WeatherWhys Blog

2011 fire season underway

2011 fire season underway
A lawn mower sparks a grass fire in the area of Lotus Lane and Watts Drive in southeast Bakersfield on Wednesday, May 25, 2011. Two sheds burned in that fire.

Our monsoon season has begun earlier than usual (normal is mid-July). And although triple digit heat started a bit late, it too has made up for lost time. We end the abbreviated work week with day number 7 of Heat Wave #2. It will be the 12th 100-degree day, compared to a normal occurrence of 13 triple digit days by now. So we’re back on track after a cool start to the sizzling summer season.

This brings up wildfire season for Kern County and what that prospect may hold for residents in mountain towns. Last year turned out to be a memorable year with the massive Bull Fire north of Kernville quickly followed by the West Fire near Tehachapi and Crown Fire southwest of Lancaster. We usually see very hot and dry weather in the summer- all conducive to fire formation. Lightning can start fires instantly, but when the human factor is included it becomes an even more dangerous potential. So this year I have added a new product to my collection of meteorological tools. I call it “FireCon”.

This stands for Fire Condition and is similar to what you might find in the high country on those signs which report fire danger- from low to extreme. The daily FireCon is gauges current weather status on favorability for wildfire formation and spread. There are only 2 primary elements:  A) Fire initiation danger and B) Growth/Spread Potential. The first calculation is known as the Fosberg Index. This was developed in 1978 by a Forest Service meteorologist who devised a fairly straight forward measurement of heat, humidity, wind and fuel moisture content. The index is high when it is hot, dry and windy with a bone dry forest. It was originally known as the “Fire Weather Index”. My second element is known as the Haines Index. It measures stability and dryness of the entire atmosphere. Both the Fosberg and Haines Indices have 2 broad components each which are calculated. Donald Haines, a Forest Service research meteorologist published his scale in 1988.

These 2 indices individually weigh the current atmospheric conditions on a scale of 1 to 5. FireCon simply adds them together. The result is a value between 2 and 10. When the sum equals a value between 2 and 4, the FireCon is declared GREEN. FireCon is YELLOW for 5-6, ORANGE for 7-8, and RED for 9-10. A RED FireCon would generally be accompanied by a Red Flag WARNING or Fire Weather WATCH.

Additionally, lightning conditions are part of the daily FireCon. It, too, is rated on a scale of 1 to 5. Lightning Activity Levels of “1” mean no lightning, and “5” means widespread coverage of lightning. Three levels of increasing lightning activity exist from 2 to 4. Both of the primary elements (Fire Danger and Growth Potential) are shown on my FireCon graphic. Whenever there is an active wildfire incident underway, channels 29/58 will display a standardized map with the current status on the fire. This will include acres burned, active acres burning and percentage contained. The active fire will also be assigned a number (again from 1 to 5) showing the aggressiveness and threat from the ongoing wildfire. That “Wildfire Category” will reflect the immediate threat level, not necessarily how much the fire has already burned. This increased fire awareness will be presented as a routine graphic through October (or the end of the fire season).