July 16th was probably my favorite chase day of 2011! We ended up in Bismark, ND, located just northeast of a mesolow and along a weak boundary that extended towards Grand Forks, ND. We ate lunch and waited in a local mall where it was cool. Temp and dewpoint were INSANE this day with my weather station reading 91/82! Crazy obs! The SPC mesoanalysis page showed a Sig Tor value in the teens and supercell composites in the 30s. Great number and not surprising based on the environment. With decent 500 mb winds aloft and respectable low level shear, we knew if any storm could get going in the capped environment, it would likely be a supercell and have a definite tornado potential. By mid afternoon, towers developed along the boundary and late afternoon, our supercell, the storm of the day, would form. Made it really easy for us to intercept since we were basically 30 miles from the congestus that ended up growing into our tornadic monster.
By 4:15 pm, our storm had developed a good updraft and downdraft, and it immediately developed on skinny pencil funnel that extended halfway to the ground. At 4:30 pm, a major wall cloud had formed, and was developing strong rotation. At 4:33 pm the first of 4 tornadoes touched down. It lasted until 4:38pm when it dissipated. The storm quickly cycled and dropped another much more significant tornado at 4:41pm and lasted until 4:55pm. This tornado was much stronger and developed a significant debris cloud. Both of these tornadoes occurred just northeast of Regan, ND. After the second tornado dissipated, the storm started its cycling process again, and this lasted quite awhile. It never looked like it would produce another tornado while we maneuvered to get back in front if it (lots of flooded roads to work around!), and it pummeled us with hail to golf ball size.
Finally, south of Bowdon, ND, we were able to get back in front of it and dropped south about 8 miles to get a view of the updraft. It looked in a considerably weakened state, with a strung out updraft and smaller core, but it managed to drop a truncated elephant trunk shaped tornado about 10 miles to our west. It was briefly on the ground, 2 minutes and fell apart. The southern end of the storm became very well organized as a lowering formed directly west of us and started spinning as it approached our location. You could hear the waterfall sound as the RFD blasted around the now rotating wall cloud. A substantial cone shaped funnel formed at 6:25 pm and touched down a mile to our northwest at 6:29 pm. It stayed on the ground and morphed from a truncated cone, to “Wizard of Oz” type tornado, to a stove pipe and then an amazing double walled beast as it passed less than a mile to our north! What an incredible tornado! At 6:41 pm it dissipated and the storm rapidly weakened.
At that point, we decided since we needed to be in Grand Forks for the night, we would leave our dying storm and head towards Grand Forks, only to be greeted by a tornadic supercell east of Devil’s Lake! We stayed with this cell for an hour, until it lined out and weakened. We made it to our hotel by 11PM, with all guests (and my guide!) in great spirits! It isn’t often you see what we did this day, and to have it over mainly open terrain is even better. Beautiful storm, magnificent tornadoes and little damage.