Dust before storms: the phenomenon explained
RAINFALL in the southwest has given some relief to formerly bone-dry properties this week, but the welcome thunderstorms were often prefaced by massive clouds of red dust.
The impressive dust storms have become a common sight over the past few months thanks to some massive weather systems coming in from interstate.
Forecaster Rosa Hoff told News Corp the wild weather in the west was caused by two systems working on top of each other.
“A surface level trough has been hanging out further to the west, and it has been stretching all the way from Mt Isa down to the Maranoa and Warrego,” she said.
“We are seeing a large portion of the shower and storm activity to the east of that trough, but it is only one contributing factor to the activity we are seeing.
“We also have an upper trough which has been moving over in the past few days, and it is what exacerbated our chance of seeing some showers and storms.
“The inland trough that has been lying through central and western Queensland has had some quite strong southerly and south-easterly winds which have lifted up some dust from South Australia and even a bit of New South Wales as well, and caused it to be raised in Western Queensland.”
While the rain event dumping considerable totals on many properties is rare, the dust storms are becoming more common, and are travelling a long way to get to the southwest.
In future the massive bodies of dust won’t necessarily bring rain behind them every time, however, as this week’s event required many aligning factors.
“The trajectory we have seen this dust travel on has been something we have seen quite a bit over the past few months, while the heightened shower and storm activity we are seeing (this week) is really helped along by an upper trough we are seeing over southeast Queensland at the same time,” Ms Hoff said.
“You can’t say it is always the same phenomenon where the dust precedes the rain.
“Commonly we see thunderstorm activity to the east of a trough and our chances of dust are more to the west, but only if the wind conditions are strong enough and coming from the right direction, and we have some atmospheric instability too.”
This brief period of atmospheric instability brought varied totals across the region, with patchy falls totalling from 3mm to well past 40mm depending on location.
Between January 16 and 17, the highest official totals from across the region were:
- Augathella: 5mm
- Blackall: 33.6mm
- Bollon: 4mm
- Charleville: 5mm
- Cunnamulla: 25mm
- Injune: 46mm
- Mitchell: 40mm
- Morven: 17mm
- Quilpie: 3mm
- Roma: 43mm
- St George: 23.2mm
- Surat: 28mm
- Tambo: 5mm
- Thargomindah: 11.8mm