A bout of strong winds overlapping with bone-dry weather will lead to a major episode of dangerous wildfire conditions across parts of Colorado and New Mexico on Friday.

The National Weather Service Storm Prediction Center has placed cities including Colorado Springs and Pueblo, Colo., and Albuquerque in a top-tier “extremely critical” risk category, writing that a “volatile combination of very strong/gusty winds, anomalously warm/dry conditions, and near-record dry fuels will encourage extreme fire-weather conditions.”

Red-flag warnings, which highlight the potential for rapid fire spread, blanket New Mexico, eastern Colorado and the Texas Panhandle, as well as much of Arizona, western Nebraska and western Kansas.

Fire conditions will begin to manifest Thursday, especially in the Southwest, before worsening into Friday and expanding into the eastern Rockies and western Great Plains. That’s when the Weather Service warns the weather “will become favorable for rapid fire growth and erratic fire behavior.”

“Fires may quickly become out of control,” it writes, with winds forecast to gust between 45 and 60 mph. High-wind watches stretch from the Texas and Oklahoma panhandles through the High Plains and into the Sandhills of Nebraska.

This is occurring as the Tunnel Fire northeast of Flagstaff, Ariz., had burned nearly 20,000 acres as of Wednesday evening. The fire tripled in size from Tuesday, torching two dozen structures and forcing the closure of Interstate 89.

Conditions for battling the blaze will remain challenging through Thursday, with a red-flag warning in effect until 8 p.m. local time. Winds could gust to 40 mph amid relative humidity as low as 10 to 15 percent.

The setup

The ingredients for a major fire-weather “outbreak” were beginning to come together Thursday as a zone of low pressure was taking shape just north of the Four Corners region. It will intensify over the next 24 to 36 hours before ejecting out of the Rockies and strengthening over northwest Nebraska.

That low will swing a sharpening dryline eastward over the High Plains on Friday and Saturday. A dryline is the leading edge of arid air from the Desert Southwest as it encroaches into a mild air mass laden with Gulf of Mexico moisture. The resulting clash will brew strong to severe thunderstorms from the Texas Panhandle to eastern South Dakota on Friday.

Behind the dryline, humidity will plummet. Relative humidity levels of 5 to 15 percent will be common as air sloshes down the Rockies on west-southwesterly winds. That results in “downsloping,” with parcels of air drying as they sink to lower elevations. The downsloping and resulting warming will sap the already dry ground of much of its remaining moisture.

The drying air will accelerate through the Front Range into the Plains, with the strongest gusts Friday and Saturday in central New Mexico, eastern Colorado and western Nebraska and Kansas. That’s roughly the same region where precipitation has ranged about 60 to 80 percent below normal over the past three months.

Denver has seen no snow this April, compared with an average of more than half a foot, and appears likely to post its shortest snow season on record.

The U.S. Drought Monitor indicates that most of eastern New Mexico, eastern Colorado or the High Plains are in a severe drought, while a Level 4 (out of 4) “exceptional” drought engulfs a wide swath of the Texas Panhandle and the Hill Country.

Temperatures between 20 and 30 degrees above normal also will intensify the fire risk, particularly on Friday ahead of a cold front advancing through the region. High temperatures in eastern Colorado and the western Plains are forecast to soar into the 80s and even low 90s, challenging records in some cases.

Impacts

With the particularly dry and windy conditions, the stage will be set for any sparks to ignite the landscape like a tinder box. The worst comes Friday and Saturday, when cities including El Paso and Denver, Aurora and Lakewood in Colorado will face “critical” fire weather. Areas just east of Denver will deal with “extremely critical” conditions.

“Any fire that starts will have the potential to spread rapidly, and would be difficult if not impossible to control,” wrote the Weather Service in Boulder, Colo. “Avoid any and all outdoor activities that may produce a spark and start a fast moving and potentially destructive wildfire.”

In a hazardous-weather outlook released to the public, the Weather Service’s advice was unusually grave.

“If you live in a vulnerable area, it would be prudent to have a go bag ready with important documents, medications, and valuables in the event of an evacuation,” it wrote.

The past several weeks have featured a slew of fire weather outbreaks. On March 29, several fires erupted along the western Oklahoma border with Texas. The town of Durham, Okla., was evacuated to the south while other fires burned near Crawford, Okla., and Canadian, Tex.

Nine days earlier, more than a dozen serious fires burned across the Southern Plains in a similar episode. Brown County, Tex., was placed under an evacuation order.

Colorado, at the heart of the risk area on Friday, ended 2021 with tragedy after a wildfire in late December torched more than 1,000 structures near Boulder. The Marshall Fire caused half a billion dollars of damage. It came on the heels of Denver’s driest July-through-December on record, with record-low snowfall.

In March, a second blaze near Boulder, known as the NCAR Fire, burned 190 acres and forced 19,000 people from their homes.