Rainfall and temperature of late...

The weather that we are experiencing at the moment throughout Australia is phenomenal. We have disaster relief programs brought on from flooding in the north of Queensland and the tragedy of fire in Victoria. I have pulled some data from the Bureau of Meteorology website that exemplifies the bizarre nature of the weather experienced this year already.

Rainfall
The rainfall data shows some very interesting trends throughout the country. Firstly, you can tell from the first figure the vast amount of rain that has fallen in northern Queensland. A quick check of some centres indicates some amazing facts. One of the wettest weather stations this year has been Hawkins Creek, just NW of Ingham, where since the start of the year, 2,694.2mm has been recorded, including 1376.8mm in the last 12 days! That yearly total to date represents over three times the annual average rainfall for Perth and over twice that of Sydney! Needless to say, with that much rain falling in the region, flooding is a major issue. Flooding has also gripped large parts of the western edge of Queensland from Burketown all the way down to Birdsville. The Diamantina, Gregory, Nicholson, Albert, Leichhardt, Flinders, Cloncurry, Norman and Gilbert Rivers, just to name a few, are all presently on flood watch; many of them have been on flood watch for almost a month. Note also the interesting rainfall pattern in Western Australia. There has been more rain falling in the arid interior of WA then there has been on the coast. No doubt, the pattern of rainfall from Port Hedland down to the Nullarbor was due to the passage of various rain-bearing depressions and Cyclone Dominic, although this pattern of elevated rainfall through the interior of WA is evident over the last 10 years or so, often independent of cyclone activity… interesting!! Note also on the map that much of the area devastated by the recent bushfires in Victoria have received little to no rainfall. Apparently, much of Victoria experienced a relatively wet December which helped to boost understorey vegetation. Following this, a very dry January and heatwave at the same time (see below) resulted in all this ‘fuel’ drying out.

The second figure I show is the percentage of yearly rainfall received to date. What is amazing on this figure is that as of the 11th February, much of northern Queensland has already received their average rainfall for the year, with some places in the Gulf country already having received over twice their average yearly rainfall already… and it is only the 11th February! If they don’t receive a single millimetre for the rest of the year, they would already have received twice their yearly rainfall. Unfortunately, there appears to be no end to the rainfall in the immediate future.

Temperature
As we have seen, the Victorian bushfires are unprecedented in the sense of ferocity, intensity and loss of life. What hasn’t helped has been the incredible temperatures experienced throughout the southern states in the last 2 months. On Saturday 7th February, the day the fires claimed so many lives, Melbourne experienced their hottest day in 151 years of records; 46.4 degrees, or 20.6 degrees above the January average! Add to this, temperatures of 36.4, 43.4, 44.3 and 45.1 between January 27th and 30th, and you have some strange weather! Likewise, at the same time, Adelaide sweltered through temperatures as high as 45.7 degrees, and for 13 days between Monday 26th January and 7th February, the temperature only dropped below 36 degrees on one day, and included 8 days over 40 degrees! The cause of much of this heat was the presence of a heat trough (shown as a dashed line) perched just to the west of Adelaide and Melbourne around the time of the heatwave, which was being held there by a high pressure system in the Tasman Sea, and brought hot dry winds from the NW over the parched, dry and hot inland. Any time you see a trough line to the west of where you are, expect hot weather, especially if it plants itself there for days! This is regularly seen in Perth, and you watch; those days they expect hot temperature, you can almost guarantee a trough just off the coast, and as soon as it passes, it dramatically cools down. On 8th January, the maximum temperature reached just 24.8 degrees compared to 41.5 degrees the day before. Likewise, on the 8th January in Melbourne, the temperature reached just 22.5 degrees compared to 46.4 degrees the day before; a 23.9 degree turnaround. That same trough line that brought this hot weather then cooked Sydney for an extra day as it moved east, bringing 42.5 degrees to Penrith, before dropping to 23.6 degrees on Monday.



The image I show here is the maximum temperature anomaly (that is, the differnce between that observed, and the long-term average) for both the month of January, as well as the last 7 days, which shows the uncharacteristically high maximum temperatures in the southeast of the country and the extraordinarily cooler maximum temperatures in the gulf country of northern Queensland, associated in part with all the rain they have received.

These patterns of temperature and rainfall have given rise to the current state of northern Queensland and their floods and the devastaing bushfires in Victoria. We can only hope that the coming months ease the burden on the people affected by these unsual weather events. Check out on the Bureau of Meteorology website, as well as the Weatherzone website, which you can register with to get really good weather information, outlooks as well as interesting weather news and facts! ENJOY!