Stunning NOAA map of Tennessee’s 1000-year deluge

15 sites had rainfall exceeding maximum associated with Hurricane Katrina landfall

What is a 100 year flood? A 100 year flood is an event that statistically has a 1% chance of occurring in any given year. A 500 year flood has a .2% chance of occurring and a 1000 year flood has a .1% chance of occurring. The map below relates [the] amount of rainfall that fell to the chances of that amount of rain actually occurring.

Nashville1 5-10

Climate Progress has been documenting the woefully underreported Tennessee deluge of 2010 aka Nashville’s ‘Katrina’. It was an off-the-charts extreme weather event that human-caused global warming set the table for and almost certainly made more intense, as a leading climate scientist explained to me (interview to be posted next week).

But I didn’t understand just how unprecedented this superstorm was until I saw the above map from the Office of Hydrological Development at NOAA/NWS.  I have never seen a map like this before, but then that may be because there simply aren’t many events to rival this one.  Look at the red streak, which is the area hit by a greater than 1000-year deluge.  And look at how much of western Tennessee was slammed with a greater than 500 year downpour.  This is the “high water” of Hell and High Water.

The NWS has more maps that put the deluge in perspective, including how it compared to Hurricane Katrina’s rainfall:

May 1 and 2, 2010 Tennessee Rainfall Totals

Here are some amazing factoids:

  • Fifteen (15) observation sites had rainfall measurements exceeding the maximum observed rainfall associated with Hurricane Katrina landfall.
  • The two day rainfall of 13.57 inches at Nashville International Airport shattered the monthly rainfall record for May which was 11.04 inches.
  • The rainiest month in Nashville is 13.92 inches in January 1950.
  • Nashville International Airport experienced its 1st and 3rd rainiest days on back to back days.
  • The heaviest rainfall occurred in a swath across Davidson, Williamson, Dickson, Hickman, Benton, Perry, and Humphreys Counties.  An average of 14 to 15 inches of rain fell equivalent to 420 billion gallons of water in just two days.

And here is what Katrina did:

Hurricane Katrina Rainfall Totals

So yes, this superstorm deserve to be called Nashville’s Katrina.  It is all the more stunning for having generated so much rain without actually being associated with a hurricane, similar to the Georgia superstorm from September (see Weather Channel expert Stu Ostro’s discussion of Georgia’s record-smashing global-warming-type deluge).

I suppose people can stick their head in the sand water if they want, but CP readers understand that this is the shape of things to come for many of the world’s great cities if we stay anywhere near our current greenhouse gas emissions path.  More on the way.

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15 Responses to Stunning NOAA map of Tennessee’s 1000-year deluge

  1. paulm says:

    BTW I believe that area had already had a 100yr flood event 2 weeks earlier!

  2. Leif says:

    I am beginning to doubt that part of the public or any of the GOP would recognize a climatic disaster in any form. In which case they are unfit to judge and should not be allowed a seat at the table.

  3. Dan B says:

    Stu Ostro’s post was a stunner to me – missed it when it was first posted. The turbulence in the atmosphere explains many of the weird, wacky (for pollyanna’s), and woeful (for the gloomy) weather events we’ve seen, in increasing numbers, over the past 5+ years.

    I seem to recall similar extreme perturbations to the Jet Stream as a leading indication of a “reset” of the Jet Stream to a new track – farther north. This would lead to more extreme storms farther north and to an expansion of the sub-tropics, very disturbing for the immense populations living in these regions: Sub-Saharan Africa, Mediterranean, India, Mexico, SW US (& SE?), etc.

  4. Bob W says:

    Is the good news about superstorms that they are a negative feedback? Evaporation absorbs energy, massive clouds reflect sunlight, the winds disperse heat towards the top of the atmosphere, and precipitation is cold… Is this considered in climate models?

    Bad news: Besides the poor souls who now occasionally get clobbered, when will the frequency increase enough to make certain areas uninhabitable, even cause repeated crop failures that endanger the food supply?

    The ‘Star Trek’ series often used fantasy cultures as metaphors for our own possible futures. It ironically rains heavily all the time on profit happy Ferenginar.

  5. Leif says:

    The energy of ~1,000,000 nuclear bombs a year needs to manifest itself someplace. 4% more water vapor, (the volume of 1.5 times Lake Superior), must fall some place.

    Global Warming = Local Storming…

  6. David B. Benson says:

    Joe Romm — Advice on notation, if you will.

    When writing a quantity with absolute value between zero and one, always include the leading zero before the decimal point.

    As in 0.1%

  7. paulm says:

    Flood Causes Record Unemployment Spike

    NASHVILLE, Tenn. — The flood is now the worst disaster in Tennessee history and has put a record number of people out of work.

  8. mike roddy says:

    There’s a reason this hasn’t been covered in MSM. Katrina gave Gore’s movie a lot of traction, and the owners of this country don’t want more of the same.

  9. Dan B says:

    Re: Bob W @3.

    Albedo effect is part of climate models. White clouds reflect more heat than dark ocean or land. However clouds still absorb some heat. A white surface in bright sun still becomes warm.

    Some climate scientists believed that the planet would regulate greenhouse gas warming with increased cloud production. That was shown to be incorrect more than 100 years ago. One of the hidden parts of the solar gain equation is water vapor – invisible but a better greenhouse gas than CO2. Also cloud cover does not make an area much colder since it helps hold heat near the ground at night. As is apparent with AGW the upper layers of the atmosphere become cooler while lower layers become warmer because the heat can’t escape back to space (re-radiate) as rapidly because greenhouse gases reflect heat back towards the surface.

    And clouds in a heating world won’t necessarily be dispersed like an even white blanket, the type that would be needed to effectively reduce heat gain at the surface. They’re more likely to become taller and aggregate into storm systems due to increased heat, more thunderheads, more intense downpours, etc.

    It’s fairly simple math that’s been born out by complex computer simulations and real world observations.

  10. Barry says:

    If only we could stop here and deal with thousand year floods as the new “normal”.

    But we can’t. As Dr. Hansen points out in his new book, there are three things that will ensure our new “normal” will be much worse:

    1) there is more warming in the pipeline from CO2 we have already emitted

    2) our infrastructure and energy systems will take years to move away from fossil fuels ensuring lots more CO2 even after we decide to do something about it

    3) our “faustian bargain” with aerosols. burning coal and diesel and other fossil fuels also releases gobs of aerosols that temporarily masking some of the CO2 warming. when we stop burning fossil fuels to curtail CO2 we will also curtail the cooling aerosols. aerosols will disappear in a couple years but much of the CO2 will stick around for millennia. the result will be a rapid and nasty warming bump we can’t escape.

    imagine being in a desperately overheated room and realizing that the thermostat has a thirty year delay built in. oh, yeah…we don’t have to image that…we get to live it.

    Senators, can we please put a big, life saving, danger-Will-Robinson, pollution penalty on fossil fuels now? Do we need to lose Florida first?

  11. Dan B says:

    Barry @8;

    “Do we need to lose Florida first?”

    My bet is we’ll “lose” something like agricultural production in the Midwest to drought and/or violent storms (prior to harvest) – or – much of the forests of the American west to conflagrations long before Florida goes under the waves.

    Rocketing food prices and viscerally horrific scenes of firestorms would do much to put the country into panic and the economy into a(nother) tailspin.

    Florida will go under the waves many years after the unseen and unknown horrors have made their point. The unprecedented violence and unpredictability of weather will most likely throw our civilization into chaos before the sea rises appreciably.

  12. Anna says:

    When I moved to Rio one year ago locals were shaking their heads saying “it’s been raining so hard for two years now, when’s this going to stop?”
    Now one year later it still hasn’t stopped, and I personally have never before in my life seen so much water coming down. Beginning of april the rains killed 200 persons here in Rio, it was terrible. This summer(i.e. January) the water temperature was 8 degress Celsius (46 F) _above_ average, and the newspapers reported that the scientists were baffled and had no idea why.
    How can that be? How can it be that scientists say they have no idea why the sea is so much warmer it causes a whole season to rain away?
    Tourists are abandoning Rio…it just rains too much.
    I wish I had a map like yours for Rio.

  13. PurpleOzone says:

    New Hampshire had 4 deluges beginning in late February and for the next month. Intense rain in sheets that went on and on. I ditched plans to go out during the last one; a man who didn’t was killed by a tree that fell from the sodden earth onto the parkway.

    Most of the storms dumped 6″. The first had howling winds that snapped or ripped apart trees. I’ve no idea what wind speed is necessary to twist a trunk into splinters. 2 weeks ago crews were still working to remove the trees from roofs. The ones that fell in yards are still there. 5 or 6 trees went down within a hundred yards of my building, fortunately none on a structure.

    Rainfall in March set a huge record. Main street in Salem, an old city, was impassable twice. Widespread flooding and damage. The national media gave little coverage.

    People this was predicted by the climate scientists and is happening in many places. It gets worse.

  14. paulm says:

    #1 That should have been 100yr precipitation event (not flood) …

  15. Doug Bostrom says:

    Ping to Joe on paulm’s comment #7,

    Flood Causes Record Unemployment Spike

    NASHVILLE, Tenn. — The flood is now the worst disaster in Tennessee history and has put a record number of people out of work.
    May 26, 2010 at 7:57 pm

    Seems that would make a great topic for a post.