This was the week when everyone had a taste – literally – of what is said to have been one of the worst dust storms for over 70 years. It all started on Monday 21st when an intensive low of 960hPa developed in The Bight. A cold surface trough associated with this system moved across Victoria and into NSW and SE Queensland. Overhead instability of the atmosphere was intensified by troughs in a NW cloudband. On Wednesday we had hot gale force winds whipping up red top soil from out west, including silt possibly from Lake Eyre, and then depositing some 75,000 tonnes an hour of dust along the east coast. Sydney airport closed early in the day and planes diverted to Brisbane. On the Blackall ranges the day started with a slight haze. At 1.15 pm winds backed to SSW and widespread dust moved in dramatically dropping visibility to 300m. The wide spread dust cleared the region by the following afternoon and made Thursday a day of mopping-up grit that had penetrated everywhere. Vehicles needed cleaning, also air conditioner filters. Washing machines were kept busy.
Pollution count was the highest on record with 15,000 micrograms per cubic metre, whereas the norm is 20 micrograms. A normal bush fire records about 500 micrograms a cubic metre.
Similar weather phenomena occurred again on Saturday evening 26th. .At 9.00pm wind backed to southwest bringing in once again widespread dust to the region. On this occasion the dust was less dense due to lighter winds and less noticeable during hours of darkness.
|
Sept 2009 |
Rain 9 am |
Evap. |
Soil @20cm Temp.&(Moist) |
Gust Knots |
Bright Sun Hours |
Cloud 3pm |
| Mon 21st |
Nil |
5.4 mm |
18ºC(102) |
15 |
8.3 |
2Ci |
| Tues 22nd |
Nil |
4.0 mm |
19ºC(119) |
23 |
8.0 |
6Cs |
| Wed 23rd |
Nil |
6.0 mm |
19ºC(120) |
29 |
7.0 |
Widespread Dust |
| Thurs 24th |
Nil |
5.4 mm |
18ºC(119) |
22 |
8.3 |
Haze |
| Fri 25th |
Nil |
4.6 mm |
17ºC(120) |
20 |
8.3 |
Smoke |
| Sat 26th |
Nil |
5.2 mm |
18ºC(130) |
20 |
8.0 |
Haze |
| Sun 27th |
Nil |
6.0 mm |
18ºC(155) |
21 |
8.3 |
Widespread Dust |
Please go to “This Month” page for more data