Derecho Iowa Corn Damage Imaged By Satellite

September 5th, 2020 by Roy W. Spencer, Ph. D.

Corn crop destroyed east of Cedar Rapids on 10 August 2020 (Matt Rogers).

The August 10, 2020 derecho event caused an estimated 40 million acres of nearly-mature corn crop to be significantly damaged or destroyed, mainly in Iowa, but also in portions of Nebraska, South Dakota, Illinois, Minnesota, Wisconsin, Indiana, Ohio, and Missouri.

I put together this NASA Terra satellite MODIS imager comparison of the area as imaged on September 2 in both 2014 (a normal crop year) and in 2020, a few weeks after the derecho struck. This date is sufficiently past the event to show areas where the crops are dead and dying. (Click on image if it doesn’t animate.)

Derecho damage to midwest corn crop as seen by the NASA Terra satellite MODIS imager on September 2, 2020 compared to the same date in 2014. (Click on image to animate).

The dashed line in Fig. 1 shows the approximate area where crop damage seems most extensive.

What Causes Derechos? How Common are They? Can they Be Predicted?

Derechos are severe thunderstorm “squall line” high wind events that are particularly widespread and long-lived, typically moving rapidly across multiple states. This video taken in Cedar Rapids shows about 25 minutes of very high winds, with occasional gusts taking out trees and tree limbs.

Derechos are particularly difficult to predict. For example, the NWS Storms Prediction Center early morning outlook (issued at 7 a.m.) for severe weather showed little indication of unusual severe storm activity prior to the August 10 event.

Fig. 2. Storms Prediction Center outlook for severe thunderstorms on 10 August 2020, issued at 7 a.m. CDT.

Once the derecho formed over eastern South Dakota and Nebraska, though, the forecast advisory was updated to reflect the high probability that it would persist and move east.

Like all severe thunderstorms, we know that derechos require an unstable air mass (usually during summertime), with some wind shear provided by an advancing cool front and upper-level trough to the west. But most of these synoptic situations do not cause derechos to form, and forecasters can’t predict one every time such conditions exist or there will be a lot of false alarms.

The following plot shows an 18 year climatology of derecho events during May-August of 1996 through 2013 from a 2016 study by Gaustini & Bosart

Fig. 3. Climatology of progressive derecho events for the warm season (May–August) of 1996–2013. The number of progressive derechos passing through a given 100 km × 100 km grid box over the 18-yr span is located at the center of the grid box and is plotted for those boxes containing at least one progressive derecho. (From Gaustini & Bosart, 2016 Monthly Weather Review ).

Note that a farmer in the corn belt will be impacted by maybe one or two derecho events per growing season, depending upon their location, although ones of the severity of the August 10 event are much more rare. Of course there is nothing a farmer can do about such events, even if they were accurately forecast.

Given the central placement of derecho activity in the corn belt, I suspect that these events are made somewhat worse by the huge moisture requirements of corn, which leads to very high dewpoints (oftentimes in the low-80s F) when the corn is actively growing and transpiring water. Any extra water vapor is extra fuel for these storms.

83 Responses to “Derecho Iowa Corn Damage Imaged By Satellite”

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  1. Norman says:

    The center pine tree could only take so much. That is quite damaging. The many trees make the power restoration a real problem.

    Also in Iowa this year of 2020.

    Extreme drought in a large area of the state.

  2. Ric Werme says:

    I was in northeast Ohio for the 1969 July 4th derecho. It remains, by far, the most amazing thunderstorm I’ve been in, especially the lightning that crawled along the bottom of the clouds.

    We didn’t have much tree damage, but some tornadoes wiped several houses off the ground about 10 miles away.

    That doorbell video shows wind and rain far beyond what I had to deal with.

    My brother and sister were at different events on the Lake Erie shore. My sister saw the storm surge – my brother was in it.

  3. Lasse says:

    I follow a vlog about a farm in the cornbelt.
    Cole the cornstar(
    They shoved damaged buildings and corps on the ground.
    Harvest will tell what they can rescue.

  4. Nate says:

    Wow, never heard of


    ” are made somewhat worse by the huge moisture requirements of corn, which leads to very high dewpoints (oftentimes in the low-80s F) when the corn is actively growing and transpiring water. Any extra water vapor is extra fuel for these storms.”

    Could this extra transpiration also explain the relatively lower warming rate in this belt, that you discussed recently?

    • CoRev says:

      Nate, wouldn’t having higher water vapor disprove GHE if it cooled? Though, it might prove the negligible effects of GHE. Just speculating.

    • Nate says:

      Having extra water evaporate would cool the surface. A well known effect.

      Whether that would lead to extra tropospheric humidity or clouds and what type, and whether this would lead to additional ghe warming or cooling is an open question.

  5. ren says:

    Currently, the solar disc without spots and coronal holes.

    • istexuberant says:

      A brief one blew out half of the windows on one side and tore off all the roofing on another. Also, I’ve weathered many storms, including Gilbert (on Cozumel) in phrazle 1988. Since I didn’t hear a roaring wind, I know they weren’t above 180 mph, but they were still likely over 100.

  6. konrad says:

    Impressive storm damage visible in true color imagery. Would be interesting to see analysis of IR imagery.

  7. garyH845 says:

    Wonder what the top wind speed was in some of those gusts? Have been a couple of microbursts – Denver back in ’70’s 80’s.
    One ripped all the shingles off one side – and blew out most of the windows on that side, but lasted only for a couple minutes. And, have been thru a few hurricanes, inc Gilbert (on Cozumel) in ’88. So, I know that they weren’t 180 mph+ (missing that screaming wind sound), but surely were well north of 100.

  8. ren says:

    In three days, the cold front would strike again across the Midwest.

  9. Snape says:


    Gilbert was a monster. Do you have any stories to share?

    • garyH845 says:

      Well, we were supposed to leave that day. Had only heard of it the night before. Woke up – could already sense the change in weather. They were evacuating the hotel – so went straight to the airport. Airlines chickened out early, so could not get out. At dark got a motel room – 2 story concrete reinforced bldg w/ concrete bathtub roof (water came in handy later). Except for windows a structure like that is perfectly safe. Met people. Hunkered down – finally called my bro who was supposed to pick us up at airport in L.A. He was freaking out, said that Dan Rather just said they expected everyone to die on the island – never did like Rather. But that was the 1st I knew what it was.

      Around 11-midnight was getting a few early bands and they turned the power off to the whole island – smart move – no fires. . . but suddenly all the sounds became so much clearer.

      Had a double eyewall as it passed – unbelievable sustained 180ish (gusts of 220-225) winds – for a couple of hours late the next morning. It had lasted so long that when it stopped, we all went out walking around – were just off the south eye wall – could hear it over there – but could not see any sky – did not know it was the eye. Found out soon enough. Back side was intense but over in only a few hours.

      Was a week before we could get out – airport was heavily damaged. Pres of Mexico came on our last day there – which messed up the effort – and his jet almost crashed. They’d taken off – watched it – did a U to go to the mainland and was hugging the trees (what was left of them – not much) the whole way. Had some sort of mech issue.

      Our room at the hotel – was 2nd floor. the Deck, bedroom, and bath – up to the shower wall – were gone.

      Got to go – here’s a video from across the way in Cancun. Cheers. Talked to Chris Landsea off and on about it. He’d flown into it and did a detailed report on it (mailed me an autographed copy).

      Home video from Cancun Playa del Carmen, Mexico

    • garyH845 says:

      Here’s a pic – this should have been taken as we were walking around on the south side of the eye.

  10. Snape says:

    Everything has lined up to make the wildfire situation in California really dire.

    An unusual lightning outbreak 2 weeks ago started fires all over the place, followed by record breaking heat. Now, offshore winds are in the forecast (hot and dry) and no rain in sight.

    If it doesnt rain before the Santa Ana season kicks in this fall……?

  11. ren says:

    Cold fronts are arranged along the jet stream that falls from the north-west Canada.

  12. Steve says:

    Cool post – thanks.

  13. jane says:

    This is like a hurricane-in that the more water in the atmostphere the stronger they are. Farmers dump huge amounts of water on there crops over a large area, it evaperates and makes nasty weather.

  14. Roy W. Spencer says:

    Nate, yes, there’s a published study that says the corn crop has reduced summer warming.

  15. skeptikal says:

    The loss is the farmer’s own fault. Instead of planting corn, they should be planting something more robust, like… say… windmills.


    • Nate says:

      Interesting, since you bring that up.

      A lot of corn is used to produce ethanol. It turns out that the end-use energy of Ethanol divided by input solar energy in Iowa, is ~ 0.1 %.

      IOW the efficiency of harvesting solar energy this way is 0.1 %.

      Compare this to a solar array with total eff 10%. That is 100 x higher.

      So perhaps the farmers should plant solar panels, harvest the electricity, and sell it to be used in, say, electric cars?

      No tilling needed.

  16. ren says:

    Great snowstorm in the Rocky Mountains.

  17. Snape says:

    Fires are burning up and down the west coast. This is whats happening not far from where I live:

    The smoke is oppressive, even indoors.

  18. Snape says:

    I took a drive this morning towards Mill City, OR, hoping to get a video of the fire in the distance. The road was closed before I could get that close, but amazing how dark it was, ashes falling like snow in the headlights.

    Apparently, most of the rural community has burned to the ground.

  19. Snape says:

    The summer of 2017 was the smokiest anyone living in the PNW had ever experienced. Not even close. The summer of 2018 was just as bad.

    Whats happening right now is probably worse than both years combined. Off the charts in the modern record.

  20. Snape says:

    As usual, Cliff Mass has an excellent, big picture breakdown:

  21. ren says:

    Again, a large increase in galactic radiation due to the weak solar wind.

  22. Snape says:

    [Again, a large increase in galactic radiation due to the weak solar wind.]

    Every time I see the word galactic, all I can think of is Star Trek or Star Wars. So even if you are 100% correct and this is important information I should know about, still sounds too goofy to take seriously.

  23. Scott says:

    >> The August 10, 2020 derecho event caused an estimated 40 million acres of nearly-mature corn crop to be significantly damaged or destroyed, mainly in Iowa, but also in portions of Nebraska, South Dakota, Illinois, Minnesota, Wisconsin, Indiana, Ohio, and Missouri.<<

    Something is wrong here. Either the estimated acreage impacted is too great, or the qualifiers "significantly damaged or destroyed" are too strong.

    According to the USDA, farmers planted an estimated 92 million acres of corn this year. If almost half the corn crop were "significantly damaged or destroyed", corn futures prices for 2021 delivery would have gone vertical. Yes, corn prices have increased about 10% or so since the August 10 event, but that is not nearly enough if market participants were pricing in a crop failure of almost half the crop.

    Also, on August 13 the USDA published its estimate for corn yields. On that date it expected farmers would set a brand spanking new inter-galactic record of 181.8 bu/acre. (I suppose we give partial credit to the so called "climate crisis" for this productivity gain?)

    Not sure if the Aug 13 estimate takes into account the Aug 10 event. It may have occurred too close to the release date to revise yield estimates. Guess we'll see when the September report is issued in a few days.

    Regardless, we don't need the USDA September report. We can conclude based on the behavior of market participants that USDA will not revise production estimates down by much. I'll be surprised if it is more than a percent or two.

  24. Snape says:

    The state government in Oregon really messed up. High winds, and red flag warnings were forecast for last Sunday. They arrived as predicted.

    We should have learned the lesson of Paradise, Ca, and shut off power in advance. Instead, in places like Mill City, power lines were blown over and fires were ignited.

    The fire there grew to 500 acres that day. 48 hours later, more than 130,000 acres were burning.

    From what I can tell, all available helicopters are being used to rescue folks surrounded by flames, rather than fight the fires or report on the damage. Could be wrong.

    500 Square miles are currently burning across the state. Zero containment so far. Weather is supposed to help by Friday.

  25. Snape says:

    [The Northwest Interagency Coordination Center said Wednesday morning that fires in Oregon and Washington burned 515,135 acres in 24-hour timespan, and the U.S. Bureau of Land Management said in a tweet Wednesday that 27 large fires are burning more than 900,000 acres in the Northwest currently.]

  26. Gordon Robertson says:

    What’s with 2020? First covid, then this, among other disasters.

    Temps fell 60F in Denver yesterday, first time since the 1960s. Claim is the weather came from Canada. I can assure you, no one here in Canada sent it. We got it from up north.

  27. ren says:

    Two tropical systems in the middle Atlantic merge into one tropical wave.

  28. ren says:

    Hurricane Paulette’s eye is visible at 49W and 22N.

  29. ren says:

    When Paulette exceeds 60W, it will be above the hot water surface.
    A tropical storm over southern Florida will enter the Gulf of Mexico.

  30. Bindidon says:

    ” Smoke from the USA in Germany

    The worst fires ever recorded are raging on the west coast of the USA. The smoke rose to great heights and made it across the Atlantic to Germany.

    More than 12,500 square kilometers of land on the US west coast have already been destroyed by flames. That is an area almost as large as the German federal state of Schleswig-Holstein.

    About 500,000 people had to leave their homes and at least 26 people were killed. ”

    Sounds very, very derecho.

    Keep cool!

    J.-P. D.

    • Gordon Robertson says:

      binny…”Sounds very, very derecho”.

      We don’t have those conditions on the West (aka Wet) Coast.

      Portland, Oregon and Seattle, Washington, the state immediately north of Oregon, are also the home to the idiots who have been burning and looting in the name of protest. One idiot in Oregon has already been arrested for arson.

      The governments in both states, who are Democrats, have been openly supporting the violent protests as have media idiots like CNN. These fires in Oregon and Washington are unprecedented and I think a lot of it is related arson.

      I live just north of Washington State and we have no fires up here. Nor have I ever seen the likes of this.

      • Bindidon says:


        As always you twist reality until it becomes what you want it to be.

        SEATTLE Emergency responders in the Pacific Northwest are fighting misinformation along with raging wildfires as people spread unsubstantiated social media posts blaming coordinated groups of arsonists from both the far left and far right for setting the blazes.

        The FBI said Friday that its investigated several claims and found them to be untrue, while officials in Oregon and Washington state have turned to Facebook to knock down the competing narratives some posts blamed far-left antifa activists and others claimed the far-right group the Proud Boys was responsible for the fires scorching wide swaths of the region.

        All what you tell is dumb trash – be it Moon’s spin, viruses, temperature measurements, Earth’s energy balance, Einstein’s results, etc etc.

        You are and keep a childish, dumb, contrarian, antiscientific person.

        J.-P. D.

        • Svante says:

          Add gullible.

        • Gordon Robertson says:

          binny…”As always you twist reality until it becomes what you want it to be”.

          Have you not heard the term “fake news” over in Germany? The media here in North America is slobbering all over itself to defend terrorists, rioters and arsonist. It was the FBI who participated with the Democratic Party to start the Russia-Trump collusion theory. They are currently under investigation.

          Where’s the proof for the media-weenie theory that rioters and arsonists are not involved. How would you check that? These idiots are throwing molotov cocktails at police stations and police cars, do you think arson is beyond them? While they are doing all this, the Democrat governments involved are cheering them on.

          As for svante’s claim of gullibility, that’s like the pot calling the kettle black. He is one of the most gullible posters around.

          • Svante says:

            Goddy, you really swallow just about every conspiracy theory you see. Like the one about the Magnitsky act. If you’re not gullible you’re russian.

            Trump’s “fake news” meme is joke.

          • ClintR says:

            Bindidon and Svante don’t get it. The fires are on the west coast of US. West coast of Canada is not having any fires. B and S can’t figure it out.

          • Gordon Robertson says:

            svante…”you really swallow just about every conspiracy theory you see. Like the one about the Magnitsky act”.

            As I have said before, you have a strong appeal to authority in your arguments. The Magnitsky Act is based on a travesty of justice. Bill Browder, who is behind it, was fleecing Russian companies And Serge Magnitsky was an accountant enabling him by finding loopholes in Russian law. The creeps went as far as using disabled people to get around Russian tax laws.

            I have no interest in taking the side of Russia, all I know is that Russian people have suffered mightily over a century and I objected to Wall Street pigs going into their country to exploit them. I also objected to one of their own aiding and abetting a creep like Browder.

            Browder is no Boy Scout, he had strong affiliations with the Wall Street Mafia who caused the US grievous problems in the early 2000nds. Obama hired some of the creeps as advisors after they helped ruin the country. Browder is a hard-hearted capitalist who did not give a hoot about the Russian people. He got caught scamming and he got the boot. Magnitsky was also fleeing Russian when he got caught.

            Magnitsky was in poor health and he was doing OK in one Russian prison. His mother testified that he was not treated badly. Then the Russians moved him to a prison where the medical facilities were not good and he succumbed to his health issues.

            If you want to read a good account of the conspiracy to relate Trump to Russia, read Ball of Collusion by Andrew McCarthy. He is a right winger but he claims to have admired Comey and the work of the FBI/CIA. He was a federal prosecutor who worked with them on many occasions.

            He explain how laws were flagrantly breeched from a prosecutor’s POV and he does not try to protect the FBI from their blatant collusion with the Obama administration and Hillary Clinton. Strok, who was high up in the FBI, openly admitted to a hatred of Trump and he interfered to protect Hillary Clinton from using a government server illegally.

            Don’t talk to me about conspiracy theories when you openly butt-kiss Democratic criminals and their allies in the FBI.

      • Norman says:

        Gordon Robertson

        Have you forgotten recent history?

        British Columbia had a large wildfire just two years ago. What was the cause of this one? Do you also have idiot that start forest fires there as well?

        Also most the fires are caused by the massive amount of dead trees killed by beetles. If you have millions of dead trees and get a dry year, you are in for bad fires. No one has the money to remove the many dead trees, probably the fires will kill of the beetles and the forests will regrow and bloom and be nice and green until the beetles come back and kill them.

        California has over 100 million dead trees just waiting to burn up. Colorado has over 800 million dead trees. Most killed by insect activity.

        • ClintR says:

          Norman is now trying to be an authority on insects. That goes along with his effort to be an expert on trees.

          As usual, his knowledge fails him. He doesn’t even know what a pine tree looks like!

  31. ren says:

    The BOM and NOAA forecasts match. The Nino 3.4 index in November will reach -1.5 degrees C.
    You can expect high northeast winds on the west coast of North America, drought in California and numerous wildfires.

  32. ren says:

    The onset of the 25th solar cycle is weak. Sunspots show extremely low magnetic activity.
    During the coming winter, the northern hemisphere will experience extreme stratospheric intrusions.

  33. ren says:

    Sally’s tropical storm will bring flooding along the coast from New Orleans to Panama City.

    • Snape says:

      Regarding how the Oregon fires started….. most were most likely started by downed power lines – high winds. Some started in mid-August by lightning, then fanned into much bigger fires on September 6. Arson is being investigated for a small one which ended up merging with the Almeda Fire (a homeless man in Phoenix, Or).


  34. jane says:

    this seams like a horazonal tornado fueled by crop irragation water.

  35. ren says:

    A latitudinal stationary front over the southern states stops Sally at the Gulf Coast.
    Another hurricane is approaching the Caribbean.

  36. ren says:

    Hurricane Sally’s eye approaches New Orleans.

  37. Carbon500 says:

    A favourite piece of music of mine is entitled ‘Seis por Derecho’.
    A Seis is a South American dance, but internet translations as to the exact meaning of ‘derecho’ seem to vary!
    Let’s have some music. Here’s virtuoso guitarist Alirio Diaz playing the piece (written by Spanish composer Antonio Lauro):

    Could the derecho described by Dr Spencer be the inspiration for the title of this piece? It seems plausible I think.
    Are there any Spanish speakers out there who might like to comment?

    • Gordon Robertson says:

      derecho can mean ‘right’ in Spanish.

      el ojo derecho = the right eye.

      or it cam mean ‘straight’.

      por aquí se va más derecho que dando un rodeo por el parque =

      this way it goes more straight than taking a detour through the park

      Roy defines a derecho as: severe thunderstorm “squall line” high wind events that are particularly widespread and long-lived, typically moving rapidly across multiple states.

      A squall line could mean ‘straight’.

      From wiki: “Derecho comes from the Spanish adjective for “straight” (or “direct”), in contrast with a tornado which is a “twisted” wind”.

  38. Carbon500 says:

    Hi Gordon – thanks for your detailed considerations, they’re much appreciated.
    I understand that ‘seis’ also means ‘six’ in Spanish, and some writers have postulated that this refers to the six strings of the guitar. Composer Antonio Lauro (1917-1986) was a guitar virtuoso, so this seems plausible.
    I suppose we’ll never really know what he had in mind when he gave the piece this title, but it’s certainly a high-energy composition.
    There’s plenty about Lauro on the internet – I find that the arts make a fascinating diversion from science and technology!

  39. ren says:

    Sally comes to Alabama.

  40. ren says:

    Sally will stay longer in Alabama.

  41. ren says:

    Sally can cause floods in Georgia and South and North Carolina.

  42. ren says:

    The Nino 3.4 index will soon drop to -0.8 degrees C, which is full La Nina conditions.

    • Gordon Robertson says:

      norman…”A number of groups and individuals are claiming that the recent major wildfires in the Pacific Northwest are predominantly or significantly the result of climate change produced by increasing greenhouse gases”.

      That’s the new science: the scientific method has been eliminated and science is now based on how many people agree on a point, even if the point is absolutely ludicrous.

      It has not escaped my attention that the fires happened at the same time as lunatics from BLM, Antifa and Democrat-supported terrorists are also involved in arson at police stations.

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