June 19, 2019

From my morning storm chasing forecast discussion email:

"Day 1 Today: Despite the vote of no confidence from SPC, we are traveling north with reckless abandon for the surface low in South Dakota. Low and warm front a little further south than previous runs. Expect a line of small storms to erupt by mid afternoon from near Pierre to south in central Nebraska. I like the backed winds, a little bitter flow aloft aloft and aid in lift/vorticity from the surface low so prefer the northern end of the setup than the southern, but could be supercell well south. Instability is very narrow and relatively modest, storms may outrun this axis pretty quickly and dissipate, so get on them sooner than later. Storm tracking southeast down the warm front could spin up a tornado.

Secondary targets: Pretty supercell and "rogue" tornado possible in the basin west of the Big Horns, or on the east eventually even.

Monster CAPE in North Texas. Shear a little light, but extreme instability can compensate and do crazy things. Definitely chase if you're in the DFW area. CAMs hint at evening initiation.

MO Bootheel for a late afternoon show as the line of storms moves through. Catch them there before they track into the ugly terrain Illinois and grow into an MCS.

Day 2 Thursday: Large CAPE plume ahead of the frontal boundary and displaced flow to the west. Still CAMS have supercells plotted tracking down the warm front side of the plume with favorable low level shear. Western Iowa, maybe Council Bluffs, is primary target for a southeast moving supercell down toward KC. Some monster helicity tracks on the CAMs has me raising an eyebrow. A southeast moving supercell in extreme instability can do some crazy things, but beware of HP storm mode. Dews over 70 degrees and lack of venting aloft will cause storms to dump rain into their hooks. Don't drive across the big green ball of the hook. I don't want to have to hear about how you were in fine position later."

Brindley and I targeted Pierre for some afternoon supercells. We intercepted a gorgeous storm northwest of town amid the rolling green grasslands. The base sported a thick inflow band and a wall cloud attempt for a bit before it started to fizzle. Rain from a cell to the south encroached so we dropped south and west to play that cell instead.

Convection exploded on the southern side of the storm as we setup for time lapse and still sfrom the west.

Chunks of scud appeared to flow into the base as what looked like a robust wall cloud took shape. We scrambled east to make a more conventional supercell/tornado play on this feature, but as we got underneath, it instead appeared to be a dump of coold outflow fanning out below the base that was kicking up a large lowered gust front. The feature fanned out and dissipated a short while later. Steep lapse rates were making for robust thunderstorms, but it appeared we didn't have the shear to sustain them for long.

We continued east of Pierre getting immediately underneath the base as a storm took on supercellular characteristics. An RFD clear slot appeared and the base churned with a swirl of rotation. The storm didn't organize any further, but the rotation overhead was dramatic looking for a short while. We continued south to a couple other bases, but the day started to wind down as the storms outran the narrow and dwindling instability. We continued down to Mitchell for dinner and a room.