One year ago today, on March 31, 2023, after years of storm chasing, I finally had my first successful intercept of a large, intense, photogenic tornado.
I arrived in position on the supercell thunderstorm southwest of Keota with the EF3 Ottumwa-Farson/Martinsburg tornado already ongoing. After watching it approach for a few minutes, the storm cycled right in front of me, with a cloud of rising dust beneath a nub funnel rapidly coalescing into a classic cone funnel which within minutes expanded to a violent stovepipe and then a wedge as it crossed Iowa Highway 92 to my west and sped off to the northeast.
I went all the way east on 92 to Iowa Highway 1 and then north through Kalona, where I observed the storm's next cycle. The Keota tornado vanished in a wall of rain in the distance, as a narrow elephant's trunk funnel snaked out of a new wall cloud out ahead of it, which I observed for just a minute or two before it became invisible against the no-contrast clouds and encroaching rain. This was the Amish-Frytown EF0. I aborted the chase here as the supercell was becoming absorbed by the squall line that had been bearing down on it, but continued to produce additional strong tornadoes including the Coralville EF2, whose damage path I encountered while northbound on US-218 trying to get back to Cedar Rapids and head home.
0:00 Turning right from southbound County W-15 (330th Ave.) onto westbound IA-92 southwest of Keota, Ottumwa/Martinsburg tornado ongoing in the distance to the southwest.
1:43 Rising dust beneath an area of tightening rotation in the clouds becomes apparent, out in front of the dark mass of the original tornado.
2:25 The "rising dust" coalesces into a clear tornadic debris cloud, with the clouds above tapering into a funnel and extending to meet it. Moments after forming, the tornado is already flinging out huge pieces of structural debris.
2:46 The funnel fully condenses into a classic cone tornado (the video thumbnail, and my channel icon since I started this channel!), an appearance which lasts only a few seconds as the funnel quickly becomes shrouded in dust while condensation wraps in around the top, marking the beginnings of the dramatic tornado cyclone or "collar cloud."
3:30 The funnel appears to undergo some sort of vortex breakdown at the surface, becoming diffuse with multiple vortices and helical vortices before re-organizing as a whirling column of dust rises to meet the rapidly forming "collar cloud."
4:17 The dust column fills in up to the base of the collar cloud as the tornado tracks toward Highway 92, meanwhile the old EF3 tornado is still ongoing as the dark mass to the left (which I had stopped paying attention to at this point!). An explosion of debris fills the air just before the tornado crosses 92 (fortunately, per the damage surveys, it appears all the structures impacted south of 92 were farm outbuildings and not houses).
5:00 Seconds after crossing 92, the tornado expands into a wedge and churns across the field to my northwest. While taking some DSLR photos, I neglected to notice that I hadn't screwed the pan friction down tight enough against the stiff inflow winds, which had caught my camcorder and panned it off the wedge. However, it doing so it caught a glimpse of the roping out Ottumwa/Martinsburg EF3, which had become visible as the dust shroud around it began to fall away.
5:30 The wedge pirouettes away across the field, moments before doing EF4 damage to houses just northwest of Keota proper.
6:15 Phone footage as I'm northbound on IA-1 at the intersection with IA-22 at Kalona. The tornado, hidden by rain, has just passed west of Wellman almost 7 miles away to the west-northwest, but the storm's rain-free base and inflow tail fills the entire sky to the west and north.
6:45 View from IA-1 just north of 110th St. as the Amish-Frytown EF0 forms as an intermittent debris whirl benath a sinuous elephant's trunk funnel, racing away on its path along Angle Road SW and quickly becoming invisible against the clouds. I ended the chase at this point and transitioned into trying to get out of the area without getting run over by any of the storms which were rapidly beginning to grow upscale.
7:53 Sirens sounding in Iowa City as I'm waiting at the lights on IA-1 to get on US-218 northbound.
8:23 Encountering tree limbs down on US-218 from the Coralville EF2 which has just passed through; moments after I pulled over my GoPro on the dash captured a dramatic CG lightning strike which ends the video.
Негізгі бет Ғылым және технология March 31, 2023 Storm Chase: Keota, IA EF4 Tornado (1-Year-Anniversary Edit)
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