Another Derecho, Anyone?

A derecho is defined as " a storm complex traveling more than 400 miles, producing damaging wind gusts of 58 mph (60 knots) or stronger along its path. Some gusts must exceed 75 mph. The width of the damage path must be at 60 miles wide."

The Storm Prediction Center (SPC) posted a Day 2 Enhanced Risk (Level 3 of 5) for central Iowa to eastern Indiana at 12:30 pm on Sunday, July 14, 2024. This prediction of a large swath of severe weather would indicate a confidence for a derecho-like event. 

11:31 am CDT, Monday, July 15, 2024. The SPC upgrades its outlook to a Moderate Risk (Level 4 of 5), a 10% hatched tornado probability stretching from eastern Iowa to northeast Indiana (above center), and a high probability of wind (above right). 

1:59 pm. Mesoscale 1630 is posted, outlining a 95% probability of the issuance of a severe thunderstorm watch in an area stretching from western Iowa to western Indiana. The actual watch would be issued a short time later.

4:14 pm CDT. Now at my stationary spotting location on Sutton Road (right) at Central City Road (background, left), west of Central City, Iowa in Linn County. A severe-warned storm is approaching from the west (left and left center in image). 

4:26 pm. Looking northeast at the underside of an enormous anvil cloud, ahead of the approaching severe-warned thunderstorm. My spotting vehicle, equipped with amateur radio and weather radio, is seen in the foreground. 

Radarscope image for 4:36 pm CDT, showing the approaching storm beginning to become more linear and bowing out just west of my location. 

4:50 pm. Tornado warning is issued, and sirens sound. Area that is tornado warned is toward the left in the image.

4:52 pm. Radarscope dual pane image, showing the tornado warning polygon, with reflectivity at top, and velocity at bottom.

5:23 pm CDT. Cell phone Emergency Alert sounds, valid until 6:00 pm. I decide to move back south toward Cedar Rapids, where a "tail-end Charlie" storm feature is approaching, which seems more "favorable" for significant severe weather.

5:28 pm Radarscope dual pane image, with a hot spot to my southwest. Now at my new stationary spotting location on North Marion Road, about a tenth-mile north of County Home Road, north of Marion, Iowa in Linn County.

5:31 pm CDT. Looking southwest toward tornado warned area, with the sky becoming very dark in a short amount of time. Nikon Z6ii camera.

5:31 pm. Go Pro Hero 4 Silver video frame capture. Lightning bolt. With the energy of the storm increasing, many positive CG lightning strikes were occurring in this area, including one that struck just 50 yards from this location, sending sparks flying from a telephone pole!

5:33 pm. Tornado warning polygon and my spotting location (blue target icon). 

5:35 pm. Cell phone Emergency Alert for a tornado warning sounds again. 

5:51 pm. Go Pro video frame capture showing estimated 70 mph winds and rain slashing my windshield. I reported this situation to the Linn County Amateur Radio Emergency Services (ARES) network via amateur radio. 

5:55 pm. Emergency Alert sounds again, warning of a severe thunderstorm warning with possible 80 mph winds. Thankfully my spotting vicinity was spared from significant wind or flood damage that impacted other areas, including a 97 mph wind gust reported near Holy Cross in Dubuque County. Some three tornado reports were also confirmed in the state from this storm that was later confirmed as a derecho.