Victoria: Winter Averages and Rainfall 2009

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Victoria: Winter Averages and Rainfall 2009

Post  Karl Lijnders on Tue Sep 01, 2009 10:50 am

From previous thread and discussion.....

Anthony Violi yesterday at 6:26pm

This is the best period of below average rainfall we have ever seen...been fantastic, been average or above the last few months..unfortunately not everywhere but we are blessed out here.

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hillybilly Yesterday at 7:38 pm

This is the best period of below average rainfall we have ever seen...been fantastic, been average or above the last few months.


Anthony much as I wished you were right I can't agree. Our rainfall in Ferny Creek has been 150mm below average over the last 4 months. It is a similar story across most of central Vic and Melbourne has just marked it's driest Jan->Aug on record. Coldstream had just 58mm in August (about 30mm below average) and I suspect that only March has seen average rainfall there. This year is shaping up as an absolute shocker except along the coast and parts of the west (unless we get a really wet spring).

We have had a huge number of rain days - I've had rain on all but 4 days in the last ~6 weeks but only one day managed to get to 20mm on one day.

The obs I've seen suggest we are in a classic green drought. The warm nights and frequent light falls mean that the annual vegetation looks great but below the surface it is horribly dry.

On a positive the next week does look pretty promising for more regular top ups.

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AUSSKY Yesterday at 8:42 pm

Missed that snow....Clyve said there were some good flurries around 2am but they didn't settle at his place either..ahem, I woke up but couldn't e bothered to get out of bed

Re soil moisture - we've been planting hazelnut trees and finished just as the rains really started .... the soil moisture had got down to 30cms very rapidly and the soil at that depth was becoming unworkable (before that, it had been only the top 2 - 3cm that were at all damp). The swale drains in my road have some permanent water in them now and our grounds aren't drying out at all after 300 or so mm in the past 3 months...all the dams in the area suddenly filled overnight (some were only half full previously) on about 26th of the month (from Gisborne to out past Trentham), so this part of the state is pretty happy atm

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droughtbreaker Yesterday at 11:09 pm

Good point to bring up about the 'green drought'. It seems that almost every year we get one of these at this time of year where it greens up to the point you'd swear we'd had a wet year. Having said that, this month has been genuinely wet since the 16th. 2.7mm in the gauge this evening. I'm unable to record at the official time of 9am and record in the evening instead but never the less I got 104.9mm for the month as of 6pm tonight.

The month started off with 'dribs and drabs' with just 25.8mm to the 16th on around 8 days. After the 16th however we got 79.1mm on the same number of days, so that's over three times the amount of rainfall in the same time period for the second half of the month, basically some 'decent' falls from strong and productive fronts. As a result, the ground is actually sodden, there is water lying around the place locally and you actually squelch into the ground in some parts of the yard and it's muddy, a scenario we rarely see these days whereas the soil used to be completely waterlogged for about 4 or 5 months a year in the 'good ol' days' of the 80s and 90s. Not sure exactly how far the moisture goes down in the soil in terms of cm or anything like that but i would suggest there is better soil moisture here currently than we've had for about 5 years at this time of year.

Final winter total ended up 234.3mm against an average of 261.6mm. Still technically below average , but only barely so with 90% of the mean (for the last 35 years at my place) achieved for the entire season.

So while it has still been a terribly dry year to date, (just 345.4mm against an average of 542.8mm, i.e. 63.6% of the mean), Jane's post tells the story for this area, we are doing well all of a sudden and the latest model outlook continues along the same lines of the last fortnight. If it wasn't for the horror of a nightmare of Jan and Feb where we got just 5mm (losing 104mm of our average yearly rainfall in the process), our situation would not be anywhere near as hopeless. It would still be a bit dry but nothing statistically significant. Blame Jan and Feb for this horror year. I understand though that the western half of Melbourne and inner suburbs have had a bad year all year including winter and this month.

If we get average rainfall for the rest of the year (almost a pipe dream the way our general climate is now), we will end up with 657mm. That would be yet another ridiculously dry year but nothing record breaking as a stand alone year.

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Anthony Violi Today at 2:49 am

And thats my point DJ, if this is the worst drought we will have we have nothing to worry about. Our dams are overflowing for the second consecutive year...a lot of places granted arent as lucky, thats why i said we are blessed. Been below average for years and we still get plenty of rain, there have been lots more shorter but more severe droughts in history. The 1982/3 drought was extremely severe

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Johnno Today at 9:23 am

Try telling that to the people living just North and West of Melbourne Anthony whats happening here at the moment is 10 times worse than 82/83. Andrew has had more rain this Winter (which is still techincally below average there) than I have had all year! Puts things in perspective eh?
180mm here in 8.5 months (since Mid December last year) if that doesn't say alot nothing will.. I would take the "below average" that your having to this ridicolous out of this world record breaking dry this way.. At least in 1982 by Early Spring this area already had 250mm+ so do the math mate and see which one is more severe out this way we are smashing it here at the moment compare to 82 if that was severe than I have no words to describe what the heck this is around here now. My point is I'm not saying it is like this right across Victoria but I can definetly say it is alot worse than 82 out this way. May not be as widespread as 1982 but in some areas its worse/ More severe namely this area and East Gippsland which have had a shocker of a year as well.

I wouldn't get your hopes up for Thursday either looks very little in that for me the rainband looks like formiing North and East of us little to late for Central Victoria and Melbourne again & even if it does peak over us don't we ever learn that in 30 knot+ N winds these systems rarely produce in Melbourne? Whats going to be different this time to all the other 100's of times which has happend in recents weeks/months/last few years? If anyone has an answer please tell me cos I don't freaking know and see any differance to all our other 30 knots+ N wind systems and rainbands for Melbourne which 99 out of 100 times rarely work for us either way doesn't look good be lucky to score half a mm out of that band and mabye 2mm at best Eastern suburbs but thats only my opinion

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That is where we are up too..... Very interesting debate so far.
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Re: Victoria: Winter Averages and Rainfall 2009

Post  Melbourne Skywalker on Tue Sep 01, 2009 2:26 pm

I totally back you here John. I cannot remember the last time we had a day of rainfall in double digit figure totals here around the Caroline Springs & surrounding area's. It's been terrible. Unfortunately we are not the only ones either. Those in East Gippsland & up in the North West of the state have suffered too. BTW, barely 30mm of rain fell in my area during August.

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Re: Victoria: Winter Averages and Rainfall 2009

Post  Anthony Violi on Tue Sep 01, 2009 4:26 pm

And this is why this drought is different...82/83 affected the virtually the whole Eastern seaboard. We have places here that are just managing to get by, like us. Only one year the dam, a 4 million gallon one, hasnt filled up. We have had enough water to get by every year for the crops..mate 83 there was no grass. At least the last few years the grass is dead but its there. 82/83 was beyond belief...

We have been getting 60% or so out here the last 10 years and going along ok...and thats all you can ask. Interesting to see that some places have had very low rainfall, whilst others havent done too bad..
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Re: Victoria: Winter Averages and Rainfall 2009

Post  Karl Lijnders on Tue Sep 01, 2009 11:01 pm

Do we suggest that this is climate change or cycles???
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Re: Victoria: Winter Averages and Rainfall 2009

Post  Melbourne Skywalker on Wed Sep 02, 2009 6:50 am

It's a good question Karl, but one which doesn't have an easy answer. Some say it's just a cycle, but I have to say it's a bloody big cycle if thats the case. I remember growing up in the 80's and you couldn't go outside during winter as it was too wet. I grew up on a property in Epping and there was mud everywhere and the tanks were always full. Unfortunately conditions have not been like that for a very long time. I think over-development of our land and increasing population might have something to do with our changing climate, but don't lean towards one definate answer.

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Re: Victoria: Winter Averages and Rainfall 2009

Post  Karl Lijnders on Wed Sep 02, 2009 5:36 pm

It is certainly interesting as the Melbourne area has been the hardest region in all of Australia in the last 3yrs going by the rainfall maps. Scary to think!!! But makes sense!!!
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Re: Victoria: Winter Averages and Rainfall 2009

Post  hillybilly on Fri Sep 04, 2009 6:06 pm

Do we suggest that this is climate change or cycles???

I think we have to move beyond that question in many ways. It's a fact it's got hotter across Australia (about 1C) and the globe (about 0.8C). That's the equivalent of (effectively) moving climate zone about 100km towards the equator (or taking 2-4 weeks out of winter and adding them to summer). Whichever way you look at it, you can't make that change in temperature and expect rainfall to stay the same.

The main feature of this drought is the very poor autumn rainfall that we have been getting year after year - http://www.bom.gov.au/cgi-bin/climate/change/timeseries.cgi?graph=rranom&area=vic&season=0305&ave_yr=0. This means that we are always playing catch-up for the rest of the year. Spring has also been pretty fickle (though it's not totally clear that this variability is anything different from what has happened in the past).

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Re: Victoria: Winter Averages and Rainfall 2009

Post  Johnno on Sat Sep 05, 2009 6:45 am

I do agree from the late 80's Autumn rainfall has decreased alot but do recall 2001 DJ of 2 months of 100mm+ for Melbourne (March & April 2001) so it was a very wet Autumn even though May was dry... So the Question is do you mean Victoria as general being below average since 89 for Autumn or Melbourne?

95 and 96 wasn't to bad either 1996 we had 130mm for Melbourne in April infact the first 4 months of 1996 the Melbourne City already had 400mm+ rainfall! Shocked Hard to even comprehend these days considering its only just barely passed 200mm into the 9th month of the year. So yes I do agree rainfall has declined since 89 in Autumn but don't agree that was our last wet Autumn in Melbourne since then.

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Re: Victoria: Winter Averages and Rainfall 2009

Post  windyrob on Sat Sep 05, 2009 3:05 pm

96 was the last wet year Jonno, Most of the dams were close to overflowing. 97 the drought started and melbourne water supply dropped 25% in one year. Somewhere during the 97-00 enso events something shifted, causing an increase in convection plus heating in west pacific warm pool plus decrease in global humidity. What causes what is open to speculation! Until it shifts again i doubt we return to a wetter climate. Here are the some graphs that show the show the shift.



All very interesting!
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Re: Victoria: Winter Averages and Rainfall 2009

Post  Karl Lijnders on Sat Sep 05, 2009 10:56 pm

Very interesting thoughts here.

What I have also noted in my weather observations has been the increased wet period that seems to occur between November and just before Christmas, that 6-8 week period over the 3/5 years has been very stormy with unprecedented tropical moisture, thunderstorm/severe thunderstorm and rain events. But somehow as we get past Christmas, the tap turns off!!!

Last year we had an amazing run of low pressure systems moving through inland regions and causing rain/storms. I think we had about 6-7 of them in a row!!!
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Re: Victoria: Winter Averages and Rainfall 2009

Post  hillybilly on Sun Sep 06, 2009 6:18 am

I do agree from the late 80's Autumn rainfall has decreased alot but do recall 2001 DJ of 2 months of 100mm+ for Melbourne (March & April 2001) so it was a very wet Autumn even though May was dry... So the Question is do you mean Victoria as general being below average since 89 for Autumn or Melbourne?

I'd put April 2001 down to a freak event - the month saw a huge cut-off which was not unlike the Feb 2005 system - so I wouldn't really take much it. We have always had freak events and that was one of them - indeed anecdotally we seem to have had quite a few of these including the huge June 2007 storm.

If you look at the whole of Vic the last state average autumn which was above average was 1989 - the west have all been below average or just on average.

BTW Windyrob there is theory bouncing around that major El Nino events act as "golden gates" through which the climate system passes to never return back to its previous state. Due to greenhouse we have a monotonic warming background trend of 0.15C/decade. This doesn't appear as a straight line but rather as a series of step ups to a warmer climate.

If you look at southern Australian rainfall we have seen two abrupt shifts which have been permanent (thus far in our records). The first was in the 1970s and the second in 1997 (both periods when we saw strong El Nino events). There is some hints that a third one may have happened in 2002 but that is highly speculative. This theory will be tested when the next big El Nino comes - which could well be next year if this El Nino doesn't develop properly (in some ways it looks like the half hearted El Nino attempt in 2001).

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