By: Jo Baeza , The Independent 04/23/2004
Tom Schafer-The Independent
Mike Cothrun, assistant fire management officer for the Lakeside Ranger District, takes fuel samples from a tree at the base of Porter Mountain.
LAKESIDE RANGER DISTRICT - Drivers on White Mountain Road might have noticed that Smokey the Bear changed his fire danger sign from "Low" to "High" this week. Most White Mountain residents are aware of the USDA Forest Service signs now that fire season has begun. Few people realize how much scientific data and high tech equipment it takes to determine the daily fire danger.
Every day during fire season, fire management officers in the various ranger districts use data from the Zone Office in Springerville to determine the resources they will need to fight a wildfire if it breaks out. The data will tell them how much and what kind of equipment they will probably need, what they will need to do to protect the lives of firefighters, and how they can inform the public of the danger.
Fire weather forecasts are determined from fire weather observations taken at 2 p.m. in more than 1,000 weather stations across the contiguous United States. These observations are reported to the Weather Information Management System. The national data is combined with local information such as topography and fuel conditions. All this data is processed through the National Fire Danger Rating System to generate results that determine the fire danger in a particular place on a particular day.
One of the major components of fire weather forecasting is fuel moisture. Fuel moisture content is the amount of water in a particle of fuel after it has been oven-dried. Fuel moisture content is measured in both live and dead fuels.
Mike Cothrun, assistant fire management officer for Lakeside Ranger District, takes regular fuel moisture readings. Cothrun said, "I take readings on live and dead fuels in different classes of fuels about once a week during fire season."
Fuel classes are divided into 13 fuel models from four major vegetative groups - grass, shrubs, timber and slash. Fuel models help fire management officers determine fire behavior.
Cothrun uses both 1-hour fuels and 10-hour fuels for his readings. One-hour fuels are fuels that burn quickly with a relatively low intensity, such as pine needles and grass. Ten-hour fuels are branches between 1/4 inch and 1 inch in diameter.
Cothrun's first step is to determine the best place to get his fuels. He said, "The interface is our greatest concern, so ideally we take one around Lakeside and one near Sierra Pines."
On April 14 Cothrun drove up to Porter Mountain at mid-day and hiked around the slope looking for a good place to get his samples. "My first reading is taken from a southwest aspect where you get the most wind during the day," he said. "It's nice we've had this recent moisture, but it could dry out fast with the wind."
He searched around trees and fallen branches to determine where he could get his best samples of pine needles and wood. He said, "I need a piece that is solid but aged. It can't be real punky or too green, still having resin. I try to take a sample from the center."
When he found his "perfect" sample, he logged the latitude and longitude, so he could come back to the same spot later and determine long-term drying trends. Then he sawed a round of wood from the branch. He cut the core into chips and put them in an airtight container out of the sun.
Returning to the station, Cothrun cut the green pine needles into short pieces like a chef making a salad. He fed them into a Computrac Moisture Analyzer. When they "baked" for 15-20 minutes, he took a fuel moisture reading by dividing the weight of the moisture in the fuel by the oven-dried weight and multiplying by 100.
He said, "During the Rodeo-Chediski Fire we were getting 3 percent or less for fuel moisture readings. If it's in the single digits, it's pretty dry. The fuels will burn quite readily."
When Cothrun is not firefighting, he is doing prescribed burns on Lakeside Ranger District. He said, "When I'm doing a prescribed fire, I take fuel moisture readings a week or two weeks ahead to see if there's a drying trend. We set up a fuel moisture prescription to see what kind of consumption we'll get, and how the fire will go."
The fuel moisture reading is combined with other weather data from a RAWS (Remote Automatic Weather Station) at Lakeside Ranger Station. Once the weather data had to be taken daily by a person. Now it is all transmitted automatically by satellite. All the data goes into a computer at the Zone Office that determines the fire danger for the day and forecasts it for the next day over the entire zone.
The combined weather information is used in writing burn plans for prescribed burns, as well as in firefighting. It tells fire management officers what to expect in the way of flame length, rate of spread and spotting distances.
Accurate weather data is essential to fighting wildfires under the conditions existing today across America. The National Fire Danger Rating System helps districts decide their staffing levels for the day. Staffing levels tell district rangers what their daily response needs to be for fire suppression. For example, if conditions call for a "Red Flag" day, the preplanned response calls for engine crews to move quickly toward any fire that breaks out across the forest. In some cases Red Flag designation calls for an automatic air tanker initial attack response.
"Adjective classes" are used in fire prevention. They are the classes familiar to the public. With signs and radio spots, the fire prevention officer lets the public know what the fire danger is for the day. The classes are low, moderate, high, very high, and extreme.
From now on until the monsoons are underway, White Mountain residents can stay in touch with the fire danger by watching Smokey on the highway and listening to the radio. Fire season has begun, and residents need to heed the famous words of Smokey: "Only you . . ."
Dennis
