Portland Maine to Spokane Turbulence Forecast

PWM → GEG · 2,262 miles · ~5h 1m

What to Expect

Your flight from Portland, Maine, to Spokane covers a good chunk of the country and, like any cross-country trip, will likely involve some turbulence. The first bit over the Atlantic Seaboard often sees clear-air turbulence (CAT), which can happen even in seemingly clear skies. As you cross the Northern Appalachians, expect possible mechanical turbulence, which is when the wind interacts with the mountains. Over the Great Lakes, especially in colder weather, you might encounter lake-effect turbulence. Moving into the Upper Midwest and then over the Great Plains, you're back into areas prone to clear-air turbulence. Finally, as you approach Spokane over the Northern Rockies, be prepared for mountain wave turbulence, caused by air flowing over the mountains. Remember, pilots are trained to handle all of these common weather patterns. It's all part of the job.

The Portland Maine to Spokane route crosses the Northern Rockies, a rugged expanse of high peaks in Montana, Idaho, and Wyoming. Mountain wave turbulence is frequent here, especially when Pacific storm systems push strong winds over the Continental Divide. Pilots often report moderate chop between 30,000 and 40,000 feet over this region.

Turbulence Factors on This Route

• Clear-Air Turbulence (CAT): The Atlantic coast jet stream and land-sea temperature contrasts create frequent clear-air turbulence at cruising altitude.
• Mechanical Turbulence: The Northern Appalachians generate low-level mechanical turbulence during strong post-frontal northwest winds.
• Lake-Effect Turbulence: The Great Lakes produce lake-effect convection and low-level wind shear from land-water temperature contrasts.
• Mountain Wave Turbulence: The Northern Rockies generate powerful lee waves when Pacific fronts drive westerly flow across the high terrain.

When Is This Route Bumpiest?

For the smoothest possible ride on this route, aim for summer or early fall. The atmosphere tends to be more stable then, reducing the likelihood of those clear-air bumps over the Plains and Midwest. Winter, late fall, early winter, early spring, and spring tend to be the bumpiest times. The increased temperature differences create more clear-air turbulence, and the mountains generate more pronounced waves. Plus, the Great Lakes can really stir things up with lake-effect turbulence when the weather is colder.

Tips for This Flight

If you are concerned about turbulence on this route, booking a morning flight could give you a slightly smoother experience because the air tends to be calmer earlier in the day. Any turbulence you do encounter will likely feel like driving on a slightly bumpy road, not usually anything alarming. To help stay relaxed, choose a seat over the wing, which tends to experience less motion, and focus on deep, slow breaths. Remember, the crew is well-prepared to handle any bumps, and their priority is always your safety and comfort.

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Forecasts based on NOAA HRRR and GFS atmospheric model data.