Derecho

Image Credit: NBC News Screenshot

You know when things get weird when one sees green sky produced by hot air coming in contact with a band of rapidly moving showers or thunderstorms thus producing a long lasting wind storm of biblical proportions, this time in South Dakota. 

South Dakotans are accustomed to the storms known as derechos — they’ve had two recently. What they’re not used to seeing is skies that turn green right before severe weather tears through the region.

A derecho, which the National Weather Service describes as a powerful wind storm extending more than 240 miles, moved through South Dakota and other parts of the Plains on Tuesday and brought powerful winds — up to 99 miles per hour in some areas.

But before the derecho (pronounced deh-REY-cho) hit Sioux Falls, S.D., the storm caused the skies to turn green, an unusual weather phenomenon. Many people on social media shared images of the green skies, which were also captured on South Dakota Department of Transportation traffic cameras.

Development of derechos

Factoid

The unusual green color in the sky sometimes occurs before or during a storm depending on how sunlight interacts and scatters among different particles in the atmosphere, a meteorologist with the National Weather Service said.

A shelf cloud along the leading edge of a derecho in Minnesota