April 4: Round 2 of Severe Weather in Iowa

 

Convective outlooks by the Storm Prediction Center (SPC) leading up to April 4, 2023 in the midsection of the US looked eerily similar to the event on March 31 that produced significant tornadoes and was forecasted as a rare High Risk. Moderate Risks were forecasted again in north and south regions (above). Left panel was captured at 5:45 am on April 4, and 12:20 pm for the right panel. Some of the more flamboyant YouTube forecasters even pondered if this event might be more significant than the first. I thought that line of thinking was a long shot.

9:12 am CDT, Tuesday, April 4, 2023. National Weather Service Quad Cities Warning Coordination Meteorologist Rich Kinney for the second time in five days emails out a heads-up notification for storm spotters.

11:30 am. SPC Convective Outlooks--Categorical, tornado, hail and wind.

3:45 pm. SPC posts Mesoscale Discussion 456, predicting the likelihood of a tornado watch for southern and eastern Iowa at 95%.

3:49 pm. My home Tempest Weatherflow weather station showing east winds, with a temperature of 56.5 degrees F--fairly cool--but with 53 degree dew points.

3:50 pm. Satellite image. Sunny in the southwest part of Iowa, with cumulus clouds beginning to bubble up in the unstable atmosphere. 

4:55 pm. Storm near Des Moines growing and casting a shadow in this satellite image. 

5:01 pm. By now storms are erupting in western Iowa, and also entering southeast Iowa, but with a conspicuous storm-free area around Cedar Rapids. (Note all the activated Spotter Network icons on this WeatherTap radar map). Because there was nothing threatening the areas around Cedar Rapids, I remained at home with only about two and a half hours of light remaining, waiting to make a decision.

5:08 pm. Tornado Watch 115 is issued, valid until 10:00 pm.

5:48 pm. WeatherTap radar map showing my location in Cedar Rapids, with storms still at either side of my area. The red on the map indicates the Moderate Risk. It was time to make a decision to pick a storm to intercept, and I quickly chose the southern storm to the southwest, currently in Ringgold County. My plan was to drive to the Van Horn car dealership on US Highway 30 near Newhall, Iowa in Benton County and wait for it to arrive.

6:58 pm. At the Van Horn car dealership. Radarscope image of tornado-warned cell with a hefty hail core. This storm was to my southwest and tracking in my direction. 

7:24 pm. At Van Horn car dealership. Only 11 minutes until sunset. Image looks southwest. Churning mammatus clouds above. The tornado warned cell was about 55 miles distant, just east of Grinnell.

7:25 pm. Looking southwest. The lighter colored tornado-warned storm can be seen through a gap in the darker foreground clouds.

7:29 pm. Similar view with my spotting vehicle in the foreground. Mammatus clouds hang over the tornado-warned storm along the horizon, now located about 50 miles distant.

7:47 pm. Already past sunset and getting darker. I now had to make a decision to stay here or head back toward home. Spotting solo in the dark is inherently dangerous. The approaching storm cell to my southwest was still tornado warned and packing a strong hail core. I decided to leave before it impacted me. Like my decision to leave Hills, Iowa five days earlier, this proved to be the prudent choice. One and a half inch hail fell here after I left.

My new spotting location was Noelridge Christian Church in Cedar Rapids, about a mile from home. The former tornado warned cell, now downgraded to a severe thunderstorm warning, was tracking northeast and passing my location to the west, as seen in these Radarscope reflectivity and velocity images from 8:20 pm.

The storm cell was alive with lightning discharges. This is a stacked image of four shots, all 8 second exposures at f/3.5, ISO 250, and 18mm focal length, seen from 8:37-8:43 pm. Looks west from Noelridge Christian Church. Storm is about 17 miles distant.

8:48 pm Radarscope image. Severe-warned storm cell is tracking northeast and passing to my west. My location is the blue target icon.

8:54 pm. Lightning flashes looking northwest. 8 second exposure at f/3.5, ISO 250, 18mm focal length. Storm was located just east of Vinton, Iowa, in Benton County.

9:00 pm. Looking NNW at the departing storm. Unusual feature is backlit by lightning from this 20 second exposure at f/5.6, ISO 160, 18mm focal length.

9:02 pm. Similar capture. In short order with the storm having passed and the danger being minimized, I excused myself from the amateur radio net I was checked into and headed home. A "capping" layer in the atmosphere inhibited much of the tornado potential on this day in Iowa. It could have been worse than it was, and it was nowhere near what March 31 produced. Nikon D7200 DSLR camera.