[Model Output Discussion 29th December - Into mid-Winter.]

My money is on the ECM

This is what we will see in 48 hours

ECM had forecast this northerly very accurately at 9 days out (216+)

GFS was having none of it.

With the ECM now showing these anomalies at day 8 and 9, I disagree with those saying the cold spell is over.

There is very good potential down the line, and a small shift west in the medium range (120-180) could easily see cold air flooding across the UK

Eagerly awaiting the ECM ensembles...

 

[Model Output Discussion 29th December - Into mid-Winter.]

Cold air flirts with the eastern UK throughout the ECM run... surely all we need is a relatively small shift west to see this cold air flood over the UK?

This is the anomaly for 24 hours from now.

and 96 hours

Taking 96 hours as FI, the outlook looks extremely blocked, plenty of potential going forward into January IMO.

Cold runs do not guarantee cold, just as mild runs do not guarantee mild weather. Its just a forecast from a computer program.

[Model Output Discussion 29th December - Into mid-Winter.]

1 minute ago, abbie123 said:

So is that it then game over for cold and snow .

A horrid 06Z for sure, however 6 hours ago the GFS was going for a northerly where now it wants to bring in a south westerly.

This is only at 168 hours out, the difference between the runs is astounding.

A step back for sure... but with such huge swings in model output I wouldn't take anything seriously from the models to be honest.

Huge differences even at 120, FI is 96 hours in my opinion

 

[Model Output Discussion 29th December - Into mid-Winter.]

The "roller coaster" of model watching can be fun at times, especially when trending towards cold and snow.

However, at times like this, with considerable uncertainty, it is best to take a step back and view all model outputs, and not to take anything beyond 144 too seriously from any model output.

The 12z GFS may predict mouth-watering northerlies and easterlies, packed with copious amount of countrywide snowfall.

That it in itself would mean nothing, just as the 06z GFS means nothing. It is a forecast, not a prophecy... It can and will change.

Anyone getting frustrated... try just focusing on output within 144+... it will make the whole process of model watching a lot more clearer and enjoyable.

 

 

 

[Model Output Discussion 29th December - Into mid-Winter.]

22 minutes ago, karlos1983 said:

Actually I think "bi polar" describes the weather better than this thread or its members. We just go up and down with it. Totally normal if you ask me when reactive to nwp models, which change in the GFS case, 4 times a day! Unhealthy would be a better way to discribe this forum, much like alcohol, but try going  week without either....

I myself have learned this year to never get too excited about anything beyond 144, and especially to assess model output as a whole over 12 hour intervals. The other models dont have 06z/18z runs so there is nothing to compare it to at that given time.

The ECM and GFS means still support the Northerly

06z operational is clearly going to be a mild outlier.

A lot of people seem to be convinced that the models have crystal balls.... if the 06z does not even have support from its own ensembles.... how can you use that single model run to write off the next cold spell?

Insanity in my opinion. If the GFS and ECM 12z means both swing away from the northerly, then I would be worried, Until then, pretty much as you were... cold and blocked outlook.

Deep cold and snowy conditions remain a low risk but the possibility is still there. Some snow showers, possibly heavy in some areas, are still possible from this second northerly. the snow may well remain as high pressure is set to take over, could maintain snow cover for days.

Outlook is promising, but nothing set in stone. 

[Model Output Discussion 29th December - Into mid-Winter.]

Just now, Rocheydub said:

Indeed it is, but only one in the reliable time frame.

Look, I love cold and snowy weather, as much as anyone here, but I'm a realist. This is a major step back from what we were expecting from the NWP today, no doubt. It can change, and I hope it does, but the snowmageddon runs from yesterday could only go one way, sadly it did!

Not sure I agree with that. Its not a step back in my opinion, more of a cha cha.

The snowmageddon charts from yesterdays 06z are still perfectly plausible.

Todays 12 and 18z above. What I believe we are lacking on these runs is the deep low heights over europe to drag bitter cold air over the UK.

The core of the Block is still in roughly the same place as yesterday.

To say "it can only go one way" is too pessimistic in my opinion. At that range, who can say it will not swing back the other way i.e towards a cold and snowy pattern?

 

[Model Output Discussion 29th December - Into mid-Winter.]

 

All of these anomalies are from a single run, the 18z GFS.

Absolutely stunning,The potential from these runs is fantastic.

Blocked, Cold/very cold and potentially snowy conditions look likely to persist into the foreseeable.

 

 

 

 

 

 

[Model Output Discussion 29th December - Into mid-Winter.]

A lot of focus on the long range output. Though it is very promising, I do believe we could see widespread snow from this second northerly.

Comparing the ECM and GFS at 192, looks like enough uncertainty remains for widespread snowfall to potentially be a threat?

Certainly looks like it may be more potent that the first northerly

 

 

[Model output discussion - 5th December 2016 - Into Winter we go]

Difference between the 18z and 12z at 198 is huge over the atlantic and Greenland.

By the looks of it this ridging in the atlantic is dealing a good bit of damage to the PV.

 

 

 

[Model output discussion - 5th December 2016 - Into Winter we go]

Superb ECM mean. Goodbye Euro High!

Looking further ahead, looks like the ECM mean is still hinting towards a second northerly.

The mean anomaly at Day 10 shows good support for the operational. There is clearly a very strong signal for heights to build in this region.

Exciting times ahead.

 

 

 

 

[Model output discussion - 5th December 2016 - Into Winter we go]

I can understand the gloom given the very underwhelming December. Many of us (especially myself) were chasing day 10 charts that were constantly being pushed back. We aren't seeing that now.  

The screenshot below is from the meteoearth app. I believe it uses ECM data. It is quite useful for me as it only goes out to 5 day preventing too much excitement over charts too far into the future to be reliable.

 The brilliant charts we had earlier on in the season never got into the 5 day timeframe. The screenshot below shows,by a country mile, the best chart of the winter so far, very encouraging as we head into January.

We had an extremely blocked autumn. It's typical in December for the jet stream to be very active, now as we head into January hopefully we will see blocked conditions take over once more, this time with a much larger cold pool to tap into ...

[Model output discussion - 5th December 2016 - Into Winter we go]

What a corker from the pub run on christmas day

[Model output discussion - 5th December 2016 - Into Winter we go]

.         Probably the best anomaly I've seen from the ECM all winter.... Wow.... what a turn around in the output just in time for Christmas!! Will this repeated on tommorows output ? Fingers crossed, looks very encouraging to me.

[Model output discussion - 5th December 2016 - Into Winter we go]

27 minutes ago, mhielte said:

Exactly where the MetO wants it to wander to?...

"There is also the potential, although with very little confidence attached to it, that pressure may also build to the west of the UK across the Atlantic, and this would bring a high chance of seeing a colder interlude develop." from their extended outlook

 

ECM isn't completely alone either.

The GFS 06z was showing something similar yesterday.

Could be just a fluke, but if we see signs of this tommorow aswell, it may well be something to watch.

 

[Model output discussion - 5th December 2016 - Into Winter we go]

The members are scattered towards the end of the month

However, when you view only the next week or so, it looks like the AO is set to rise, one member almost reaching +6

Thereafter, all members show a sharp decline in AO

Im unsure what model(s) is used for this forecast, hopefully its on to something. 

 

[Model Output Discussions 06z 04/11/16]

I was too busy to view the forum yesterday,very encouraging to see a number of experienced forecasters come on board!

Also a fair bit of pessimism aswell.People have too high expectations IMO. You have to understand how limited our knowledge of meteorology is.

As ive said before, the models are just computer programs trying to predict the flow of atmosphere.

These computer programs would probably be very effective at predicting air flow in a laboratory for example.

Consider the earth's atmosphere has a mass of 5.5 quadrillion tons. Then consider the millions of variables affecting the weather, and all of the unknown variables (do the models even take solar activity into account?)

The models do their best to predict patterns based on information they have been programmed with.

One experienced forecaster, viewing several runs from different models, will be far more reliable than any given run on its own IMO.

But even they are not pshyic.... what will happen beyond the 7th of December for the UK ? The short answer is, nobody knows.

The met office, for the UK weather, will produce the most reliable forecasts, however again they are not psychic..

If they were, there would be no point in having this forum would there? it does annoy me when people slander others opinions because "the met are not onboard". 

Im far from an expert, but looks clear to me that the vortex is mostly over the Siberian side, the vortex over Greenland, and especially the Canadian arctic looks incredibly weak.

 The aleutian high is now being modelled to move towards us, the atlantic  still shows no sign of recovery, and the atmosphere.. to my untrained eye... looks primed for a significant cold spell.

I personally will be enjoying the sharp frosts, ice and dry weather. You get the feeling that we could have -20 850's across the entire country, and people on here would complain about the air being to dry for snow. People should learn to enjoy the moment.

The only one in control of the weather is mother nature, with well over 2500 hours of winter left, im pretty confident almost all will see snow at some point

 

[Model Output Discussions 06z 04/11/16]

26 minutes ago, SteveB said:

In a standard Winter when the Vortex is resident in it's normal place & normal Strength, then yes a sinking high would be the form horse.

But the vortex is weak & not in it's usual place, this leaves options on the table, hence why Meto update is a little cautious.

All to play for still, and the chase for snow is still on, you could never have said that at any point last Winter....

Plenty of nice chilly night to come too, with some hard frosts.

I was thinking the same thing

That aleutian high anomaly seems to be growing larger on each run, could we not see a link up between these two highs with a bit of tweaking?

 

[Model Output Discussions 06z 04/11/16]

There is a 12 hour difference from the ECM here, as the 12z has not come out yet, but i think there is more of a 3 way split at 144+

 In my opinion all models are struggling with the pattern and I believe each model would be vastly different at 240+

GFS certainly wants to build higher heights over Greenland than the other two, but the UKMO looks worse than both to me in this area.

Im not knowledgeable or experienced enough to give an accurate figure... but I have seen drastic turnarounds in the UK weather at just over 72 hours out from the models.

I would definitely say that at 144 hours out, there is too much uncertainty to say the GFS can be completely discounted just yet.

[Model Output Discussions 06z 04/11/16]

GFS and UKMO completely different for the UK on this run.

GFS sticks to its guns, it was the first to pick up on retrogression to Greenland and always been the most bullish/consistent with a cold pattern for the UK.

 Im going to stick my neck out and say the GFS is on the money

What a fantastic start to winter if this verifies!

Watered down from the 06z, and perhaps will be further watered down than is currently shown, but surely this is plausible scenario, considering the GFS has been consistently showing this as have its ensemble means. If its not possible why is being predicted repeatedly from the GFS?

though yes, it remains not the most likely scenario, because of lack of cross model support,All eyes to the ECM....

 

[Model Output Discussions 06z 04/11/16]

The persistence of blocking in the atlantic and low heights over iberia on the 06z is remarkable

What a fantastic way to start winter, hopefully the ECM jumps on board.

[Model Output Discussions 06z 04/11/16]

Not entirely sure, but looks like the retrogression to Greenland/Hudson Bay is (finally) creeping into the reliable timeframe from the ECM/GFS means,these  charts are only 168+ hours out.

Looking at the day 10 means, looks like a lot rests on the block setting up in a favourable position, looks promising to me but risky with the atlantic door (potentially) open.. however potential then for frontal snowfall events as the atlantic pushes into cold air entrenched over the UK interesting times ahead.

 

[Model Output Discussions 06z 04/11/16]

Fantastic run from the 18z tonight.

Aside from the brilliant cold and snow prospects, 3 day snapshots of the run show completely blocked weather for the next 16 days.

Very encouraging that the atlantic is still failing to fire up, and the low heights over Iberia are refusing to budge

The trend in recent weeks has been to send energy south over the UK and towards Iberia.Charts like the above have been shown on a number of runs and I think this is what will happen, not the coldest scenario but certainly potential for snow.

The cold airflow may miss the UK, but the outlook is very blocked and stacked with potential for cold and snow

[Model Output Discussions 06z 04/11/16]

Best anomaly charts at 216+ ive seen in a long time from the GFS and ECM, if it's still there tommorow I'd say we may well be facing a decent cold spell

[Model Output Discussions 06z 04/11/16]

Just now, CreweCold said:

Divergence will be stark in this pattern because you either get sufficient WAA and a stronger block that sustains or you don't. It's as simple as that. Knife edge stuff but the direction of travel today has been good with that low exiting stateside being held back more on more each run.

yes agreed, it all rests on this WAA event , otherwise back to square one it seems.

and yes it's definitely been good viewing today, nice to see these lovely charts creeping closer to the reliable rather than the opposite for a change! 

[Model Output Discussions 06z 04/11/16]

Best chart ive seen in the reliable (sort of) timeframe, only 180 hours out and it strongly hints towards retrogression.

Divergence in the output beyond day 10 is ridiculous.