AWF Climate Outlook - Spring 2012

[johnno]

Have to disagree with you Karl this isn't a seasonal thing with temps up to 2-3c below average off the NW coast for this time of the Year and the same off Java. The Indian ocean was completly different around this time of the Year in 2009 and 2010 late Winter as we came into Spring, 2009 we had a weak El Nino while the Indian remained Neutral North and NW of OZ despite a weak El Nino hence why our rainfall was quite good through August to November cos of the ssts NW of OZ remaining average & 2010 was the exact opposite to now a Strong La Nina and record warm ssts off the North and NW Coast for this time of the Year due to Negative IOD hence why every little system that came through even the weakest off troughs would drop a heap of rain on us.

[johnno]

Yes the IO will improve but wont be til the end of Spring. Lets go by your theory anyway that the ssts in the IO make a drastic improvement the next few weeks anyway we know it takes the atmosphere another 3-4 weeks to respond to the ocean temps I can preety much guarantee September will see below average rainfall through alot of Australia away from the Victorian coast and October won't be much different anyway thats my 2c had this theory for 2 months now and August has seem to gone on the dry side & I don't mean "seasonal dry" I mean below average rainfall for alot of OZ away from Southern Victoria and I expect this trend to continue for at least another 2 months.. We know its drier in Brisbane and Sydney this time of the Year but they still average close to the same rainfall as Melbourne 50mm or so and both Cities have fallen way short of that this month infact Brisbane has had no rain which to me shows the lack of moisture with the systems that have come through this month from the NW and the Coral sea this is indicative of a Positive IOD coincinding with a weak El Nino or warm Neutral conditions.

[johnno]

Another large sign thats theres been no moisture through Central Australia past few months at all due to the cold anomalies off NW and Northern OZ

http://www.weatherzone.com.au/news/parc ... cord/22342" onclick="window.open(this.href);return false;

[Anthony Violi]

Certainly very dry through there John.

Anyhow, SOI 30 day has dumped to -5.5, with the running 90 day at -5.7.

By the end of next week we will lose the big negatives from early August so the 30 day will be down to about 3 if the dailys stay roughly the same.

http://anthonyvioli.wordpress.com/2012/ ... -update-2/" onclick="window.open(this.href);return false;

[droughtbreaker]

It's extremely likely that the next couple of months will be drier and warmer than average, at least through inland Victoria. The shift to drier conditions in response to the +ve IOD has been swift and pronounced. September and October are very strongly affected by +ve IOD. We should see some very warm/hot days when the northerlies spike so be prepared.

The inland heat is building intensely through central Aus and already signs of this potentially getting dragged down to southern latitudes in coming days/weeks. it's pretty typical of what happens with the SSTs as they are.

I agree that this will all break down by late spring and hopefully leaving us with a normal summer.

BTW: I'm not saying that we won't see some decent rain events at times and showers coming up from the south. If we get some easterly flow happening or some tropical moisture picked up and sucked into a major inland low (GFS actually has this scenario for next weekend), we could still see some widespread good falls happening. The only scenario where we are set to struggle for a while is with rain bands forming ahead of cold fronts. In 2006 we had a procession of strong cold fronts and lows and many of them were 100% dry.

[johnno]

2007 & 2008 was very similar too Andrew front after front from the west very windy through the Sep Oct period but very little moisture leaving us very dry down here both Years we had a Positive IOD through Spring and a weak La Nina just shows how much we depend more on the IOD especially this time of Year, I agree if we get weather from the SW/S or some ECL we will do well but if we get the traditional set up from the West front after front we will see below average rainfall.

Another thing I have noticed some people may agree with me others won't but it is often the calmer Springs or calmer September/Octobers we get better rainfall in Victoria well at least Melbourne not the windy ones.

[Karl Lijnders]

That is true John.

The less wind, the more rainfall we do get. I do recall a period where we had 5-6 low pressure troughs come out of the NW from WA and deliver rainfall after rainfall and no fronts at all to interrupt that sequence.

This year will be volatile to start with, large fronts, severe wind events, rain over the ranges and SW (that's how they get their rainfall!) and burst of rain statewide.

I am interested in the SSTs out in the Pacific and the slow warming trend in the Indian. I know it doesn't look to be warming, but it is about a month away from really changing.

Lots to look forward to locally however

[adon]

Very warm a breezy day today up here and I reckon this will be the same for the next month at least. I have a theory, you can see a drought in the air before it becomes apparent in the weather. I saw this two months ago just before we got the big rain. I wasnt sure whether it was just because we had just gone through a very dry period and it was the sky showing signs of that, but took note of it and told Johno.


When I say " see the drought" I mean the sky has a colour to it that looks dry. It's kind of hazy but with a slight brown tinge to it. Sort of like a dust storm in the distance but we don't actually have a dust storm coming if that makes sense.

[Karl Lijnders]

The NW of the state is generally semi arid, especially once you hit Hopetoun/Ouyen/Mildura where the annual rainfall is about the same as Broken Hill and Alice Springs. Spring/summer dust storms are the norm up there most years. This year will be pretty bad for that IMHO.

September could end up very dry but it still wouldn't be enough to call it a drought after we have had about 3 years of near record breaking rainfall for many parts of the state. If October and November end up dry as well then there will be short term deficiences for northern VIC. This is all normal variation though.

[Anthony Violi]

I just made a new post on the Indian Ocean for the coming season.

http://anthonyvioli.wordpress.com/2012/ ... -nw-coast/" onclick="window.open(this.href);return false;

Upper 300 metre temp anomaly shows a good deal of warmth through the basin, and more inmportantly North of Australia where the water will enter throught the Indian flowthrough, and the Leeuwin current.

[flyfisher]

The coral sea has warmed quite a lot over the last few weeks and is now above average. This water is now flowing into the gulf and waters on the east side are above average. The surface cool water of NW Australia has been erroded from the south, but the cool pool now extends right out into the middle of the Indian Ocean.

So for us NE winds should bring surface moisture (Troughs, storms), NW cloud bands will remain suppressed until that water NW of Aus warms up - probably too late for our spring. Water to the SW and W is warmer so good post frontal rain is likely. All in all average to above average rainfall ahead if the right systems come through.

[Karl Lijnders]

Hello FF! Welcome!

Yes looking like the fronts will continue to command the rainfall spread over southern areas of the state over the coming weeks and then increase from the NW once the IOD is in place! I think that is coming faster than what climate models indicate (which have been woeful so far!).

Looking forward to a bit more sunshine however, so longs the north gets a regular drink, I am happy.

Currently on track for September.

[johnno]

Updated Today 11/9/2012 from the BOM

Pacific near El Niño thresholds; positive Indian Ocean Dipole
Issued on Tuesday 11 September | Product Code IDCKGEWWOO

Tropical Pacific Ocean sea surface temperatures remain at values close to El Niño thresholds. Other ENSO indicators such as the trade winds and tropical cloud patterns show patterns more typical of neutral conditions. The Southern Oscillation Index (SOI) is also presently within neutral values.

Regardless of whether El Niño thresholds are reached, the tropical Pacific remains warmer than average. This, combined with other influences on Australian climate such as cooler than normal waters to the north of the Australian continent and the patterns of cloud and ocean temperatures in the Indian Ocean, tends to favour below average spring rainfall over much of Australia.

Climate models surveyed by the Bureau of Meteorology suggest sea surface temperatures in the tropical Pacific Ocean will maintain values close to El Niño thresholds before returning to more neutral values towards the end of 2012 or early 2013.

The Indian Ocean Dipole (IOD) is currently positive, with values of the IOD index consistently above positive thresholds for the past 7 weeks. Outlooks from the Bureau’s climate model indicate the IOD will likely remain positive throughout the remainder of spring. A positive IOD is usually associated with decreased spring rainfall over parts of southern, central and northern Australia.

http://www.bom.gov.au/climate/enso/" onclick="window.open(this.href);return false;

[Anthony Violi]

Shortly i will release another outlook, in the meantime here is some food for thought, and a reason why we will get plastered for years to come.

http://anthonyvioli.wordpress.com/2012/ ... this-year/" onclick="window.open(this.href);return false;

[Anthony Violi]

Quick update for everyone. I think it will unravel fairly quickly, as the movement is now on.

http://anthonyvioli.wordpress.com/2012/ ... the-shift/" onclick="window.open(this.href);return false;

[flyfisher]

Looking at this chart on weatherzone...

http://www.weatherzone.com.au/climate/i ... bal&c=ssta" onclick="window.open(this.href);return false;

The IOD has rapidly gone from +ve to -ve. Extremely rapid change over the last week. The cool water NW of Australia is gone and cool water has formed off Africa. This would set us up for NW cloud bands.

Also note the cool water in the central Pacific has moved towards the equator. This looks to cancel out the warm El-nino waters in that location. Very intersting!!

[stratospear]

I reckon we could get a heap of wild and stormy weather for October-November this year in Vic. It looks like we're in a very similar phase of the SOI to early 2010 and we all know what happened then!

[Karl Lijnders]

Hi Strato!

It does appear you are right. The early signs are good with little short waves and troughs moving through the region. I suspect the storm season will be improving as we are going. Perhaps we are a little too cool right now to get things going off over the mainland, however it is improving.

Latest SSTs look very promising and the risk of La Nina forming is increasing little by little. I am not moving away from my prediction of a weak la nina developing in the next 6 months with a strong -IOD. I think the IOD could rival 2010 at times as well so something to watch.

Big call I know, but I think even with get half the way to that result, it will mean high rainfall for us this summer!

[johnno]

Anyone notice the same pattern here by the BOM very similar forecasts?

September 2002 rainfall outlook for Oct - Dec
http://www.bom.gov.au/climate/ahead/arc ... 917R.shtml" onclick="window.open(this.href);return false;

September 2006 rainfall outlook for Oct - Dec
http://www.bom.gov.au/climate/ahead/arc ... 926R.shtml" onclick="window.open(this.href);return false;

September 2009 rainfall outlook for Oct - Dec
http://www.bom.gov.au/climate/ahead/arc ... 0922.shtml" onclick="window.open(this.href);return false;

(updated Today) September 2012 rainfall outlook for Oct - Dec
http://www.bom.gov.au/climate/ahead/rai ... tml?link=1" onclick="window.open(this.href);return false;

Im guessing the BOM are putting this down a warm Pacific and warm Indian ocean? The warm blob off the SW coast heres the thing though the warm Pacific is almost Neutral and temsp continue to fall the Positive IOD has made a remarkable transformation over the past week looks to have head back to Neutral with alot of warming over N and NW OZ and as for that warm blob SW of WA? Alot of Global models have that weakeinng and dissapearing over the next 4-6 months and if anything becoming cooler than normal so since the "Dry" outlook is based on a warm Pacific & Positive IOD and warm blob off the SW coast of WA you wonder how much of this forecast will end up becoming true

[johnno]

Heres the pattern in the same Years rainfall outlook in December for January to March (coming out of these El Nino periods) what BOM's own models forecast

Dec 2002 outlook for Jan to March 2003
http://www.bom.gov.au/climate/ahead/arc ... 217R.shtml" onclick="window.open(this.href);return false;

Dec 2006 outlook for Jan to March 2007
http://www.bom.gov.au/climate/ahead/arc ... 220R.shtml" onclick="window.open(this.href);return false;

Dec 2009 outlook for Jan to March 2010
http://www.bom.gov.au/climate/ahead/arc ... 1221.shtml" onclick="window.open(this.href);return false;

So all this media hype talk of an El Nino weak whatever it is brining little rain in the Summer, drought, very high tempertures and bushfires is ridicolous when BOM's own model always goes for a stronger chance of wetter conditions for Victoria and SE SA once the New Year starts.. Mabye for SE Qld and NE NSW but not HERE & This is based when there is an El Nino... The fact there really isn't one now and the 3.4 NINO temps continue to fall means were in a good place the next few months so either way I can't see it being dry definetly from November onwards could be even earlier