The National Weather Service (NWS) has issued a "red flag warning" across 11 states on Friday, due to conditions being prime for wildfires.
Nearly all of Wyoming is under a red flag warning, according to an NWS map, along with large swaths of Idaho, South Dakota, Oregon, Nevada, Utah, and Nebraska. Meanwhile, small sections of northern California, southern Montana, northern Colorado, and eastern Washington have also been given the same warning.
"A red flag warning is issued when we identify weather conditions that promote rapid spread of fire which may become life-threatening. This does not mean there is a fire. These conditions are either occurring now or will begin soon," the NWS explains in a notice posted to its website.
Many of these red flag warnings will only be in place until this evening when conditions are less ideal for a blaze to spark, though several regions across Montana, Wyoming, Nebraska, and South Dakota are expected to keep the warnings in place until Saturday afternoon.
The NWS issues red flag warnings to alert people about critical fire weather conditions that increase the risk of wildfires starting and spreading rapidly. These warnings are usually based on a combination of factors including low humidity, high winds, dry vegetation and warm temperatures.
When humidity levels drop below a certain threshold, fires can start more easily, while strong winds can fan flames and cause fires to spread rapidly. Additionally, warm conditions or a long period without rain can dry out vegetation, providing plenty of fuel for fires—dry grasses, trees, and shrubs ignite easily and burn rapidly.
"Winds will increase as a Pacific cold front sweeps across the Pacific Northwest. Very dry air and breezy winds will be present across portions of central and eastern Oregon and southeast Washington ahead of afternoon frontal passage. As a result, this area will be susceptible to rapid fire spread," the NWS office for Pendleton, Oregon, said on Friday morning.
Similar low humidity and high winds are responsible for the fire-prone conditions across all the warning states, with parts of Colorado possibly seeing record-breaking temperatures for this time of year.
"Gusty west-southwest winds develop over the higher terrain Friday afternoon. The strongest winds will be found across Jackson County and far northwest Larimer County with gusts to 30 mph. In addition, relative humidities are expected to fall into the lower teens," NWS Denver/Boulder CO said. "On Saturday, gusty west to northwest winds spread across much of north central and northeast Colorado. Temperatures will be very warm (possibly record breaking), leading to relative humidities of 10 to 14 percent."
This comes as large portions of California are sweltering under unseasonably hot temperatures. The NWS has put several "heat advisories" and "excessive heat warnings" into place across central and southern California, with temperatures of up to 114 degrees being forecast in some areas.
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