August 2012

August 2012 was warmer and drier than normal for the inland northwest.  Temperatures were a couple of degrees above 1981-2010 normals, primarily led by well above normal daytime high temperatures. By contrast, nighttime lows were close to normal, with a few exceptions, primarily located in some of the more sheltered locations in the northern reaches of the region reporting below average nighttime lows including a few nights below freezing in cold air drainages.

August is typically among the driest months for much of the region. Last month did not disappoint as goose-eggs and bagels were posted for Moscow, Boise and McCall. The last measurable precipitation in Boise was July 14th, McCall July 16th and for Moscow and Pullman July 20th.  Similar active dry-spells streaks have also been observed in Seattle and Portland.

Granted, this is the time of year when umbrellas and windshield wipers go out of style, and I am quickly getting out of shape due to a lack of CoCoRAHS calisthenics. But just how unusual is the current dry-spell?  Here is a look at some of the current streaks in comparison to the top two or three longest streaks for the period of record:

Moscow (current streak, as of 9/4: 46 days)
96 days: May 28-Sep 1, 1910
78 days: Aug 15-Nov 1, 1987
77 days, Jul 3-Sep 19, 1969

Boise (current streak: 52 days)
94 days, Jul 4-Oct 6, 1943
89 Days, Jun 21-Sep 18, 1957
79 days, Aug 14-Nov 1, 1987

Seattle SeaTac (current streak: 44 days)
51 days, Jul 7-Aug 27, 1951
45 days, Sep 1-Oct 16, 1991


Wildfire season has matured in the region during the later half of July into August.   Final numbers are forthcoming; however, it is worthwhile noting that three fires ( Mustang ComplexTrinity Ridge, and  Halstead fires) that started over a month ago in central and south-central Idaho have each currently burned in excess of 100,000 acres.  Not coincidentally these and other large fires in the inland northwest have been favored by dry conditions for the last couple months in the region and stressed fuels. Note that these fires have occurred despite the policy reenacted this year to put every fire out due to extreme conditions. I’m not sure what extreme conditions truly refer to, perhaps others can expand on this.

Finally, increased water usage in August due to lack of it falling from the sky and the sunny, dry and warm conditions increased water demand for irrigation and the filling of swimming pools.  In Moscow, a failure of a main well in June and increased demand resulted in consideration of water restrictions. The first couple weeks of September are expected to bring brilliant weather to much of the inland northwest with temperatures close to normal and a continuation of our dry spell.

This entry was posted in Uncategorized by John Abatzoglou. Bookmark the permalink.

About John Abatzoglou

John is an associate professor of Geography at the University of Idaho. John's interests are centered around climate and weather of the American West and their impacts to people and natural resources of the West. John and his Applied Climate Science Lab at the University of Idaho have published nearly 100 papers and book chapters on climate science, meteorology, and applied climate science connecting climate to water resources, wildfire and agriculture. The research group also develops web-based climate services that connect climate data with decision makers to help improve climate readiness of societies and ecosystems.

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