Fire Weather and Atmospheric Condition Commonalities Affecting June 2002 to 2013 Colorado (USA) Wildfires

The state of Colorado (USA) was plagued by numerous large, destructive, sometimes deadly, wildfires from 2002 to 2013. June is a very critical fire weather month in the Southwest in general and for Colorado in particular. The majority of these devastating Colorado wildfires occurred during the month of June, particularly during the first two weeks. The author will focus on twelve (12) Colorado wildfires that began during the first two weeks of June 2002 to 2013 and will examine and discuss the atmospheric and fire weather commonalities of these wildfires.

In all cases, the erratic and extreme fire behavior was the result of several converging fire weather and fuel variables. Wildland fuel indices such as energy release component (ERC) were at record levels. Long term drought had been impacting the areas and influencing lower atmospheric drying. Significant mid-level dry intrusions and dry slots accompanied with ridging often brought low humidity, warm overnight temperatures, and subsidence. Turbulent mixing often led to strong, gusty winds. Wind shifts tied to cold frontal passages often led to drastic changes in fire spread and direction that exposed additional areas to large fire growth.

Several data sources will be used to explain the June 2002 to 2013, extreme fire weather and large fire growth events. These include the classic, recognized critical fire weather patterns influencing western region wildfires, skew-T soundings, satellite/radar data, HYSPLIT backward trajectory runs, lower atmospheric stability (Haines) indices, fire weather forecasts, and drought-fuel indices.