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Winter/Spring 2013 (Model Output Discussion)

mcriot29

I know its summer but any one have any views on the signs for 2012 winter , i think a pos Nao so a mild standerd winter for ireland
Link belOw about winter
http://forums.accuweather.com/index.php?#38;showtopic=26562&st=300

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snow

winter is coming

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sponge bob snow pants

snow bunny

let it snow!!!

mild for weeks

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Tindie

Weather for week ahead, Some sleet and snow for North East of Uk
http://www.bbc.co.uk/weather/features/20486571

BLIZZARD7

UKMO AND GFS 12z's are both excellent with renewed WAA into Greenland and a completely blocked atlantic- forget about the atlantic for a while if we can make it 3 out of 3 with a good ECM...

Dan

pistolpetes11

Darkman2 has emailed over his thoughts, ( I have emailed over the site admin to ask if ok to be put up so if they say no , this may have to taken down)

A very cold period of weather is about to begin for Ireland in a pattern that will lock us in to a broadly northeasterly flow. We know this because an arc of above normal pressure will form involving a Greenland high and the Artic high pressure. This is a pattern the Atlantic will find very hard to break. It's one pattern with potential long longevity (weeks rather than days). This could be just as bad 2010 and the change will be a bit more gradual. Harsh frosts and ice will at first occur at night but through next weekend this will become a daytime problem as well. Temperatures really struggling above freezing if at all. "Ice days" are likely - that is where the temperature does not rise above freezing. Exceptionally cold nights. Temperatures as low as -7 or -8c inland is a probability not a possibility. Snow showers are likely on windward coasts alternating between east and north coasts. There is the added risk of Atlantic fronts coming up against this air at times. When this occurs snow is likely and on frozen ground this will settle. Most at risk of this element is the west and south west.

The cold weather will begin on Tuesday night with a sharp frost.

Eastcoastryan

I have feeling things are going to get interesting from Friday onwards... How about that for timing!!! If ECM come on board in just over an hour, I'll be a bit happier!

yorlum11

BLIZZARD7 wrote: »

UKMO AND GFS 12z's are both excellent with renewed WAA into Greenland and a completely blocked atlantic- forget about the atlantic for a while if we can make it 3 out of 3 with a good ECM...

Dan

Let's hope it can!

BLIZZARD7

Everyone go look at the GFS run from start to finish- never seen blocking like it, reload after reload with reverse zonality and extremely cold and snowy easterlies...

probably wont happen but worth looking at!

Dan

DOCARCH

Obviously so good.....you posted twice!

BLIZZARD7

DOCARCH wrote: »

Obviously so good.....you posted twice!

Haha yea sorry if message has appeared a few times- something gone wrong on mobile website :P

Mods delete if I double posted- I can only see one!

Dan

DOCARCH

Thrice....must be epic! :eek::)

Eastcoastryan

BLIZZARD7 wrote: »

Haha yea sorry if message has appeared a few times- something gone wrong on mobile website :P

Mods delete if I double posted- I can only see one!

Dan

I'm just buckling up my seatbelt for the ECM Rollercoaster!

arctictree

ECM and GFS completely different at t+144

ECM going for a return to raging westerlies and GFS going for a colder reload of Northerlies.

Elmer Blooker

Elmer Blooker wrote: »

the elephant in the room - the Azores high, not the strongest anticyclone but still there like a bad rash. :mad:

I knew this would happen.

Trotter

Excuse me if Im way off but looking at the latest ECM, I can see the low from the Atlantic powering through the high pressure block.

The burning question for me is has the Atlantic influenced increased or become more powerful in the last 20 years or so? I'm in my 30's and where I am on the South East coast, Ive seen heavy snow maybe 3 or 4 times from what I can remember. However Ive seen photos belonging to my parents of snow that I can only imagine in the 60's or 70's.

Watching the Atlantic powering through once again, I'm wondering has it become an invincible influence that makes cold spells more short term or turns a potential snow fest into a sleety mess as the Atlantic knocks down the door.

Sorry if its not as relevant as it should be in this thread but as I mentioned before, I'm a primary teacher and I've been doing 10 mins of weather models on the interactive board the last few days and I want to be able to explain it properly in the morning.

force eleven

ECM throws a big fat spanner in the works. Near meltdown on UK forums after GFS and UKMO but audible gasps of disappointment after that run. Unusual to see ECM so different from UKMO in my opinion. There's nothing more we weather watchers crave than the word 'consensus' but we do not have it yet. Coldies hold tight, roller coaster is ready for launch.

Jaffusmaximus

force eleven wrote: »

ECM throws a big fat spanner in the works. Near meltdown on UK forums after GFS and UKMO but audible gasps of disappointment after that run. Unusual to see ECM so different from UKMO in my opinion. There's nothing more we weather watchers crave than the word 'consensus' but we do not have it yet. Coldies hold tight, roller coaster is ready for launch.

If the next ECM is in line with this Evenings then ill change expectations, I already witnessed a meltdown on UK forums when the GFS was out of line with UKMO and expectations.

pistolpetes11

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

snaps

A lot can change again in the next runs. There's always a lot of chopping and changing in runs over 72 hour time frames. I just dont want any more rain for a few weeks.

pistolpetes11

blizzard2012 wrote: »

Devastated with this turn in events. It's bad enough being out of work coming to Christmas without weeks/months of gloomy wet boring weather. Was really positive up until this evening.

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 !

Villain

I wouldn't let one ECM run take away all the potential that exists, the Atlantic may well break through but it could be brief before another proper cold reload. Beyond 5 days anything is possible. Chart watching like this should show people why long range forecasts are a waste of time!

Elmer Blooker

The latest ME forecast issued less than an hour ago at 1930 says it will stay cool next weekend - not mention of the dreaded "becoming milder"
straw clutching time !! :rolleyes:

maquiladora

Prospects were starting to look poor for a meaningful cold spell earlier, but they are looking even worse now I'm afraid.

pistolpetes11

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

Capillatus

Fear_an_tarbh

On the GFS 144, does it look like the 'blocking' is quite slim and the low pressure near Greenland very close to us? Doesn't strike me as a major big-ass reliable block.

Speak Now

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

Wolfe_IRE

The Canadian GEM model latest run is just rolling out. It has been consistent in relation to the current cool period of weather.

It has much milder weather returning by late Friday into the weekend with little if any wintry potential in between.

derekon

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!

mickger844posts

Block still in full effect on the GFS 18z. Still all to play for but personally i would always favour the ECM over the GFS.

maquiladora

mickger844posts wrote: »

Block still in full effect on the GFS 18z. Still all to play for but personally i would always favour the ECM over the GFS.

It wasn't likely to shift to what the ECM was showing straight away on an 18Z run I think. If it does shift it will more likely happen on the 0Z.
This 18Z run looks worse than the 12Z out to 180 hours though, block shrinks faster and uppers are less cold here and even shorter lived. 24 hours or less of marginal upper temps just about covering the country at 150 hours out is not really something I'd be too bothered with personally. But at least there would be a chance of maybe a cold reload even further off in FI beyond that.

It's only the very start of winter though, but it would be nice if we got something nice around Christmas!

Speak Now

mickger844posts wrote: »

Block still in full effect on the GFS 18z. Still all to play for but personally i would always favour the ECM over the GFS.

As different as they look Mick it's all down to that Canadian low. Small changes make all the difference!