Thursday, 24 May 2012

Day 10 - May 23rd - severe thunderstorms

We started the day in Hays, Kansas. With a cold front moving in from the north-west and a modestly moist southerly flow ahead of it, we decided to head north-east into SE Nebraska. The initial target location was between Geneva and York. We had lunch in Geneva, enjoying the 34-35C heat and strong southerly winds. We had decided that if we were going to get as far as York, the east and then north option was more favourable, to keep ahead of the cold front.

We hung around there until around 4.50pm, having Skype'd my brother, Rich, and his partner, Ann, from the car.

We then headed north to Fairmont and then east past Exeter and Friend. By now, storms had developed further to the north along the cold front, but as is often the case in such situations, the activity started to build south-south-westwards along the front. We noted some towering cumulus to our west and paused to observe this. It was rapidly developing, with a very flat, firm, base - indicative of a stout updraught. We then headed north towards Seward -  by now, it had now become a thunderstorm. It had rapidly organised amongst the strong shear and started to exhibit supercellular characteristics. However, the RFD was already surging out of the storm and it quickly became apparent this would be an outflow dominant storm, as was expected. The storm had overtaken us a bit now so we had to continue north and then east towards Wahoo before we caught sight of the updraught again. The storm had become tornado warned, but I have seen no reports of a tornado. From the look of the updraught area at the times we saw it, the outflow-dominance was quite pronounced. We ran into some quite large hail, and paused to measure it...1.5 inches, which we reported via Spotternetwork - it was in the NWS obs within 5 mins, so a good dissemination there.

We saw plenty of dust whirls along the outflow but once to the NW of Omaha, we let the storm go, as we didn't think it was going to do much more.

We then dropped south ahead of the next cell, which was looking quite strong on radar. We stopped to the north of Gretna and spent a good hour or more watching the storm spit out some stunning CGs. I used Helen's Olympus bridge camera to try some 15 second exposures - I got the settings reasonably well adjusted after a while, and caught the following images. The last one has been cropped for more dramatic effect but the others are 'as is'.

Tomorrow sees the SVR risk shift into Wisconsin and environs - models are suggestive of some quite active/severe thunderstorms as the cold front moves east, and low-level wind profiles are suggestive of tornadoes. However, it also looks like with a fast moving cold front moving across, early discrete development may quite quickly transition into a fast moving squall line with a damaging wind threat, perhaps widespread. I'm not really sure the 450-500 mile drive is worth it! I'm sure a number of chasers will, and I wish them all the best, and look forward to seeing imagery of tornadoes that we've missed - however, I'm not sure we can justify the drive.


  1. Stunning final photo - well done!

  2. Georgina Plant25 May 2012 at 15:04

    Most excellent image my friend!