Severe storms over U.S. seen from space

By Phil Plait | April 30, 2011 7:00 am

On April 27, 2011, huge storms spawned enormous tornadoes which swept across the southeastern U.S., doing severe damage and killing over 200 people. It was the worst natural disaster in the U.S. since Hurricane Katrina in 2005.

The NASA/NOAA Geostationary Operational Environmental Satellite, or GOES, takes high-resolution images every few minutes. The animation below shows the southeast U.S. from GOES, and you can watch the storms erupt.

A warm, moist air mass from the south collided with a cold air mass over the States. This is how summer storms usually form, but this situation was amplified by the jet stream, which was blowing between them. This generated fierce local systems that spawned over 150 tornadoes in the course of a single day.

It’s unclear but unlikely this particular event was due to global warming, but many models indicate such storms will increase in number as the planet warms. Despite a lot of political noise, the overwhelming scientific consensus is that global warming is indeed real. We may see more storms like this in the future.

NOAA/NASA, GOES Project Science team. Original animation by Jesse Allen.

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Comments (33)

  1. Thameron

    What we need is…more carbon dioxide in the atmosphere! Burn that coal and oil! Let’s get all of it up there and see what happens. What could possibly go wrong?

  2. There were three or four tornado warnings around Maryland too. I hope this isn’t the beginnning of a new tornado alley.

  3. Daniel J. Andrews

    One analogy I heard was weather events (severe storms, droughts etc) was like rolling a die loaded to come with sixes. When you roll a six, you don’t know if that particular six came up because it was loaded or because you’re going to get a six one-sixth of the time anyway. It is only over a number of rolls do you start to detect sixes are coming up more often than they have in the past.

    The analogy was also stretched to say, we aren’t just rolling sixes, but we’re now rolling 7s and the occasional 8–i.e. seeing things that are more extreme than they have been in the past.

  4. Nothing good ever comes from moistness.

    As the nuns used to say.

  5. Jason

    Global warming will make more US land available for windmills, Thus a reduction in our reliance on Co2 based power. See? The world by proxy fixes it’s own problems! 😀

  6. @ ^ Jason : Err .. how do you figure that?

    Despite a lot of political noise, the overwhelming scientific consensus is that global warming is indeed real.

    Meanwhile yet another stake :

    gets driven through the heart of the already deader than a decapitated and exploded zombie heart of the “climategate” non-scandal. Plus another through the stake crowded chest of Watts Up With That‘s credibility & the climate contrarians.

    For Whatever little Its Worth my condolences to those affected by these latest disaster in what’s already turning out to be a horror year for “natural” disasters & unnatural ones too. :-(

  7. Pete Jackson

    Global warming will increase evaporation and hence (since what goes up must come down) overall precipitation as well. And as part of this process, tornados will likely increase in numbers also.

    But both computer models and actual observations predict that the polar areas will warm more than the tropics. Hence the temperature gradient with latitude will decrease, so wind driven by purely temperature differences, such as typical fall and winter frontal movements, may well decrease.

  8. Ella

    I’m glad you made a post about this. Fox News had an article up almost straight away when the story broke about the number of people killed. The headline said that a NOAA scientist says the tornadoes aren’t global warming related. Whilst I may not be a meteorologist, I could tell Fox was trying to buffer the comments against those that will speak out about climate change.

  9. ntsc

    There was a tornado warning in southern NY as well, Rockland and Orange Counties. Don’t ever remember one before.

  10. The first time I ever heard the term “el Nino” was in the early 80’s when I was caught up in the severe flooding in Marin County, Calif. Back then, “el Nino” was described as a once-in-a-century event where a specific region in the Pacific becomes unusually warm, adversely altering normal weather patterns. Soon after, people across the country became familiar with the term and we were getting them every 9-10 years. Now it seems we are getting them every 2-3 years.

    Humans are just like frogs. Try to put us in a pot of boiling water and we will immediately react. Put us in a pot of room temperature water and slowly turn up the heat, and we will blissfully relax in our new found jacuzzi until we are cooked.

  11. RaginKagin

    Not to really argue the point too terribly, but this is the second worst recorded outbreak in American history, the first being almost 40 years ago…So, though I am in no way trying to deny that global warming is real, I don’t think its a stretch to say this system was anything more than a result of a perfect storm scenario and not a direct result of global warming. It is the season, the conditions were right, there is nothing to suggest that 50 years ago the same situation wouldn’t occur, or that a hundred years ago it did but we simply didn’t have the means of recording it nor the population density to feel its full effect.

  12. Robin Byron

    Spent ten years smack dab in the middle of tornado alley in Oklahoma so I’m now happy to be in the boondocks of South Carolina. Never the less, we had two days of tornado watches and warnings here this week but only had some slight damage from straight line winds. For that, I am grateful. The death toll for the storm is now at 340 and rising. That shouldn’t happen in this day and age.

    During the 53 years I lived in San Diego, we never had any weather. Course I was in the ocean most of that time so maybe I just didn’t notice.

  13. Shawn S.

    I live in Tulsa, OK and I am shocked we got so lucky. Only a few tornadoes. Looking at the map and the HUGE mass of cloud violence just to the east of where I live I count myself lucky.

  14. psweet

    I think we’ve got the wrong idea of causation here. For any weather event, there will be proximate causes — a warm, moist air mass colliding with a cold, dry one just below the jet stream, in this case. Global warming involves adding energy into a very complicated system. So if we’re asking would this particular event have happened if we hadn’t been altering the system, the answer is clearly no. What would have happened instead, it’s not possible to say.

    On the other hand, we can look at the frequency and intensity of storms as a distribution, and ask if that distribution is significantly altered by global warming. I’m not aware of more than one or two attempts to do this outside of tropical storm stuff, but I would hope someone’s looking at it.

  15. Brad

    While sea temperatures are higher, the real culprit here is the strong and south jet stream, and I don’t think I’ve ever heard of global warming’s effect on that (though I would like to hear it).

    I appreciate the global warming issue, but to be honest, Phil, it seems like you’re using this event to arouse your allies rather than broach the infinitely fascinating science of tornadoes. I am a hobbyist meteorologist (obsessed with severe weather), and I can tell you that this outbreak is completely precedented and more importantly, *should be expected by every resident living east of the Rocky Mountains* every year. We have had incredibly severe outbreaks of tornadoes in all decades, like in 1930, 1974, 1999, and now in 2011. If you want to posit a link, there may be one connecting those outbreaks to the La Niña years, but even that is not proven yet.

    These things happen. They’ve happened before (and were even worse, if it can be believed), and they will happen again. We only finished the NEXRAD radar system in 1997. Prior to that, who even knows how widespread the tornado outbreaks truly were. We have more eyes and cameras now, and a radar network with very few holes. We have 90 million more people living in this country than we did in 1974 and urban sprawl is in full effect. Realistically, almost all of the deaths in this disaster were avoidable, but sadly they still happened.

    You said, “We may see more storms like this in the future.” Not “may”, but “will”. The tornadic supercell thunderstorm is a *permanent* feature of the American continent and we will see an outbreak of this scale probably once or twice a generation, with or without global warming.

  16. cool

    “It’s unclear but unlikely this particular event was due to global warming, but many models indicate such storms will increase in number as the planet warms. Despite a lot of political noise, the overwhelming scientific consensus is that global warming is indeed real. We may see more storms like this in the future.”

    THIS IS SO RIGHT. But scientists knew about THAT in 1973 already.

    “As the winds swirl around the globe, their southerly portions undulate like the bottom of a skirt. Cold air is pulled down across the Western U.S. and warm air is swept up to the Northeast. The collision of air masses of widely differing temperatures and humidity can create violent storms—the Midwest’s recent rash of disastrous tornadoes, for example.”,9171,944914,00.html

  17. cy

    I don’t get the whole “this was global warming” thing. It was in the low 80’s in Alabama. Certainly thats not unusual for late April.

    This outbreak happened because it was a near perfect set up with the wind profile of the atmosphere. The wind increased in speed and direction as it rose causing extreme helicity and the mid-levels of the atmosphere (700mb to 500mb) were cooling rapidly with height which increased instability and caused a CAPE of about 3000 J/kg^2.

  18. toasterhead

    The science-deniers and moon hoaxers are all blaming HAARP, chemtrails, and even wind turbines for the outbreak. It’s sadly comical.

  19. réalta fuar

    @Brad You’re exactly right. Trying to link this disaster to global warning in order to score cheap political points is, in a word, disgusting, and a tactic one would expect from Fox (or as some of us say, Faux) News. I do think however that most of the casualties were NOT preventable: when tornados like these hit metropolitan areas where homes typically don’t have basements, there’s very little that can be done. Single family dwellings just cannot stand up to 350 km/hr winds.
    Please don’t mistake me: global warming is real and the world-wide consequences will be severe, but that’s a story for a different time.

  20. Quiet Desperation

    Cool, I suppose. I’d rather see Reed and Joel driving the Dominator into the things. 😉 I only hope they were filming for the next season of Stormchasers.

    I don’t get the whole “this was global warming” thing.

    It’s a lie to cover up that we’re heading for a new ice age. You heard it here first.

    Looking at past major events, it looks like just a Gaussian tail event- 3 sigmas, maybe? I dunno, maybe I’m jaded by my satcom work where we fret over 9 and even 10 sigma cases.

  21. Quiet Desperation

    The science-deniers and moon hoaxers are all blaming HAARP, chemtrails, and even wind turbines for the outbreak. It’s sadly comical.

    Turbines? Really? You have a link to one? I’d like to see that.

  22. toasterhead

    I’ve only seen the turbine in one place so far, a comment on this Truthout story: It may not be a widespread meme, but it wouldn’t surprise me if it catches on.

    Oh, I’ve also seen a few Facebook and Youtube comments blaming the shifting of the magnetic pole. Because apparently cold and warm air masses are magnetic.

  23. Tom

    Yesterday the Houston Chronicle print edition front page headline over photos of tornado damage in Birmingham read: “Death from the Skies.”

  24. Quiet Desperation

    @toasterhead – Thanks. Looks like someone taking the butterfly effect literally again.

    Newton did not say “For every action there are infinitely incalculable amounts of reaction.”

    You might as well claim that we could stop tornadoes with just the right small force applied in just the right spot and-


  25. MadScientist

    “It’s unclear but unlikely this particular event was due to global warming, but many models indicate such storms will increase in number as the planet warms.”

    Ah, models. The question is: can you trust those models? I don’t know if the IPCC still have that disclaimer up on their web pages: “It is difficult if not impossible to determine if storms are increasing in severity or frequency.” I pointed out years ago that it is not scientific to make claims that storms will increase in number and severity due to global warming unless you have a means of (a) measuring the number, (b) measuring the severity, (c) showing at least a correlation with increased warming (that’s the trivial part since CO2 is going up up up). Otherwise it’s a case of “well, I think the number and severity should go up, but I can’t test it so I’ll simply make a baseless claim.”

    @oddTodd#11: That’s funny – way back then I understood ‘el Nino’ to be a somewhat regular if not predictable event. For fishermen on one part of the planet, if the fishing was good it must have been ‘el Nino’ – the Jesus baby – bringing them good fortune. I hate the ‘el Nina’ thing because, unlike ‘el Nino’, it has nothing to do with mythology; personally I think it should simply be an ‘el Nino’ spell or not.

  26. Damon

    I guess because hurricanes attacked the deep south for once God didn’t do it this time? How convenient.

  27. jfb

    There’s a paper (PDF) available at the NOAA Storm Prediction Center that shows tornado activity has been pretty flat over the last 30 years, so it’s very unlikely that these particular storms are GW-related.

  28. Tanya McPositron


  29. Maria

    We do I torture myself and read youtube comments? It’s like driving by a car wreck and slowing down to see the carnage.

    I can’t fathom mocking the situation just because it struck the south. The south is huge. It’s an ecologically and culturally diverse place and historically rich. Yes, it is full of stupid people. As if New York isn’t, or the mid west, or California, or hell anywhere else on this spinning rock. But there are also intelligent people. There are damned good people in the south, who fight for science, and fight for education. We are not all uneducated buffoons.

    People died. Lots of people. The snide “where’s their god now?” and “serves them right for not supporting science!” type of comments are messed up. Meh. I’m done feeding trolls now.

  30. Joseph G

    @Maria: It’s not the first time that the YouTube comments section has made me lose faith in humanity. Is there something about digitized video that stimulates some folks’ verbal diarrhea glands?

  31. Andrew EM Cameron


    There is an add for Dr. Bernstein’s diet that keeps popping up on the video. I realize it has nothing to do with you and everything to do with the linked site and some kind of add software from google. It’s just sad that woo has found a way to sneak through the cracks and wind up on a reputable skeptical blog like yours.

    Great post! Informative, amusing, thank you.

  32. pastor david

    I encourage serious minded students of science to take haarp tech alot more seriously. Yes, alot of fringe types have muddied the waters of clear thought. That is the oldest trick in the book to block intelligent debate. Please do not dismiss the FACT that our govt. is not telling anyone the truth about anything – haarp is a patented reality & quite capable of creating serious weather anomylties.


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