What to know about red flag warnings as Utah’s wildfire season heats up
A red flag warning needs three ingredients: it has to be windy, very dry and there needs to be plenty of wildfire fuel, such as dry grasses and shrubs.
There’s been no shortage of all three in southeast Utah lately, as the region makes a rapid transition from off-the-charts-snowy spring to tinderbox-dry summer.
The National Weather Service has issued numerous red flag warnings for Grand and San Juan counties in recent days, meaning the conditions in those areas are ripe for potential wildfires — humidity below 15%, winds above 25 mph and critically dry, plentiful fuels that are primed to burn.
Mark Miller is a forecaster at the NWS office in western Colorado, which issues warnings for that part of Utah. Humidity levels in southeast Utah, he said, have dropped to the single digits recently.
“With it being so dry and with the fuels just ready to go,” Miller said, “we're pretty much issuing red flag warnings almost every day at this point.”
So what should Utahns do when there’s a warning in their area?
It starts with the obvious: be careful with fire on those days. Make sure campfires are completely snuffed out. Don’t throw lit cigarettes out the car window. Avoid lighting fireworks near grassy areas — something that might be easier said than done during a month that contains two of the four annual holidays when Utah legalizes their use.
There are less obvious things to be careful about, too. On a dry, windy day, target shooting or dragging a trailer chain with its sparks flying could lead to an unintended blaze.
But with near-constant red flag weather, Miller said, there’s a concern that residents will become numb to the warnings. So sometimes when weather conditions are on the borderline, he said, forecasters choose to hold off on issuing a warning — so that people are more likely to pay attention when an especially dangerous day arrives.
“If you have a red flag warning every day, it defeats the purpose,” Miller said. “We try to differentiate a little bit between the marginal and higher-end days … just to focus on the ones that can really cause issues.”
Utah’s wet winter helped keep the early part of this year’s fire season relatively quiet. But that comes with its own set of problems.
All the extra grass and brush that grew with the above-average moisture is quickly heating up and drying out — transforming into kindling for future fires.
Mike Seaman is a meteorologist with the National Weather Service office in Salt Lake City, which oversees the rest of southern Utah beyond Grand and San Juan counties. The reason there haven’t been more red flag warnings in his area, he said, isn’t because the dry, windy weather stops at the county line. It’s because the vegetation in south-central and southwest Utah has been slightly slower to dry out than their neighbors in the southeast.
Other agencies, such as the Bureau of Land Management or the Utah Division of Forestry, report those fuel conditions to NWS by checking how dry vegetation is on the ground. The fuel levels in St. George just crossed the critical threshold a few days ago, he said, and the fuels in nearby Iron, Garfield and Kane counties will likely join them any day now.
“It's definitely becoming a concern across southern Utah,” Seaman said. “A lot of the grasses [and] the brush are just starting to get to the point that they’d be available to burn and carry fire fairly readily.”
With gusty conditions sticking around and virtually no precipitation in the forecast for the next two weeks, he expects red flag warnings to be a big part of southern Utah’s summer.
The summer monsoon season that typically brings rainy relief to southern Utah is already delayed and will likely be shorter than average. The shift to an El Niño weather pattern is partly to blame, Seaman said, along with the abundant snow cover and soil moisture from this wet winter, which could also be keeping monsoons at bay.
How soon this summer’s rains arrive in southern Utah — and how long they stick around — could make the difference between an average fire season and a bad one.
“If we do get the monsoon, it very well may just shut everything down for the year in terms of fire weather,” Seaman said. “If we don't get the monsoon … we could see a significant increase in the fire activity as we get into the later part of the summer.”