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Is US Weather Becoming More Variable?

April 15, 2012

 

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We are often told that our weather is becoming more unpredictable and extreme. Global Warming will bring more rain to some areas while making other areas drier.

Is there any truth in this?

 

Well, certainly not in the USA. The NCDC fortunately provide comprehensive climatic data, which allows us to check these things out. Consequently, we can look at precipitation records year by year back to 1895 and see them split into  nine separate regions.

http://www.ncdc.noaa.gov/oa/climate/research/cag3/regional.html

I have taken the period 1901-2010 and identified the top 10 driest and top 10 wettest years in each region. The number of such extreme years occurring in each decade are shown below.

 

  WEST NORTH
WEST
SOUTH
WEST
WEST
NORTH
SOUTH EAST
NORTH
CENTRAL SOUTH
EAST
NORTH
EAST
TOTAL
1901-10 3 0 4 1 3 1 1 1 1 15
1911-20 1 0 0 1 2 0 1 0 1 6
1921-30 2 4 2 2 2 1 2 5 1 21
1931-40 2 2 1 4 1 3 3 1 0 17
1941-50 2 3 2 0 3 0 2 2 2 16
1951-60 2 2 3 2 4 2 2 1 1 19
1961-70 0 1 1 0 1 3 1 1 4 12
1971-80 1 1 1 2 1 2 2 2 2 14
1981-90 4 3 4 3 0 4 1 2 2 23
1991-00 2 3 1 3 2 2 3 2 1 19
2001-10 1 1 1 2 1 2 2 3 5 18
TOTAL 20 20 20 20 20 20 20 20 20 180

 

A “normal” decade, of course, would come out with 1.8 extreme years per region, or 16.4 for all nine regions. So clearly the latest decade works out as pretty unexceptional and, furthermore, shows a trend back to “normal” weather after the more volatile decade of the 80’s. The following graph gives a better perspective back to 1901.

 

 

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The last decade is clearly in line with most of the previous decades of the 20thC. Only the 1910’s and 1960’s had significantly more stable weather.

Global Weirding? Not in the US, at any rate.

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3 Comments leave one →
  1. Mike Davis permalink
    December 25, 2011 12:41 pm

    It is a travesty they can not find a trend towards more extreme weather when the models provide scenarios of more extreme weather. It is just so weird that no matter how much the tweek the models they can not get them right.

  2. grayman permalink
    December 25, 2011 8:22 pm

    Yes it is true. Drought in one region and more rain in a different region. Been happening since the beginning of time. I think the extreme weather they speak of is in terms of Money, other than that it is still the same. I am so tired of their reliance on models to tell us that this or that is going to, or happening now . They need to get out of the ivory towers and see for them selves. Earth will do as it always has done no matter what we think or do.

    Merry Christmas.

  3. ferd berple permalink
    December 27, 2011 5:26 pm

    This graph of BEST shows clearly that temperatures over the past 200 years are becoming less extreme. The lows are increasing and the highs are decreasing.

    http://woodfortrees.org/plot/best-upper/trend/plot/best-lower/trend

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