More rain! As the strong La Nina conditions really begin to kick in around the world for the first time since 1982/83 and 1973/4, South-Eastern Australia has been suffering some torrential rains, the worst of which have occurred over the past couple of weeks. December here in Canberra is usually a pretty dry month, with an average monthly rainfall of 52mm. We got 73mm on the 2nd of December alone. When its cooler its just persistent, when it gets hotter you get thunderstorms, wave after wave, three or four bands a day (or night) which each drop several mm of water. The dams are full for the first time in a decade. The drought is well and truly over, so much so that the farmers are losing more crops than they normally do due to a lack of water. Rainfall records have been tumbling, some absolute records have fallen, its been Australia's wettest spring on record. Last week people were talking about it being as wet as it was during the previous La Ninas, not necessarily unusal, but then we've had this week on top of it and things have got worse!
On the day with 73mm, the storm drains were at maximum capacity, the Lyneham wetlands site 50m or so where we live was beginning to flood, Sullivan's Creek (really just another storm drain) was running over its banks slightly in places. See attached photos. The duck pond on campus had two exits instead of the usual one. Canberra got off lightly though compared with other places around it. Its easy to forget but this city is over 600m up (the highest village in England (and possibly the UK) is just 463m, the pub that gets snowed in all the time is at 520m) and so isn't really floodplain territory. Down to the west, in the floodplains things have got really bad. The town of Wagga Wagga especially.
from www.actewagl.com.au
Its felt drier here the last week, we've even had a couple of nice days, but the ground is sodden, and when the rain arrived again in the middle of this week, it caused widespread disaster across New South Wales, incluing Queanbeyan (which is kind of part of Canberra, but kind of not) whose flood waters peaked at +8m overnight. The town is pretty much split in two and has been declared a natural disaster zone. Tuggeranong (another distant part of Canberra) allegedly received over 100mm yesterday and has topped 400% of its typical December rainfall already. The Queanbeyan sewage works have been flooded too, which means Lake Burley Griffin is out of action due to contamination, so theres been no sailing for the last week. The dam at the end of the lake has all its flood gates open. Other ACT dams are overtopping.
Its going to be an above average cyclone season in the North too.
Rainfall should return to normal levels around April sometime!
Going all sciency it looks like the La Nina conditions are actually weakening slightly, in which case the comparisons to be made are to 74/75. Here's the November SST anomaly map. That is a very warm anomaly surrounding Australia and thats why its raining so much!
from www.bom.gov.au
from www.bom.gov.au
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