Fire danger: What goes into calculating this threat

By Candace Campos - Meteorologist

Posted on @FFS_Orlando/Twitter

The Wildland Fire Danger Index is used to describe the potential for a fire to start and the amount of energy that would be required to fight that fire on any given day

Especially during the dry season, meteorologists, including here at News 6, will use this index to explain  the severity of the fire danger.

In Florida the Fire Danger Index uses two specific factors in its calculations.

Energy release component: This is a unit that considers the severity of fire fuels. It includes how dry the surrounding vegetation is and the behavior of the wind. The drier and breezy the conditions are, the higher the energy release component will be. 

Relative humidity: This the percentage of the actual water vapor that is in the air. A muggy and foggy day will have a higher relative humidity value compared with a drier day.

In some situations, low relative humidity does not always mean a high fire danger, and vice-versa. This is the same  for energy release component. A high energy release component does not specifically mean a potentially active day.

Both variables need to be in play for the fire danger index to increase.

The fire index scale goes from low to moderate, high, very high and extreme. Each region has its own specific range that best reflects the fire behavior to them. 

Florida Forest Service ERC and RH indexes.

The Fire Danger Index is calculated daily, based on the National Weather Service forecast for that particular area. This observation is usually taken at 1 p.m. each day.

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