El Nino 2015/16

[Bradley]

So to summarise RWood in your opinion did the NIWA team who put out their predictions for a hotter and dryer summer for all parts of NZ but the west coast of the SI get it right with their prediction allowing for all the data they had (or should have had) at the time about El Niño and its effects on NZ? As in they actually did more then just read from a text book about what El Niño would do and not allow for those other factors Tony noted above, MJO etc etc?

[Nev]

So to summarise RWood in your opinion did the NIWA team who put out their predictions for a hotter and dryer summer for all parts of NZ but the west coast of the SI get it right with their prediction allowing for all the data they had (or should have had) at the time about El Niño and its effects on NZ? As in they actually did more then just read from a text book about what El Niño would do and not allow for those other factors Tony noted above, MJO etc etc?

That's not what NIWA predicted at all Bradley. Besides, temps and rainfall for January so far have been virtually the complete opposite of December, essentially cancelling each other out, and we still have another month to go.

Below is an exerpt from NIWA's summer outlook released on Dec 3rd…

NIWA - Seasonal Climate Outlook: December 2015 - February 2016

Outlook Summary

December 2015 - February 2016 temperatures are most likely (45% chance) to be near average for the north and east of the North Island as well as the east of the South Island. Temperatures are about equally likely to be near average (40% chance) or below average (40-45% chance) for all remaining regions of the country.

December 2015 - February 2016 rainfall is most likely (45%) to be below normal for the north and east of the North Island. Seasonal rainfall totals are about equally likely to be near normal (35-40% chance) or below normal (35-40% chance) for the west of the North Island as well as the north and east of the South Island. Rainfall is equally likely to be near normal (40% chance) or above normal (40% chance) for the west of the South Island.

NIWA Outlook for December 2015 - February 2016.png

[spwill]

Metservice rural outlook was for a cool January across NZ

[TonyT]

So to summarise RWood in your opinion did the NIWA team who put out their predictions for a hotter and dryer summer for all parts of NZ but the west coast of the SI get it right with their prediction allowing for all the data they had (or should have had) at the time about El Niño and its effects on NZ? As in they actually did more then just read from a text book about what El Niño would do and not allow for those other factors Tony noted above, MJO etc etc?

Not that I am particularly wanting to defend NIWA from you, but you need to remember that a lot of the factors I mentioned can't be well predicted in advance (eg week to week movements in the SOI, the intensity of the MJO, etc). So you need to think about these as factors which can complicate and sometimes derail a seasonal prediction, not factors which can necessarily be used in advance to make the prediction.

Most El Ninos bring increased westerly quarter airflow, especially once the El Nino has peaked and continues to move towards La Nina. Thats the "text book" I read from when making a seasonal prediction. Having one month without the westerlies (and with the rain and humid northerlies we have seen this month) doesnt make the seasonal prediction wrong. I am still as confident of "mostly drier than normal months" through much of this year as I was before January started.

Oh, and one third of summer is still to happen (if you like to use the 3 month December to February delineation) so its too early to call the result yet. Far too early if like me, you thunk summer lasts a bit longer than February. And, finally, I dont recall many (or any) forecasters calling for a "long dry hot summer". Thats a phrase the media seemed to pick up and run away with of their own accord. In fact, I can specifically recall saying to a reporter that it might be "long dry cool summer" in Canterbury, because of the uncertainty about temperatures we knew existed at the time!

[RWood]

Just as a PS about summer seasons here - both extreme ends of the rainfall spectrum have occurred in El Nino conditions; wettest summer 1976-7, 2nd wettest 1939-40, and 6th wettest 1957-58. At the dry end, 1972-3, 1986-7, 1963-4 and 1982-3 (using the ONI index).

[TonyT]

http://www.stuff.co.nz/national/7644984 ... rm-and-dry

Interesting to see this article headlined "Good chance next three months will be warm and dry", yet if you look at the figures on the maps, no part of the country has a greater than 45% chance of being warmer than normal, and nowhere has a greater than 40% chance of being drier than normal. So, in fact, the conclusion is the opposite of the headline. It should read "Good chance next three months will not be warm and dry".

[Richard]

oh gees, stuff strikes again. What's got me thinking lately is if they are reporting such incorrect figures as what's being reported in the last week regarding our weather, what other news are they misquoting, probably a hell of a lot i would suspect.
Is stuff becoming a new age form of internet Chinese whispering??

[Rogue]

Loved how Stuffs Sunday storm coverage was still riddled with images of Fridays and Saturday's watches and warnings... Pretty appalling, severe weather is important for a lot of people and their article made little sense.

[jamie]

It is looking quite likely that for the next two weeks we will have very little to no rain here.

5.2mm since the 20th Jan (5mm in the last 20 days but add 14 more days and we will likely be 34 days with just 5mm)

21.8 since 9th Jan (22m in the last 30 days but add 14 days and we will likely be 44 days with only 22mm).

Early Jan really was a saving grace for us. Some have been lucky to catch late Jan afternoon showers. Without the rain early Jan we would be stuffed here after the dry December. We have also had quite a number of days at 28 or above this year too which has helped to dry the ground out rapidly. We have had 6 days above 28.0 and 10 days above 27.0.

I get the feeling this dry spell is really going to dig in its heels now and become a disaster for Farmers around here (making major losses as it is without a drought), an avg dairy farm owner in Waikato will be making a $230k loss from June 1 2015 to May 31 2016.

While its not the type of dry conditions we would expect with El Nino (very few cloudy and cool W to SW winds) it is still dry none the less. I really hope the rain can arrive by end of Feb.

[Bradley]

Just as Tony predicted it looks to be fairly certain now that the SAM played a larger role in February's record breaking temps around New Zealand then the actual El Nino event did:

http://www.stuff.co.nz/science/77551404 ... t-february

[TonyT]

Just as Tony predicted it looks to be fairly certain now that the SAM played a larger role in February's record breaking temps around New Zealand then the actual El Nino event did:

http://www.stuff.co.nz/science/77551404 ... t-february

That article is a little lacking. SAM (or the Antarctic Oscillation AAO as most people call it) is not a process or a driver of anything in the atmosphere. Its a pattern which reflects other things which are happening. SAM did not cause February's warmth. It merely reflects the processes which did. Consider that the AAO was also in a strongly positive phase for almost all of January too, and that month was cooler and wetter than normal for Canterbury!

Go back and read the monthly summaries for the 2009/10 summer and the parallels with this season are quite striking (not exactly the same month for month, but the pattern and trend over the late spring/summer/early autumn period as a whole). 09/10 was a Modoki El Nino, and with the way the temperature patterns for this current El Nino spiked strongly in 3.4 but were not near record levels in 1 & 2, then its looks as though this event was more "Modoki-like", which partly accounts for it having some "less than typical El Nino" patterns associated with it.

[RWood]

Round these parts this Oct-Feb has been sunnier, warmer and drier than for 2009-2010...of course the autumn may play out differently...

[NZ Thunderstorm Soc]

...but SAM, did stuff up, according to me and reading Paul Gorman's article, what could of been a stormy summer, here, which I was expecting right from the middle of last year when I did expect events to happen from the strong El Nino event which we have just had.

[spwill]

...but SAM, did stuff up, according to me and reading Paul Gorman's article, what could of been a stormy summer, here, which I was expecting right from the middle of last year when I did expect events to happen from the strong El Nino event which we have just had.

With a positive SAM the colder upper troughs tend to stay south of NZ . During Jan/Feb the upper air stayed mostly warm over all of NZ, hence the lack of storms for the eastern South Island . We had some storms over the NI but the high low level moisture was the big ingredient with these, northern NZ has good exposure to tropical moisture.

[tunster]

Just as Tony predicted it looks to be fairly certain now that the SAM played a larger role in February's record breaking temps around New Zealand then the actual El Nino event did:

http://www.stuff.co.nz/science/77551404 ... t-february

That article is a little lacking. SAM (or the Antarctic Oscillation AAO as most people call it) is not a process or a driver of anything in the atmosphere. Its a pattern which reflects other things which are happening. SAM did not cause February's warmth. It merely reflects the processes which did. Consider that the AAO was also in a strongly positive phase for almost all of January too, and that month was cooler and wetter than normal for Canterbury!

Isn't the AAO designed to be a measure of the ebb and flow of the westerly wind belt around Antarctica? In that sense, it can be used to explain things. "The westerly flow over NZ was weakened because the westerly wind belt was contracted towards Antarctica" does count as an explanation to me, though it doesn't explain why the belt contracts and expands.

I guess the risk with this stuff is you end up in circular explanations. If you just blindly say "the AAO was positive therefore we had more blocking highs" it could be construed as you saying "we had more blocking highs because we had more blocking highs" due to the way that the AAO is measured (I think one of the statistical modes is the 700hPa heights in the vicinity of NZ). That's always a danger with flagrant use of some of these indices.

For me the real questions are - what causes the westerly wind belt to contract and expand on a sub-seasonal scale? I really hope no one will ever answer that by saying "the AAO"!
And what determines its longitudinal pattern? For example, later this week we have a mid/high latitude blocking high VC NZ, but south of Australia, the situation is quite westerly. We quite often see that. I doubt we'll ever be able to predict these planetary ridge/trough setups far in advance (there is some hope over the one month period, sometimes the EC32 gets it right), and especially in the southern hemisphere where there are no continents to provide a low level forcing like they get during winter months in the NH.
The other question is how do the AAM and ENSO interact and do they influence each other? I don't think there's much correlation between the two for starters. It seems like physically they would only influence each other on the faintest of scales, although each of them would probably provide a measurable input to global atmospheric angular momentum changes.

[TonyT]

Some good comments and good questions there. I think one linkage between AAO and ENSO is probably the MJO - we now know that westerly wind bursts from the MJO have a significant impact on the development (and probably decay) of ENSO events. What is the relationship between MJO and AAO I wonder? Is the AAO reflecting back certain phases of the MJO? Thats probably where I would be looking.

[RWood]

I recall some years ago now discussions about whether or not the IPO (or PDO) was an independent phenomenon... No idea what has been concluded since. One has to wonder whether any of these well known systems is truly independent.

[Richard]

The rate of cooling of the waters off Ecuador & Colombia has really taken off in the last few days.Has it reached the neutral yet.

[Manukau heads obs]

this shows the steady decline
http://www.weatherzone.com.au/climate/i ... p?c=nino34

[jamie]

What ever it is I hope we get decent rain soon. We are currently pulling stumps out of the peat for next summers crop paddock.

There is dust down to the clay 1m deep and even then the clay coming up with the stumps roots isn't wet. Usually we would have a water table in the peat and the stumps would be soaking wet. They are very dry.

[Manukau heads obs]

if you dont get rain this sunday then its back to a big fat high...

[Richard]

this shows the steady decline
http://www.weatherzone.com.au/climate/i ... p?c=nino34

ok ,so its a long away yet from neutral, July at least?

What sorta stumps are they Jamie

[Manukau heads obs]

it is interesting how there is a patches of cooler than normal water showing off the south america coast now
it could be that this El Nino switches quickly to a La nina by spring time

[jamie]

They are old swamp wood Richard. I would think its all kaihikatea (spelling?). The trunks are well gone, all lifted out of the ground over the past 80 or so years of being farmed. As the peat has shrunk the stumps have moved closer to the surface so hence we need to pull them out

I should also add that in the last ten years we have seen a massive drop in the peat. Much faster than we ever had and it's because of these droughts. Peat is like a sponge and needs to stay wet. When it drys out it shrinks.

[Manukau heads obs]

cant see much rain over the weekend...tv1 weather just showed rain moving south to auckland tomorrow?..cant see it...