The
Storm Prediction Center (SPC) Convective Outlook is shown above.
The Weather Channel's (TWC) Dr. Greg Postel named two areas in the midsection of the U.S. where tornado formation was possible on this day, Friday, May 24, 2019. Postel's forecast was this: The Texas/Oklahoma area ("A" in the top graphic) would have more instability, but the Iowa/Illinois area ("B") contained more wind shear and therefore had a slightly better chance of tornado genesis. This would prove to be absolutely correct, although not initially without some doubt for several hours.
With conditions in Cedar Rapids, Iowa becoming more and more favorable as the morning passed, I activated my
Spotter Network ID around 12:30 pm, but the watching and waiting game would last about another three hours. Around 3:30 pm the SPC posted a severe thunderstorm watch probability for the eastern half of Iowa. It was time to pick up my storm intercept partner and future son-in-law, Billy Gant. My target spot to await storm initiation was one of my favorites of recent times--a gravel road just under two miles east of Ainsworth, Iowa in Washington County. This location was prime if storms would form in all directions of the Slight Risk area and immediate relocation would be necessary. Conditions there were indeed favorable: temperature of 81 degrees F, dew point 79 degrees, humidity 94% and wind out of the south to southeast.
5:11 pm CDT. In position on Yucca Avenue, .1-mile south of Highway 92 and 1.9 miles east of the town of Ainsworth. Some cloud formations and cumulus towers had begun to form but as time passed it was looking like maybe this wasn't going to happen after all.
For an hour curious passersby came and then drove on, chatting with us about the possibility of bad weather. All we could give them was "maybe." Just as it started to look like it might become a bust, we observed a storm cell to our northwest, growing more robustly than others. Above, I captured what was actually a forming supercell at 6:15 pm. The supercell was about 30 miles distant, located near North English, Iowa. Since this was beginning to look interesting, Billy and I agreed to set out and head toward it.
We had no sooner gotten into our car to move when our weather radio sounded a tornado warning. Above is an IEM radar image capture for 6:20 pm, the time this cell went tornado-warned.
As it turned out, we were actually in perfect position to intercept this storm. In short order we were back on US Highway 218 and northbound as this image from 6:22 pm shows. We were 1.5 miles north of Ainsworth and about 25 miles south of the storm, which was located just NW of Wellman, Iowa.
6:25 pm. A little closer to the supercell and it is growing bigger in size. Its cloud tops (echo tops) would eventually reach around 45,000 feet.
6:29 pm. Now it had become real--Emergency alerts on our cell phones were going off.
6:33 pm. This two-stitch panorama looks northeast while we continued northbound on US Highway 218. Low on the horizon was an inflow tail cloud, feeding into the storm toward the left of the image, a further indication of its strength.
6:34 pm. Now looking west. Not to disappoint, a large updraft with a wall cloud was beginning to blot out the sun. This supercell meant business now!
6:41 pm. We had minutes earlier pulled off the Hills, Iowa exit in Johnson County, and were negotiating Observatory Avenue, then 540th Street SW. A needle-thin funnel had now touched the ground and become a bonafide tornado.
6:41 pm. Zoomed-in image a short distance from the previous image.
6:44 pm. Go Pro video frame capture westbound on 540th Street SW west of Hills, Iowa, showing towering updraft and tornado.
6:45 pm. Stationary now on top of a hill on 540th Street SW, about 3.4 miles WSW of Hills. This Go Pro video frame capture looks northwest at the EF1 twister which is approaching, but passing about 2.5 miles to our north.
6:45 pm. Approaching stove pipe tornado to our northwest.
Radar frame capture corresponding to 6:45 pm, showing base reflectivity image of the storm. The target icon shows our position in relation to the tornado (black arrow). White arrows show storm track.
Base reflectivity and base velocity images for 6:46 pm.
6:48 pm. Go Pro video frame capture. Tornado is showing a spiraling horizontal tube. Some who were closer to the tornado at this time reported a loud "roar," but from our position it was inaudible.
Map and graphic showing the tornado's track in relation to our position. The tornado tracked a safe 2.5 miles to our north.
6:49 pm. Go Pro video frame capture. Tornado to our north is now displaying multiple vortices.
6:50 pm. Tornado is beginning to lift.
As the tornado lifted, we decided to follow it. We were eastbound on Bayertown Road SW about 3.5 miles west of Hills, Iowa. The storm cell had seconds earlier possibly dropped to the ground an elephant trunk funnel. The above image shows the funnel retracting from its parent cloud at 7:04 pm.
7:57 pm. Preparing to call off the chase and head for home. This image looks east at the departing storm while southbound on Baker Avenue (X30), about 3 miles north of West Branch, Iowa. The storm is about 14 miles distant. An exhilarating afternoon/evening of storm intercept! This was Billy's first tornado, and it was the BEST kind: clear view, safe distance, breathtaking structure, track mostly through farmland, no hail, minimal property damage and no injuries or fatalities. Nikon D7200 DSLR camera.
Read more...
Posts
