A Look Back in October...A Look Forward to this Winter

It's been no secret that the past couple of weeks have seen well above average temperatures so far in the month of October.  When looking back during this same time last year temperatures ended up below average.  During the first 12 days of October '09, the average high was 53.5°.  This year we're at a very warm 75.8° - over 20° warmer!  So why is this?  Well, we might be able to contribute it to the fact that we have transitioned into La Nina, whereas last year we were in an El Nino.  Sometimes during the falls months heading into a La Nina we tend to see above average temperatures before the winter months begin.  According to the Climate Prediction Center La Nina is expected to last at least into the Northern Hemisphere spring 2011, with predictions of a strong La Nina by the November - January season before beginning to weaken some.  Typically during a La Nina year, there is an above average chance of precipitation in the Pacific Northwest and below average precipitation across the southern tier of the country.  La Nina impacts across the region include an increased risk of extreme precipitation events as well as an enhanced threat for more frequent cold snaps.  This graphic from the

NOAA/ESRL Physical Sciences Division in Boulder, Colorado shows the threat risk for a colder and snowier than normal winter.  The second highlights precipitation.  The past couple La Nina events we've had around the area have tended to see above average snowfall and below average temperatures.