The Australian Storm Chaser September 2003 Final

The Australian Storm Chaser Volume 1 Issue 2 September 2003 Volume 1 Issue 2 September 2003 FREE Major Supercell Outbreak 30 March 2003 Video clip by Jimmy Deguara of the (Photo by Dave Ellem) A wedding the previous evening did giant hailstones thumping vehicle not dampen my enthusiasm for chas- [43seconds - 3.84mb WMV] ing this day. And after a quick final check of the usual models and vari- Although March is still officially a ables, and knowing that others could part of the severe storm season in not chase, I headed off solo to my New South Wales, the frequency of target of the mid-north coast. severe weather experienced is nor- mally lower - particularly supercell The trip up to Taree was definitely outbreaks of this nature! From reports Full report of HP beast available enlightening as massive v-shaped backsheared anvils of storms brought The windshear profile of this outbreak a smile to my face. was very impressive. With a southwest jet at 40-45knots at 500hpa and about 27knots at 700, storms were going to move generally northeast and north northeast if left movers. Com- bined with instability, sufficient heat- ing, cold air aloft (temperatures down to -17C on the mid-north coast) and a filtering through, this outbreak and good moisture profile, reasonably others this month have caused consid- long lived supercells were likely. erable damage in many less populated Hailstones of golf ball size and accu- areas particularly along the coastline mulated hail were likely as well as the outside of Sydney. The most common usual strong winds. The cap was not damage has been to vehicles due to the greatest and improved further large hailstones. This particular event north but the air was still sufficiently though produced some hail sizes into unstable to produce rapid develop- the giant category (diameters > 5cm) ment. On the lower mid-north coast, in some areas. By far the highlight of initiation was to occur earlier. The this month's storm structures was this environment was sufficient in my HP supercell mothership captured opinion to even produce isolated tor- further north later that afternoon by nadoes if conditions locally were ideal. Michael Bath, Dave Ellem and Rod- Storms were already developing on ney Wallbridge. the ranges by late morning to the southwest of Taree and anvils were rapidly streaming northeast. It was encouraging to observe inflow winds from the east to northeast although not strong. Occasional staccato lightning bolts were observed as the storms intensified and approached. A couple of cumulus developed rapidly 1 The Australian Storm Chaser Volume 1 Issue 2 September 2003 along the northern anvil - similar be- quent though nothing out of the ordi- my favour was that wind was from the haviour to what I had observed in nary. south and I was heading generally Tornado Alley last year. The up- north - with and not against the falling draughts exhibited twisting structure My mind was set on the impressive hailstones. The wind was not very or corkscrew effects. These remained structure and contrast exhibited by the strong either. Otherwise the damage rain free for some time as they contin- storms to the north. But yet again, would have been disastrous. ued to grow and became more organ- trees and mountains made viewing ised. difficult and since the road twisted About 15km south of Kempsey, the and turned, it became difficult to hold heavens opened!! The frequency of bearing with respect to the main cell. the pounding from giant hailstones The main views of the structure oc- meant it was time to take shelter. Next curred around Kew and it was clear road left, and I was quickly huddled this was a right moving storm. Rea- near trees. Footage of the hailstones sonably impressive though insuffi- reveal dominant hail being golf ball cient time to stop yet again. with larger thumps from hail I believe to be up to 7cm in diameter (though I entered the core of the storms from not measured - more analysis later). the south side. Hail and mostly heavy The hail bounced to about a metre or Suddenly, at 1:10pm, whilst moving rain made driving hazardous. Aqua- more after impacting the ground to a different position, I noticed what planing in some sections forced me to whilst large splatters also occurred. looked like a significant funnel cloud. drive well below the normal speed. I zoomed in immediately with the Passing the Port Macquarie turn off, video camera. It was in the correct sunshine could be seen so locating on quadrant where the wall cloud was to the northern side was a good option. be expected. This storm was defi- Then suddenly, "thump"!! These were nitely severe with hailshafts develop- larger stones from the sound though ing around the forward flank and the sporadic and isolated. It was inevita- core region. This was not a HP super- ble. I was under the development area cell. It looked classic based on overall of the supercell core most likely the structure. I remained at this vantage second cell that was moving left and point a little while longer, and moved in the same direction as I was. Radar north once drops of rain developed. shows this cell develop a main large core rapidly about this time. The trip north revealed more of the impressive activity well off the coast, the side anvil of the complex I was under and also the development of impressive structure of the two cells developing along the anvil mentioned above. The hammering was now so violent from these hard stones that I huddled It was impossible to predict where the next to another tree hoping to mini- next pelting would occur and each mise damage. My car became covered time, there were isolated large with leaf letter. This all lasted a mat- thumps. No place to take cover, I con- ter of a few minutes. tinued on hoping to get onto the northern side. Passed the Telegraph Heading north once again to remain Point turnoff though, I knew my car with and ahead of the storm was a I was more interested in positioning was in for a pounding. What I was not good decision. Measuring hailstone with this particular storm outside of expecting was the hail to grow from 4 size was at a lower priority as the odd the rain. But with the rain around, I to 5cm diameter maximum hailsize to stones were still falling and I was kept moving north to find a better a barage of hailstones in the range afraid of injury. A few smaller golf position. With the rain, mountains and 6cm to 7cm!! The vehicle was ball sized hailstones had fallen in the trees, the view was hopeless and in pounded so hard I was concerned car whilst filming. The main core had the end, I never stopped to observe at windows were going to smash. I could moved off to the east of the main all. It would have been good to ob- feel the vibrations of the largest hail- highway. What it left in its wake was serve if not briefly the structure that stones. And these were hard stones a carpet of immense leaf litter. This had produced the funnel. Only too - unlike anything I had observed was the first time I had observed a glimpses of this region seemed to previously on my Australian chases. carpet of leaves all over the road (the confirm classic structure. Lightning in The odd hailstone would splatter on Pacific Highway) since the Sydney- this region seemed to be more fre- the windscreen though. What was in 2 The Australian Storm Chaser Volume 1 Issue 2 September 2003 hailstorm April 1999. I had also entered another region of The chase was not a very long chase hail from a line of cumulonimbus that overall as was to be expected on this slowed down my progress. I needed day with fast moving storms but defi- fuel so stopped at the service station. nitely provided some intense mo- This was the first chance I had to in- ments. The following is an assessment spect the "dented mess" - see below. of the hailsize based on video stills and leaf size from deposited in the same storms. This is important in try- ing to determine an acceptable range of hailsize limit since it was not measured. The damage as observed below was significant - more so than observed in The Oaks hailstorm event December 2001. Side panels have dents despite the lack of severe winds. Roof damage was the most severe followed by the bonnet and then boot (consistent with the larger sheet metal area used). Please note the calipers have been opened in all pictures to 5cm spacing. These pictures below are meant to illustrate the approximate view and distance of the hailstones. Due to being in the storm, one tends to lose track of time. So it was a sur- prise when I noted I was entering Kempsey 80km/h zone. In fact I was delighted as I knew this was the start Was the chase over? No chance of of the river plain with excellent views for chasing. It would allow me the opportunity to observe the structure of From my assessment of comparing this likely supercell. Once out of the the latter two pictures, it seems the main township, I was treated to an hailstones were at least greater than impressive structured classic supercell 5cm. From the type of damage, I do complete with wall cloud and inflow believe hailstones of at least 6cm are into the leaning main tower as well as responsible for the larger dents.

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