October 24, 2021

Sunday, October 24 looked like a solid, no brainer chase day. A strongly sheared, destablized warm sector was a day's drive on a weekend.

The setup featured a deepening surface low over the KC area, and deep trough ejecting into Missouri with a warm front draped across northern MO into IL and a cold front running south southwest on the KS/MO border into OK.

A kicking low level jet and southerly surface winds had forecast effective storm relative helicity exceeding 300 m2s2 across much of the open warm sector. Coupled with modest to moderate instability, the setup supported supercells and even strong tornadoes. To get a discrete supercell moving off the cold front into a strongly sheared warm sector usually yields highly chaseable storm modes with visibile tornadoes. The problem with this setup was the location, with storms possibly tracking into the gnarly Ozarks terrain of central and southern Missouri. I hoped to intercept storms early in their life cycle toward the Nevada, MO area, colocated with the jetmax and best shear/instability combinations. Then I'd hopefully get a tornado before storms transitioned into a line over the Ozarks. I shied away from the warm front along highway 36 and "cold core" corner of this setup up north of KC as the warm front was plotted to be sharp, reinforced by ongoing morning precip. I expected storms up there to cross into cool stable air, or be too socked in with low clouds and rain so preferred discrerte cells coming off the cold front.

By midday of the event it became appearent that the pattern had changed. I had already committed to my Nevada, MO target though and was out of range of the other targets by the time I made the realization. Morning convection had cleared and the warm front lifted further north and was more diffuse. Meanwhile to the south, surface winds veered in the warm sector.

The result was that the targets on the surface low and down the warm front were now preferred with the best directional shear and instability combinations. Storms to the south would struggle against veered surface winds and getting off the undercutting cold front.

I stopped short of Nevada, MO to reassess and check data and realized I needed to start moving north. A tornado watch was issued by 2pm. The low lit up first with a tornado report in Kansas and several warned storms tracking into the St. Joe area. I wouldn't catch those before they crossed the warm front I figured so I targeted the northern end of a developing line of storms south of Kansas City. I hoped the northern most would lead the parade into the backed surface winds north of I-70. I planned to intercept near Sedalia. I grabbed a quick lunch while awaiting a dominant cell to emerge. Radarscope indicated one in particular with strong outbound velocities indicating a robust gust front and prolific lightning activity, hinting at a robust updraft. That was my storm. I just needed that robust updraft to track into more favorable directional shear. I ran southwest out of Sedalia and started looking for views through the trees. I spotted a ragged gust front from a few miles out. The storm needed time to organize and with fairly fast forward speed, I held my ground to let it come to me.

I moved down the road to get a more open view and then I could see that inflow notch was already moving north of me (area obscured by trees in this photo). It had also already become totally rain wrapped. The storm immediately went into a high precipitation state. It wasn't at all what I had originally expected given what had been advertised as a strongly sheared setup with great helicity. The storm picked up a severe warning and I turned around and headed back into Sedalia to stay ahead of it. The veered low level winds made for a fast storm motion and I was overtaken by the rear flank gust front on the east side of town. The storm picked up a tornado warning while I was caught in the core, and that was followed a couple minutes later by a report of a rain wrapped circulation with some debris in the air. I followed the highway east out of town until I emerged out of the southeast corner of the core, the circulation crossing a couple miles behind me to my northwest. Through the heavy rain wrapping, I never had any chance of a visual on it.

I blasted east with a handful of other chasers, hoping to stair step and meet the storm again up in Kingdom City where it would hopefully cycle in the better backed winds to the northeast and maybe clean out its rainy RFD. Radar trends made it appear that the storm was instead gusting out, however. I eventually ended the race and turned around to catch the next cell in the line. It was smaller and unwarned, but it had a nice shape and tiny couplet on the radar, and it would conveniently cross the highway I was already on. A gust front illuminated in golden sunset colors emerged. It was pretty but didn't do much in the way of rotation.

I ran east and north to stay ahead of the cells, but also to head in the direction of home as it seemed my chances were dwindling. North of Jefferson City as the sun set, the storm was lit up in beautiful colors with a disorganized block wall cloud. I didn't really stop to shoot it as I didn't want to get run over again. I ducked between cells north of I-70 and then followed by the line all the way home as ongoing tornado warnings and a tornado emergency continued after dark in southeast MO into southwest IL. Springfield, IL was even tornado warned at one point, but the huge gnarly embedded HP didn't have any confirmed tornado reports come in off of it.