado are only 110–115 m s–1, the diameter of the core flow region is as large as 1600 m at some observation times. Wind speeds capable of causing significant damage, > 43 m s–1, extended across a swath over 7 km wide (Table 1), which is substantially wider than the damage swath of the Hallam, Nebraska, tornado of 22 May 2004 (McCarthy and Schaefer 2005).

Wurman, Joshua, Paul Robinson, Curtis Alexander, Yvette Richardson, 2007: Low-Level Winds in Tornadoes and Potential Catastrophic Tornado Impacts in Urban Areas. Bull. Amer. Meteor. Soc., 88, 31–46.

 

[DNewman]

I suppose it depends on how you define a tornado's width, doesn't it? As we've seen most recently with the El Reno tornado, that can be a bit of a thorny question. The 3 May 1999 Mulhall, OK tornado immediately comes to mind as well. If you were to use the diameter of 43 m/s wind gusts as the "width" of the tornado itself, you'd wind up at ~4.3 miles.



Wurman, Joshua, Paul Robinson, Curtis Alexander, Yvette Richardson, 2007: Low-Level Winds in Tornadoes and Potential Catastrophic Tornado Impacts in Urban Areas. Bull. Amer. Meteor. Soc., 88, 31–46.

I never doubt that tornadoes could be very wide up to 4 miles or even 3. Especially considering the El Reno tornado was 2.6, nearly 3 miles wide. I believe the more we study tornadoes, the more well find out about how much larger they can be .