|
Post by twawki on Oct 18, 2008 3:06:52 GMT
La Nina has popped up on various threads and thought it would be good to look at the prospects of one developing on a dedicated thread.
Whilst we have recently come out of a La Nina it looks like another one is building, potentially stronger. The outcome if this happens is that there will be another cooling signal to build on the last one.
Additionally whilst many weather services have previously predicted ongoing neutral conditions there are signs that some are starting to change their forecasts;
Wild storm summer season likely for QLD Marissa Calligeros | October 17, 2008 - 2:14PM
Queensland ... batten down the hatches and prepare for what could be one of the wildest summer storm seasons on record.
A string of low pressure systems that are expected to develop off the east coast in January are characteristic of a La Nina event, with strong cyclonic activity typical under such conditions.
While stopping short of confirming a severe La Nina system was certain, the Bureau of Meteorology's Queensland regional director Jim Davidson told brisbanetimes.com.au patterns indicated a "bias" toward a fierce storm season.
University of Southern Queensland climatology expert Roger Stone agreed Brisbane's summer would be wet.
"There is a 70 per cent chance of well above average rainfall this summer," Mr Stone said.
He said La Nina was characterised by warmer than normal water in the Coral Sea and Gulf of Carpentaria and colder conditions in the central Pacific and equatorial regions (the opposite of El Nino).
Although average maximum temperatures are expected to remain below 30 degrees come January, humidity levels will rise.
"Despite the odd sultry day, we're in for a cooler summer," Mr Stone said.
Hallmarks of a La Nina event - including increased cloud cover and strong easterly winds across the Pacific - are likely to raise humidity levels above 50 per cent.
In January this year, Maleny recorded 59mm of rainfall, Mapleton 65, West Bellthorpe 25, Harper Creek 31 and Mt Mee 13. Mr Stone said similar conditions would push ensure Brisbane's struggling Wivenhoe Dam would rise to well past the 40 per cent storage mark.
The Bureau will reveal its predictions for the summer cyclone season on Monday.
|
|
|
Post by twawki on Oct 18, 2008 3:44:08 GMT
|
|
|
Post by twawki on Oct 18, 2008 4:05:28 GMT
|
|
|
Post by kiwistonewall on Oct 18, 2008 4:45:04 GMT
|
|
|
Post by Pooh on Oct 18, 2008 7:28:49 GMT
The two references above are to web pages. As you know, each is bracketed by URL tags that you placed by selecting the link in your post, and then clicking the 'World' button in the Add Tags row. That displays the web page, but does not display the graph in your post.
(unsure how to post the visuals so they come up in here and update so if any one can help would be much appreciated ;D) Posting Images:I think what you wanted to do was include the graph on the SOI link, so that it would be shown in the post as updated. I think that Kiwistonewall solved the problem by going to the graph on the SOI web page, right-clicking the graph for " Properties". From the properties panel, he copied the Location of the image, which reads "http://www.bom.gov.au/climate/current/soi.gif". and pasted it into his post. Then, selecting the Location just pasted into the post, click the " picture frame" button just to the right of the "World" button in the Add Tags row. This puts a pair of square-bracketed "img, /img" tags around the Location. I have tested .gif and .jpg images successfully. Others may work; haven't tried them. See Open Forum, Forum Functionality Test « Reply #2 on Oct 3, 2008, 6:17pm>>
And if Kiwistonewall found a slick way to do this, my apologies to him and please let us know! ;D
|
|
|
Post by kiwistonewall on Oct 18, 2008 8:14:08 GMT
That's exactly what I did.
|
|
|
Post by alex4ever on Oct 18, 2008 10:03:29 GMT
hmmmm a new la nina,.... and we had one la nina last year.....hmmm what a coincidence....!!! and its very strange to have a second la nina in a row...... maybe sun triggers it?! ;D
|
|
|
Post by dopeydog on Oct 18, 2008 11:55:37 GMT
Here is the latest analysis of the MEI www.cdc.noaa.gov/people/klaus.wolter/MEI/which predicts that a La Nina is likely. "Consistent with re-emerging La Niña conditions, there are now more observed key anomalies in the MEI component fields that exceed or equal one standard deviation, or one sigma (compare to loadings figure), with several of them flagging typical La Niña features, while El Niño-like features are still present as well." One thing, and all of you know how I feel about agw, I don't believe that solar minimums and maximums directly effect phases of the PDO or AMO. We were going to slip into a neg. PDO whether we were at a minimum or maximum. Salinity and the thermohaline circulation are probably a bigger factor and I think "tipping points" are a mechanism involved. Now lets agree on one thing, while people are still posting on this site and it seems like fewer and fewer do it every day; Lets not dignify agw by capitalizing the acronym!
|
|
|
Post by woodstove on Oct 18, 2008 13:32:24 GMT
Dopey observes that fewer folks are posting on the site each day. I know Kevin is working on the redesign. This transitional design has made it less likely for me personally to spend time on the site and less likely for me to post. The old format was, in a nutshell, easier on the eyes.
That said, I want to express my gratitude to Kevin for creating and managing one of the most informative and lively sites on the Internet, one that is bound to see huge traffic increases during the next decade.
|
|
|
Post by duwayne on Oct 18, 2008 14:51:53 GMT
An increase in the La Nina to El Nino ratio is to be expected in the current Ocean Current (PDO, AMO, etc) down cycle. Look for more, stronger and longer lasting La Ninas. And expect the opposite for El Ninos. The next 30 years should be somewhat similar to the 1947-1977 period in the chart below.
|
|
|
Post by nautonnier on Oct 18, 2008 16:45:50 GMT
The next 30 years should be somewhat similar to the 1947-1977 period in the chart below. Which just happened to be the years where the ' we are all going to die!" group were convinced we were entering a new ice-age.
|
|
|
Post by walterdnes on Oct 18, 2008 20:50:53 GMT
I downloaded the ENSO MEI index data from www.cdc.noaa.gov/people/klaus.wolter/MEI/table.html and parsed and imported it into Excel. The data begins in 1950, so it catches most of the 1947..1976 cooling. I calculated average values for the well-known "panic periods". Positive is El Nino, and negative is La Nina. - Jan 1950..May 1976 -0.343 The ice age is coming, the ice age is coming!
- Jun 1976..Jul 1998 0.554 The hothouse is coming, the hothouse is coming!
- Aug 1998..Sep 2008 -0.056 The beginning of theGore Minumum? How long will it continue?
As you can see, El Nino and La Nina aren't "merely weather", they're climate. The periods I chose co-incided with PDO phase shifts. This indicates that PDO influences the frequency of El Ninos and La Ninas, which in turn influence global mean temperatures. It wasn't until I plotted the data that something hit me over the head. The period from December 1989 to August 1995 was one giant, long El Nino! That's 69 months, almost 6 years. The 3 spikes during that period may look like separate events, but it was really one long (almost 6 years) El Nino. Yes, there was a dip in temperatures, during that time, but it was "artificial" in that it was caused by Pinatubo erupting.
|
|
|
Post by dopeydog on Oct 18, 2008 23:22:20 GMT
Yes, it looks like there were 5.5 years from where the 3 month rolling average dipped only twice to -.01.
Good point.
Typical of a positive PDO as the future will confirm.
|
|
|
Post by Acolyte on Oct 18, 2008 23:45:30 GMT
Dopey observes that fewer folks are posting on the site each day. I know Kevin is working on the redesign. This transitional design has made it less likely for me personally to spend time on the site and less likely for me to post. The old format was, in a nutshell, easier on the eyes. That said, I want to express my gratitude to Kevin for creating and managing one of the most informative and lively sites on the Internet, one that is bound to see huge traffic increases during the next decade. *grins* Have you modelled that? I hope you've properly concealed your proxy data. ;D I agree with the sentiments expressed - I enjoy coming here so i add my thanks. I'm curious - I find the current pages quite easy on the eyes, so I wonder... how many members here are using recently purchased LCD screens & how many are on CRT's? For those on CRT's, (I'm a helpdesk consultant) something that may help is to go into Display properties & increase the refresh rate to the maximum supported by your screen. For WinXP - right-click the Desktop, choose [Properties] then the [Settings] tab. Click on [Advanced down the bottom then [Adapter] then
|
|
|
Post by twawki on Oct 20, 2008 8:17:17 GMT
The weather bureau says Queenslanders should begin preparations for this year's cyclone season. Bureau of Meteorology regional director Jim Davidson says the water temperature in northern Australia is warmer than usual indicating a La Nina weather system is forming. www.abc.net.au/news/stories/2008/10/20/2395929.htmWith another la nina forming how does that affect the northern hemisphere winter?
|
|