You've heard me talk about La Nina before, but it has been a while. We've been under the influence of El Nino since last Summer, but that time has come to an end. Check out the sea surface temperature anomalies in the Pacific:
That blue shading that extends westward from the western tip of South America, is reflective of the building La Nina. In fact, La Nina has rapidly materialized since April. The animation below shows the change:
Computer models also show La Nina continuing to get strong and maintaining itself well into Winter:
The last time La Nina visited Southern Colorado was the Winter and Spring of 2005-06 and 2008-09. Southern Colorado was plagued by high fire danger and drought, and near record low snowfall. Here is what the prevailing pattern looks like during La Nina:
That huge blocking high pressure is responsible for diverting the main storm track to the north and east, and leaves us with dry and windy weather. Not good...
While we'll continue to follow La Nina very closely, it looks like it is a certainty that we'll be in line for below normal precipitation for the Fall and the Winter. Conversely, it does mean big snows for the northern and central mountains of Colorado. That means a big recovery from last Winter. Some bad, with a little good...
Chief Meteorologist Brian Bledsoe