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#1003847 - 02/08/2011 10:06 Re: Predictions for spring and summer 2011-12 [Re: GrizzlyBear]
Keith Offline
Meteorological Motor Mouth

Registered: 16/12/2001
Posts: 6453
Loc: Kings Langley, NSW
It's something to do with the elliptical shape of the orbit I think, or the plane of the orbit. I don't know where I read it now.

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#1003850 - 02/08/2011 10:15 Re: Predictions for spring and summer 2011-12 [Re: Keith]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2141
Loc: Manilla, near Tamworth NSW
Pete, this is off topic, but I reason quite differently about the sun's path.
We think of the year being broken into four equal parts by the two solstices and the two equinoxes. As you imply, they are not equal. Based on Wikipedia, southern hemisphere autumn to winter and winter to spring are the long intervals, at 93 days each. SH spring to summer is 90 days and SH summer to autumn is the shortest at 89 days.
http://forum.weatherzone.com.au/ubbthrea..._var#Post855531


Edited by Surly Bond (02/08/2011 10:18)
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#1003853 - 02/08/2011 11:08 Re: Predictions for spring and summer 2011-12 [Re: Surly Bond]
Keith Offline
Meteorological Motor Mouth

Registered: 16/12/2001
Posts: 6453
Loc: Kings Langley, NSW
In the US the seasons start on the climatological change (when the Sun crosses the Equator and back etc) ie the actual day not the start of the month it happens in.

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#1003859 - 02/08/2011 12:10 Re: Predictions for spring and summer 2011-12 [Re: Keith]
Big_Pete Offline
Weatherzone Addict

Registered: 19/12/2004
Posts: 1955
Loc: Perth
Wasn't last winter a real ripper for you guys over east? I'm pretty sure I remember snow falling in SA and NSW. We had a totally fail winter last year but now the pattern seems to have changed. Looks like the eastern states are already into spring, yet SW WA is still getting regular cold fronts. Still its only August.

With the higher sea surface temperatures off the west coast, how will this affect spring frontal systems? As there'll be stronger surface heating caused by the NW'lies, I was wondering if increased thunderstorm activity could continue well into spring.

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#1003931 - 02/08/2011 20:34 Re: Predictions for spring and summer 2011-12 [Re: Big_Pete]
GrizzlyBear Offline
Weatherzone Addict

Registered: 23/06/2011
Posts: 2359
Loc: Yetholme [1180m] Central Table...
Yes August was pretty good last year and a fairly decent spring too. Its quite odd how 2007 August was Hot, 2008 Cold, 2009 Hot, 2010 Cold and now 2011 Hot again no doubt.

As for summer must be a pretty good bet it will be very long and very hot given its nearly summer now.

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#1003940 - 02/08/2011 21:25 Re: Predictions for spring and summer 2011-12 [Re: GrizzlyBear]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2141
Loc: Manilla, near Tamworth NSW
Originally Posted By: PeterDuke

I only just noticed this but August has been alternating hot/cold for a few years now;
2007 August HOT
2008 August COLD
2009 August HOT
2010 August COLD
2011 August ??? – (Looks like it will be HOT)


At my place the pattern is not nearly so neat. It goes:
August 2007: warm nights;
August 2008: cold days, cold nights;
August 2009: warm days, warm nights;
August 2010: cold days.
I find that cycles up and down each two years in a given calendar month hardly ever happen. I would not expect them because the cycles that I have found do not have a period of exactly two years. Also, August has not been anywhere near the peaks or troughs in the temperature curve lately.
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#1003967 - 03/08/2011 07:21 Re: Predictions for spring and summer 2011-12 [Re: Surly Bond]
GrizzlyBear Offline
Weatherzone Addict

Registered: 23/06/2011
Posts: 2359
Loc: Yetholme [1180m] Central Table...
Yes, Surly, I agree it is unusual, but seems to be happing this way atm. I see up your way its pretty close to that pattern also.

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#1003992 - 03/08/2011 10:28 Re: Predictions for spring and summer 2011-12 [Re: GrizzlyBear]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2141
Loc: Manilla, near Tamworth NSW
Peter
Here is my complete sequence of August temperature anomalies:

August 1999: normal;
August 2000: normal;
August 2001: normal;
August 2002: warm days;
August 2003: normal;
August 2003: normal;
August 2004: normal;
August 2005: normal;
August 2006: normal;
August 2007: warm nights;
August 2008: cold days, cold nights;
August 2009: warm days, warm nights;
August 2010: cold days.

There is only one biennial cycle so far in daily max and daily min anomalies, and they are not in step with each other.
I think there is nothing to suggest that temperatures this month will not be normal, as they were in more than half the Augusts on this record.
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#1004078 - 03/08/2011 19:22 Re: Predictions for spring and summer 2011-12 [Re: Surly Bond]
ColdsnapIII Offline
Meteorological Motor Mouth

Registered: 19/01/2007
Posts: 6500
Loc: Mount Macedon, VIC
23C today in Melbourne is absolutely ridiculous to the point of being surreal. It more or less matches the crazy heights seen at the end of July 1975, albeit a handful of days later.

Today in Victoria was genuine extreme weather, equal in significance in every way to Black Saturday, just the winter equivalent.


Edited by ColdsnapIII (03/08/2011 19:23)

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#1004118 - 03/08/2011 21:46 Re: Predictions for spring and summer 2011-12 [Re: ColdsnapIII]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2141
Loc: Manilla, near Tamworth NSW
ColdsnapIII
A max temp today in Melbourne of 23 degrees is only 8 degrees above normal for August, or 9.5 degrees above normal for July.
Surely this hardly rates a mention, does it?
I don't usually mention any single day's temperature as abnormal unless it is at least 10 degrees above normal.
Is Melbourne climate more equable than I have been led to believe?
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#1004215 - 04/08/2011 12:43 Re: Predictions for spring and summer 2011-12 [Re: Surly Bond]
ROM Offline
Meteorological Motor Mouth

Registered: 29/01/2007
Posts: 6628
Just for amusement as any weather occurrence nowadays that is a bit unusual is regarded with great consternation and much reading of the tea leaves as to what it ordains regarding the global climate and "we all be rooned" school of disaster predictions, I dug this up;

Christmas Day 2006 it snowed in North Dandenong, Melbourne. Elevation only 60 metres above sea level.

Then you have the ; Snow fall in January 2010 at Shannons Flat. NSW

And that was from only a quick google

I think there was also some snow on a Christmas day way back in the 70's or thereabouts so at 73 years old and having personally and directly experienced most of what the weather can throw at us, when I see the apparent consternation of some here and elsewhere on some higher than usual temperatures during winter I also ask, weren't those mid summer snow falls at least an equally unusual and "extreme" event?
But, sensibly, those snow falls were in the end regarded as "just weather" and not something with all sorts of possibly serious connotations for the future.
There is now a tendency to panic by sections of the community when it sees apparent weather phenomena it doesn't understand or falls outside of that apparent weather nirvana where nothing ever changes from their preconceived ideas on what weather is.

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#1004218 - 04/08/2011 12:49 Re: Predictions for spring and summer 2011-12 [Re: Surly Bond]
Tom1234 Offline
Weatherzone Addict

Registered: 08/04/2011
Posts: 1709
Loc: Port Stephens
Originally Posted By: Surly Bond
ColdsnapIII
A max temp today in Melbourne of 23 degrees is only 8 degrees above normal for August, or 9.5 degrees above normal for July.
Surely this hardly rates a mention, does it?


why do you say "ONLY" 8-9c above average?
8-9c above average is pretty siginificant and i think people feel its less significant because its winter which means its 23c. 9c above average in summer for most places away from a sea breeze would mean 38-39c which is significant.

yes 23c doesnt feel hot, but its pretty abnormal for the first few days of August.

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#1004222 - 04/08/2011 13:35 Re: Predictions for spring and summer 2011-12 [Re: Tom1234]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2141
Loc: Manilla, near Tamworth NSW
I judge daily temperature anomalies worth mentioning if they occur in only one or two years out of ten.

Taking daily maxima at my site, anomalies above +8 degrees happened in seven years out of twelve. There were seven in 2002 and fifteen in 2009. There was NO trend: the first six years had 16, and the last six years 18. Anomalies above +10 degrees, which I regard as noteworthy, came only in 2002 (1) and 2009 (8). The highest positive anomaly, +13.2 was on 20/11/2009.
Still on daily maxima, extreme negative anomalies are generally larger than extreme positive anomalies. Anomalies below -10 degrees occurred in 11 years out of 12. The lowest negative anomaly, -15.3, was on 14/2/2009.

I measure my daily anomalies against a continuous curve of normals: a harmonic curve fitted to 10-year averages beginning March 1999. I consider the BoM anomalies measured against monthly averages as too crude for the 21st century. As PeterDuke pointed out, the recent high temperature would have had a much greater anomaly assigned if it had come a couple of days earlier, in July.
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#1004306 - 04/08/2011 18:56 Re: Predictions for spring and summer 2011-12 [Re: ROM]
Max Record Offline
Weatherzone Addict

Registered: 18/04/2009
Posts: 1659
Loc: Adelaide
Originally Posted By: ROM
... when I see the apparent consternation of some here and elsewhere on some higher than usual temperatures during winter I also ask, weren't those mid summer snow falls at least an equally unusual and "extreme" event?
But, sensibly, those snow falls were in the end regarded as "just weather" and not something with all sorts of possibly serious connotations for the future.
There is now a tendency to panic by sections of the community when it sees apparent weather phenomena it doesn't understand or falls outside of that apparent weather nirvana where nothing ever changes from their preconceived ideas on what weather is.


That's right, I did see a comment on here regarding cold temperatures being "weather" and hot (or comparatively hot temperatures) as "climate". Whatever suits their agendas, I guess...
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#1004307 - 04/08/2011 18:57 Re: Predictions for spring and summer 2011-12 [Re: Surly Bond]
GrizzlyBear Offline
Weatherzone Addict

Registered: 23/06/2011
Posts: 2359
Loc: Yetholme [1180m] Central Table...
One thing with anomalies that never ceases to amaze is how out of place the Sydney obs always are, have a look at this quote from this link.

"Sydney also had its second warmest mid-winter day on record on Wednesday, reaching 25.7 degrees. The mid-winter record was set on 24th July 1990, when Sydney's temperature reached 25.9 degrees."
http://www.weatherzone.com.au/news/record-stretch-of-warm-weather-for-sydney/18254

This immediately struck me because July 1990 was one of coldest I have ever seen on the CT's, when Canobolas towers were damaged by ice. The 3-4 weeks leading up to this warmer day there was continuous snowcover on the CT's. Anyway there were 2 warm days that coincided with this warm spell when it reached 18 in Bathurst and 14 in Yetholme. This time Bathurst has gone as high as 21.5 and over 20 for about 4 days so far I think. So in fact this warm spell is much more significant than the 1990 one being compared to.

As for anomalies values it does depend your location a LOT and the time of year at your location a LOT. For Melbourne in winter that is a very large anomaly also in high locations where inversions are weak anomalies will never get as large since the temp measurement is more representative of the free atmosphere.

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#1004323 - 04/08/2011 19:37 Re: Predictions for spring and summer 2011-12 [Re: GrizzlyBear]
MRF Offline
Weather Freak

Registered: 26/02/2011
Posts: 353
Loc: Gladstone QLD
Latest ENSO Wrap Up came out yesterday:

Neutral conditions remain in the tropical Pacific
Issued on Wednesday 3 August

Neutral ENSO conditions persist in the tropical Pacific, with most atmospheric and oceanic indicators at near normal levels. Pacific Ocean temperatures have cooled over the last month, but remain within neutral thresholds. Atmospheric indicators of ENSO such as trade winds and cloudiness near the date-line have fluctuated around normal.
The majority of international climate model forecasts of ENSO show that neutral conditions are likely to continue for the remainder of the southern winter and into spring with the chances of an El Niño developing now considered unlikely. In fact, more models are now predicting further cooling over the coming season.
The influence of the Indian Ocean Dipole (IOD) on Australian rainfall is currently neutral. Our climate model, POAMA, suggests there remains a chance of a positive IOD event forming during late winter. In the past, positive IOD events have been associated with drier conditions over parts of Australia, particularly in the southeast, during winter and spring.

Next update expected by 17 August 2011

http://www.bom.gov.au/climate/enso/

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#1004330 - 04/08/2011 20:09 Re: Predictions for spring and summer 2011-12 [Re: MRF]
MRF Offline
Weather Freak

Registered: 26/02/2011
Posts: 353
Loc: Gladstone QLD
Another big wet season unlikely: BOM
Posted August 04, 2011 19:16:10

The Bureau of Meteorology (BOM) is hedging its bets on how much rain will fall in Queensland next summer, but it is unlikely to be as wet as the last one.

BOM spokesman Dr Jeff Sabburg says a wet La Nina pattern has shown no signs of developing.

This time last year there were strong signals of the La Nina event that caused flooding to 70 per cent of Queensland over summer.

"We're in the predictability barrier stage where it's very difficult (to forecast summer rainfall) unless there's very strong signals, which there was last year," Dr Sabburg said.

"So if anything, it's unlikely, even if you did get something like a La Nina, that it would be as intense as it was last year."

And forecasters have also deemed it unlikely that an El Nino event - a drought - will develop.

But the bureau will not rule out anything until next month.

"We can't say with any confidence whatsoever what's going to happen past spring at this point in time," Dr Sabburg said.

"It's just speculation of what's going to happen in the summer at this point."

At the moment all signs point to neutral weather patterns, meaning average rainfall and temperatures.

"Last year at this time we had all the precursors of the La Nina. Now because we've got nothing brewing, now it's hedging each way," he said.

"But it's fast getting to the point now where it will lock in and stay neutral.

"The likelihood of anything happening other than neutral is dimming."

He said rainfall for south-east Queensland from August to October would be average at 100-200mm.

Temperatures for the next three months were likely to be higher than average during the day, and slightly higher than average during the nights, Dr Sabburg said.

http://www.abc.net.au/news/2011-08-04/another-big-wet-season-unlikely-bom/2824850

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#1004331 - 04/08/2011 20:10 Re: Predictions for spring and summer 2011-12 [Re: MRF]
HumphreyBear Offline
Weatherzone Addict

Registered: 31/01/2008
Posts: 4167
Loc: Southern Sydney
I think 1990's warm day in Sydney was probably a one off and ahead of a monster cold change. Here we have a monster block and the heat is deeper, hence warmer at higher elevations. Many of Sydney's worst sprummer days are the result of adiabatic warming in strong NW'lies. Temp may have only been 14 at Yetholme when Sydney had 26 in these conditions.

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#1004334 - 04/08/2011 20:19 Re: Predictions for spring and summer 2011-12 [Re: HumphreyBear]
Long Road Home Offline
Meteorological Motor Mouth

Registered: 08/10/2007
Posts: 8597
Loc: Northern Beaches Syd
Only 27 days now til spring, cannot wait. This has been one of the worst winters i can remember for the basin, all starting from that major cold blast in May and just dragging on and on with cold pool after cold pool. The 17-18c this evening is good don't get me wrong, but doesn't make up for the horrid cold days we've had.. bring on some warmth already!

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#1004337 - 04/08/2011 20:34 Re: Predictions for spring and summer 2011-12 [Re: Long Road Home]
ColdsnapIII Offline
Meteorological Motor Mouth

Registered: 19/01/2007
Posts: 6500
Loc: Mount Macedon, VIC
To settle the argument, it was warmer in Melbourne yesterday than Brisbane by 0.3C and only about a degree lower than the warmest temp Brisbane saw for the whole of July.

In Mildura yesterday it was actually warmer than Cairns. Cairns is around 17 degrees latitude and Mildura is 34 degrees. I find it quite extraordinary that people in Cairns could have head down to Mildura for a bit of extra warmth. laugh Normally we are talking the other way around at this time of year.

Anyway it was the warmest day on record in Melbourne for the middle winter period, and probably in most parts of the state from what I saw in the obs. This was followed by what I believe to be Melbourne's warmest winter night on record.

The maximum in Melbourne yesterday was only a couple of degrees below the Jan and Feb average. In equivalent terms it is a Black Saturday type scenario, just in winter and not summer.

It was even 17 degrees here yesterday at 520m asl in central VIC, which is starting to get into twilight zone territory. Usually at this time of year we are scraping into low double figures for the first time since around mid June. Not this year though, spring has definitely come early.





Edited by ColdsnapIII (04/08/2011 20:37)

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