Model output discussion - 1st December onwards

[January Snowstorm]

Folks it's worth remembering that the weather can change and take us all by surprise with very little notice.

The fact that all models agree on mild doesn't mean a whole lot. We have seen plenty cases of cold in the past where all agreed and were wrong. 

I'll leave you all with 2 facts this evening

Christmas day is not decided and won't be until at least Friday of this week. Anything inc snow can still happen

The current incessant wet spell is a carbon copy of early winter 2009. Then along came a dramatic switch that led to the most bitterly cold winter of a generation 

 

Edited December 15, 2015 by January Snowstorm

[mulzy]

28 minutes ago, knocker said:

Looking at tonight's GEFS five day anomalies highlights the major change of the retreat of the east Atlantic trough and the positive heights build just the east of the UK. No mayor change vis the pattern over the Pole and upstream pattern. This will have the effect of more settled weather over the UK over New Year albeit rather unseasonable warm

Charts weatherbell

 

 

I don't think it will be unseasonably warm at the surface.  It might even be colder than average...

[phil nw.]

1 minute ago, bobbydog said:

yes phil, its still there. considering recent runs have been generally consistent overall, maybe this is the 'messines ridge' we have been waiting for to destroy the vortex...

I actually noticed +ve ht anomalies up there a couple of days ago on one of the naefs runs but didn't put too much credence on it.

It's good to see this signal re-appear.

Let's hope it continues now although it's best not to hang our hat on it too much yet as it may only be the first sortie on the vortex.Wavebreaking tends to ebb and flow so we may see the strength and amplitude vary on this for a while.

 

 

[knocker]

3 minutes ago, mulzy said:

I don't think it will be unseasonably warm at the surface.  It might even be colder than average...

You could be right but I was just using the GEFs temp anomaly.

 

[IDO]

11 minutes ago, January Snowstorm said:

Folks it's worth remembering that the weather can change and take us all by surprise with very little notice.

The fact that all models agree on mild doesn't mean a whole lot. We have seen plenty cases of cold in the past where all agreed and were wrong. 

I'll leave you all with 2 facts this evening

Christmas day is not decided and won't be until at least Friday of this week. Anything inc snow can still happen

The current incessant wet spell is a carbon copy of early winter 2009. Then along came a dramatic switch that led to the most bitterly cold winter of a generation 

 

Just seen the BBC weather and they said no sign of cold at Christmas. ECM Christmas Day also going mild South & average north:

  

Tweet from one of the pros: 

PaulKnightley Very mild this week. Looks like the weather type will continue. Don't believe rubbish about a cold Xmas. 15/12/2015, 18:34

[mountain shadow]

4 hours ago, January Snowstorm said:

Folks it's worth remembering that the weather can change and take us all by surprise with very little notice.

The fact that all models agree on mild doesn't mean a whole lot. We have seen plenty cases of cold in the past where all agreed and were wrong. 

Sorry JS that is just not true.

Recent advances in medium to longer term forecasting mean it is extremely unlikely that a cold spell will just suddenly appear without being forecast 

A average to mild Christmas day was nailed on about a week ago.

[January Snowstorm]

6 minutes ago, IDO said:

Just seen the BBC weather and they said no sign of cold at Christmas. 

I'll make one last comment this evening. They may well be right but Christmas day is 240hrs away. When last has the gfs or ecm been right at 240hrs ? The last frame of the ecm (240) is usually rubbished as not having a clue with wild swings from run to run

[Eskimo]

2 minutes ago, January Snowstorm said:

I'll make one last comment this evening. They may well be right but Christmas day is 240hrs away. When last has the gfs or ecm been right at 240hrs ? The last frame of the ecm (240) is usually rubbished as not having a clue with wild swings from run to run

No, but you can gather general trends and the trend remains the same, wet and occasionally windy. 

[feb1991blizzard]

1 minute ago, January Snowstorm said:

I'll make one last comment this evening. They may well be right but Christmas day is 240hrs away. When last has the gfs or ecm been right at 240hrs ? The last frame of the ecm (240) is usually rubbished as not having a clue with wild swings from run to run

But that's why Ensembles are used and there is no clustering that shows any cold on the GEFS and very few on the ECM.

[January Snowstorm]

The ensembles are as fickle as the models and chop and change. Yes the trend is mild wet all am saying is its not certain yet. By the way would disagree that advances in forecasting allow us to forecast beyond 7 to 10 days. Most experts would agree that outside of a general rough idea 10 days is absolute limit

[feb1991blizzard]

Just now, January Snowstorm said:

The ensembles are as fickle as the models and chop and change. Yes the trend is mild wet all am saying is its not certain yet. By the way would disagree that advances in forecasting allow us to forecast beyond 7 to 10 days. Most experts would agree that outside of a general rough idea 10 days is absolute limit

we are within 10 days now, that whole suite will not suddenly flip to -7c  and below uppers in the next 2 days and by then it will definitely be too late.

 

 

[Timmytour]

I don't think even the bookies, keen for their usual flurry of excited bets on a White Christmas, could drum up trade from the current models.  Hard to remember the last occasion when the first couple of weeks of December didn't raise at least a flicker of something for them

[Eskimo]

1 minute ago, Timmytour said:

I don't think even the bookies, keen for their usual flurry of excited bets on a White Christmas, could drum up trade from the current models.  Hard to remember the last occasion when the first couple of weeks of December didn't raise at least a flicker of something for them

2013?

[tight isobar]

Well its ALL eyes on mjo phasing and inducing heights at Scandinavia' although right at the very end cross suites. 

Certainly a possible/eventual solution evolving. ...but will take a whole lot of meandering' around available data in coming days.

Just to lighten a few dull spirits

Perturbation "5"....again a far cry from reliable time frame. But another otherwise tentative atm sign!!!

[Frosty.]

The Ecm 12z shows polar maritime air flooding in across the north and west during christmas eve so there would be a risk of wintry ppn on northern hills, it doesn't look as mild next  week, more seasonal compared to the extreme mild this week. I will take this crumb of comfort that next week will not be blow torch mild!

[Timmytour]

38 minutes ago, Timmytour said:

I don't think even the bookies, keen for their usual flurry of excited bets on a White Christmas, could drum up trade from the current models.  Hard to remember the last occasion when the first couple of weeks of December didn't raise at least a flicker of something for them

 

34 minutes ago, PerfectStorm said:

2013?

Three days in advance for our newspaper friends.... http://www.express.co.uk/news/uk/449815/Snow-warning-Winter-2013-will-see-a-White-Christmas-across-UK-says-shock-weather-forecast

[kev238]

In these types of set up it is quite possible to forecasts trends and patterns for 10 days 

The overwhelming signal is more of the same up to Christmas with perhaps a more westerly component next week than the southerly of this week 

I hope it stays insanely mild this month so we smash temperature records 

 

 

[ANYWEATHER]

Hello! Both ecm and gfs still show the Uk on the cusp of some colder more seasonal weather come Christmas! The problem the models are having is with the Euro High ,which has been forecast to diminish ,but unfortunately is still being modelled. I Hate that Euro high like everyone else who likes seasonal weather. Theres no doubt the Atlantic is in charge but the high level of Shannon entropy or uncertainty on how cold it will be is proving very difficult to model. Mother Nature has a habit of making up for lost time....

Edited December 15, 2015 by ANYWEATHER

[Timmytour]

2 minutes ago, ANYWEATHER said:

Hello! Both ecm and gfs still show the Uk on the cusp of some colder more seasonal weather come Christmas! The problem the models are having is with the Euro High ,which has been forecast to diminish ,but unfortunately is still being modelled. I Hate that Euro high like everyone else who likes seasonal weather. Theres no doubt the Atlantic is in charge but the high level of Shannon entropy or uncertainty on how cold it will be is proving very difficult to model. Mother Nature has a habit of making up for lost time....

That Euro high is like a trampoline....every time you thing somethings going to break through it, it springs back up

[Hocus Pocus]

1 hour ago, feb1991blizzard said:

But that's why Ensembles are used and there is no clustering that shows any cold on the GEFS and very few on the ECM.

Indeed, I would only go against them if there was uncertainty but for me it looks relatively clear cut  up until Xmas, thereafter we start to see divergence  as what's been discussed in the proceeding posts.

Edited December 15, 2015 by Hocus Pocus

[Man With Beard]

In all honesty, I'm not seeing any realistic signs of a change even after Christmas. In the chart below (T288, 27th December), the mean ensemble chart doesn't hide too many twists in the tale:

The 1030mb mean high is usually my threshold for being likely to verify even at long range - and there it is over Italy.

The stability is further evidenced by quite a stable "spread" chart - very stable for the SE in particular considering it's T288 (probably meaning storms likely to track over the north rather than south, as they higher the uncertainty on spread charts):

Can it get worse for coldies (better for mildies)? Yes it could, see below - sorry to compound people's misery further - it's only one ensemble member after all - but it's just that I didn't think a chart like this was even possible for the last week of December:

From Autumn straight into Spring on that one. 

Something quite dramatic is going to be needed to kick us out of this cycle before too much of winter has passed.

[Singularity]

So it is that we find ourselves looking at the very thing Tamara explained that we should look for about a fortnight ago; tropical and extratropical signals engaging in the Pacific with high amplitude.

We just need the convection to progress further across the Pacific before decaying than the current ECM (and more substantially GEFS) ensemble means are suggesting. From past observations I've noticed that when GEFS is more amplified than ECM it tends to wind up closer to the mark, and this is often the way round the two models are. At the moment we have the reverse, though, so I'm less sure what to expect - but generally speaking the MJO does have a habit of progressing further east than model output in the 240+ hour range suggests.

The GEFS has trended toward more of an MJO signal and there has also been a corresponding shift in the AAM outlook, the model being dragged kicking and screaming toward a more positive outlook (literally). Just look at the differences between the output of the 7th and that of this morning:

Neutral by the 18th has become neutral by the 25th! Not long beyond the end of this run, I'd expect to see a substantial climb back to +ve AAM should the greater MJO propagation prove to be the way forward. Indeed, it may happen sooner than that.

 

Looking at the 500 hPa charts, I see the 'Super Sceuro High' just about manages to show its hand in the ECM 12z det. run. Meanwhile the Atlantic features a substantial trough digging well south, another feature of the amplification and with the potential to throw some exceptionally warm air in our direction for a time - not that we're hard pressed to find that at the moment!

[bobbydog]

reality check here- the models are in good agreement- a white christmas for most of us is highly unlikely. a white new year even- unlikely. get over it...

however.... whilst we are probably going to see some unseasonably high temps over the next couple of weeks, it could be the pre-cursor to the big event. lets face it, a white christmas is nice but in reality, rare. if the (somewhat consistent) modelling is correct, we could be looking at a wave-breaking event, throwing some very warm air into a very cold (-85c) vortex. we all go on about "coldies" but in reality we mean 'snowies' . the vast majority are looking for 'cold' but snow is the real goal. we want winter to be snowy, not just cold. whats the point without snow? its just cold!

anyway, as i said, it may get warmer for now but smash up that cold vortex and its got to go somewhere! actually, the charts we are seeing now are not a million miles away from 1947. in reality, having read up on it, be careful what you wish for..

Edited December 15, 2015 by bobbydog

[Milhouse]

1 hour ago, tight isobar said:

Well its ALL eyes on mjo phasing and inducing heights at Scandinavia' although right at the very end cross suites. 

Certainly a possible/eventual solution evolving. ...but will take a whole lot of meandering' around available data in coming days.

Just to lighten a few dull spirits

Perturbation "5"....again a far cry from reliable time frame. But another otherwise tentative atm sign!!!

No prizes for guessing which ensemble member the above chart relates to.

[knocker]

The ecm anomaly at T240 has the trough just to the west of the UK with slight ridging to the east with a familiar pattern upstream. Thus a continuation of the WSW flow over the UK with temps above average. In the ext period at T360 the main difference is the vortex now back over NW Greenland and amplification of the European HP which is now ridging NE to southern Sweden. Thus the UK still in the SW flow and the more settled weather may be influential a bit further north and the temps still above average.

 

Edited December 15, 2015 by knocker