I got thinking about this while reading the thread on Doppler at Tamworth vs. Grafton.
In 1997, I laid my hands on a book "Willies Willies and cockeyed Bobs - tornadoes in Australia" ( a book which, ironically, I lost on my way back to Australia after seeing my first tornado in 2001!) the information in it suggested to me the presence of a great tornado hinterland west of the northern and central tablelands of NSW.
If any of you have looked through the NSW severe storms database, there does appear be a disproportionately high number of tornadoes reported from the NW Slopes and Plains region, some of which were evidently quite destructive. Even in recent times (~2005), a substantial tornado was reported to cross the Oxley HWY near Coonabarabran. In 1996 there were 3 tornadoes reported from the general area. In 1999, Jimmy and Michael saw what looked like a funnel cloud to the ground through rain. Jimmy chased a storm with a rotating wall cloud and low base near Coonabarabran in Dec 2005. There are localised, narrow swathes of tree damage through the Pilliga scrub (so I am told). The region sits in a good location to benefit from the typical upper level system. Big storms are part and parcel of life out there. But tornadic supercells?
I must say though that over the last 8 or so years that we have had good access to computer models, I have not seen many situations that would support the presence of any 'tornado alley'. Most notably, there does appear to be issues with T/Td spreads such that on many days tornadoes are effectively ruled out. Good 0-3 km shear seems lacking and deep N-NE flow is a rare event on storm days.
So, are these 'tornado' tracks through the scrub the result of dry microbursts (we know there are plenty of those out there!) and/or'
Are the eyewitnesses reporting 'scudnadoes'? or;
Is the accumulation, in the database, of genuine tornado reports over time the result of 'freak' events that occur only rarely
Or is our meteorological vision of this part of Australia, and indeed much of eastern Australia, tainted by what has been a dry climate cycle over the last decade?
Personally, I suspect the latter is at least partly responsible. I always say that Sydney's climate, well over the last decade or so is drier and less stormy then a 10-year period that you might pluck out of the 70s and 80s. Whether such wetter phases translates to more tornadoes or simply more rain events / thundery weather, I dont know. It is also worth noting that the traditional chase areas of the US southern Great Plains appear to be going through a quiet phase (many veteran chasers will tell you this with the halcyon days being in the 70s and 80s). I doubt these observations are simply the case of nostalgia.
Let's hope whatever factors drive such climate cycles swing back to our preferred direction and we enter a wetter, longer-term cycle in our climate (and for more important reasons than seeing tornadoes of course). It would be an interesting period to chase the NSW slopes.
