Obscene hodographs and the roll cloud of doom

03 June 2014

Today was one that had received lots of attention from hobbyists and professionals alike for several days. Hobbyists were discussing “ground munching tornadic mesocyclones” while even the professionals were talking about a key forecast element- the hodographs – as “obscene”.

The breaking down of the weaker weather patterns that had prevailed over the last few weeks was set to be a dramatic one. A strong upper trough would pivot from the central high plains through the Midwest through the day, associated with a powerful jet streak. This was set to induce rapid cyclogenesis at the surface which would, in turn, create a potent setup for severe weather. The winds at the surface would be strong (30mph+) and from the south, bringing plentiful moisture with them and providing a strong southerly component to the shear profiles. The strengths of these southerlies would also potentially reverse a warm front that was progressing down the Midwest – turning it into a cold front (in practice it didn’t, the resultant stalled diffuse warm front was key to the main initiation of the day). Between the lower southerlies and the strong upper winds the bulk shear would be over 60kts and veering with height in a textbook setup for supercell development.  

While the fundamentals of the setup were very good there was considerable uncertainty introduced by outflow from the storms the day before. The main area of risk for severe weather was north of the warm front in northern Nebraska. This would yield severe and messy weather. Our hope was for some more discrete convective development further south.

We started the day in Kearney, Nebraska and made extensive use of Maccy D's wifi for a mammoth planning session.

Weather forecasting!

Our first move took us closer to the Kansas border to where models were forecasting storms to break out. As expected severe storms kicked off in the north and looked as messy as a toddler’s birthday party. Meanwhile we waited expectantly for something to happen. The atmosphere felt thick with humidity and the surface winds were constant and very strong. Any time we drove around you would need to constantly steer into the wind due to its strength and persistence.

Eventually some initiation kicked off much further west than we anticipated, but it looked good and we set off as soon as we could. On getting underneath the storm it initially looked disappointing, and the most interesting thing around appeared to be the ridiculous “Dominator 17” or whatever number they are on now (Reed Timmer’s effort at a storm chasing Dalek, and no, it can’t climb stairs).

The dominator is waiting for the weather

However before long the storm started exhibiting some great structure.

Weather Photo rotating meso

Unfortunately it was moving quickly and we soon had to leave it to head off into the wider areas of bad weather. Fortunately a new storm was firing even further west so we headed for this. It looked great on radar but unfortunately our arrival appeared to kill it. Its death throw, however, was a roll cloud which rolled over us in magnificent style. The following sequence of pictures are over the course of about 3 minutes, showing you how quickly this roll of cloud was moving!

Roll cloud 1

Roll cloud 2

Roll 3

Roll 4

Roll 5

Roll 6

After this had passed we headed on to get a closer look at the remnants of the storm which was now pretty much dead, but we caught sight of another very unusual cloud. It was too far away to get a better view of, but looked uncannily like a distant mountain.

Mountain Cloud

Finally we decided to take a look at the updrafts that were now going up behind us. These were dramatic but they were now not able to turn into storms as an Elevated Mixed Layer (EML) had arrived creating a sharp layer of warm and dry air which would inhibit any further development. The updrafts were magnificent nonetheless and so we watched them as the sun set.

Timbo Sunset

The day had pretty much gone to forecast in the moderate and high risk areas, but we had really been chasing a slight risk and, as they sometimes do, these don’t materialise as expected. We still saw some amazing things though, and while it wasn’t quite the weather we’d hoped for it was a very memorable chase.

Key points:

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

SPC 01:00UTC day 1 forecast for Tue June 2014

SPC Day 1 Weather Reports for the day.

SPC storm reports for Tue June 2014

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