The fuels surrounding the Decker Fire are extremely dry and prone to ignition right now, fire behavior specialist Scott Cones said.
Fire behavior specialists use a statistic called the Energy Release Component (ERC) to measure how hot fuels will burn if they catch on fire. The ERC uses a composite fuel/moisture index, including both alive and dead fuels, to predict potential fire intensity.
The ERC for fuels near the Decker Fire Thursday was in the 99th percentile for days between April 1 and Oct. 31 from 1968 to now, Cones said. That means the area is as dry as the driest 1 percent of days in that time frame.
Cones said the ERC is affected by humidity recovery, snow and other types of precipitation and is hard to forecast.
Hot, dry, windy weather sucks the moisture out of fuels, public information officer Rick Barton said, which leads to the high ERC. Conditions are really, really dry, he said.
This dryness is unusual, particularly given the wet spring Salida experienced, Barton said, but after midsummer the usual afternoon rains didn’t appear.
The high ERC means fuels around the fire are more prone to ignition, Barton said. If fuels surrounding the fire catch an ember, they have a 70 percent chance of ignition.
The high ERC also indicates fuels have the potential to burn hotter and consume more than with a lower ERC, Cones said.
Fire behavior analysts calculate the ERC daily, Barton said, and take the last seven days into account.