Model output discussion - winter proper underway

[feb1991blizzard]

Clusters aren't quite as bad as I feared, at least the Atlantic trough is showing signs of digging, lets hope its just a timing issue and if eps went to d20, a decent cluster would carve a ridge to the NE out.

[bluearmy]

I think the revved up Atlantic is where the modelling has been headed for days now ???

Seems the idea is that the jet heads for Iberia (cold zonality sinking south and then heights building to the ne) but the 12z' suites seem to have backed off a bit later in week 2. Only one set of runs so best to wait for the 00z runs. 

[northwestsnow]

1 minute ago, bluearmy said:

I think the revved up Atlantic is where the modelling has been headed for days now ???

Seems the idea is that the jet heads for Iberia (cold zonality sinking south and then heights building to the ne) but the 12z' suites seem to have backed off a bit later in week 2. Only one set of runs so best to wait for the 00z runs. 

18z isn't going to offer any comfort either blue..

[johnholmes]

Sorry but I have to say this, another single model output at silly time scales and some of you are worrying. Beyond 144h or 168h stop comparing every run to the last. Compare like with like. That way you stand a better chance of picking up any developing pattern and some possible continuity. Neither will the clusters help comparing with the last output. Sorry but it is true.

One or two of you will end up with ulcers come the end of February.

[feb1991blizzard]

Yes, that's why I wasn't getting all stressed when the atlantic trough kept being modelled, I never bought into the Greenland height thing of the last 30 hours or so modelling, the thing that's got me angry is the lack of scandi highs at the end of the ens member runs, I wanted them to increase not decrease by now.

[johnholmes]

11 minutes ago, bluearmy said:

I think the revved up Atlantic is where the modelling has been headed for days now ???

Seems the idea is that the jet heads for Iberia (cold zonality sinking south and then heights building to the ne) but the 12z' suites seem to have backed off a bit later in week 2. Only one set of runs so best to wait for the 00z runs. 

Very true looking at the 500 mb anomaly charts. Yes I know they are mean charts but they chop and change, usually, much less than the synoptic outputs. Also looking at 500 mb is much more likely to give a better idea of the model as at that height, what scuppers a lot of model programming is humidity and at that level there is very much less than lower down in the atmosphere.

Edited December 15, 2017 by johnholmes
spelling

[phil nw.]

Just looking at the eps clusters and the theme does seem to ease the jet south as we go further out.Only a smallish clustering yet for a dive se and is the one with ht anomalies building to our ne-so that signal is still alive albeit not yet compelling.

[bluearmy]

2 minutes ago, northwestsnow said:

18z isn't going to offer any comfort either blue..

never ever going to get stressed out by a low res gfs ............

maybe one day (though by the time that model is worth analysing post day 8, global warming will have made cold chasing redundant !!

[johnholmes]

3 minutes ago, feb1991blizzard said:

Yes, that's why I wasn't getting all stressed when the atlantic trough kept being modelled, I never bought into the Greenland height thing of the last 30 hours or so modelling, the thing that's got me angry is the lack of scandi highs at the end of the ens member runs, I wanted them to increase not decrease by now.

In meteorology it is a waste of time getting angry with any model. Is there a scientific meteorological reason for those heights to increase? To me just quskly scanning through the run the answer is no. Science not anger is the way to approach things.

[bluearmy]

1 minute ago, phil nw. said:

Just looking at the eps clusters and the theme does seem to ease the jet south as we go further out.Only a smallish clustering yet for a dive se and is the one with ht anomalies building to our ne-so that signal is still alive albeit not yet compelling.

So many clusters Phil - i take that as a sign of 'no confidence in the suite'

[johnholmes]

20 minutes ago, northwestsnow said:

Goodness me there is some absolutely frigid air spilling south through Canada on 18z

Thats just going to fuel an already angry Atlantic..

Just look at those 850s at 186hrs!!

Look at the 500 mb flow or better still the 300 mb flow, the answer is there plain to see. Also something a bit technical; a confluent trough coming out of Canada and a diffluent ridge at the end=rapidly moving weather systems and tending to deepen as they run across the Atlantic

[feb1991blizzard]

1 minute ago, johnholmes said:

In meteorology it is a waste of time getting angry with any model. Is there a scientific meteorological reason for those heights to increase? To me just quskly scanning through the run the answer is no. Science not anger is the way to approach things.

Early January?  yes according to some pro's and more knowledgeable amateurs on here and the MO text update suggests blocking likely somewhere although they tend not to put pressure patterns on their updates.

[northwestsnow]

18z is taking a piece of the vortex towards NWRussia but its also leaving a large chunk over eastern canada spewing energy across the Atlantic- downstream we have heights across Europe.

A familiar set up.

[phil nw.]

1 minute ago, bluearmy said:

So many clusters Phil - i take that as a sign of 'no confidence in the suite'

I think the general theme of unsettled westerlies is pretty solid blue?Certainly many options later on wrt possible placement of hts se/e/ne or even n on one small cluster,i wish these images covered a larger area!

[johnholmes]

4 minutes ago, feb1991blizzard said:

Early January?  yes according to some pro's and more knowledgeable amateurs on here and the MO text update suggests blocking likely somewhere although they tend not to put pressure patterns on their updates.

I was referring to this latest run not to what is being predicted using other methods. The 18z does not suggest heights should build, other runs may do, may have done so earlier as I have not been watching previous runs.

[feb1991blizzard]

1 minute ago, johnholmes said:

I was referring to this latest run not to what is being predicted using other methods. The 18z does not suggest heights should build, other runs may do, may have done so earlier as I have not been watching previous runs.

Sorry - wires crossed - I was talking about recent ensembles suites - yes your right, the trough showed no signs of disrupting at all, it was fierce all the way through.

[blizzard81]

I am coming to the conclusion that the last few days of Dec will be absolute key to the the fortunes of the rest of the winter ahead. Fwiw I don't think any of the models have a clue about what the weather conditions will be across North West Europe at that time. 

[bluearmy]

1 minute ago, blizzard81 said:

I am coming to the conclusion that the last few days of Dec will be absolute key to the the fortunes of the rest of the winter ahead. Fwiw I don't think any of the models have a clue about what the weather conditions will be across North West Europe at that time. 

really ?  What on earth can happen at the end of December that will affect the whole of February? 

[January Snowstorm]

One thing always surprises me is those who look for cold even when it won't snow. I mean there's nothing to be gained by 4/5 C and cold rain. Surely it may as well be 13 and pleasant?!

I get the whole seasonal 'feel' thing but in the end of the day snow is our love not cold rain.

Regarding this evenings runs nothing much on offer right now but things can change quickly and those calling Christmas 10 days out is folly. Sunday at the earliest so still 2 days to hope for change

[Man With Beard]

32 minutes ago, feb1991blizzard said:

Totally agree but Man with Beard (and he gives balanced opinion of output) said that only 3 of 50 even LOOKED LIKE they MIGHT go on to deliver cold so I would suggest the MO would have not been expecting that when they wrote their outlook, plus they mentioned (or someone did) that they were saying SSW not out of the question, but that hasn't really progressed, plus I cant see the EPS 46 hiding anything special - One caveat I suppose battlegrounds aren't off the menu.

Thanks for the vote of confidence Feb!  However, I would caution placing too much faith in my observations, when I look through these ensembles I do so at break-neck speed (it may come across that I have forever to look at these charts but I really don't!!!).

There's also a little problem in comparing the clusters with the individual members - the clusters deal in 500mb heights, but the most useful chart I've found on weather.us is the pressure charts - and they aren't exactly the same.

Reconciling the ensemble members to the clusters - the truth is that there were a lot more than 3 members with higher pressure to the north, but not in positions to deliver cold (I mean cold enough for lowland snow in central areas) within a few days after that; but of course with higher pressure / better heights further north, there is the possibility that the pattern could eventually move far enough south to allow much more of a northerly influence.

And if my hunch about the clusters is right (that each cluster isn't showing the mean of the cluster, but rather an example of a run within the cluster) - it perhaps makes less sense to take the EPS clusters as the exact gospel on what the whole ensemble suite is showing - rather, it would be an indication only.

The clusters do suggest the jet being further south than usual by the end of December - but I'm not seeing it far enough south to bring widespread cold - it might well be cold enough for the north of the UK for snow of course. I think the real risk, instead, is of very deep lows barraging right through the centre of the UK rather than tracking NW as they normally do. It's worth emphasising that this trend has been there for a few days now, and the long-term trend has survived the slight backtrack to a minor north Atlantic ridge around 22 December.

Actually, on going through weather.us again (not so busy right now ) - I could up my estimate of 3 runs going cold to 5  . Happy days  

[blizzard81]

3 minutes ago, bluearmy said:

really ?  What on earth can happen at the end of December that will affect the whole of February? 

Well for a start the whole of February doesn't really cut it for me personally. My cut off is mid Feb for meaningful snow. In answer to your question though, I have not seen one forecast or forecaster going for a back loaded winter so Jan looks to be our best bet this season. 

[feb1991blizzard]

Much better 18z GEFS - signal back to raise heights to n-ne.

[Tracy Flick]

4 minutes ago, feb1991blizzard said:

Much better 18z GEFS - signal back to raise heights to n-ne.

A "glass is half empty" take would be Glacier Point's dreaded Euro high might be starting to appear.

As ever, hoping I'm rubbish at this.

[Weathizard]

5 minutes ago, feb1991blizzard said:

Much better 18z GEFS - signal back to raise heights to n-ne.

At day 10 plus yes... seen that so many times in the models then a shortwave turns or energy spills out of the vortex and wrecks everything.

One thing that is evident is the Canadian/Greenland vortex segment looks there to stay to me and that is mildly concerning.

[feb1991blizzard]

Another example of how the first 10 GEFS members seem to be tweaked for blocked outcomes - a lot more Northern blocking in the first 10 than the second 10.