Willow the Wisp

10 May 2015

Today was another split risk across the US. A shortwave impulse was heading toward Texas with storms forecast both in the vicinity of this and along the dryline. Whereas further north the surface low continued to  track northeast of its current position through northeast Nebraska and southeast South Dakota and Iowa. Even a few days back we had decided to play for the northern option due to better chase territory and it being in closer proximity to yesterday’s chosen target.

It was near midday just south of Norfolk, Nebraska and we saw a few cells developing above us. However, in an attempt to put into practice what we have been learning we continued driving east to get closer to the east side of the low in the hope that any cells developing here would have greater tornadic potential due to the better wind shear, with the surface winds flowing more perpendicular to the identified front associated with the low. As it panned out however, the entire region just became a cluster of small single cell and multi cell storms and nothing was developing into anything photogenic or discrete. So after getting rained on, a lot, we headed further north keeping in close vicinity of the low but to put ourselves under clearer skies in the hope that being int an area of max heating might help (both with the storms and our spirits!)

Driving up through South Dakota was great and the new 80mph speed limit helped us gain ground quicker. The diminishing storms to our south had all but petered out by this point and we were struggling to understand why the bad weather had halted in such fashion under what was progged to be an enhanced risk day. We looked at all the current weather charts to see if we could work out what had gone wrong. The 700mb temperatures were warmer than those forecast – perhaps the region was therefore under some kind of cap, which can act like a lid and contain what available energy there is closer to the surface, which at the current time was only modest at best.

It drew closer to 5pm – the magic hour of convection but the few little storms that sprung up along the I90 through South Dakota weren’t amounting to much either. We pulled off the I90 and hung around for a while and patiently waited. Tim attempted some time-lapse photography of the dying cells but ended up getting his camera equipment and then himself entangled in some unexpectedly electric fencing. I wrote some blog bits and tried to catch a butterfly.

All the while there was a storm starting to look quite healthy that had popped up above us. Trying to not get too over-excited we continued passing time until it was apparent this storm had legs. We jumped into the car and shot north to get closer to the developing updraft. A funnel cloud was reported by some chasers further up the road. We went as fast as we could, but a 30mph speed limit forced us to crawl, for what felt like forever, through a nearby small town. As soon as we emerged the other side, there above the trees we could see another funnel forming. As we sped down the road I grabbed some shots from the car using the snappy cam. It was beautiful and very reminiscent of Willow the Wisp. The speed at which the air was turning through this twisting turning funnel of air was both incredible and beautiful. It danced behind the trees for about a minute before eventually roping out.

Supercell Storm

Non Supercell Storm Tornado1

Non Supercell Storm Tornado2

Non Supercell Storm Tornado3



We have since been researching this type of tornado as it didn’t appear to develop from a rotating wall cloud as we are used to. We think it was a nonsupercell tornado (NST) which can develop from storms that aren’t rotating and are usually shorter lived and weaker, although there have been occasions in the past where they have been quite powerful. In fact, the day before we arrived in 2012 there was an outbreak of NSTs in Kansas with one reporting EF3 damage. The more I read about these tornadoes the more they have become my most favoured type. They tend to be accompanied by less precipitation and can often form from clouds with much higher bases, which, to me, makes for a much more dramatic effect. So that’s what I think I’ve now become – not just a storm chaser, but a nonsupcell tornado chaser. As if seeing a normal one wasn’t hard enough!


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

SPC 01:00UTC day 1 forecast for Sun May 2015

SPC Day 1 Weather Reports for the day.

SPC storm reports for Sun May 2015

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