With gusts in Boulder peaking at more than 100 mph Wednesday and Xcel Energy shutting down power lines to at least 50,000 people along the Front Range as part of its Public Safety Power Shutoff procedure, it’s worth noting that extremely high winds are not unusual for Boulder and the Front Range.

Chinook winds are warm, dry, downslope winds that occur on the leeward (eastern) side of the Rocky Mountains, particularly along Colorado’s Front Range from Denver to Boulder and north to Fort Collins.

Westerly air flows over the Continental Divide, rises on the west side, cools, and precipitates moisture as rain or snow. As the now-dry air descends the eastern slopes, it compresses and warms at about 5–10 degrees per 1,000 feet of descent, often raising temperatures dramatically — sometimes 30–50 degrees in hours — while lowering humidity.

In the Front Range, Chinooks are “snow-eaters,” rapidly melting snow and drying fuels, which heightens wildfire risk.

MOUNTAIN WAVE AMPLIFICATION

Strong westerly flow perpendicular to the Rockies creates lee waves or mountain waves: standing atmospheric waves downstream of the barrier.

Under ideal conditions — a stable layer above the mountains and strong pressure gradient — the waves amplify. Air accelerates downslope like water over a rock, forming a “hydraulic jump” where winds surge to hurricane force (often 80–150 mph in canyons and foothills).

Boulder sits in a “sweet spot” for amplification due to its position at the base of the Flatirons and the Continental Divide’s topography, with extreme gusts focused in areas like the National Center for Atmospheric Research Mesa Lab south of Boulder.

These events occur mostly from September to June, triggered by high pressure west and low pressure east.

Going back to 1967, the Boulder area has seen at least 16 windstorms with wind gust velocities exceeding 100 mph.

According to the National Oceanic and Atmospheric Administration, the highest wind speed ever recorded in Boulder happened in 1971 and clocked in at 147 mph.

At 2:30 a.m. Jan. 16-17, 1982, NCAR recorded a gust of 137 mph and 20 gusts greater than 120 mph were recorded at the NCAR campus on Roberts Mesa south of downtown Boulder. The 1982 storm cost the city about $10 million. Reports say 40% of buildings in Boulder suffered some damage from the Chinook winds.

At least six people have died as the result of high winds in the Boulder area since 1969.