After a few down days this day had me really excited from a few days out, this I believe was the chase day of the 2017 season so it was important to get this one right. I positioned us overnight in Cheyenne as that is where I was expecting the biggest concentration of severe the next day. Overnight model runs from the HRRR painted an exciting picture from the chasers point of view not so much for the population that lived around here. Run Below showing a string of pearls tornadic supercells.
Upon awaking the next morning I could not believe what I was seeing, a Moderate Risk and a 15% Hatched tornado chances for Wyoming, this is the first time ever Wyoming has had anything over a 10% Hatched and an extremely rare set-up! Most of the big risks for 2017 had gone down the pooper so I was still cautious even during the morning of the chase day. The set up was very volatile, surface dewpoints of low 60’s and with our elevation at 6,000ft asl this was as good as 75-80f in lower elevations like Oklahoma, surface temperature of the mid seventies was also perfect, LCL’s around 400metres, 45knts of shear and a lifting warm front, nirvana conditions! The morning was foggy and once that burned off fast moving cumulus ripped northwards getting torn apart by the shear, this certainly looked like a tornado day! The one thing I was cautious about was a strong cap in NE Colorado with temps of 16-18c would storms be able to sustain themselves before being killed by the cap, so thinking was to go a little bit further north away from the cap and we headed for Chugwater along with quite a bit of convergence! A special balloon sounding was performed around 1pm which we watched!
Just after this at about 2pm the first Wyoming storm started to get organised SW of Chugwater but this was moving straight north along the mountains to our west, this area of Wyoming is like tornado central for supercells that turn right so I was hopeful we could get an early tornado under our belts and enjoy the rest of the day. We headed west just north of Chugwater and got our first look at the storm and it looked very HP in nature, not good when 4″ hail was being forecasted! About this time also a PDS Tornado Watch was issued, incredible never seen before this far west in the history of the national weather service!
The Supercell turned right as expected but I was still not feeling it and 3 Supercells had by now initiated along the front range in Colorado around the Fort Collins area and 1 just SW of Cheyenne. The decision was made to bomb back south about 50 miles and get a look at these by now tornadic storms. The cap was not killing them as the models said and they were starting to move into some incredible synoptic conditions. We got a first look at the top supercell near Cheyenne and it was a nice LP transitioning into Classic, we stopped east of Cheyenne and watched a weakly rotating wall cloud for a while always keeping a check on the 2 Supercells to our south that looked perfect on radar.
The next big decision was made around this time to concentrate on the bottom 2 supercells which looked amazing and we dropped further south to the town of Carpenter to watch, we were now surrounded by 3 Tornadic Supercells – what a sight!
The picture above is of the Middle Supercell and I made the only wrong move of the day by moving north with this storm at this time as it was rotating hard and putting down funnels, the storm to the south which would become the Cyclic Supercell of the day/year was still looking like it had lots to do to become organised. So north we went by about 10 miles up towards the I80. Around this time the Southern Supercell went nuts and dropped a stunning white cone tornado right over Carpenter where we were sat 20 minutes before (Thats Chasing) and to show how close we still were, we still managed to watch it when it was quite strong and a stunning rope out.
A quick look at this storm I knew this was the one to be on today, a real cyclic beast of a storm that had 3 Mesocyclones and 3 hooks at times. I punched back through west of Pine Bluff to get South East of the storm taking a few golfball sized hailstones. When we emerged it was a funnel fest with lots of Mid level funnels and shear funnels, the storm was cycling at this stage and was about to go into tornado rampage mode as it crossed into the Nebraska Panhandle.
We continued east to Kimball and then had a great north road to be just south of the Supercell, about this time the structure was stunning and reminded me of the Westpoint (NE) storm from 2014! But the added bonus this time was it had a tornado dangling underneath the middle mesocyclone! Tornado number 2 in the bag for today!
We continued north with the storm and stopped after a few miles as Tornado number 3 occured from the furthest west Meso this time.
But the storm still was not done and Tornadoes 4 and 5 quickly followed this time from the furthest North East Meso, it really was a game of hand offs from the meso’s on this storm which just never occluded for some strange reason
Just after tornado number 5 we went really close into the RFD area and nearly got side swiped by a 2000lb barrel that was getting blown east at a rapid speed. My white chase car below!
By now the Storm had transitioned into a HP Supercell but we did manage 1 more Tornado near Harrisburg before we watched some lightning grabbed some petrol and started to make our way back towards Denver for the start of Tour 4. The structure was still stunning at this stage though
All in all I am pleased how today turned out with 6 Tornadoes on a tricky day, we could have stayed north but maybe some luck in having to stay close to Denver paid off today, there were tornadoes further north but they were harder to see over some tricky chase terrain up towards the Black Hills area. Some maps and reports below for the day!