Thursday, October 11, 2012

Record Warm Start to October at Barrow

For the first time in nearly a century of instrumented weather observations at Barrow, the average temperature for the first ten days of October was above freezing. The average temperature of 32.1F is 0.6 degrees warmer than the previous record of 31.5F in 1977. During the first ten days of the month Barrow set two record highs (41F on the 5th and 38F on the 6th) and was within a degree of the record high on the 7th with a high  of 37F. The 1981-2010 normal temperature for this period is 23.5F.

Okay, whoop-dee-do. Half a degree. Breaking a record set 35 years ago. However, when taken in context, the significance becomes unequivocal. Here is a plot of the mean temperature for the first ten days of October since 1920 (blue) and the 10-year running mean (black). Notice that there was a bunch of warm periods in the 1930s and 40s, but since 2002 there have been ZERO cold starts to October. It wasn't like this in the 30s. The lack of near shore sea ice does not guarantee there will be record warm temperatures. But it does mean that even over as short of a period as ten days, there are many more ways to be warm (compared to long term societal and environmental expectations) than otherwise.

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