This day will go down in history for South Australia as one of the great storm outbreaks of recent history. For anyone who lives north of about Balaklava, supercells affected a large swath, dropping multiple tornadoes on the many supercells that formed on a sharp cold front. This front, in response to a very deep developing low pressure system contained a shear profile more typical of the united states, and combined with a very wet winter and start to spring from the negative IOD, meant instead of dry air being dragged in from the continent we had relative to the time of year, high moisture levels. Add the vorticity from the wrapping front, and north-east winds of considerable strength ahead of the front, we had an environment primed for supercell development, despite modest CAPE (up to around 1000 j/kg). A powerful divergent jet stream above would have assisted storm development greatly in the instability department.
By mid morning, we had a rather lightning active mid level rainband develop out ahead of the front, in response to huge upper divergence from the jet exit of a VICIOUS 500mb jet moving in from the west. Apart from producing some locally intense Cg action, it acted to transport moisture from the mid levels to the surface, another necessary ingredient for lowering LCL’s in the afternoon, and providing a deeper moisture profile for storm development.
I drove out to the north of Blyth to watch it move in. It had that classic high shear, mid-level thunderstorm sky we often see in South Australia this time of year. A cell rapidly developed out ahead of the line, and proceeded to drop a barrage of Cg’s, running right over the top of me. They weren’t very pulsy, however they were very loud, with huge cracks associated with them. I had many bolts within a few km, the closest hitting <300m from me in a paddock and beading out.
I drove back into Blyth, being flanged the whole time, ears ringing from the close ones. I take a short video on my phone, and manage to capture one closish Cg on the back end.
Now that this excitement had passed, my attention turned to the clear air behind, and the currently invisible passage of the front. I knew I would have trouble chasing these cells, with the Barunga Ranges off to my west. Roads are few and far between over this range, and tend to diagonal themselves across it. I also knew there was a chance cells would become too cluttered along the front as it progressed, so it was either sit on the Barunga Range and follow it east to the Clare Valley (therefore risking only seeing a linear line), where it would overtake me due to road networks, OR to drive to the coast to see the cells as close to initiation as possible, and have no road options to persue them with, however with what I believed to be a greater chance of seeing the storms in discrete modes. I chose the latter and drove over to Port Broughton. It’s hard to say whether this was the right choice, as it would turn out that storm cells would remain relatively discrete throughout the afternoon and would produce a significant tornado at my home town which I would have seen with the first option. However, instead I did get to see a very powerful supercell anchored on the cold front put down many funnels, and one short lived tornado, as well as a tornado at Crystal Brook on a weaker, but still significant supercell to this ones north. Unfortunately with storm chasing, decisions like this often need to be made, you simply can’t be everywhere at once!
I get to Port Broughton as the absolutely enormous anvils of the developing supercells to the west moved over. It was at this point I could tell for sure the cells had anchored onto the cold front…success!! This was key for increasing helicity in the storms vicinity and increasing updraft strength with the forced lift.
I linger, very carefully watching radar to make the critical decision of where to go. On days like today, core-punching a storm can mean severe hail damage to your car, or being trapped by falling trees or flooding. You also need to be acutely aware of cells forming ahead of the line, right movers especially as these can rapidly develop and create potentially damaging storms, just ask the people at Cleve whom had just had a right mover drop large hail as the above image was taken.
A left mover had anchored on the line, and it become obvious that this was the cell to watch. I determined the downdraft region was going to t-bone Port Broughton, so to see the inflow region and flanking line I would need to head north, so I did. My decision was made, I would have to abandon this storm as it went past as there were no roads to track with it short of corepunching through this dangerous storm.
I park in a very clear area with great views all around and sit for over half an hour now, watching the spectacle unfold. Slowly but surely the flanking line and wall cloud of this supercell came into view.
And then sure enough, a tornado rapidly forms, drops to the ground and dissipates in a rather short amount of time…success! My first ever mesocyclonic tornado.
The cell moves forward, and continues its relentless efforts to put down tornadoes. It was a strange feeling, having wind nearly at my back that was not only strong, but moist as well. Something rarely seen ahead of storms in Australia, the crucial lower level jet which greatly increases tornado chances.
The storm gets closer, and what I believe to be an updraft replacement cycle occurs. The storm also starts to look mean…very very mean. An eerie green glow emerges the closer it comes, and as I start to see storms EXPLODING to the north of this one, I begin to get nervous, I have a dangerous supercell to my south ready to put down a tornado any minute, and rapidly developing cells sandwiching me in to the north.
I accept the fact that at least one of the right movers heading in from the north will hit me, so I wait for it to pass to the south, which would allow me to see this mesocyclone up close and personally!
I take this image and then floor it to the north to get to my NW road option and out of danger. I take no pictures until I reach the highway, but have to corepunch in front of a fairly benign looking cell coming down from the north, which blows at least 100km winds sideways across the road, with the odd bit of small hail and spray everywhere. The trees are swaying over the road but I just manage to get out to its east before the worst of the core crosses the road…success! I have avoided damaging my car in any way.
I take a moment on the highway to see if there is anyway to get back in front of the southern cell. I rapidly conclude there isn’t, i’ll be driving directly under a rotating wall cloud region and then core punching the worst to do so…bugga! The cells to my west and north are rapidly developing and closing in quickly, nothing for it but to head to Crystal Brook to seek shelter, I simply can’t outrun this.
I snap this last shot of the line and drive into Crystal Brook. I turn the corner and see a large piece of roof flying hundreds of metres in the air…oh crap I’ve made a mistake. I see more bits of tin roofing being wrapped around in the air, low cloud rotating above and the trees being shredded down the road. I slam the car into reverse and this fast moving and nearly invisible multivortex tornado moves diagonally towards me at fast speeds, probably around 50km/h as a rough estimate. Rapid motions are observed at ground level and i whip the car around, turn left and watch the tornado pass to my east by a couple hundred metres as I sit in the ‘bears cage’ region of the storm. The trees in front of me get a clipping from this tornado and are violently thrown around. It passed and I drive a short distance down the road to find a front yard full of trees, powerlines down and the owner visually distressed, whom I don’t think had any idea what was coming, it came through very quickly.
Then comes the rainfall a couple of minutes afterwards. I carry on to find the source of the airborne debris. 90-100km winds and some very heavy wind come through.
I go a bit more up the road and see the very real damage from the near invisible tornado. The damage path was sporadic, this thing was briefly touching down and bouncing through the town. I talk to a local who saw the worst of it happen and he mentions a thin wall of black…given the wetness and the fact it was across an oval…we have had a condensation funnel touch down, gain momentum and slam through the netball courts. This guys property had faired okay, but a large piece of wood and bounced straight through his fence knocking it down, and there was a hole in his shed roof from debris.
I head in for a closer look, now it is all good and well to see pictures of tornado damage, but seeing it first hand is something else. This was only a weak tornado, but it became quickly apparent that had anyone been outside in this, they would have been killed.
These weren’t the only severe storms of the day, oh no. I believe the biggest tornado of the day belongs to north of Melrose, where some very wide and severe damage was recorded. River reds de-branched and stripped, and some severe property damage. If anyone reading this knows of any pictures of this tornado I’d love to see them!
So far based on pictures I have seen, I think we can confirm 5 tornadoes, and possibly 7 or 8 damage paths possibly so far. This truly was an exceptional storm outbreak, thanks to a very powerful weather system. Something very rarely seen in South Australia. All types of severe weather would result from this low. A day I will never forget, and some things I might never see again.