WeatherWhys Blog

A new wildfire scale

A new wildfire scale
Firefighters prepare to attack flames as a fast moving wildfire nears Palmdale, Calif. on Thursday, July 29, 2010. (AP Photo/Dan Steinberg)

We all know what a category 5 hurricane is, or the damage that can be done by an EF-1 tornado. But why hasn’t anyone thought about coming up with a standard Wildfire Scale? Well, after last week’s major fires that developed in a flash and stalked portions of Kern County- that is exactly what I propose.

For many years the media has communicated intensity ratings of hurricanes using the Saffir-Simpson scale disseminated by the National Hurricane Center. A similar rating describes tornado damage, formerly the Fujita Scale (F-Scale) and now the enhanced, or EF Scale researched and reported by the National Weather Service. The public is also well acquainted with earthquake intensity, characterized by the popularly known Richter Scale, or moment magnitude and the lesser known Mercalli Shake Scale through products of the US Geological Service.

With all of this in mind, it would be helpful for the general understanding of potential dangers posed by western US rangeland and forest fires to develop a standardized Wildfire Categorization protocol, issued by Incident Commanders. My draft concept has the implied goal of achieving a meaningful Wildfire Threat Magnitude classification that can be both observed (current state of the fire) and forecast (expected condition in the upcoming 6 hours).

Here is how it works: Once a wildfire develops in Kern County (or anywhere else in the US), the nearest firefighting agency arrives on scene and sets up a staging area from which to manage the conflagration. An incident team is assembled with a commander who directs the firefighting effort. After assessing the situation, a control line is established in order to ultimately surround the fire with defensible space that lacks fuel for the fire to progress. It is in this initial stage that the Incident Commander would give the fire a name and make the appropriate declaration, usually a category 1 or 2 wildfire. It also gets a color code- yellow, orange or red.

The domain of wildfire ratings goes from category 1 (incipient- initial), to category 2 (growing and threatening), to category 3 (major aggressive fires), to category 4 (major aggressive fire of at least 5,000 acres expanding at 400 acres per hour), to category 5 (major very aggressive fire of at least 16,000 acres expanding at 1000 acres per hour or more).

Contributing factors to how an incident commander would rate these fires include: the state of ground (burnable fuel), topography (fire enhancement potential), weather (short term forecast of temperature, humidity, wind and lightning) and downwind structures (threatened property).

Routine reports would be sent out at 7 AM, noon, 5 PM and 10 PM daily. The progress of each fire could be followed on an almost hourly basis. Here are a few examples of what it might look like:

The “Starbuck Fire”- Southern Sierra (5 PM Update)
Category 4 RED- 9,000 acres, 10% contained, expanding 600 acres/Hr

The “Drew Canyon Fire”- San Gabriel Mountains (Noon Update)
Category 5 RED- 25,000 acres, 9% contained, expanding 1,100 acres/Hr
**Happy Valley Threatened- Mandatory Evacuation**

The “Simon Creek Fire”- Los Padres Nat’l forest (7 AM Update)
Category 2 ORANGE- 900 acres, 0% contained

I would love to get some feedback on what the public thinks about such a protocol. Please respond to this blog, if you have a comment, or send me an e-mail at with any ideas of your own.