It is official. The BOM has declared that Australia has entered two climate phenomena El Nino and a positive Indian Ocean Dipole (IDO). This means that Australia is in for some very hot and dry conditions over this summer.
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00:00 Hi there, I'm Angus here at the Bureau of Meteorology and today, Tuesday the 19th of
00:04 September, the Bureau has just declared the onset of El Nino, which will continue to affect
00:09 us through spring and into summer.
00:11 Today we are joined by special guest Zee Wing, who's a climatologist here at the Bureau.
00:16 Thanks for joining us, let's get right into it.
00:18 Why is now the right time to declare El Nino?
00:21 So the Bureau looks at both the atmosphere and the ocean when declaring an El Nino.
00:26 And recently we have seen some changes in the atmosphere that indicate El Nino is underway.
00:32 Okay, changes in the atmosphere, what exactly does that mean?
00:35 So one of the key indicators we look at is the pressure pattern.
00:39 During May we did see the pressure pattern hint towards El Nino, but that was short-lived.
00:44 We saw it go back towards neutral during June, but now this recent shift back towards El
00:49 Nino values, we believe is a sustained shift towards El Nino.
00:53 Okay, so El Nino's here and this time it's here to stay, but I noticed that in the declaration
00:58 we also talked about another climate driver that affects Australia, the Indian Ocean Dipole,
01:03 the IOD, being positive.
01:05 Tell us a little bit about that.
01:06 Yeah, that's right Angus.
01:07 So the positive Indian Ocean Dipole occurs to the west of Australia in the Indian Ocean,
01:13 whereas El Nino is in the Pacific Ocean to the east of Australia.
01:17 So with the positive Indian Ocean Dipole, we get cooler than average waters closer to
01:22 us in Australia, and this tends to lead to reduced rainfall over central and southern
01:26 Australia as well as warmer temperatures.
01:28 Okay, so we've got El Nino and we've got the positive Indian Ocean Dipole together.
01:33 Does that mean big changes for our long-range forecast?
01:36 It's a really good question Angus.
01:39 So we don't actually expect to see a shift in our long-range forecast just based on the
01:43 declaration of these two drivers alone.
01:45 This is because our long-range forecasts have already been including the influence of the
01:50 development of these drivers, and that's what we've been seeing in the forecast, warmer
01:55 and drier conditions.
01:57 What it does mean though is that we can have increased confidence in how our forecasts
02:01 are going, because now we can see they are properly representing these two climate drivers,
02:06 whereas previously a few months ago it was not so clear.
02:09 Okay, so I'm just going to pull out a couple of key words that you said there, warmer and
02:12 drier, and that's nothing new.
02:14 We've been warm and dry for a little while as anyone who has been trying to ski over
02:18 winter will well know.
02:19 Yeah, it's been a different year this year and we've just come off the back of our warmest
02:23 winter on record for Australia.
02:25 Wow, warmest winter on record.
02:26 So let's have a look at a couple of maps here to see how that might continue into spring.
02:30 So this map is for the next few months showing chance of unusually dry, what does that mean?
02:36 So the chance of unusually dry, that refers to rainfall being in the bottom 20% of the
02:41 historical record, so looking at the more extreme end of dry rainfall.
02:45 And what we can see in this map is that particularly over south-east Australia as well as south-west
02:50 western Australia, we do have at least three times the chance of getting those unusually
02:55 dry conditions.
02:56 Okay, so dry for lots but particularly in the south.
03:00 Now this is a similar type of map, this is chance of unusually warm.
03:03 Now when you look at this from your climatologist point of view, what stands out to you?
03:07 So this map, the unusually warm maximum temperature map, we really see the chance of having unusually
03:15 warm conditions being over western Australia as well as parts of south-east Australia.
03:20 But Australia as a whole does have an increased chance of seeing unusually warm temperatures.
03:25 So we're likely to be warm, we're likely to be dry, to me that says increased risk of
03:29 bushfire and we've actually got this map here from AFAC showing some of the areas through
03:33 spring which are likely to see increased risk of fire including much of central and eastern
03:38 Australia.
03:40 So thank you very much for joining us today Zee, that is the declaration about El Nino
03:44 but if you'd like more information about El Nino or the IOD or the long range forecast,
03:49 it's all available at the Bureau website which is bom.gov.au.
03:53 That is us for today, we'll catch you next time.
03:54 [Music]