Winter Model Discussion - The Hunt For Cold - 10th Dec

[chris55]

I wonder if someone can answer a question while it's quiet.

Do other weather fans on forums at other locations in the world go through the same emotions run to run like we do?

Would someone from Milwaukee for example, who lets say is a massive snow fan, see T240 showing blizzards and automatically know with a fair degree of certainty that this or that weather chart will come to fruition? obviously location is perhaps key here but I hope you get my drift.

Basically do the models ever get things very accurate / spot trends better for certain locations around the globe?

I'm not quite sure how the rest of the worlds weather forums deal with there weather forecast chat, but if you have ever looked at the NewYork ensembles there are often a "tad" more options available!!!! Everything is always bigger in the US, lol. Obviously all to do with being on the eastern side of a continent but they always make ours look so measly!

GFS with snow into the Westcountry on Thursday morning!

Edited December 10, 2012 by chris55

[snowmadchrisuk]

Yes those wonderful ensembles that led us all up the garden path in the last few weeks only to implode, but the law of averages says we will strike it lucky at some point.

Maybe , but I don't think the P/V will be able to take many more blows and I would say look West , as there will be little of the PV left at all by that stage... Azores extending North is my next punt, and maybe some link up with the Arctic High eventually . Trying to look at the bigger picture at the minute and looks likely the middle winter month may eventually provide the goods at what would be the perfect coldest time for it to happen..

[Cheshire Freeze]

this thread amazes me that so many can write cold weather off for the next few weeks.

I suppose it's the same way that people were writing off the chances of milder weather until Christmas and maybe beyond a couple of weeks back . The main difference is those posts had a plethora of 'likes' by the side of them.

[lorenzo]

Look west not east!

Start hoping for some amplification in the eastern USA, the limpet trough isn't going to sink without that

The chances of a long draw easterly are low but the ridge to the east can impart some forcing on the trough if it has some help, that way you might get a shot of colder air as the trough sinks.

The Azores high needs to retrogress and slow down the Atlantic thats what we're looking for.

Agent Sussex, the people of the Hunt for Cold thread will be relying on your in depth Reconnaissance of the NOAA aviation stuff for first signs of this happening across the states. Really don't see it playing out as flat as depicted on the GFS 12z. Patience again needed.

C'mon the Greenland High !

[Severe Siberian icy blast]

Well the Easterly has been pushed away as we all know, and reading through this thread amazes me that so many can write cold weather off for the next few weeks.

Just look how the models have performed over the last 3 weeks... terrible !. With the Polar Vortex so unstable, the models really are struggling.

So i would say anything after the weekend is all to play for,

As Frosty posted early'er, Cold can appear on the models as fast as they can drop it. And battleground snowfall can pop up within hours.

Still all to play for in my opinion. We are 10 days into Winter..

Agree with what you say but battle ground snow fall can only pop up out of no where if we already have cold air in place, after thurs we don't , but the models can pick up a new trend out of no where but can't imagine it happening anytime in the next 10 days now to be honest, hope I'm wrong though.

[Catacol]

Well you know I did mention earlier today that the charts looked to be trending towards a Bartlett style set up , but hey what do I know...I'm just a weather enthusiast who keeps repeating myself and who knows nothing

And as such a keen weather enthusiast I'm sure you have also checked the 2m anomaly chart for the same period... which points to below average temperatures. Not that it means anything really, of course.... this long range stuff is just pie in the sky.

I must say it makes me chuckle to see so many people suddenly changing their tune only a matter of days after an easterly was forecast. It is as though a switch has been flicked and weeks of weather has suddenly turned around.

What nonsense. The weather will do what it will do, but 2 observations from me:

1. It is beyond doubt now that the vortex is behaving very erratically because it is under such pressure. This means NO to a sustained zonal period but YES to the possibility and probability of vortex segments still influencing our weather and high pressure at high latitude frequently. Once the vortex has actually shifted over to Siberia then it will be interesting to see what medium range ensembles throw up...

2. The MetO do not put a lot of effort into long range forecasting. They take a hybrid view of a couple of models out to a month, but I have heard nothing to suggest that any part of their day to day working pays much attention beyond about 10 days. They have far more pressing things to deal with such as the run of daily TV and radio forecasts to think about and short term warnings such as they are. The fact that the Met have followed the current model predictions with their own long range comments is exactly what we would expect. Remember that their own Mogreps and EC analysis of last week was favouring cold; that has proved, in the 7 - 10 day range to be wrong... so dont be surprised if that forecast changes again!

For now I think we are in limbo. After the excitement and shocking backtracks of the last few days where the energy to our west was obviously underestimated we have to wait a few days now for the next pattern shift. Wet and windy after this block retreats a bit.. but then what? I was wrong last week so my thoughts are of dubious value - but for what it is worth I think a backing up of the pattern is still likely once the vortex is repositioned.

If you like wind, rain and live in the south then the end of this week will be right up your street!

Edited December 10, 2012 by Catacol_Highlander

[bluearmy]

Yes those wonderful ensembles that led us all up the garden path in the last few weeks only to implode, but the law of averages says we will strike it lucky at some point.

but they didnt karl. not until late in the day did they begin to agree on the easterly. and within a day or so, the shortwave appeared on the operationals. there has been little gefs fi agreement recently. if you can afford to lose 10 mins from your evening, look through the 12z NH set post T192. you will see a right mish mash of solutions post the mid atlantic ridge. bits of vortex flying around all over the place. any agreement with this general lack of trend is notable. it just says to me that the longer term models remain clueless. i suspect thats why stewart hasnt posted for a day or two. maybe he doesnt believe what the trop modelling is churrning out so what is there to say?

[Severe Siberian icy blast]

85% Of the 12z GFS Ensembles go for Mid Atlantic or Greenland pressure rises at +240 ,, thats a large percentage and something to watch ,

Can you post the ensembles showing this pls ?

[Polar Maritime]

but they didnt karl. not until late in the day did they begin to agree on the easterly. and within a day or so, the shortwave appeared on the operationals. there has been little gefs fi agreement recently. if you can afford to lose 10 mins from your evening, look through the 12z NH set post T192. you will see a right mish mash of solutions post the mid atlantic ridge. bits of vortex flying around all over the place. any agreement with this general lack of trend is notable. it just says to me that the longer term models remain clueless. i suspect thats why stewart hasnt posted for a day or two. maybe he doesnt believe what the trop modelling is churrning out so what is there to say?

Exactly BA

[LomondSnowstorm]

ECM has the low 20mb weaker at +72 than the GFS, on mobile so can't post the chart unfortunately

[Severe Siberian icy blast]

but they didnt karl. not until late in the day did they begin to agree on the easterly. and within a day or so, the shortwave appeared on the operationals. there has been little gefs fi agreement recently. if you can afford to lose 10 mins from your evening, look through the 12z NH set post T192. you will see a right mish mash of solutions post the mid atlantic ridge. bits of vortex flying around all over the place. any agreement with this general lack of trend is notable. it just says to me that the longer term models remain clueless. i suspect thats why stewart hasnt posted for a day or two. maybe he doesnt believe what the trop modelling is churrning out so what is there to say?

Possibly, he talked about a false dawn, but it's just sheer pathetic that we end up with the piece of energy from the vortex left over us, it's a nightmare for me as Iv been so upbeat for so long about this winter , but exhausted already after this last 3wks or so when it bagan.

[Catacol]

i suspect thats why stewart hasnt posted for a day or two. maybe he doesnt believe what the trop modelling is churrning out so what is there to say?

Either that or there HAS been a big shift in the background signals. However I doubt that: a few days wouldnt change those signals and I suspect you are right - no comment to make right now.

However he will acknowledge I expect that the uncertainty he pointed to over the energy coming out of Canada has rather wrecked our week because that energy was underestimated. I wonder what might have transpired had the error on that modelling been the other way, and more energy sucked over to Siberia. Hey ho - I dont suppose we will ever know that now. The models surely cant be wrong in the 96h time frame, can they?

[Bradowl]

Indeed, though I think on this occasion they're now fairly confident the mild weather will win out.

Not much sign of anything really cold materialising up to Christmas now.

The mild did win out back then but the cold returned and more severe than the previous cold spell.

[Summer Sun]

Can you post the ensembles showing this pls ?

The only 12z ensembles I'm aware of been out now are the GFS ones unless snowmadchrisuk, was looking at some other ensembles

[Severe Siberian icy blast]

The only 12z ensembles I'm aware of been out now are the GFS ones unless snowmadchrisuk, was looking at some other ensembles

That what I was thinking as them ensembles don't tell the story he was regarding the Atlantic ridge , thanks anyway.

[Summer Sun]

From Fergie in the south west thread

Hot off press from new modified UKMO-GM - - snow amounts are increased now early Thursday for this region and other parts of southern England. Interesting look about it. Northern limit is around M4 before it dies away. Mostly 200m upwards but UKMO suggest to low-levels around M4 corridor (they supplied a sounding for Swindon to demonstrate this potential).

Something for our south west members to look forward to potentially

[phil nw.]

Plenty of Atlantic energy now set to dominate our weather by the end of the week.Low pressure coming across the UK and grinding to a halt just to our east as it hits the edge of the Siberian block.

Looking at the ens means it looks like we are going to be stuck with an upper trough close by during the following week with winds from a westerly quarter.

http://modeles.meteo...21-1-240.png?12

The ens graph indicates fairly average temperatures in the unsettled cyclonic pattern.

http://modeles.meteo...ndres&runpara=0

Unfortunately with little amplification upstream and that residual section of vortex over Canada ejecting further lows into the Atlantic it`s difficult to envisage any quick change to this expected westerly pattern.

The latest MJO forecast is for placement in Phase 1 which ties in quite well with ens means and last night`s CPC day 8-14 mean ht anomaly chart

That Trough around the UK and those northern heights just not near enough to stop the Atlantic at the moment.

[lorenzo]

AO negative since around 20/24th November, periodicity for AO phases anywhere between 30 - 60 days. I reckon that this is on track with what was expected in terms of background signals. http://www.cpc.ncep....hgt.ao.cdas.gif

Edit updating link to historical values.

Edited December 10, 2012 by lorenzo

[Summer Sun]

ECM's take on the weeks low

Now what is interesting is that the cold air once again move back over the UK early next week (never really leaves the far north)

This is where it is on the 15th

By the 16th the low is starting to weaken slightly as it moves east and temperatures start to fall again

By the 17th the low continues to head east is that another low coming our way to our west?

All of the UK is back under some cooler air again

[Snowly does it]

Well the ECM is little help for cold. We are stuck out to day 9. Better hope for some flakes here tonight!

Looking west as others have said is the answer. In a crazy vortex situation your enemy can be your friend and vice versa

[Frosty.]

but they didnt karl. not until late in the day did they begin to agree on the easterly. and within a day or so, the shortwave appeared on the operationals. there has been little gefs fi agreement recently. if you can afford to lose 10 mins from your evening, look through the 12z NH set post T192. you will see a right mish mash of solutions post the mid atlantic ridge. bits of vortex flying around all over the place. any agreement with this general lack of trend is notable. it just says to me that the longer term models remain clueless. i suspect thats why stewart hasnt posted for a day or two. maybe he doesnt believe what the trop modelling is churrning out so what is there to say?

I really have invested a lot of time chasing the prolonged cold spell most of us thought was signed, sealed and delivered but surely you must agree it's all gone a bit pete tong? especially now the meto have changed their tune in the 6-15 day range. I'm not saying we won't have a cold spell because we are in a better synoptical position than a year ago but it looks like we are again looking for T+240 range to show a flicker of something for us to cling to again.

[Gavin Hannah]

The 12Z made me want to tear my eyes out..... That Low looks like doing some serious damage to the Ski slopes by the end of the weekend.

Only the ECM keeps Scotland under colder uppers until end of Fri but the milder air could really put a dent in the snow cover.

Unless we get a miracle.... prepare for some wet and windy weather by end of the week.

Once we get to day 5+, it's any ones guess what will happen. I think a retrogression of the LP NW is the only thing that will allow the Easterly HP to advance westwards. The danger is that the LP just fizzles out and is replaced with another one.

[fromey]

evening all.

Ian F has posted in the S/W thread about Thursday, makes interesting reading for us in the south.

a little bit of an upgrade for us.

fromey

[Jonan92]

Interesting ridge

[Summer Sun]

t192 see the low moving down the Atlantic and tries to introduce milder air to the south again the north hangs on to the cooler air also note the high pressure building up north, northern blocking perhaps?

Edited December 10, 2012 by Gavin.