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Posted at 04:31 PM ET, 07/10/2012

How statistically unusual was the heat wave?

For some commentators, the recent heat wave signified nothing - other than a few extra drops of sweat.

Take Washington Post columnist George Will, who was completely underwhelmed by the recent spell of sweltering temperatures.

“How do we explain the heat? One word: summer,” he said on ABC News’ This Week Sunday morning.

The blog Watts Up With That also attempted to downplay the heat - arguing hotter temperatures occurred during the 1930s.

Watts took a swipe at Capital Weather Gang [bold text indicates my added emphasis]:

“[CWG is] trying to make a run of the mill summer heat wave seem like an event of unprecedented global warming proportions. It isn’t, and not even close compared to weather records history of the past.”

But the numbers reveal this heat wave was, in fact, extreme if not extraordinary.

Our analysis, while conceding comparing temperatures from today to the 1930s has complications, showed the recent heat wave was comparable to if not hotter than anything from the 1930s.

Weather hobbyist Don Sutherland, who participates on the AmericanWx.com forums, posted a compelling analysis demonstrating the exceptional nature of the recent heat in D.C. I’m reproducing part of it here-

If one examines the facts, the recent outbreak of heat was not a “run of the mill summer heat wave.” At the height of the heat wave, some cities in a region encompassing the Great Lakes. Ohio Valley, Tennessee Valley, Southeast, and Mid-Atlantic regions saw high temperatures crest 3-4 standard deviations above normal.

With Mr. Watts taking a shot at The Washington Post’s Capital Weather Gang, a closer look at the heat in Washington, D.C. is in order.

Some key statistics:

June 28: High: 96° (1.464 Sigma above the June 28-July 8 Average High for the 1981-2010 base period); Statistical Probability: 7.160%

June 29: High: 104° (2.801 Sigma above the June 28-July 8 Average High for the 1981-2010 base period); Statistical Probability: 0.255%

June 30: High: 97° (1.631 Sigma above the June 28-July 8 Average High for the 1981-2010 base period); Statistical Probability: 5.145%

July 1: High: 99° (1.965 Sigma above the June 28-July 8 Average High for the 1981-2010 base period); Statistical Probability: 2.471%

July 2: High: 95° (1.297 Sigma above the June 28-July 8 Average High for the 1981-2010 base period); Statistical Probability: 9.732%

July 3: High: 98° (1.798 Sigma above the June 28-July 8 Average High for the 1981-2010 base period); Statistical Probability: 3.609%

July 4: High: 99° (1.965 Sigma above the June 28-July 8 Average High for the 1981-2010 base period); Statistical Probability: 2.471%

July 5: High: 100° (2.133 Sigma above the June 28-July 8 Average High for the 1981-2010 base period); Statistical Probability: 1.646%

July 6: High: 100° (2.133 Sigma above the June 28-July 8 Average High for the 1981-2010 base period); Statistical Probability: 1.646%

July 7: High: 105° (2.968 Sigma above the June 28-July 8 Average High for the 1981-2010 base period); Statistical Probability: 0.150%

July 8: High: 102° (2.467 Sigma above the June 28-July 8 Average High for the 1981-2010 base period); Statistical Probability: 0.681%

June 28-July 8, 2012 Period: Mean High: 99.5° (2.057 Sigma above the June 28-July 8 Average High for the 1981-2010 base period); Statistical Probability: 1.984%

Consecutive 100° Highs: 4 (Statistical Probability of such an Occurrence during the June 28-July 8 period: 0.00000734%)

[In my opinion], any person possessing reasonable knowledge of meteorology, climatology, and/or statistics could only reject the hypothesis that the recent heat wave was not an extreme event.

D.C.’s heat wave followed exceptional year long warm event in continentall U.S.

On the national level and in a longer term context, wunderground's Jeff Masters noted the last 13-months of record-setting temperatures across the continental U.S. reflects “one in 1.6 million odds” according to NOAA.

But some have voiced concerns about that number.

Climate blogger Lucia (of the Blackboard) called it a “meaningless statistic” describing flaws in that way it was calculated.

Similarly, atmospheric scientist Michael Tobis, who blogs for Planet3.org, wrote: “I don’t doubt that something very odd is going on [with U.S. temperatures] but the number represents a common elementary statistical error and is in this case excessively alarmist.”

Lucia took it upon herself to perform a revision of the NOAA/Masters analysis and still found this warmth represents an exceptionally rare event : “The probability of the recent event really is quite low . . . I am getting a probability less than 1 in 100,000...”

Related: NOAA scientist: 80 percent chance recent heat records due to climate change

By  |  04:31 PM ET, 07/10/2012

Categories:  Latest, U.S. Weather, Climate Change, Local Climate

 
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