Happy New Year Everyone!!
Thanks to John for allowing me the chance to do a guest blog about southern Idaho’s December weather (or lack of weather) and a little about some work we are doing here at Boise State.
In southern Idaho, December’s weather was dominated by a persistent ridge of high pressure (both aloft and at the surface) that brought nice sunny days throughout most of the month with little precipitation falling. This dry month (8th driest on record) follows a November that was the second driest since 1940, the combined months precipitation was 0.69 inches compared to an average combined total of 2.90 inches. In addition to lower than normal precipitation, Boise’s temperatures averaged slightly higher than normal (even though an inversion was present much of the month) with the months average maximum and mean temperatures being 41.5/31.3 degrees (F) compared to the 30 year averages (1981-2010) 37.5/30.7 respectively. Minimum temperatures were slightly lower than the average 24.0 at 21.0 degrees (F). Boise did not fare any better in the snowfall department. With the mostly higher than normal temperatures, snowfall did not even reach the half inch mark for the month.
The results of the combined low precipitation and slightly above normal temperatures of Boise over the last couple of months can also be seen in the surrounding foothills and mountains of the Boise River Basin. Bogus Basin Ski Area (just north of Boise) typically opens up in mid December and runs until spring break. Historically, 6 January was the latest opening date on record (since 1964). Today being January 5th and there no perceivable snow on the ground, it looks like an unfortunate record may be set this year. Up in the mountains of the Boise River Basin conditions are a little better, but not much. At the start of December the basin average precipitation totals (from NRCS SNOTEL) was at 73% of normal, by the first of January that percentage was down to 58%. These kinds of total make it rather tough for long-range streamflow forecasts to achieve much skill. To that end, the remaining section of my guest blog is dedicated to some work I have done in that arena.
As part of my PhD work I have developed a technique for development of teleconnection (e.g. MEI, PDO, etc…) based forecasting models to predict total natural streamflow of the Boise River at quarterly and annual scales. This water year’s forecast was issued 16 Oct 2011. The first quarter forecast for natural flow (Reclamation calculated Qu) for Lucky Peak Reservoir was 186,000 acre feet (185,957 to be exact), observed flow was 175,893 acre-feet (http://www.usbr.gov/pn/hydromet/yearrpt.html). Forecast error was 5.72% (10,064 acre-feet difference). Last year’s (water year 2011) first quarter forecast error was 4.20%. As we move into the New Year, I will continue to monitor the year’s weather and flows to see how the developed forecasts fares in these rather unique conditions.
If you are interested in the work I am doing, you can visit my web page for additional info (http://earth.boisestate.edu/people/graduate-students/mel-kunkel/). I welcome questions or comments.