“When the Gales of November Came Slashin’*”

The hurricane-force mountain wave winds that annually torment residents living in the foothills of the Great Smoky Mountains and which contributed greatly to the deadly wildfires in late November 2016 are probably as old as the mountains themselves. Yet much about these winds remains a mystery.

One reason for the mystery is the scarcity of professional-grade wind measuring equipment (anemometers) in the isolated areas where the wave winds occur. Many official weather-monitoring stations are located at airports because the terrain is flat and unobstructed by trees or man-made structures. The foothills of the Smokies are the opposite of that. The equipment and its power source also must be capable of enduring extremely high winds.

Additional monitoring sites and sturdier equipment would help meteorologists better understand and predict the wave winds, and that knowledge could potentially save lives. Even without the involvement of wildfires, wave winds regularly knock down thousands of trees, threatening human lives and causing power outages that can take days to repair.

Meteorologists do know the winds are most likely to occur between October and April when southerly airflows encounter a stable air mass building up south of the mountain range. Stable air masses are subdued by a “lid” of air pressure that discourages the masses from rising. When the mass does get forced up and over the mountain range, it descends rapidly on the leeward side. The damaging winds then roll over the foothills like a mountain stream over a boulder; hence the name.

While coastal residents receive warnings of approaching hurricanes days in advance, area meteorologists have only recently been able to predict wave winds. And even now the timing and expected intensity of the isolated winds are extremely difficult to forecast.

Mountain wave winds of over 100 miles per hour have been recorded several times in the Smokies. On the night of November 28-29, after the best anemometers lost power and quit reporting, scientists estimate that gusts exceeded 110 miles per hour, making the storm comparable to a Category 3 hurricane.

*From “The Wreck of the Edmund Fitzgerald,” lyrics by Gordon Lightfoot