September 2011

Much of the Pacific Northwest (and western US as a whole), was compensated with a “summerlike” September featuring temperatures 3-7F above normal and nominal precipitation. My cocorahs gauge was so inactive that spiders decided to call it home. The forecast for the next couple weeks suggests that these spiders get on an ark, or learn how to swim.

Most stations recorded one of their warmest September’s on record (among the top 10 warmest September’s). Boise checked in with its warmest September, although caution should be taken in interpretation of a single station setting a record; as the influence of an urban heat island for Boise has likely contributed to some degree. A few rounds of large-scale ridging allowed for widespread warmth across the interior West during September, as a rather deep Aleutian Low forced the storm track into SE Alaska and BC.  Ketchikan, AK recorded 28.33 inches of precipitation in September, only 15 inches more than climatological normal.

Despite starting summer off in a funk, averaged over the four month span June-September temperatures for much of the inland northwest around normal and precipitation well below normal.

The late-season comeback of sorts contributed to a boom in wildfire activity, that we’ll get into in a subsequent post.  The prolonged warm and dry conditions also were beneficial to much of the apple crop in Washington State.

Water supply is quite healthy as carry over moisture from the wet winter/spring persist and longer-term drought indices suggest soils are still quite moist across the northern tier of the US.

Finally, a few fun stats on the # of days this month (and for 2011) at or above 90F

City                September        Normal          Year-to-Date            Normal

Boise, ID               9                        4                         57                           46

Spokane, WA       7                        1                         16                           20

Missoula, MT       3                        1                         23                           22

Pullman, WA        7                        2                         14                           17

Next month the outlook for winter 2011/12.

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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