At 18z, the low should be near Pierre with some mid level subsidence and capping in place. East of the low across Eastern SD, it should be pretty clear. The mid level subsidence and capping should help to hold off cloud formation for a while. This is excellent as it should help to prepare the atmosphere in Eastern SD ahead of the huge low.

My target is Artesian, SD (Just NNE of Mitchell) in Sanborn, County for initiation between 2-3 p.m. Storms should race off to the NE, tracking through towns like De Smet, Hayti, Watertown, Milbank, Ortonville, Morris and Alexandria before starting to lose tornadic characteristics quickly after sunset. I think a long-lived tornadic supercell may indeed be likely, and chasers are probably going to be chasing well behind a damaging tornadic supercell and finding nothing but debris in their path.

My advice is to plan ahead, stay ahead of the storm, and perhaps to it’s east. If you fall behind, don’t follow directly behind it because any damage in your way will likely set you back with no chance of catching up. Parallel the storm track to the right….stay in it’s inflow side.

Some other notes on the setup over Artesian:

  • Strong ESP parameters with low level MLCAPE and 2km lapse rates
  • Mostly clear skies during the day
  • Plenty of instability
  • Plenty of moisture and moisture depth
  • Strong boundary
  • 50 knot 6km shear
  • Strong cap in area, but eroded along the boundary… which is great with such a dynamic forcing setup
  • With capping and shear, we may have a string of pearls supercell setup with a broken line of tornadic supercells
  • LCL Height projected at 1500meters. This is borderline. You could certainly have tornadoes with such a high LCL Base, but much higher than this is pushing things. Fortunately, as cells move NE, the LCLs drop gradually, and storm relative influences may bring this lower. Therefore I think we’re fine for tornadoes. Also, a little higher base may be good for visibility if we’re playing catch up a lot.
  • My severe index is maxed out. It’s never been a value of 50 that I’ve seen, and has reached the theoretical/joke level I designed classified as ‘Armageddon’

    See the sounding for Artesian, SD:

    4pm severe areas:
    		 7pm severe areas: