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Constant Cold snaps possibily triggering a +IOD effect?

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johnno
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Constant Cold snaps possibily triggering a +IOD effect?

Post by johnno »

Just wondering guys is it possible this cold weather that we are seeing fairly constantly from Cold air driven from the South constantly to Northern Australia may trigger a +IOD as we moved deep into June and July? Seems like this cool weather (below average temps preety constantly) that Northern Australia has been seeing alot of the past 6 weeks is intensfying and spreading colder than normal ssts through Northern Australia and gradually spreading North and West through Paupa New Guinea & Indonesia which to me is borderlining of a possible +IOD developing.. And we know what +IOD's result in below average rainfall more often than not for Southern and SE OZ through Winter & Spring.


http://weather.unisys.com/surface/sst_anom.gif" onclick="window.open(this.href);return false;

http://www.weatherzone.com.au/climate/i ... jsp?c=ssta" onclick="window.open(this.href);return false;
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Ken
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Re: Constant Cold snaps possibily triggering a +IOD effect?

Post by Ken »

In short, it's possible, although the movement of the cooler surface water has to fight against the prevailing surface currents off the southwest coast of Indonesia (unless there's upwelling of cooler subsurface water) which normally flow SE'wards. It's a bit of a shame that modelled IOD forecasts have a lot more uncertainty compared to ENSO forecasts, largely due to the higher uncertainty in the SST analysis of the Indian Ocean (not helped by the lack of a dedicated extensive network of buoys , underwater profilers, etc like there is for the tropical Pacific Ocean for ENSO).
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johnno
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Re: Constant Cold snaps possibily triggering a +IOD effect?

Post by johnno »

Thanks Ken, check out the lastest ssts anomalies ..

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

Not looking too good the signs are definetly there that we may be entering the 1st phase of a +IOD
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Ken
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Re: Constant Cold snaps possibily triggering a +IOD effect?

Post by Ken »

Yeah, I check global SST's pretty much every few days. The possibility of a weak positive IOD phase has also been mentioned in some of the ENSO Wrap-Up's over the past month or so e.g. http://www.bom.gov.au/climate/enso/

We wait and see.
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johnno
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Re: Constant Cold snaps possibily triggering a +IOD effect?

Post by johnno »

Starting to look more and more likely IMO this doesn't mean for sure that we will see a dry winter and first part of Spring but does increase our chances of a drier few months coming up, already Northern inland areas of Vic have had a fairly dry April, May & June. Rainfall will increase later in the Year IMO as the IOD effect wears off and La Nina bounces back. If The SAM moves more into Negative than Positive over the coming months Southern areas may still see close to average rainfall.

SAM has been about average since Mid March.. Here is the rainfall from April to June for Victoria...

http://www.bom.gov.au/jsp/awap/rain/ind ... th&area=vc" onclick="window.open(this.href);return false;

Last 3 months rainfall for Victoria is a combination of SAM being near average, La Nina coming to an end & cooler than normal ssts developing North of Australia which looks to be the beginning of a weak to moderate Positive IOD.

http://www.cpc.ncep.noaa.gov/products/p ... #composite" onclick="window.open(this.href);return false; <<<< SAM

http://www.weatherzone.com.au/climate/i ... jsp?c=ssta" onclick="window.open(this.href);return false; <<< Ssts Anomalies
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Pete
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Re: Constant Cold snaps possibily triggering a +IOD effect?

Post by Pete »

Won't the positive IOD mean that the highs will move back further south again and southern WA would be drier? I noticed that the models are already starting to show the highs going south into next week. :(
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