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Winter/Spring 2013 (Model Output Discussion)
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I knew this would happen.Elmer Blooker wrote: »the elephant in the room - the Azores high, not the strongest anticyclone but still there like a bad rash. :mad:
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Although I have liked the signs from the charts recently , there was always that nagging feeling that MT was not on board !,
I tend to side on the ECM myself when it comes down to a battle between different models,
UKMO
ECM
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http://www.theweatheroutlook.com/twoother/latest.aspx
Cold spell – now in doubt?
Posted Sun, 25 Nov 2012 19:19:08
The weather looks likely to turn colder during the week ahead, though there is more uncertainty now than had looked likely in the last few days. Before I look at the prospects I’ll quickly try and address the question I was asked on Twitter earlier, “Why do the computer models vary so much from run to run?” I think there are 2 main points in answering this. The first is the models we discuss are global and not UK centric. This means small localised changes can have a massive impact on the forecast weather in one part of the world but be virtually unnoticeable when looking at the global pattern, which is generally more stable from run to run. The UK being on the edge of a continental land mass is particularly prone to seeing big shifts in the forecast weather resulting from small localised model output changes. The second point is that when computer models generate different solutions from run to run it can mean the solution is very uncertain and small changes to the starting conditions can result in a different outcome down the line.
So what are the prospects? The latest 12z GFS / GEFS favours a cold spell, with the risk of snow in places. However, the 12z ECM which is generally considered the gold standard of medium range computer forecasting models is now hinting at a very different outcome. I’ve pasted in the ECM 12z 144 hours ahead MSLP /500 hPA chart below, and what it shows is the cold spell being ended by Sunday 2nd December, almost before it has started! If the ECM 12z operational run is correct the cold spell will be a non-event for the UK.
Which outcome is more likely? For days there have been variations in the expected length and severity of the potential cold spell, but tonight ECM has pulled a rabbit out of the hat by more or less ditching it completely. My view is to stick with a colder outlook for the moment, but take note of the ECM 12z operational run and to look at where it sits in its ensemble set (ECM has 50 ensemble runs, this compares with the GFS which has the 21 GEFS ensemble runs). The GFS / GEFS runs again later today starting at 21:30GMT so that will give another clue but won’t be conclusive, however, I’d expect things to become progressively clearer as we go through tomorrow. I’ll post updates 0 -
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Blocking really drives the models nuts, FI starting at T72/96!
UKMO looked so great but ECM has kicked all the optimisim into touch.
Still with the huge spilt in the polar vortex wouldnt write anything off yet.
Winter starts next Saturday and we're already pulling our hair out
Pre 2010 i didnt even look for an easterly before Christmas :pac:
Still at this stage id settle for a dry spell
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pistolpetes11 wrote: »Your not in the rite place if this devastates you , there will ups and downs a plenty over the winter .
The models as Snaps said can and will most likely change before they get a real grip on the eventual outcome.
Keep an eye on what MT is saying too and you wont go to far wrong !
Hi Blizzard2012, don't be too downhearted - technically, winter has not even begun.
Pistolpetes makes a valid point - you really can't trust the models past 72/96 hours. Going by your recent posts, I think you might have put too much trust in the models and in particular, trends that were nearly or just over a week away. They are not to be trusted!
Also two other points,
1. Don't get fooled into thinking December 2010 will happen again. It most likely will not happen this year, if you take the law of averages.
2. I have said this before and he has not let us down. MT Cranium was never on board in terms of this upcoming "cold spell", which now looks like being a 24 hour cold snap. I would advise (and this is based on experience), that when MT indicates snow could be on the way to Ireland, you get your snow shovel ready. Until then, tread cautiously! Check out his daily forecasts on this very board........his "guidance" is usually spot on.
Take care my friend -enjoy this weather forum as there are some great people on it and you can learn a lot.
However, the key point again is don't build yourself up again to be disappointed. We have a long 3 months of model watching ahead!
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This discussion has been closed.
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