High Water: Coastal North Carolina’s second 500-year rainfall in 11 years

They just don’t make 500-year weather events like they used to.  Just look at how much of coastal North Carolina got hit by over 10 inches in the past 5 days, over 12 inches, and even over 15 inches.

Steve Scolnik of CapitalClimate has the story and the data:

3 PM Update: An additional 0.30″ has fallen in the last hour with visibility reduced to 1.5 miles in continuing heavy rain.

Original post: Excessive rainfall in the Cape Fear region of North Carolina from a tropical conveyor belt including the remnants of Tropical Storm Nicole has broken the total rainfall record from Hurricane Floyd in 1999. The Floyd rainfall has been described by the National Weather Service as a once-in-500-year event.

The NWS reported this morning that the 19.66″ at Wilmington in the 3 days ending yesterday is the highest 3-day total precipitation in records that began in 1871. The 10.33″ on Monday is also the second highest all-time single day amount following Floyd’s 13.38″ on Sept. 15, 1999. The September total so far of 20.84″ through this morning is the second highest for the month behind 1999. Heavy rain is continuing at Wilmington, and an additional 0.45″ has fallen in the 6 hours ending at 2 pm EDT.

The map to the right (click to enlarge) from NWS shows North Carolina 7-day total precipitation ending at 8 am EDT this morning. The purple area extending from eastern South Carolina northward through the southeastern coast of North Carolina and to the Virginia border represents 10-15″ of precipitation, with a smaller area near the coast of 15-20″.

According to the NWS report, here is how the current event fits in with previous history:

SUNDAY    SEP 26   0.59 INCHES
MONDAY    SEP 27  10.33 INCHES

#1  13.38 INCHES   9/15/1999 (HURRICANE FLOYD)
#2  10.33 INCHES   9/27/2010 (MONDAY'S EVENT)
#3   9.56 INCHES   8/31/2006 (TROPICAL STORM ERNESTO)
#4   9.52 INCHES   9/29/1938
#5   8.04 INCHES   8/18/1879 ("GREAT BEAUFORT HURRICANE")  

#1  17.71 INCHES   9/15 & 9/16 1999 (HURRICANE FLOYD)
#2  14.73 INCHES   9/14 & 9/15 1999 (HURRICANE FLOYD)
#3  12.29 INCHES   9/27 & 9/28 2010 (MONDAY/TUESDAY'S EVENT)
#4  11.87 INCHES   10/7 & 10/8 2005 (TROPICAL STORM TAMMY)
#5  11.54 INCHES    7/7 & 7/8 1950  

#1  19.66 INCHES   9/27 - 9/29 2010
#2  19.06 INCHES   9/14 - 9/16 1999 (HURRICANE FLOYD)
#3  17.71 INCHES   9/15 - 9/17 1999 (HURRICANE FLOYD)
#4  14.73 INCHES   9/13 - 9/15 1999 (HURRICANE FLOYD)
#5  13.44 INCHES   9/11 - 9/13 1984 (HURRICANE DIANA)  

#1  20.25 INCHES   9/26 - 9/29 2010
#2  19.06 INCHES   9/14 - 9/17 1999 (HURRICANE FLOYD)
#2  19.06 INCHES   9/13 - 9/16 1999 (HURRICANE FLOYD)
#4  17.71 INCHES   9/15 - 9/18 1999 (HURRICANE FLOYD)
#5  14.73 INCHES   9/12 - 9/15 1999 (HURRICANE FLOYD)  

#1  20.66 INCHES   9/26 - 9/29 2010 (ONGOING EVENT THROUGH 720 AM...)
#2  19.06 INCHES   9/14 - 9/18 1999 (HURRICANE FLOYD)
#2  19.06 INCHES   9/13 - 9/17 1999 (HURRICANE FLOYD)
#2  19.06 INCHES   9/12 - 9/16 1999 (HURRICANE FLOYD)
#5  17.71 INCHES   9/15 - 9/19 1999 (HURRICANE FLOYD)  

#2  20.84 INCHES   2010  (ONGOING EVENT THROUGH 720 AM...)
#3  20.10 INCHES   1877  ("HURRICANE FOUR")
#4  18.94 INCHES   1984  (HURRICANE DIANA)

In June, Dr. Kevin Trenberth, head of the Climate Analysis Section at the National Center for Atmospheric Research, explained the link between global warming and extreme deluges:

I find it systematically tends to get underplayed and it often gets underplayed by my fellow scientists. Because one of the opening statements, which I’m sure you’ve probably heard is “Well you can’t attribute a single event to climate change.” But there is a systematic influence on all of these weather events now-a-days because of the fact that there is this extra water vapor lurking around in the atmosphere than there used to be say 30 years ago. It’s about a 4% extra amount, it invigorates the storms, it provides plenty of moisture for these storms and it’s unfortunate that the public is not associating these with the fact that this is one manifestation of climate change. And the prospects are that these kinds of things will only get bigger and worse in the future.

The past 12 months have been the hottest on record, according to NASA.  So perhaps it isn’t completely surprising that we are seeing these record-smashing deluges.  But the number of these beyond-extreme events just in the United States alone ought to make people take notice:

And, of course, another part of the world has been even more devastated by deluges and flooding, albeit while receiving only moderate attention in this country (see Juan Cole: The media’s failure to cover “the great Pakistani deluge” is “itself a security threat” to America).

Remember, we’ve only warmed about a degree Fahrenheit in the past half-century.  We are on track to warm nearly 10 times that this century.  In short, we ain’t seen nothing yet!

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18 Responses to High Water: Coastal North Carolina’s second 500-year rainfall in 11 years

  1. Kim Kramer says:

    Just to clarify, I meant that there would be a 500 year event SOMEWHERE in the world once or twice a week.

    World population = 6.6 billion
    Average city size = about 200,000 people
    Number of cities = about 33,000
    If each city experiences a 500 year extreme weather event once every 500 years, there should be at least one city experiencing an extreme weather event every week.

  2. Leif says:

    So how much water does an extra 4% water amount to? Last winter the same question came up and an answer computed by another commentator, (johna @ 14, link below) estimated about the volume of 1.5 times the volume of Lake Superior looking to fall someplace.

    It is interesting to note that as that water precipitates out in rain, or snow in the winter, that that water is “gone.” No, this is the new “Normal” as new water vapor quickly evaporates into the warmer atmosphere replacing whatever fell.

    Twice as much by 2050…

    Tick-tock, Tick-tock…

    Sustainability is a Human Right!

  3. Michael T says:

    Excellent post Joe!

    NASA has just posted two detailed discussions about the summer of 2010:

    How Warm Was Summer 2010?

    2010 – Summer Data Update

  4. toby says:

    Jim DeMint will be telling people that Jesus is crying … anything but global warming.

  5. Rob Honeycutt says:

    Kim Kramer… So, why is it you associate weather events to cities? How many cities did this weather event cover at one time? And over what period of time? Do sparsely populated areas or areas of fewer cities have fewer 500 year events? Do more densely populated areas have more 500 year events?

    Do you get my point?

  6. Peter Bellin says:

    I think it is appropriate to state that this rain event is a result of climate change. The warmth of the oceans this year is clearly a result of increased heat; I reject the scientific hedging in this case.

    (Thanks, Michael T, for the 2010 NASA Update. I forwarded it to my colleagues.)

  7. Mark says:

    So if we have two extreme storms (previously thought to be 500 year events) in 11 years, what do we call these extreme storms now?

    Once in 11 year storms?

    I’m sure it is more complicated than that, but it would seem for sure that they can no longer be called 500 year events and maybe not even 100 year events.

    How is this sort of thing calculated?

  8. Aaron Lewis says:

    It looks to me like this rain event results from the same jet stream pattern as the Feb. 5-6 snow event. (see ) It will be interesting to see what the NOAA Attribution Team say that is different from what they said for the Snow Event.

    My take is that CLIMATE CHANGE has shifted the circulation patterns in the atmosphere and the Atlantic Coast should just prepare to deal with this until CLIMATE CHANGE pushes us past another tipping point. That is, do not expect a regression toward the mean or toward some previous climate. Expect more weather.

    Why do I think this is CLIMATE CHANGE rather than just strange weather? Read Dr. Deming on the behavior of systems.

  9. Watts His Face at WTFUWT (no link, since you really don’t want to go there) is already spinning the angle that Nicole was extremely weak as a tropical storm. (Which, of course, is technically a True Fact.)

  10. GFW says:

    On the issue that Kim raised and Rob commented on, do we have a standard scale for “weather correlation in space and time”? I mean if there’s an extreme wind event in Kirkland WA, and one in Lynnwood WA (about 10 miles away) on the same day, that’s the same event, not two events. But if they’re separated by two days … are they separate?
    I’m thinking both the spatial and temporal scales are different for different types of extreme weather. We know temperature anomalies correlate over hundreds of miles, and heat waves/cold snaps usually last several days. Extreme rain events tend to be more local, and flooding is often determined by local geography, so you’d need a concept of “flooding district”. Droughts on the other hand are only definable over multi-year time frames and cover large areas again. So, it would be very useful, but likely very difficult to gain a good understanding of how many 500y X-type events should be expected per year in a given large region (the US, the World).

  11. Wonhyo says:

    GFW #10: You’re obfuscating the issue. The records and statistics presented show that the majority of the top 5 rain events for 1-, 2-, 3- 4-, and 5-day all time records for the same region of North Carolina have occurred in the last 12 years. This is not consistent with natural variation when there is over 100 years of records. If this were natural variation in a random process with constant mean and stable variation, most of the top five records would have occurred early in the recorded history, with a few occasional records broken more recently, and broken by small margins. The records presented show that records are being broken by large margins, within the last 12 year, out of a 100+ year history. Furthermore, the margin by which the records are being broken is getting larger, not smaller.

    Another indicator that has been shown on CP is that the number of high temperature records broken is twice as large as the number of low temperature records that are broken. Again, if this were a stable climate, the frequency of new low records would be approximately equal to the frequency of new high records.

    One can use FUD to confuse any individual piece of climate science data (and the deniers do exactly that), but put the evidence together and it is clear that the climate is breaking out of the stable and moderate pattern that has supported the development of human civilization over the last 10,000 years.

  12. Rob Honeycutt says:

    Thanks GFW… I believe Kim is vastly misinterpreting what a 500 year event means. By Kim’s analysis we would be having 1000 year flooding events twice a month somewhere on the planet. That is just not correct on so many levels.

  13. GFW says:

    Rob, yeah, I think there are a lot less potential flooding districts than Kim’s guess. I’m just not sure how to divide the world into such districts. The catchment area for a modest river might be one district, while the drainage area of a great river system like the Mississippi might have a couple dozen.

    Wonhyo, you’ve mistaken me for a disinformer. I don’t want to obfuscate at all. I want to understand what “100 year flood” or “500 year drought” really means in such a way as to clearly communicate to the public the unprecedented (at least during the period of human civilization) nature of what is going on. Indeed, when records cluster like the top 8 hottest years (globally) all occurring in the last 10 years, that’s a clear signal – we just need a better way of explaining that for rainfall events.

    You’re correct about the 2:1 ratio of new high temp records to new low temp records – that’s a pretty dramatic indicator. Now if we just had something that clear for rainfall …

    Part of what you said was statistically wrong though. While it’s true that if you measure something that varies stochastically around an unchanging mean, the rate of new records should start high and decrease over time, if at any moment in time you ask “when did the top 5 values prior to now take place” they should be spread out randomly in the measurement period, not preferentially clustered at the beginning. That’s because the 2nd highest, 3rd highest, etc. need not have been the previous record-holder. They may have been recorded after the current record.

  14. Inverse says:

    100 year record maybe broken soon!!!

    We’re now at the first of October, and there’ve been no Category 3 or higher hurricanes (IH) to make landfall in the U. S. so far this season. The chances of a U. S. landfalling IH decrease significantly after 1 October. Over the past half-century, the only IHs to make landfall in the U. S. after 1 October were Hilda (1964), Opal (1995), and Wilma (2005). Hilda and Opal were already named tropical storms on the map as September ended—the only case forming in the month of October was Wilma.

    If an IH does not make landfall in the U. S. during the remainder of this season, this will make five consecutive seasons without an IH landfall in the U. S. The last such instance of this (based upon the current HURDAT file) was 1910 – 1914.

  15. Richard Brenne says:

    Inverse (#14) – There have been plenty of Category 3 and 4 hurricanes in the Atlantic Basin this season and the previous four seasons, they just haven’t made landfall in the U.S. (not the only place on Earth that matters, no matter what some might think).

    It’s like the U.S. is represented by a person in a small, one-room shack and hurricanes are represented by a drunk who’s blindfolded and firing a shotgun randomly around the room. You can be lucky for a while, but not indefinitely.

    During this hurricane season there have been plenty of other storms in plenty of other places, like this current rainstorm, the one that killed hundreds in a Mexican landslide, and plenty of dramatic heat events, with 17 national all-time heat records broken on four continents while no all-time cold records have been set in 2010.

    The devastating floods in Pakistan were fueled by high sea surface temperatures in the Indian Ocean, severely impacting millions and those who die of a combination of related issues like famine, heat, cold (most escaped with only their lightest summer clothes and are already suffering from cold) and disease has numbered in the thousands and will likely end up in the tens of thousands.

    This has increased dissatisfaction with a government we’re supporting, but that fundamentalists could overthrow. Then our soldiers might be fighting and dying in Pakistan in addition to two other Muslim countries. If things took an exceptionally bad turn, nuclear weapons could be used.

    So while you appear to be gleefully pointing out a quite random fact (climate change is likely intensifying hurricanes that do form, but weather steers each individual hurricane), there is, sad to say, plenty of suffering to go around due to climate change.

    And, even sadder, as Joe says, we ain’t seen nothin’ yet.

  16. fj2 says:

    Worse than human enemies waves of catastrophic climate events can cripple this country and the DoD must reinvent itself to meet the threat.

  17. Mark says:

    from the weather underground website:

    The hurricane seasons with the top ten number of named storms North Atlantic since 1851 to the present:

    includes the years

    2000, 2001,2004, 2005, 2007, 20008.

    Anyone who can’t understand the implications of that, is beyond reason.

  18. dyuane says:

    We got 16 inches of rain in Charleston. We needed the rain but I wish it could have came in June. I not going to complain.