Model Output Discussion 1st January 2014-06z onwards.

[johnholmes]

IF the UK does go into the cold air can we all remember one VITAL thing, that is for those discussing will it won't it snow in my back garden at extended time frames. By extended I mean ANYTHING beyond about 24h. Think back to summer rainfall, how accurate for amount, timing and places was any model at 24h let alone discussing it at 120h or more? Rainfall needs essentially only one variable compared to the 7 or 8 to get snow. Please remember this before arguing about one item or another with one another.

I have lost count how many times I urge caution re snow predictions beyond, sometimes even less than 24h EVERY single winter. 

[garbagebags]

IF the UK does go into the cold air can we all remember one VITAL thing, that is for those discussing will it won't it snow in my back garden at extended time frames. By extended I mean ANYTHING beyond about 24h. Think back to summer rainfall, how accurate for amount, timing and places was any model at 24h let alone discussing it at 120h or more? Rainfall needs essentially only one variable compared to the 7 or 8 to get snow. Please remember this before arguing about one item or another with one another.

I have lost count how many times I urge caution re snow predictions beyond, sometimes even less than 24h EVERY single winter. 

Very good point. However summer rainfall isn't a very good example because they were isolated thunderstorms which is a completely different beast and impossible to predict where they will spring up exactly. Fronts are much more predictable. 

[tight isobar]

IF the UK does go into the cold air can we all remember one VITAL thing, that is for those discussing will it won't it snow in my back garden at extended time frames. By extended I mean ANYTHING beyond about 24h. Think back to summer rainfall, how accurate for amount, timing and places was any model at 24h let alone discussing it at 120h or more? Rainfall needs essentially only one variable compared to the 7 or 8 to get snow. Please remember this before arguing about one item or another with one another.I have lost count how many times I urge caution re snow predictions beyond, sometimes even less than 24h EVERY single winter.

bang on JH, a tiny island in the northern hemisphere surrounded by water . difficult prognosis for anyone in precipitation variant with what we may or may not be facing *complex*....

[The Eagle]

The orientation of the trigger low over us is a little awkward at 168 - a tortuously slow process that delivers eventually but more than likely breaks down quickly to as in previous runs. Still it's far better than the UKMO.

[garbagebags]

True but it's quite a bit further east which will mean it will be harder for the cold to reach us (or in reality, simply not reach as far west)

 

Starting to see evidence of this creeping in now. 

[WhiteFox]

Very good point. However summer rainfall isn't a very good example because they were isolated thunderstorms which is a completely different beast and impossible to predict where they will spring up exactly. Fronts are much more predictable. 

Yes, but the elements involved in turning the front to snow are much harder to judge, especially where there are battleground scenarios. It's much easier to forecast that showers will be of snow in a cold Easterly flow (although not the location) than it is to predict that an incoming front will be of snow.

As far as UKMO goes at t144, it doesn't worry me in the slightest because:

1. It will have changed by tomorrow

2. Even if that did verify it would go SE

 

As John keeps saying, it's the pattern that matters, not the location of each individual isobar on each run every 6/12 hours!

[Tim Bland]

Out to the end of next week and only the far NE / scotland is bennefiting from the colder uppers. I have a feeling the synoptics are starting to go the wrong way for people in the south and west

[Team Jo]

Some illustrative charts to substantiate some of the commentary would be great. Especially if the commentary is a one line, non descriptive statement.

 

Thanks.....

Edited January 9, 2014 by Team Jo

[SMU]

The margins of todays runs very fine, but at this stage none of them at 144 show the bend in the isolines into the continent- therefor the probability of widespread snow would be less favourable as they are still pulling to wet dewpoints ( with the exception of the extreme North & NE)

 

Good job its at 144 as a long way away & subject to change-   but indeed this mornings outputs are tinged with a tad of disappointment, not massive downgrades per say, but the first bite of the cherry looks to be missed to the NE by around 150 miles.

 

& the Second bite will need trough disruption & that SE feed to make a major difference to the UK, - all the while the background pattern hasn't changed the finer detail has just moved against us this morning- all be it within an error rate it could move back again.

 

S 

Edited January 9, 2014 by Steve Murr

[Cheshire Freeze]

Seen enough, Atlantic high is going to muscle in here and drag everything S before it even properly gets going. Poor 6z TBH

 

[garbagebags]

sorry can't post pics at the Mo. Basically this run has the high over Scandi sitting further east making it harder and harder for the cold to reach us. 

Ridge in the Atlantic is also further east putting us in a very tight squeeze. 

So far only Scotland clipping the cold.

[Tamara]

Some excellent posts of measured analysis this morning that read between the lines very well indeed - the one from snowking being just one case in point

 

The modelling, not unsurprisingly, is a dogs breakfast for the outlook next week and much as suggested last night its hard to have confidence beyond the start of next week and the initial attempts at trough disruption.

 

The EPS members, from a model watching perspective, are fascinating this morning with a mix of solutions that include some of the cleaner, colder solutions that the GEM continues to epitomise. Equally there are some that are messy and fuse together the trough ejections as they progress erratically across the atlantic - in doing so they spill extra energy NE'wards and delay and restrict the cold air advection SW 'wards. In a nutshell, the EPS members epitomise the array of solutions we see from the UKMO operational, the GFS and GEFS members and the ECM operational itself

 

 

I think we should be highly encouraged this morning by the signs that the build in pressure to the NE is a feature that looks like it is not to going to go any place too soon and this encourages the growth and establishment of the associated cold pool just where we want it to be, but also it means that condusive feedback cycles to promote a -AO are created the longer it sits there. In this way, the more resistance it is going to put up to the low pressure sequence as it bumps up against the cold denser air and with trough disruption becoming more and more progressive.

 

This is much as alluded to by IF last night and reflects what many of us know already that modelling usually becomes too progressive in trying to remove a classic establishing winter seasonal cold block, such as we have seen do battle with the atlantic over the decades. On this basis, whilst the models continue to struggle with the initial phases of trough disruption, we should equally take any any longer term modelling that tries to flattern the pattern and bring back the atlantic to any extent with a pinch of salt.

 

This last part about any suggested return to zonality takes us one stage further in positive thinking. With every indication of further and stronger anti vortex ammunition lining up in the medium and longer term, then the Scandinavian High setting up shop looks to get just the boost it needs, when it needs it, with the jet stream becoming ever more compliant as westerly energy momentum in the atmosphere continues to decay.

 

On this basis I think we can afford to take a glass full approach in that any GEM type fast track to widespread cold next week is simply a large bonus to a pattern progression which is leading to ever growing potential to cold solutions anyway the longer time goes on. The chances that something will give at some stage are gaining momentum now for sure. Its 'game on', as some of you boys would say. 

 

This winter has been a turgid grind for several weeks enduring an atlantic barrage - its time to sit back and enjoy a much more fascinating and enjoyable ride which increasingly bodes well the further we go through January and perhaps more especially into February for the main course. I believe we can afford to wait a little longer (that is if we have to)

 

This is the closest to a rampette I have come this winter  and whilst caution is still required, and progress will be erratic, the fun part of model watching this winter has arrived and its time to enjoy it whatever happens

[frosty ground]

Seen enough, Atlantic high is going to muscle in here and drag everything S before it even properly gets going. Poor 6z TBH

 

Is it thou?

http://www.wetterzentrale.de/pics/Rtavn18615.png

[cyclonic happiness]

IF the UK does go into the cold air can we all remember one VITAL thing, that is for those discussing will it won't it snow in my back garden at extended time frames. By extended I mean ANYTHING beyond about 24h. Think back to summer rainfall, how accurate for amount, timing and places was any model at 24h let alone discussing it at 120h or more? Rainfall needs essentially only one variable compared to the 7 or 8 to get snow. Please remember this before arguing about one item or another with one another.

I have lost count how many times I urge caution re snow predictions beyond, sometimes even less than 24h EVERY single winter. 

True John! Even when you have a heavy band of snow but 30 miles from you, it can still split up at the last minute and fizzle out. It's happened here so many times I've lost count. I do feel a bit happier about the models, but cautious, they tell fibs!

[cooling climate]

I think it is becoming clear that we are likely to see a sausage orientated

shaped high. Not a bad run so far considering it is the 06z run and although

it  has corrected further east with the block I would not be surprised to see

this correct back west in future runs.

[garbagebags]

552 line Appearing over Finland. Low over France not really helping. Maybe continent is just too warm still? Give me a greeny any day. 

 

 

Edited January 9, 2014 by garbagebags

[Cheshire Freeze]

Is it thou?http://www.wetterzentrale.de/pics/Rtavn18615.png

 

Yes, we're in danger (on this run) of forming one large mid latitude block across the UK, whilst the Atlantic creeps in slowly from the NW......and that would be painful.

Edited January 9, 2014 by CreweCold

[shetland islands]

Hopefully Shetland will see some of theose cold uppers next week?

[cooling climate]

Well I would be quite happy to bank this run. Taking it at face value, precipitation charts etc.

If the reality is something like this then I think most would be happy.

[The Eagle]

NAVGEM moving toward UKMO. The orientation doesn't look great.

 

Edited January 9, 2014 by The Eagle

[Tim Bland]

06a delivers in the end. By next Sunday the block has orientated sufficiently to give a NE flow under -8c uppers giving widespread snow showers to most. looks like the PV to our north is strong enough to evebtualy topple the block though unfortunately. If we had seen this run 3 weeks ago though we would be jumping for joy!

[Ali1977]

This is looking good IMO, heights into Greenland

Never quite made it...

Edited January 9, 2014 by Ali1977

[garbagebags]

This is looking good IMO, heights into Greenland

Much Much less heights into Greenland than the 00z though? no?

[shaky]

Well if the models dont improve this evening am afraid where looking at maybe a new trend where more energy will be goin north east!!fingers crossed but its going to be a long day!!

[i luv snow]

Some people have spoken too soon, the 6z does get there by next weekend! However there will doubtless be further changes to come over the next few days. I will be looking (and hoping) for the block to be further west than on this run! The joy of model watching....

Edited January 9, 2014 by i luv snow