If you've built a campfire, you know some basics about predicting wildfire.
Grasses and twigs burn right away and then they burn away.
Small sticks or narrow split logs will burn longer, and they do the work of lighting the big logs.
READ: Tracking the latest on Utah's wildfires
Those big logs, once burning, will burn all night if you don't douse them with water.
Speaking of water: If your firewood is wet, you're in trouble.
Those who predict wildfire danger first look at water... or lack of it.
Firefighters nationwide look to the Wildfire Assessment System (WFAS) as a place to see where danger is the highest.
A key metric: fuel moisture. Anything under 30 percent moist is considered dead fuel.
Those grasses and twigs up to half and inch thick are 10-hour fuel. After 10 hours of wet weather, it's soaked and won't burn.
The wildfire assessment system says Utah's 10-hour fuel has between 1-4 percent moisture. Perfect kindling.
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Sticks and smaller branches up to three inches in diameter are 100-hour fuel. That's four days of wet weather to make it tough to burn. Again, Utah's 100-hour fuel is entirely under 5 percent moisture content.
And the big branches up to eight inches in diameter are 1,000-hour fuel. They're considered dry through about a month and 10 humid days.
More than half of Utah is under 5 percent moisture here. The rest, with 6-10 percent moisture, would still make prime firewood.
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The experts combine this rating with weather to predict where they'll need resources, and Utah is the bullseye on their maps.
Those fuel moisture levels are used to put together the Energy Release Component, or ERC.
The ERC is meant to show the amount of energy available in the form of dry fuel for a fire to devour. It examines live and dead fuel conditions and combines them to form a prediction of the potential strength of the fire at what they call the "flaming front" at its head. Utah's ERC levels were more severe than any other state on May 22.
