How Weather Impacts Forest Fires
A wildfire – also known as a wildland fire – is a fire that typically occurs in rural areas and is classified by the type of combustible vegetation where the event takes place. The location specific terms used range from a bush or brush fire to grass, forest and desert fire to veld, peat, hill and vegetation fire. Some of these fires burn out of control and destroy property.
The Major Causes of Wildfires
There are four main causes of wildfire ignition. They include lightning, spontaneous combustion, volcanic eruption and the most common: human-caused. Of the human-caused wildfires, there are four additional sub-categories which include arson, powerline arcs, sparks from equipment and motor vehicles and discarded cigarettes/campfires that are not properly put out.
How Wildfires Spread
Wildfires spread based on four main components: the type and availability of flammable material, the vertical arrangement of that material, the moisture content of that material and the weather conditions. The topography of the region surrounding the fire also plays a part in the way in which it spreads along with the density and arrangement of the fire fuel.
The Different Types of Wildfires
Ground fires are fueled by various types of underground organic material. These fires generally burn by smoldering. This is why a ground fire can burn slowly for a long period of time such as several months.
Surface fires – also known as crawling fires – are fed by vegetation that is located low to the ground including fallen timber, grass, leaf litter and other debris. These fires burn at lower temperatures and move slowly.
Ladder fires burn hotter and move faster as they consume small trees, vines and invasive plants that populate the area between low-lying vegetation and tree canopies. Fallen trees and branches also contribute fuel to these fires.
Crown fires – also called aerial or canopy fires – are fed by material that is suspended at the level of the tree canopy. This may include tall trees, vines, mosses, branches and leaning trees. The density of the crown fuel impacts this type of fire considerably.
Weather Conditions And Wildfires
Various weather conditions play a huge role in the development and spread of wildfires. Drought, heat waves, lightning storms and high-pressure ridges increase wildfire risk and affect the behavior of these fires. Fire seasons grow in length when wet years are followed by warm periods and climate cycles such as El Nino contributed to the conditions greatly.
Records indicate that since 1985 snowmelt that has occurred earlier in the spring following by lengthy warming trends has impacted the length and severity of the wildfire season in Western North America – California and British Columbia in particular where wildfires have destroyed millions of acres of forest and in many cases burned up nearby communities.
The 2017 Wildfire Season
Last year several records were set through wildfire activity. In British Columbia, a total of over 3-million acres was burned. Three records were set during the season including the largest total land area burned in a single fire season, the largest number of evacuees in a single fire season (approximately 45,000), and the largest single fire ever to burn in the province.
Montana saw 1.29-million acres burned in 2017 which ended only because of rain and snow activity in mid-September. California was also hit hard during the last wildfire season. The late fires in October destroyed 8,900 structures, burned 240,000 acres and killed 44 people. The single largest fire in California history was the Thomas Fire which was active in December. It burned a total of 281-thousand acres of forest in Southern California.
WeatherBug Provides Alerts To Warn You Of Severe Weather
From current conditions to air quality forecasts that can impact your health during wildfire season, WeatherBug has the information you need at your fingertips. Download the app from www.weatherbug.com or from your favorite app store.