Watch Hill firefighters responded to a small but quickly spreading brush fire today on Turtleback Road. The fire was extinguished within minutes and the total burn area was less than half an acre.

We would like to remind all residents that brush fires can and do occur during the summer even when most of the forest is very green. It only takes a ignition source and a few minutes for a small fire to start and then spread rapidly.

In fact, the Fire Danger Rating today for our area was classified as " Class 5 EXTREME"

For those that are curious, the Rhode Island Department of Environmental Management, Division of Forest Environment is responsible for calculating and distributing the potential fire rating each day.

According to their website and Facebook page, as fuel types and conditions, and recent, current, and predicted weather play an important role in determining the risk for serious brush fires, a system has been developed to analyze these and other factors. Using complex mathematical calculations, a numerical value which correlates to “risk” is derived. This number can fall into any of five groups or “Classes”, and the result is reported as a “Class (blank)” fire danger. This system, in one form or another, is used throughout the United States and is called the “National Fire Danger Rating System (NFDRS)”.

There are two primary factors that determine fire danger risk: “Spread Index” and “Buildup”. “Spread Index” is a calculated number relating to wind speed and fuel type, and is a prediction of how fast the fire will spread across the surface fuels. “Build-up” is a calculated number that relates to how deep the fire will burn into the ground. Added together these two numbers determine the “Fire Index” which will give us our class day.

It is important to note that brush fires can happen in the summer even when everything is green. The summer season which is basically from the end of May through the beginning of September is a common time for brush fires. At the beginning of summer, once the trees and shrubs have fully “leafed out” and there is full canopy cover, there is more moisture in the fuel (fuel moisture), and the fuels on the forest floor are not being dried by the sun’s rays. The risk for brush fires decreases. However as the summer goes on and we end up with dry conditions we can start to have summer fires. These fires burn in the duff layer which is the upper layer of the forest floor and is comprised of fallen needles, leaves, and organic matter. Once you get a “ground fire” ignited it tends to burn deep and it takes lots of water and effort to put these fires out.

What does all this mean to the firefighter? The higher the spread index value, the faster the fire will move across the ground especially in fine fuels such as grasses or dry leaves. Under these conditions a fire can spread very quickly. The higher the calculated build-up number, the longer the firefighters can expect to remain on scene. This generally happens during summer drought conditions and usually requires the addition of wetting agents to help water penetrate deeper into the duff layer in order to extinguish the fire.

Remember, if you see a brush fire, please call 911 immediately.

Even a small fire can spread rapidly under the right conditions.