WITNESSING A DERECHO

DERECHO, SIOUX FALLS, SD

Red sky in the morning, sailor take warning,

Green sky in the afternoon, pilgrim take cover soon!

I recently ran across a photo from South Dakota that triggered a latent memory from my childhood in Kansas.  The photo captured a rare sight that is only seen during a violent weather event which meteorologists call a derecho which means “straight ahead” in Spanish.  That’s the first and last time that I witnessed a green sky in the west and just as rare an event when the storm reached our neighborhood.

A derecho is a widespread and long-lived, fast moving, straight line, storm that can extend for more than 250 miles and include very strong, severe, damaging winds and wind gusts.  The green, apocalyptic-looking sky implies that the deep blue clouds are saturated with water and ice particles which scatter the short wavelength blue light rays.  When the longer wavelength red sunset beams of light illuminate the blue objects in the sky, it morphs to green.  It’s an indication that the ice particles have been tumbled up and back down in the turbulent clouds until the hail stones weigh enough to strike the earth’s surface.  This intense weather event can even spawn destructive tornadoes and downward microbursts.

Back in Kansas, I recall standing on the sidewalk outside our home when the approaching storm caught my attention.  I could see distant lightning flashes and the thunderous responses getting closer together as the storm gathered nearer.  And as it ominously came closer to me over the neighboring homes and elm trees, I saw the blue sky turn into that apocalyptic green as if the world was coming to an end!  I ran inside the house and called my mother to come outside and see this green mass descending upon us.

We stood together on the front porch for some sense of security and then witnessed a second anomaly that I’ve never seen since.  The skies opened with a torrential rain and large hail pummeling the land across the street, but our side of the street was spared.  Not one drop of rain or hail crossed that road and the storm passed almost as quickly as it arrived. 

Watching the skies actually turn from a bright blue to an ominous dark green probably couldn’t compare to the ancient Egyptians watching the Nile River turn from a deep blue to a blood red or the worst thunderstorm ever of hail and fire during the ten plagues.   But it left an indelible memory with an impressionable young Kansas boy that day.