July 2, 2020

From Anton's morning forecast discussion:

"We should be near Moorcroft WY for relatively early initiation (certainly by 20z). This is where the high CAPE air advects farthest to the northwest beneath the moderate southwest flow aloft. Complex terrain there will easily break the cap for us. An additional positive factor, which may develop though I am not sure, is that low level flow may actually become easterly or northeasterly on the west side of the surface trough. Here is the NAM3 temp/pressure field projected for 20z.

The 20z CAPE field shows this westward push as well

I note the Platte Valley also doing its thing with a tongue of high CAPE sustained around Torrington, but the overall flow looks to be better up in the Moorcroft-Sundance-Belle Fourche corridor.

For the North Dakota option, I see two significant problems from a tornado perspective. 1) Anvil shadowing from upstream convection firing early. 2) Little if any directional shear in the boundary layer. "

July 1 was a down day/ferry day for the group. The documentary film crew left us to go interview Bill Reid and Tempest Tours. We headed west from Jamestown, ND back to Dickinson and then spent the day hiking around Theordore Roosevelt National Park where we too bumped into Bill Reid and Tempest.

On July 2 we drove down into South Dakota and then stepped west across the border into Wyoming. Towers were already springing up on the west side of the Black Hills and we watched from a rest area off I-90.

Anton spotted a mid-level funnel cloud in some towering cumulus overhead.

It was likely the wrap up and tightening of a dying updraft, the rotation increasing as the updraft tube narrows and withers away.

Storms over the Wyoming Black Hills showed some low level rotation, but failed to build to the point that they had any real tornado play on them.

We tracked them back into western South Dakota, but we soon found ourselves chasing orphan anvils as cells died in the capped air away from their sources of lift. Meanwhile, a big supercell had erupted in the Nebraska Panhandle and was putting down tornadoes. We probably could have made it down there in time had we realized soon enough that our initial target was going belly up.

We headed back into Wyoming for a room and dinner in Gillette, stopping at Devils Tower along the way for a 2020 pandemic style group photo.