Changing Clouds Ahead

February 18, 2021

Photographer: Bonnie Keller 
Summary Authors: Bonnie Keller; Jim Foster

While driving to get my COVID vaccine a few weeks back, I noticed the odd sky pictured above near Fairfax, Virginia. You could almost believe that the road sign at right is alerting the driver to -- Changing Clouds Ahead. The air temperature at the time was 46 F (8 C). Behind me were mostly broken altostratus clouds, with sunlight streaming through. Ahead, in the background, were clouds from the cumulus family, and in the mid-ground and also above me were gray clouds that had the appearance, at least, of mammatus. Additionally, note the virga just ahead of me.

During the winter season, frontal systems and or upper air troughs can quickly change the sky cover. A weak cold front had passed through the day before, and now a shortwave trough was positioned to the east of the Appalachian Mountains. There was just enough instability to generate a few snow showers, and at one or two spots in Fairfax County, a trace of snow was reported on the ground. Photo taken on January 18, 2021.