Maleny Weather

 September Round-up

This is the time of year when our eyes scan the horizon seeking the first sign of buds bursting out in colour on jacarandas trees. The heavy scent of jasmine and freesia fills the air, joy to some and an allergy to others.

Throughout the month a persistent high pressure system centred in the southern Coral Sea showed a marked reluctance to either weaken or drift eastwards blocking the likelihood of any substantial precipitation reaching us in frontal systems approaching from the south.  The result was we have had the lowest monthly rainfall for six years measuring only 39.4 mm, representing 24 mm below the 116 year average. The season’s first thunderstorm was an isolated cell on Monday 7^th   this brought 29 mm of rain to help fill near empty tanks on some properties. Total rainfall for the first nine months of this year is on track with the all time average.

It’s been a month of high fire danger brought on by tinder dry undergrowth, strong winds, 116 mm of evapotranspiration,  solar radiation over 1000 watts per m² , low relative humidity and 231 hours of bright sunshine. This recipe for a major disaster was averted only by the skill and expertise of our local fire-fighters.

The major phenomena of the month was the widespread dust that twice covered the east coast of Australia from Sydney northwards, arriving on the Blackall Ranges on Wednesday 23^rd and Sunday 27^th.

 It all started on Monday 21^st 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.

The second phenomena occurred on Saturday evening 26^{th. .}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.

The US Geological Survey says another earthquake, measuring 6.8 on theRichter scale, has hit the Indonesian island of Sumatra.

The quake comes less than a day after a 7.6-magnitude quake in the same area, which killed hundreds of people and destroyed large parts of the region’s capital Padang.

The earlier quake struck in the early evening almost 50 kilometres off Padang, a coastal city of about 900,000 people.

Indonesian officials say they fear the death toll from the first earthquake  could soar into the thousands.

Over 140 people may have been killed after giant waves hit the islands’ coastlines early on Wednesday morning following an 8.3-magnitude earthquake in the ocean south-west of American Samoa.

From the Archives

    An earthquake measuring 7.8 on the Richter scale occurred at 3.23 am on Sunday 30^th September 2007 near the Aukland Islands and activated Australia’s first tsunami early warning buoy, sited on the ocean floor south of Tasmania. All coastal areas of Tasmania and New Zealand were alerted of a possible sea-level rise and flooding. The warning was cancelled early Monday morning when only minimal rise of sea-level occurred.

From the Archives

A dust storm occurred in the Melbourne area on Sunday 19^th December when The Tmes in London reported ‘a man riding his horse on the outskirts of Melbourne was unable to see the ears of his horse due to the streaming volume of hot, stinging dust’.