Severe weather and associated warnings are no stranger to the Northeastern United States. But every now and then, residents encounter an unfamiliar color in the outlook: red.
“If you get a red flag warning on Long Island, the hairs on the back of your neck should stand up,” said Heath Hockenbury, director of the Fire Weather Program at the US National Weather Service. “It’s something to watch out for.”
The NWS issues a range of warnings and watches, but the most important during fire season is the red flag warning, which actually appears neon pink on the weather map. However, these warnings can be issued anywhere, at any time. In mid-April, for example, the agency issued rare red-flag warnings in the northeastern United States, including the New York metro area. But unlike most other newscasts that stream from the agency, weather is only part of the message.
Red flag warnings are issued when wildfires are expected to get out of control. It’s been around since the 1960s, which makes it older than the name National Weather Service, which was adopted in the 1970s (previously known as the US Weather Bureau).
The agency raises red flag warnings when humidity drops, winds pick up, and vegetation is ripe and ready to burn. This is the last bit about potential fuels that is one of the differences versus warnings that focus on thunderstorms, tornadoes, and blizzards. The other is that humans play a major role in starting wildfires.
People cannot start a tornado, Hockenberry said, but they are responsible for about half of wildfires.
He said that while dry air and high winds can occur anywhere in the United States, the condition of trees and vegetation varies by region. In the northeastern United States, trees have adapted to deal with droughts, which means they don’t burn efficiently. This is partly why the region sees only a few red flag warnings each year.
In the southeastern United States, many trees are filled with an oily, burnable resin. When conditions dry up, Hockenberry said, the risk of fire goes up exponentially. A week without rain can scorch the vegetation.
Meanwhile, fire in the West is a natural part of many ecosystems. It only takes a few hours of low humidity for primary grasses and young shrubs to become wildfire fuel. Parts of this region as well as the Great Plains can see red flag warnings almost any time of the year.
Hockenberry said that while hot, dry weather is a hallmark of climate change, red flag warnings by themselves are not a good measure of the impact of rising levels of greenhouse gases in the atmosphere. About 8,000 are published annually across the country.
The NWS has issued more warnings than average over the past two years, but overall, the numbers are too inconsistent to elicit a trend. However, what is known is that global warming has increased the length of the wildfire season in many parts of the United States. This trend is expected to continue as the planet warms.
“We’ve been busy for a while longer,” Hockenberry said. In fact, it doesn’t make much sense to think of a specific fire season in most places; Now it has become the “year of fire”. For those who live in fire-prone areas, this will make it all the more important to heed red flag warnings.
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the quote: What to Know About Red Flag Warnings, Ominous Wildfire Forecast (2023, May 1) Retrieved May 1, 2023 from https://phys.org/news/2023-05-red-flag-ominous-wildfire.html
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