Convection Junction, What's Your Function?

The atmosphere in the midwest, and especially Iowa during August 15-17, 2025 proved ripe for storms, with many convective updrafts forming in the hot and humid conditions, but with few going severe. The images above and below were exceptions, with a potent severe-warned storm system rolling across north central and eastern Iowa through the midday and evening on Friday, August 15. These images, captured at 7:08 pm CDT (above), and 7:09 pm (below), look northeast at the departing system as seen from the Holiday Inn Express in Urbandale, Iowa.

Fast forward to Sunday, August 17. A new set of storms, with powerful updrafts and some even with lowerings formed in eastern Iowa during the evening. None of these went severe warned by the National Weather Service (NWS). This image of a growing updraft looks west at 5:05 pm CDT from Bowman Woods Park in Cedar Rapids, Iowa.

Radarscope image for 5:10 pm. The polygon box over Benton County is an advisory, not a severe warning.

5:22 pm. Looking north from the eastern border of Bowman Woods Park. Storm's anvil has a ragged appearance, not the smooth cauliflower look of a strong storm.

Radar capture for 6:19 pm. Storm looks linear and is staying north of Cedar Rapids. 

6:32 pm. "Tail-end Charlie" of the storm, centered on Coggon, Iowa in northern Linn County.

6:37 pm. Updraft looking northeast. 

6:58 pm. Similar image, but with a curious ring-like feature in the clouds--most likely from ice refraction in the upper clouds.

7:03 pm. New vigorous updraft forming as seen from the same location, but to the south. 

7:16 pm. I had actually set out on foot to capture the movement of this storm since it was so close! This image looks south from Boyson Road near the Boyson Park trailhead in Marion, Iowa. Very robust looking updraft with a forming darkening base. 

Corresponding reflective radar image to the photo above it. The blob of red east and southeast of Cedar Rapids from this cell is very evident. 

7:17 pm. Similar image with the darkening storm base appearing from the gap behind the trees.

7:19 pm. Similar image with the dark storm base now very evident to the eye.

7:25 pm. Farther east on Boyson Road near Alburnett Road in Marion. Lowering appearing from the storm cell looking southeast. An obvious lowering, but without an obvious rotation.

7:26 pm. Looking east from this location. Another cell with another strong updraft.

7:26 pm. Lowering in the southeast sky.

7:31 pm. Downdraft rain base looking southeast.

7:32 pm.  Similar image. Rainfall and lightning were becoming more intense. It was now time to move back toward home (on foot)!

8:02 pm. Back at home. Sky to the east was now on fire from the departing storm, with the added bonus of some mammatus formations in the mix.

8:06 pm. Similar image.

8:10 pm. Sky still ablaze but mammatus formations now obscured. Lots of convection on this day, but no severe warnings... (What's your function?) Nikon Z6ii camera.