Smokey Bear’s holy trinity: Why NJ’s wildfire danger is extreme right now

Wildfires in New Jersey: Serious Business

In New Jersey, nature meets the sidewalk. It is a state known for its dense forests and extensive pine barrens, right next to increasingly developed suburban and urban areas.

The state's unique combination of climate, vegetation, and human activity creates a perfect storm for wildfire ignition and growth. New Jersey experiences hundreds of wildfires each year, threatening lives, property, and natural resources.

(Note: I am using the term "wildfire" to refer to all fires that occur in the natural environment. That includes forest fires, grass fires, brush fires, etc.)

The New Jersey Forest Fire Service expends massive resources to monitor and manage fire hazards around the state. They are also charged with educating the public on fire safety and prevention measures.

In periods of drought and abnormally dry conditions, dense underbrush can quickly turn a tiny spark into a raging inferno. However, weather conditions do not cause forests to spontaneously combust. (With the exception of lightning, but that is another story for another day.) A weather forecast can ring alarm bells due to the risk for rapid growth and spread of any fire that does get started.

The classic formula for wildfire development has three components. When these three ingredients come together, the fire risk may jump to Very High or Extreme and/or a Red Flag Warning may be issued for explosive fire growth.

Ingredient #1: Dry Brush

The term "dry brush" refers to dead or dried vegetation that accumulates on the forest floor and in open areas. It ignites easily and can carry fire quickly across large areas, making this type of fire fuel especially dangerous.

There are some metrics used to measure just how dry the underbrush is, including "10-hour fuel moisture". That looks at the moisture content in twigs, leaves, and grasses. When fuel moisture is low, it means those dry fuels can ignite with minimal effort.

Ingredient #2: Low Humidity

When humidity is low, the air is dry. That means vegetation like grass, leaves, and branches lose moisture much more rapidly to the air. This drying effect can turn lush, green landscapes into highly flammable fuel. And so the likelihood and intensity of wildfires goes up.

This is one of the few instances where relative humidity (RH) is a useful weather metric. (You will notice I generally use the dew point as the measure of moisture in the air, and also as our summertime "muggy meter".) Relative humidity is expressed as a percentage, measuring the current amount of water vapor in the air compared to the maximum amount of water vapor the air can hold at that temperature. Yes, relative humidity is temperature dependent — the hotter it gets, the lower the moisture content of the air.

RH below 30% is generally the benchmark for raised eyebrows amongst fire management agencies. An RH below 20% is considered very low, and highly conducive to wildfire development.

Ingredient #3: Strong Winds

Fire danger is not just about the lack of moisture. The third critical variable in fire spread is wind. Literally fanning the flames, strong winds can exacerbate wildfires by providing the oxygen necessary for combustion. Persistent winds can also propel flames across the landscape, carry embers over long distances, and ignite new fires downwind.

Wind speed and direction are critical factors when fighting a fire, whether a wildfire, housefire, or otherwise. Obviously, it is the main driving factor in where a fire may spread and how quickly.

Sustained winds of 20 mph or higher can make it difficult for firefighting efforts to keep pace with flame spread. Wind gusts over 30 mph can cause erratic fire behavior, including unpredictable and fast-moving fire fronts.

Bonus Ingredient: Temperatures

Technically, the air temperature does not play a direct role in raising or lowering the overall wildfire risk. (Other than being tied into relative humidity, as mentioned above.)

However, extreme heat can severely affect firefighters. Crews, working hard in full turnout gear, can easily succumb to heat exhaustion or heat stroke.

Similarly, extreme cold can take a toll on firefighting operations. Water used to extinguish a fire can freeze on contact with cold surfaces, potentially leading to a very icy situation. Biting wind chills could also lead to frostbite and/or hypothermia.

So What?

Continuous monitoring of fuel moisture, relative humidity, and wind conditions is essential to protecting our precious state from the devastating effects of wildfires.

In the face of increasing wildfire risks, it is crucial for every New Jerseyan to be aware of and understand the importance of extreme fire conditions. Common sense safety and prevention tips can make a significant difference in reducing the likelihood of wildfires and minimizing their impact. Including:

1.) Stay informed about current fire conditions.

2.) On high fire danger days, be especially careful of outdoor activities that could ignite a fire, like barbecuing, using power tools, setting off fireworks, etc.

3.) Always properly dispose of cigarettes and other smoking material. Flicking a cigarette into dry brush or from a car window can start a roaring fire in the right conditions.

4.) Exercise caution when building and extinguishing campfires, limiting them to designated areas, keeping them small, and never leaving them unattended. Follow any and all campfire restrictions issued by the NJ Department of Environmental Protection or local authorities.

5.) Maintain a fire buffer zone around your home and/or business properties. That means you should clear away any dead vegetation (grass, leaves, branches) and other flammable materials. Ensure your roof and gutters are free of debris, preventing embers from igniting your home.

6.) Report any suspicious activities immediately to local authorities. See something, say something.

By adhering to these safety and prevention tips and understanding the importance of extreme fire conditions, New Jersey residents can contribute to a safer environment for all.

Dan Zarrow is Chief Meteorologist for Townsquare Media New Jersey. Check out Dan's weather blog or follow him on Facebook for your latest weather forecast updates.