Gathering Storm

Chaotic Sky - Cedar FAlls, Iowa, by Craig Johnson

Gulf moisture surged northward across Iowa on Saturday May 18th setting off showers and thunderstorms. At Cedar Falls 1.17 inches of rain fell between 5:55 p.m. and 9:45 p.m. This photo shows thickening clouds. Darker clouds are seen in the southern sky to the right. They were moving to the north (right to left).

The chaotic sky included two cloud layers; cumulus, cumulus mediocris, cumulus congestus and a second overcast layer of various mid-level clouds. A third layer of cirrus was visible on satellite imagery but not to a ground observer because of the mid-level cloud layer. Rapid vertical development is seen across the lower portion of this photo. The clouds were tilting to the left and upward due to increasing winds with height blowing south to north.