We got back on I-40 and approached Memphis, keeping barely ahead of the mesocyclone. We had to ask people sitting in back to look up out the back windows to be sure a funnel wasn't coming down right on top of us. Just as we headed to the bridge over the river we got out of the rain and pulled over to get a look.
There on the shoulder of the interstate we watched as a funnel lowered out of the meso, and headed on a path directly toward us. We craned our necks and snapped off pics and watched it get closer and closer and spin and spin and it was almost right there over us, with truck drivers honking at us to warn us and van 2 almost panicking and jumping back in their van to get away.... And we stood there taking more pics. We just could tell that it was going to go right on over us without putting down and we stood our ground. Of course, those in van 3 were instead watching as it did indeed put down, into the waters of the crazily swollen Mississippi (the reports of Mississippi flooding are not exaggerated; that sucker is all over the place, and it is now down from where it was) and all but creating a water spout on land.
So, a tornado. Right over our heads.
UPDATE: A team of storm chasers from Ireland and Great Britain also were in the area to cover the spring tornado season. Ian Carruthers' account appears in Irish Weather Online.
We stopped again to observe it just west of Memphis. It had a well defined wall cloud on it for a time but it just didn't have enough rotation on it. We saw some great CG lightning tough we all got to hear a hail roar ( when hail isn't falling to the ground, its circulating up and around the supercell with the powerful updrafts. This leads to them smashing together, causing a roar), which sounded just like constant loud thunder! Was amazing!