What goes around...

[stephbg]

Seeking advice from people knowledgeable in oceanography, currents, long term weather patterns etc. and/or people who've been alive for more than 30 years.

Comments

[drhoz]

actually, I recall a mention of a roughly thirty year cycle of climate in the South-West, so you may be right. Although it was predicting prolonged drought, not that you'd believe it given the weather this week.

[moonvoice]

We never met the July average for monthly rainfall - so even though it feels ultra-wet; it's still not above average yet, it's just different to what we became acclimatised to over the past few years.

[ariaflame]

Slight problem is that 'average' is based on 134 years worth of data. And given that the rainfall has decreased significantly over recent decades, I don't know that we are ever going to reach 'average' again. Well, eventually there may be enough dry years to bring it down, and if we have the occasional wet one we may reach the average of the time.

[cricketk]

Most rainfall graphs for Perth give you the long term average, the average from the 70's onwards and the average of the 2000's.

Water planning works on 70's onwards averages and there's some discussion about starting to work with numbers from the 2000's onwards only.

[rabbit1080]

found some stats on the internet - just a starting point, the data looks a bit hard to get to.

there are typically far fewer wet days now than in the 1970s
http://www.bom.gov.au/cgi-bin/climate/change/extremes/trendmaps.cgi?map=R__1&period=1970

dam capacity says there was basically no rain last year (dark blue line), but it looks like the local dams are currently (black line) filling about as fast as they did in 2009 (pink line).
http://www.watercorporation.com.au/D/dams_storage.cfm

[stephbg]

This one shows the fall in recent decades quite well: http://www.bom.gov.au/cgi-bin/climate/change/extremes/timeseries.cgi?graph=R__1&ave_yr=15

[ariaflame]

Then there's this. http://www.watercorporation.com.au/D/dams_streamflow.cfm Input to our dams since 1911.

[stephbg]

Ouch :-(

[moonvoice]

It is my understanding (from a book on El Nino/La Nina) that El Nino cycles only last between 3 and 7 years, and La Nina only has to last a minimum of five months to be considered a La Nina period (though this changes from country to country

[moonvoice]

Is the weather elsewhere roughly like it used to be 30-odd years ago?

Not really. Depends on where you are. But the massive heatsink in the US is the first of its kind according to recent US records. There's a good blog about weather and natural disaster events here which I find fun to keep up with; maybe give it a look? http://globaldisasterwatch.blogspot.com/

[stephbg]

It looks like the decades-long cycle I was thinking about was just the Leeuwin Current so just a local effect makes sense.