Accurate weather observations are essential for the safe management of both prescribed fires and naturally-ignited resource benefit fires. Precise measurements of parameters such as wind speed, wind direction, temperature, relative humidity, dew point, and precipitation provide reliable assessments of current conditions and allow for better weather forecasts. This results in better fire behavior forecasts.
The importance of timely and precise measurements cannot be overstated, as weather conditions directly affect fire and smoke behavior, fuel condition and flammability, and ultimately, the safety of firefighters and the public.
Kevin Osborne, a master's degree candidate in forestry sciences at California Polytechnic State University, is a first-year firefighter and member of the ten-person crew at the Sequoia Wildland Fire Module (WFM) in Springville, California's Sequoia National Forest. Osborne notes that the Sequoia WFM crew specializes in monitoring and managing prescribed and resource benefit fires, and is trained to contain wildfires when required. He says that his crew will "cut fire line, use chainsaws, hike from here to the end of the earth, and do anything any other hand crew does."
Osborne was on the scene at last summer's Sheep Fire, which was ignited by lightning on July 16, 2010 in Kings Canyon National Park. The fire spread into Sequoia National Forest, and eventually was contained along its western flank.
As part of its fire management best practices, the Sequoia WFM used a research-grade HOBO® Weather Station to collect hourly readings for weather parameters. The data were offloaded daily, graphed using accompanying HOBOware® software, and reviewed during morning briefings to inform crews of the latest fire weather trends.
Osborne reported that in one instance, during an evening burnout operation held to contain the fire, the weather station was set for readings every half hour, as darkness made it difficult to use traditional belt weather kits (a sling psychrometer to measure humidity, a wind meter, and conversion tables). He explained, "During increased risk operations where firing devices are used, having weather readings every half hour is important to ensure that temperatures, humidities, and wind characteristics do not change to conditions that could reduce firefighter safety. As each reading on the half hour was offloaded, it was read over the tactical radio frequency so firefighters were aware of the weather conditions."
Although primarily used as observational data at morning briefings during the Sheep Fire, Osborne said that Fire Behavior Analysts will be able to use the collected fire weather data in the future as inputs to fire modeling software such as FSpro (a predictive model that looks at the probability of the spread of fire). In this way, HOBO data logger information can contribute even more to the increased understanding and knowledge of fire behavior, thereby further enhancing firefighter and public safety.