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phil nw.

Winter Model Discussion - The Hunt For Cold -18z 17/12/12

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A new thread ready for the 18z GFS run,ECM ens,NOAA forecasters outputs and the later fax`s then.

Just a recap on the different model threads.

The winter / cold model output discussion thread (this one) - busy, fast moving, sometimes a bit of a rollercoaster, generally cold orientated, with views from a wide range of people with differing interests, biases and levels of knowledge.

In depth model discussion, analysis and summaries - slower moving, sometimes more technical, straight down the line type model analysis, info and discussion:

http://forum.netweat...-and-summaries/

Model mayhem - all the emotion from looking at the models, rants, ramps etc

http://forum.netweat...n-ramp-go-nuts/

As ever please keep it polite and use the relevant threads-continue here.

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Christmas is a magical time when magical things happen BBQ will not be out till June rest assured.

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Uncertainty reigns this evening, with the ECM EPS showing massive deviation at just 96hrs,

It is actually becoming quite an unprecedented model problem.

The NWP forecast for the UK is usually difficult but such varied output at just 96hrs is uncommon.

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As per my previous posts, the ECM has come on board to what I suspect will happen as we head into the New Year, this is the 3rd consecutive run that supports the Vortex setting up shop over Scandinavia. I suspect that we will have to wait a further few days before, this is practically a mimic of what happen back in 2010 in regards to how the energy coming out of Newfoundland and a low stalling over the UK practically allowed heights to build over Greenland.

Pressure should start to build over Greenland as we head into the New Year....

ecm500.192.png

ecm500.216.png

ecm500.240.png

npsh500.240.png

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To me this is the 'last throw of the dice' for this month in regards to Cold/snow, possible that the North could see wintryness but not holding my breath for other areas, but there has been some backtracking by the models for the HP to hold it's ground and retrogress west but is this just another case of the models throwing us a large red herring?

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just get that feeling with the models lately and the upgrades we keep seeing that at some point we r going to see something go snap and three or four days later we will all be in the cold

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just get that feeling with the models lately and the upgrades we keep seeing that at some point we r going to see something go snap and three or four days later we will all be in the cold

Agree with u there i can smell it in the air! I reckon we will get upgrades and more upgrades in the next few days. :)

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ECM ens, not sure what to make of it to be honest, large spread, main cluster in line with what the Op is showing and support from the control. All members trend back to average at day 9/10.

PLUIM_06260_NWT.png

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The latest fax for Thursday shows the struggle that the advancing Atlantic pattern will have as it meets the cold block to our east.The raw output at T72hrs show that cold air lurking over NE Scotland.

post-2026-0-80819300-1355776361_thumb.gi post-2026-0-63619800-1355776445_thumb.gi

A decent snow event quite possible for the north of Scotland and N.Isles,especially in the highlands.

The UKMO at T120hrs.

post-2026-0-97510400-1355776991_thumb.pn

still shows the far north under the cold south easterly flow so a 2- 3day battle to get the milder air right across the UK.

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the models have been moving the russian high a bit more west run by run in early stages before moving it back east again its kind of like there sayin (naw your no ment to be moving west son) and as we get later in the run it shunts it off back west.

the crucial point has to be that first hint at undercutting that brings the cold into the northeast and might be that snapping point.

i ment back east at the end of the first bitfool.gif

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The latest fax for Thursday shows the struggle that the advancing Atlantic pattern will have as it meets the cold block to our east.The raw output at T72hrs show that cold air lurking over NE Scotland.

post-2026-0-80819300-1355776361_thumb.gi post-2026-0-63619800-1355776445_thumb.gi

A decent snow event quite possible for the north of Scotland and N.Isles,especially in the highlands.

The UKMO at T120hrs.

post-2026-0-97510400-1355776991_thumb.pn

still shows the far north under the cold south easterly flow so a 2- 3day battle to get the milder air right across the UK.

how much of scotland do u think will see snow at 72h with that will it just be the very northeast or do u think a chance of some with me in the central belt between glasgow and edinburgh aswell

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Just another take on current modells data etc and of course the ACTUAL WEATHER .what a year its been ,the weather always in the headlines ,and looking at tonights rainfall predictions dire for many after wednesday .modells also hinting at some cold uppers aproaching our north /east this weekend .ecm hinting that our friend the arctic will drop into scandinavia at the end of its run .modells giving us a glimmer of hope one day then taking it all away the next .whilst keeping an eye on our small but very interesting island when i spent may and june in canada last year i couldent get over the amount of time the weather channels over there kept on mentioning the freak weather in the UK on their dedicated programes .well here is a thought ,currently soon to become very wet ,we have had a quick visit from the edge of the beast ,snow back in early November ,monsoon spring early summer ,so yes it could be a zonal winter BUT it could go the other way ,JAN THE 1st IS 336 hRS AWAY OR AS IV SAID BEFORE ,THE WEATHER AT THAT RANGE IS WELL ROUND THE CORNER ,sorry about Capitals keep forgetting Caps lock .wonder what surprises our friend GFS as got instore .cheers

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ПожалуйÑта, пожалуйÑта, пожалуйÑта! Отправить на Зверь Ñ Ð’Ð¾Ñтока!

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ПожалуйÑта, пожалуйÑта, пожалуйÑта! Отправить на Зверь Ñ Ð’Ð¾Ñтока!

i concur!

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Regards my last post ,i was in canada this year May and JUNE ,not last year ,drinks.gif

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So this is why the Arctic high needs watching, because the location of it may end up in Greenland, like it has showed up in the ECM, it traveled all the from the Bering Sea over the pole to Greenland which is quite extraordinary!

post-17320-0-05174000-1355778899_thumb.p

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Looking at what the models say between 96 to 168 hours using the GFS, JMA, ECM, NOGAPS, UKMO and GEM.

96 hours,

Russian High - The GFS brings it in further West than any other model the ECM and GEM both have it more West as well and agree with the GFS. We then have the JMA, UKMO and NOGAPS that have it further East,

I've marked out where the models place 1025mb so the image below is from the GFS as you can see it places it much further West than the other models which have been marked out further behind it where they place 1025mb.

Atlantic Lows - A real lot of difference between the models here but the GFS looks the odd one out, all the other models show a low around 985 to 990mb crossing the Atlantic meanwhile the GFS goes for a flat weak 990mb.

Here I have marked out where the models place the center of the low pressure systems. This goes to show the disagreement we have at just 96 hours.

Azores High - The GFS brings it closer to us than any other model the rest have a 1020mb isobar over Spain but the GFS brings it much further North into the Bay of Biscay.

120 hours,

Russian High - The ECM, GEM, JMA and GFS all have it about the same position. The UKMO and NOGAPS have it further East a lot further this is because the UKMO develops another high to our East and the NOGAPS has a shortwave holding it back.

Atlantic Lows - We have three different idea's here the ECM, GEM and JMA show two lows one that sits in the Southern Atlantic and the other one to the West of the UK like this,

The UKMO and NOGAPS go for something different they just keep it as one low and further South and also weak as well. Once again the GFS is on it's own here it has two lows in the Atlantic like the ECM etc but a lot further West and weaker then it has shortwaves crossing over the UK going under the Russian high which it places right over us.

144 hours,

Despite their large differences at 120 hours we end up with two idea's looking alike, we have the GEM and JMA putting a low over the North of Scotland and still have the other low in the Southern Atlantic. Then we have ECM, UKMO, NOGAPS and for the first time yet GFS agreeing they all show a low sitting out just to the West of the UK the strength of it differs but they all come across the same idea.

168 hours and beyond AKA FI WILL CHANGE - JMA shows low pressure sitting over the UK, NOGAPS gets high pressure in over the pole and tries to get a Atlantic ridging set up for a cold plunge in time for Christmas, ECM also gives us a tease by splitting PV and gives us a good chance for cold weather and the GFS mainly shows the Atlantic weather roll in.

Overall the models are clearly struggling with a lot of things at the moment firstly the Russian high they don't seem to really know how strong or how West it is going to push in, the Atlantic lows as well have really big differences between the models they don't seem to have much of a idea yet of what will happen. It is an interesting time for model watching with the talk about a strat warming towards the end of the month and into the start of the new year it will be interesting to watch how the models handle this.

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NOAA CPC 500Mb 8-14 day shows the high pressure edging over the pole and the low pressure over the BI sinking slowly south from yesterdays run but both very similar...see what tomorrows chart brings.

post-5386-0-44452200-1355779484_thumb.gi

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Weather master may I just say, that is an absolutely fantastic post. One of the best and most informative in a long time!

On the models, I just hope we can get the block further west, I'm certain it won't get far enough to deliver me snow but it could help stop the rain a little bit, my attentions are starting to turn to this now, from my perspective, other than that fun and games for the north and Scotland, I hope!

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Longer range ECM ensembles out, definitely a better cold cluster longer term tonight. Quite a few members also wanting to make it colder day 4-6 but op and control on milder cluster. Another day of model watching and another day of uncertainty continues....

post-16336-0-04413700-1355779945_thumb.p

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I want my easterly and i want it now.

Can the 18z deliver? Here we go, sudden onset easterly.

If it is going to happen the next 24hrs are crucial

18z out to 54hrs

Rtavn541.png

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Do we have a potential undercutter?

Looks a bit micro scale though. But it is what we want to build our sudden onset easterly.

Rtavn721.png

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Hear we go , can we get a Stella run?? Or do we get a prosaic influenced muck churned stomach turner?!! Come on gfs do the deal for us, we need , we want , we deserve it after the let down!!

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