Denver Convergence

21 May 2014

noteadThe day started around 4am after some fitful and uncomfortable sleep in the new Escape which it turns out was not suitable for sleeping in. We’d barely mustered up enough sleep for one person between us and the first few hours were spent groggily trying to either sleep more or wile away time until it was time to do something. The thing to do, it seemed, was head back to Denver to change the car again. This was feasible because the forecasts for today needed us to be in the Denver area anyway.

We arrived in Denver airport as storms were starting to fire around the region. Denver benefits (if you see it that way) from a geographical feature called the Denver Convergence Vorticity Zone (or Denver Cyclone) which combines a number of large and small scale features of topography and common weather patterns to create not only lots of storms, but when they do erupt they are more likely to rotate and become supercells. We didn’t want to start from the middle of a city but, as fate would have it, by the time we were loading our stuff into the new car there was a tornado warning covering our position. Indeed it was less than 10 miles from the airport before we were capturing some potent storm structure.

HP supercell and our new car

It wasn’t long at all before this storm turned into an HP (high precipitation) monster. The structure still had its moments. There were some fantastic examples of that green hue that we’ve come to know and love, along with some good outflow features such as “scud fingers” and clearly defined areas of hard rain and hail.

We continued east and found our way to an area that put us well under the path of the storm where we could watch it at some leisure. After a few adjustments we were positioned on a farm road a couple of miles away from the core of the storm, enjoying the structure, even if it wasn’t the most photogenic weather.

After one such tweak to our position we had a conversation about whether I should set up a time lapse. These normally require a minimum of 15 minutes of taking pictures every 2 seconds or so to be pieced together later into a high speed version of the storm’s progress. We noticed that it was propagating towards us somewhat so maybe there wouldn’t be time. In fact, perhaps we should move around now. Like, right now. We quickly got moving and headed for a main road as fast as we could, down the gravel farm track, as the winds started picking up fast and we saw a report pop up for a rotating wall cloud right on our position. We knew that the report position wasn’t correct, but it’s still unnerving. By the time we were approaching the paved road it could not come soon enough. Unfortunately the road was far from empty. In fact there were more storm chasers than you could shake a tornado at. Fortunately there was a gap in the traffic to get out of the road after an agonisingly long 20 seconds, but then we were simply joining a slow moving traffic jam. The winds were getting really strong now and there were tumbleweeds and strong rain hitting us hard from the right. It wasn’t the worst road conditions we’ve encountered by any means but the traffic was moving extremely slowly. The dynamics of people stopping by the road or pulling out from side roads or from where they were parked meant the traffic could only move at about 15mph. With the storm bearing down faster than that, and no options to move, it was a horrible few minutes until, one way or another, the traffic started to flow more freely. At that point we relaxed enough to take some video of the “chaser convergence”. This is far less dense than it had been, but you can still get the drift…

We didn’t want anything more to do with this storm, or the heavy traffic underneath it, so we decided to head south to Burlington which looked like a good spot for tomorrow, and there were some more storms down there too. As we approached the town we found ourselves heading right between two storms that were approaching from the south. Somehow, as ever, after a 2 hour journey we were cutting it extremely fine as to how viable it was to get between the storms and then west to get under them to see if there was some structure to be enjoyed. We made it in time and we were rewarded for our efforts. We found ourselves looking at a strong updraft, framed with a rainbow and a good anvil.

Rainbow and updrafts

From the other storm to our west Cambo also captured Jimmy Hendrix apparently giving some Mufasa-style pep talk to some budding guitarist somewhere to the south.

Hendrix cloud

After this structure started to give way we headed on west a little further to capture more structure in the evening light.

Evening weather photo



Today had needed, and got, a good bit of luck and resulted in quite a classic chase day. The chaser convergence was horrible (though we can’t complain as we were chasers who were converging!), but we had good structure, got scared, had to make some tricky decisions and were rewarded by some good views and pictures. All in all, I give it 6.7 out of 10, but I am a harsh marker.

SPC Day 1 Weather Outlook as at 06:00UTC (01:00 Central Time the night before)

SPC 01:00UTC day 1 forecast for Wed May 2014

SPC Day 1 Weather Reports for the day.

SPC storm reports for Wed May 2014

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