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Texas Drought In 2011

January 9, 2012
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By Paul Homewood

 

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The Texas drought of 2011 was undoubtedly extreme, but how did it compare to previous droughts in the 20thC? Annual rainfall totals were the lowest on record, but only 0.1 inch lower than that of 1917, so to call it unprecedented is perhaps an exaggeration. 1956 also was another year that was almost as dry. Significantly though, the trend, since records began in 1895, is virtually non existent, increasing at 0.02 inch/ decade.

 

                                           Annual Precipitation – Texas

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Hurricanes and tropical storms often prevent drought conditions from becoming severe, as David Roth of the National Weather Service points out in his “Texas Hurricane History” paper. On average Texas can expect one hurricane or tropical storm each year, but last year there was none. Tropical Storm Don was the nearest, but unfortunately disintegrated before reaching the coast.

However the worst droughts are those that last longer than a single year. In the 1950’s there were six consecutive years of drought lasting till 1956 and the following table, showing 2 year and 3 year cumulative rainfall totals, perhaps puts 2011 into a proper perspective.

 

  Two Year Average   Three Year Average
2010-11 21.8 2009-11 24.3
1955-56 19.1 1954-56 18.3
1954-55 20.4 1953-55 21.5
1953-54 20.8 1952-54 21.4
1952-53 23.0 1951-53 22.3
1951-52 21.6 1950-52 22.7

                                   Average Annual Precipitation

 

Based on two year rainfall, 4 out of 5 years in the long drought of the 1950’s had lower precipitation than 2010/2011, and on three year averages all 5 were worse. We don’t know, of course, how 2012 will turn out, but, as matters stand currently, there can be no question that the drought of the 1950’s was far more serious. Texas State Climatologist, John Nielson Gammon, rated 2011 as only the third worst drought behind 1918 and 1956 for this reason.

It is perhaps worth finishing by noting that the 2011 drought was geographically much more limited than earlier droughts, with only Texas severely affected this time. For instance, Oklahoma was only the 11th driest on record and New Mexico 6th. Across the South region as a whole, which includes Kansas, Oklahoma, Louisiana, Arkansas and Mississippi in addition to Texas, 2011 ranked 6th driest. The fact that the 1950’s drought was far more extensive is borne out by ranking of 2nd and 3rd for 1954 and 1956 respectively. The driest year was 1917.

 

 

                                           Annual Precipitation – South Region

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Conclusion?

While 2011 recorded the lowest annual rainfall, the drought in the 1950’s drought was longer, more intense and much more widespread. Arguably the same can be said of the 1917 event.

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