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#494125 - 31/10/2006 00:26 Re: I am backing another weak La nina
seaweed Offline
Weatherzone Addict

Registered: 13/10/2001
Posts: 1562
Loc: Robina SEQ
An interesting thought is that with global warming, all the forecasts & the paradigms they are based on that we thought will occur this season do not occur. Global warming makes our models invalid (because our models are based on history) and we have to come up with new equations to accurately forecast the weather. Hmmm...

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#494126 - 31/10/2006 07:48 Re: I am backing another weak La nina
BD (Bucketing Down) Offline
Member

Registered: 12/04/2006
Posts: 1799
Loc: Eastern Adelaide Hills, SA
Makes little or no difference seaweed If you use the latest 30 year data set always.
Above Average, Average and Below Average SST's still create a certain weather conditions whatever 30 year period you are in, even if they are warming up slowly. SST's this year created just the weather that they should have created. If you were using a 30 year data set from early in the century to try and forecast this years weather, well they may not work as well, but if you use the current 30year data set, there are no problems.

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#494127 - 31/10/2006 08:04 Re: I am backing another weak La nina
Craig Arthur Offline
Wind hazard researcher

Registered: 08/05/2001
Posts: 3549
Loc: 149.152009°E 35.187056°...
In certain applications, I'd argue it can make a significant impact. For example, the maximum potential intensity (MPI) of TC's is sensitive to the SST. If you are trying to model the maximum wind speeds over the next 30 years then using the last 30 years' mean SST may well lead to an underprediction of the MPI and hence wind speeds (given some predictions for the changes in SST). It is dependent on the rate of change though - the time scales I'm looking at are of order 100 - 1000 yrs, so the implications may well be more significant than in a prediction for the next season or two.

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#494128 - 31/10/2006 08:33 Re: I am backing another weak La nina
BD (Bucketing Down) Offline
Member

Registered: 12/04/2006
Posts: 1799
Loc: Eastern Adelaide Hills, SA
Fair enough Craig, I was referring to general weather monthly and seasonal patterns across areas, not smaller scale TC's which are, of course, influenced in intensity by higher SST's.

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#494129 - 31/10/2006 08:58 Re: I am backing another weak La nina
Tempest Offline
Weatherzone Addict

Registered: 17/11/2001
Posts: 3633
Sean M, an indication of the severity of the 97 el-nino is the amount of cold water off Indonesia. Whenever I have a look at the previous el nino SST's I'm amazed on how the waters off Indonesia and Peru gauge the situation.

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#494130 - 31/10/2006 11:15 Re: I am backing another weak La nina
P.K. Offline
Weather Freak

Registered: 03/08/2006
Posts: 641
Loc: Home of the Ashes
I did these for somewhere else but may as well post them here as well. The first is the SOI using the 1887 to 1989 base period. The second is the Nino 3.4 SSTA using the NOAA data (One less decimal place than the BoM data but it goes back further) excluding the value from this week. The +/- 0.5 lines are the NOAA definitions from what I can see on their website, and the +/- 0.8 lines are the BoM defintion from what I can tell from the ENSO updates.



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#494131 - 31/10/2006 16:01 Re: I am backing another weak La nina
E-J Offline
Weather Freak

Registered: 17/04/2006
Posts: 626
Loc: Innisfail (Mourilyan)
Quote:
Originally posted by F5:
26 drg's cyclone season starts at 12 midnight so bring it on i can handle another cat 5 for sure..
You can handle another one can you? Have you even been in one? Think about the poor people that will be cacking their dacks if another approaches the NTC.
_________________________
'Building a perpetual motion machine is easy - keeping the thing running is the hard bit"

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#494132 - 31/10/2006 19:07 Re: I am backing another weak La nina
AussieMark79 Offline
Member

Registered: 30/10/2005
Posts: 451
Loc: Lake Maquarie area, New South ...
El Nino-Southern Oscillation Update
The 30-day SOI changed marginally this week and at 28 October it was -16. Contributing pressure anomalies were +2.4 hPa at Darwin and -0.2hPa at Tahiti.

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#494133 - 31/10/2006 19:10 Re: I am backing another weak La nina
AussieMark79 Offline
Member

Registered: 30/10/2005
Posts: 451
Loc: Lake Maquarie area, New South ...
Quote:
Originally posted by F5:
there will be no weak La nino they forcast a neutral condition Eg very low perssure system will form very quickly like Cyclone larry, the water temps of the north queensland coast are warming up fast. 26 drg's cyclone season starts at 12 midnight so bring it on i can handle another cat 5 for sure..
this el nino event is getting close to 2004/05 event already. And Australia was very quiet that season.

when Nino 4 warms up east coast hits are lower probability as stronger shear than normal is experienced across QLD

Nino 4 is +1.1C anomality this week

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#494134 - 31/10/2006 20:14 Re: I am backing another weak La nina
seaweed Offline
Weatherzone Addict

Registered: 13/10/2001
Posts: 1562
Loc: Robina SEQ
Quote:
Originally posted by holts:
Makes little or no difference seaweed If you use the latest 30 year data set always.
Above Average, Average and Below Average SST's still create a certain weather conditions whatever 30 year period you are in, even if they are warming up slowly. SST's this year created just the weather that they should have created. If you were using a 30 year data set from early in the century to try and forecast this years weather, well they may not work as well, but if you use the current 30year data set, there are no problems.
The problem with your analysis is that it is very narrowly focused. For one thing I see local SST as having only a slight influence on tropical weather. When the last coral bleaching episode occurred (2002-03) we had a very dry wet season despite the hot SST's. This would of been explained by the lack of cloud heating up local waters.
With global warming, could it be that there maybe tipping points where that extra nth degree causes a weather outcome outside of what we would expect. An outcome not predicted by our dataset. That is the point we need to consider.

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#494135 - 31/10/2006 23:01 Re: I am backing another weak La nina
Sean M Offline
Member

Registered: 30/06/2005
Posts: 955
Loc: St Lucia, formerly gympie
thanks for that tempest, i always assumed it was just east pacific temps vs west pacific temps. in general that is

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#494136 - 01/11/2006 07:23 Re: I am backing another weak La nina
BD (Bucketing Down) Offline
Member

Registered: 12/04/2006
Posts: 1799
Loc: Eastern Adelaide Hills, SA
Sea-weed: The SST temps I use to forecast in my computer models have not changed in accuracy over the years. In fact, the seem to be getting better at forecasting all the time actually! If I were to see significant changes in the forecasting ability of SSt's over time, I should have seen them by now.
I am only talking about weather here, not coral or anything else like that.

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#494137 - 01/11/2006 09:17 Re: I am backing another weak La nina
*Runoff* Offline
Member

Registered: 24/01/2005
Posts: 2209
Loc: Whitsundays
No-one can say for sure if coral bleaching is not a natural thing. It seems to coincide with crown of thorns outbreaks. Maybe these things are an ingredient to keeping the reef alive in the longer term. We mow our lawn and it comes back stronger. The earth has been hotter than this before.

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#494138 - 01/11/2006 09:27 Re: I am backing another weak La nina
Tempest Offline
Weatherzone Addict

Registered: 17/11/2001
Posts: 3633
Who's mowing the lawns at the reef?

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#494139 - 01/11/2006 16:20 Re: I am backing another weak La nina
seaweed Offline
Weatherzone Addict

Registered: 13/10/2001
Posts: 1562
Loc: Robina SEQ
Quote:
Originally posted by holts:
Sea-weed: The SST temps I use to forecast in my computer models have not changed in accuracy over the years. In fact, the seem to be getting better at forecasting all the time actually! If I were to see significant changes in the forecasting ability of SSt's over time, I should have seen them by now.
I am only talking about weather here, not coral or anything else like that.
The reference to coral was only to emphasize how warm the ocean was back in 2002-03. Nothing more. *shakes head*

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#494140 - 01/11/2006 17:14 Re: I am backing another weak La nina
AussieMark79 Offline
Member

Registered: 30/10/2005
Posts: 451
Loc: Lake Maquarie area, New South ...
El Nino now meets BOM criteria

There was a general strengthening of all ENSO indicators during October. What will become known as the 2006/07 El Niņo, has now developed and is primed to enter the maturing phase, which is characterised by self-sustaining feedback between the Pacific ocean temperatures, winds and cloud patterns. Computer model guidance indicates that Pacific Ocean temperatures are likely to peak around January or February 2007.


In Brief

* Pacific climate patterns show an intensifying El Niņo.
* Equatorial Pacific SSTs have been warming and are over El Niņo thresholds.
* Subsurface temperatures have remained warm and have increased in response to a strong westerly wind burst.
* The SOI has fallen to a current (30th October) 30-day value of −15.
* Trade Winds remain much weaker than normal in the western to central Pacific.
* Cloudiness near the date-line has been increasing since late May and was much higher than average in October.
* Computer models are nearly unanimous in predicting El Niņo conditions for the rest of 2006 and early 2007.

Source

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#494141 - 01/11/2006 17:36 Re: I am backing another weak La nina
eternal rain Offline
Member

Registered: 10/07/2004
Posts: 5685
Loc: the great sydney desert
Well if its likely to peak around jan/feb its fine for us, we tend to feel less effect during that time so thats good. I also wouldnt be too fussed about this elnino. This time last year the pacific underwent rapid cooling and we headed for a weak la nina which never really eventuated, but nevertheless the continent was very dry and we had a horrible storm season. But now as we enter this worse situation - a strong el nino - we are experiencing increased rain and storm activity across large parts of the country as we head into summer months. Doesnt really make sense but hey its all good at least its something than nothing.. now we can see how we go this time.

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#494142 - 01/11/2006 17:54 Re: I am backing another weak La nina
Raindammit Offline
Weatherzone Moderator

Registered: 14/02/2002
Posts: 13363
Loc: Townsville & Bilyana NQ
Like I've said before most of the tropics also have little to worry about with El-Nino developing at this time of year, except for the far northern CYP which historically receives less rainfall than average during the summer months in El-Nino years. The rainfall outlook for the tropics over the next 3 months is actually better than this time last year, SE QLD/Eastern NSW is a different story:

October 2006 3 month outlook:


October 2005 3 month outlook:
_________________________
Belgian Gardens, Townsville NQ
Bilyana FNQ

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#494143 - 01/11/2006 17:57 Re: I am backing another weak La nina
eternal rain Offline
Member

Registered: 10/07/2004
Posts: 5685
Loc: the great sydney desert
Ill have to disagree with BoM on the 30-40% patches over NSW and QLD, i dont understand why they are predicting that. We have better set-ups for infeeds from that tropical moisture into these deep troughs we are predicted to get in the next few days and the weeks ahead (seasonally), more and stronger upper troughs than last year, and with the rain predicted for most of NSW and QLD tomorrow, inland areas will probably already receive their monthly average.

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#494144 - 01/11/2006 18:54 Re: I am backing another weak La nina
KevD Offline
Occasional Visitor

Registered: 23/09/2001
Posts: 5236
Loc: Bellingen NSW 2454
Absolutely agree with you there Bokkey. They mention the lack of rain in NE NSW because of the warm Pacific - when it is actually pretty cool off the coast of Australia and warmer in the far east near S America...Which makes no sense because 6 months ago they were referring to the warm Pacific as a good reason for little rain when we had warm ocean near us and cold ocean in the far east...Seem to be some mixed wires somewhere (and hoping it isn't me smile )

In addition - the standard el nino rain for NE NSW is for an increase of rain in an el nino...according to their data...yet with a pretty standard el nino they are predicting we will get little...Just doesn't make sense to me and when I saw their charts I immediately lost faith in their seasonal prediction models. Blair - if you are out there can you shed any light on this?

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