Day 20 - Streets and Traps (Reprise)

07 June 2012

Today we were in the somewhat unusual situation of having a second day in a row with almost the exact set up we had the day before. The synoptic scale scenario remained roughly the same, with an Omega ridge over the northern central plains. The high pressure is termed as an Omega pattern due to the shape it creates in the upper level winds as the jet stream is driven north from its otherwise westerly flow, before returning to its normal seasonal latitude after the circumventing the high pressure. You may have read articles or seen documentaries about the importance of jet streams, but I think storm chasing teaches you day in day out the ramifications of what they are up to.

These setups in Colorado involved a few factors, but probably the most important was the fact that the high pressure was causing the jet stream to make a sharp left hand turn to go north, as it was over the Colorado area. As it makes that sharp turn the air on the outside of the corner has a longer path and so it spreads out (rather than accelerating), which lowers the pressure of the air, and as air below moves to fill that lower pressure, so we get air being lifted. It is these types of behaviour in the upper air which are a key factor in determining the weather we all (at least in the mid latitudes) experience day in day out. That wasn't the only factor involved, but I won't bore you any more with details. This was going to be happening again today, and would help provide the lift to maintain the deep convection needed for some big storms.

So today would have a similar setup to yesterday, but there were some differences, and we decided to pitch ourselves a little further north to wait. We didn't have that far to go, so we wended our way there, stopping on route to take a look around a craft store. On our way out we saw a big anvil that had popped up...this was something of a surprise but after taking a proper look it didn't look like it was going to amount to much, but nevertheless it was probably a good sign.

We pitched up next to a lake in Loveland, a little north of Denver. For the next few hours we would wait, eat some food, wait some more, drink some water, wait some more, etc. After a while some clouds would look promising, then die down a bit, and repeat. As the hour where the action tends to start approached we saw a really big updraft and determined this was our target. We set off straight away, hampered somewhat by Streets and Trips inability to navigate the was a bit hectic for her, with things like roads and corners confusing her. The storm was actually starting near the same place as yesterday...damn them! We started heading towards where the target storm's "storm track" - that is the speed and direction as determined by radar interpretation software - had showed them to be heading. However by the time we got a little east we realised this was going to be like the storms the day before in another way, it wasn't moving. In fact it was reversing a bit. Yes that is different to moving in the opposite direction. The storms features all indicated it to be oriented in one direction, but its movement relative to the ground was actually going the other way.

We'd had some experience of the road network to our south that could get us there quickly, the day before. We set off that way, this time deciding that we'd ensure we stuck to tarmac roads. There was a lot of sitting water by the road and these roads get quite difficult on road tires (4wd makes almost no difference at all). Streets and Trips is mostly chosen for being free...though to be fair, the costs of using it can be quite high. It is set to avoid dirt roads, and it picked us a route south. We knew, however that one of the roads it was taking us on was a dirt road, so we were set to take a different one. As we got there, however, it turned out that there wasn't a tarmac road to be seen. Oops. And thank you again Streets and Trips for again having no idea what roads you have in you. The roads were, as expected, slippery and not ideal for our setup so we had to set course back north, to go around the outside of the storms. That would take 2 hours. We took every sensible liberty we could, but it still took what felt like forever. The one saving grace was that the storm, and its sibling, had set up either side of a main road south. Between them they were making some crazy winds as they vied for all the air in the area, but the road between them remained largely unscathed and readily passable.

Eventually we got to Limon and by this time the storm had "reversed" further south, so we took a road south and then had to get onto another farm road (no tarmac) south. We'd come a long way, and although it was raining pretty hard, the surface wasn't too bad, and we weren't going to miss this now.

As we hooned south we still couldn't see much structure in the storm, and hoped this hadn't been a wasted journey. After 15 miles, we got out of the strongest winds and found a side track and pulled into it to take in what looked to be a pretty magnificent cell. As we pulled we found our friends Pete and Nathan there already taking shots. They felt our pain for our day's problems, all storm chasers have been there...but they couldn't contain their excitement over what they were calling the best supercell they'd ever seen! We weren't too late though, the sun still had a few degrees to go before it set, and the storm structure was, indeed, fantastic.



As well as being photogenic, the storm was also a monster. We were in its inflow winds, with clouds above us being sucked into the storm at dramatic speeds. The winds where we were at the time were probably about 45mph (the situation was too frantic to take measurements!) and they had been recorded up to 65mph. Inflow winds are much more persistent than other winds you tend to experience in these situations, so these are, while more predictable, quite hard to manage. Cameras, laptops and your own eyes and skin all become vulnerable to dust, random bits of hail and other debris carried in the winds, picked up from these relatively arid landscapes.

After a few minutes getting shots the inflow band started obscuring our view, and the bits of dust, hail, gravel and cows in the wind became more numerous, so we dived south where we'd find a main road. We got to the road and headed a little closer to the storm. We wanted to get further south but the main road was now blocked, ahead, by the monster we wanted to follow. We pulled into a farm road to maybe take a couple more photos, if wind allowed, and Pete and Nathan who were behind us, pulled up and said they'd been having similar thoughts and were going to try and get south down these farm roads. We set off in tow, however we had a problem in that Streets and Trips was now becoming impossible to use and the storm was bearing down on the road behind us. The conundrum was that you had to zoom into a scale that you can't navigate with - the whole screen representing 500 yards - to be able to see these roads. Additionally the software has very little consistency with actually knowing if roads exist or not. That means you can't get any sort of strategic overview and we were relying entirely on our friends, but without any real aligned goals or understanding of what we were going to be doing. This meant that we were somewhat out of control of our own plans and therefore control over our own safety. Although Nathan and Pete have a few years experience on us, it wasn't a comfortable situation, given the monster that was behind us. Nonetheless we were bound to this plan now so we pushed on, and stopped on route to get a couple of shots of the lightning from what was now a prolific lightning producing storm. It's not easy getting shots in this environment, but such detail as you can capture do depict, at least to a degree, how epic this structure can look at night.

After this we headed on south as the storm behind us put down another tornado that we could see clearly from radar, without really even needing the reports for confirmation. It remained an extremely powerful beast.

With the storm behind us we left Pete and Nathan as they set off for a longer journey south. We setup camp in Puebla, still in Colorado. We popped out to pick up some beers, and we weren't challenged for ID, a sure sign that the last few hours had taken their toll, clearly we looked a lot older than last time we bought beer!

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

SPC 01:00UTC day 1 forecast for Thu June 2012

SPC Day 1 Weather Reports for the day.

SPC storm reports for Thu June 2012

< < Day 21 - The Calm after the Storm      :      Day 19 - Colorado Magic > >

Weather Photography Blog