Here in Clyde Park we don't get much wind compared to most places in Montana. Today however is one of those rare days when the wind blows - hard. How hard? Our house sounds like it's a balsa wood model placed in a wind tunnel.
Sometimes we get wind like this as a late summer thunderstorm approaches and we are suddenly met with a cool dry gust front; other times it's due to cold air rushing downslope from the mountains, today though it's due to high winds aloft. Currently the wind upstairs is moving between 80 and 100 knots at 12,000 feet. To be clear, that's between 92 and 115 miles per hour. Interpreted another way, the winds aloft ride the dividing line between a category 2 or 3 hurricane. At 9,000 feet it's a more mild 50-60 knots depending on where you stand since winds near the crazies are estimated above 80 knots at 9,000 right now.
Things on the ground aren't much better. The Livingston airport is reporting 61 mph gusts with an expected increase to 71 mph in a few hours. Skiers at Bridger Bowl are finding winds from the west at 46mph gusting to 55mph, that wind will undoubtedly increase as the day goes on. Glad I'm not out skiing.
What happens when all that wind hits an obstruction, you know, like a mountain range or something? It goes up or around. For pilots operating in and around Montana airspace today that means they are kayakers and raft guides carefully running the rapids. MWAV or Mountain Wave Turbulence is the particular form of rough air being experienced today. Just as river water flows over a shelf or sumberged boulder, air flows across mountains. The resultant wave is initially very abrupt. It has a high frequency and low wavelength, as the fluid moves farther from the obstruction the wavelength increase and frequency decreases. Today, those waves are powerful enough that the PIREP (pilot report) map is littered with large airplanes reporting MWAV - some as high as 40,000 feet above sea level. The good news for nervous passengers is that flying in turbulence is generally very safe as airplanes are designed to take a lot of stress, and pilots are trained in ways of mitigating excessive stress through proper flying technique.
Regardless of whether or not it's 'safe' to fly in turbulence it can be mentally and physically taxing. That's why when the big boys with their quarter million pound airplanes are reporting widespread MWAV in the flight levels, it's a good idea for the rest us with our 2,000 pound airplanes to sit out the fight unless we absolutely needed to and it's hard to say what would constitute that 'need'. As the old timers say, "I'd rather be down here wishing I was up there, than up there, wishing I was down here".