August 2011

The month of August ended with a couple warm weeks that ended our 6-month streak of below normal temperatures across much of the Northwest. Regionally, temperatures were on average 1-2 F warmer than 1981-2010 normals, with temperatures a bit more above normal for daytime highs than lows.  On the west side of the Cascades in Washington state, the streak lives on.

Overall, temperatures for climatological summer (June-August) were below normal.  I had commented that Lewiston, Idaho hadn’t reached triple digits yet for 2011 earlier last week, before hitting the 100+ mark three days in a row into last weekend.  But, despite the 8th inning rally, still ended the summer below normal, much like 2010.

The Climate Prediction Center and various mid-range forecasts are calling for a warm first half of September, with the bullseye right over eastern Washington into western Montana as a strong and broad ridge builds in across the Northwest and stops pestering Texas. Perhaps this is dare I say our rain check on summer.

The soggy days of last winter and spring came to an abrupt halt in July and in fact most of the inland northwest has received well below normal precipitation during the driest time of the year.  I didn’t hear anyone complaining about this.  I did not record any measurable precipitation between July 22 and August 29.  The Pullman airport (ASOS) failed to record any precipitation in August and recorded its last measurable precipitation in mid-July.  Further north and east a few more convective precipitation events occurred, but overall quite dry the last two months.  Again, anyone complaining?

The dry conditions seem to have allowed for an interesting change in the insects that terrorize me.  This month, along with being stung a couple of times by wasps that seem to benefit from warm & dry conditions, spider mites decided colonized my backyard weather station, basically spinning a web about my anemometer that eventually resulted in it failing to spin.  I wonder how often automated weather stations suffer from similar problems, especially when moving parts are involved.  I’ll have to think of a clever name for the phenomena in the meantime (update: Katy suggested insecterruption, meaning an interruption in data caused by insects, I like this moniker; John M. points out that mites are not insects, but a type of arachnid, and inverterruption might be a more appropriate title).

Finally, while fire season was non-existent in the northwest until a few weeks ago, the sub par precipitation along with the recent warm temperature, and forecast for a continuation of this regime for the next 10-14 days is a concern for late season fire activity.  A plot of the energy release component (ERC), which is a good proxy for potential fire “danger” or fuel dryness is showing that current values are near the extreme levels. Large wildfires tend to preferentially occur when ERC values are high, particularly when they remain elevated for an extended period.  Given the forecast the next couple weeks, this is something to keep our eyes on.  Capstone fires that occur at the end of the season can be quite interesting, especially as we move toward a time of the year when temperature/pressure gradients tend to increase, and along with them, increased wind speeds and potential for wind-driven wildfires.