Model Output Discussion 4th Dec.2013-12z onwards.

[winterof79]

That is mainly correct it would seem for most of England and Wales, however, if one lived in Inverness I'm not sure if it is so accurate. I'll bow down to superior knowledge but wouldn't the ECM's predictions for the Christmas period not give a chance of snow in Scotland, especially the North of the country. Although, as you say, it won't last any more than a couple days at best.

There is every chance that Peak district northward would be cold enough for snow if tonights ECM and GFS were to be close to verifying

http://modeles.meteociel.fr/modeles/gfs/runs/2013121612/gfs-0-240.png?12

http://www.meteociel.fr/modeles/ecmwf/runs/2013121612/ECM1-240.GIF?16-0

Indeed a couple of other models hinting at the same outcome

 

http://modeles.meteociel.fr/modeles/bom/runs/2013121612/bom-0-240.png?12

http://modeles.meteociel.fr/modeles/gem/runs/2013121612/gem-0-240.png?12

 

Quite remarkable agreement at such a range and has to be considered a distinct possibility

Edited December 16, 2013 by winterof79

[SMU]

http://www.meteociel.fr/modeles/ecmwf/runs/2013121612/ECH1-216.GIF?16-0

 

The odd glimour of hope for some for Xmas- the above chart aligns the jet into a classic scenario where an area of rain moves across the UK engaging with the cold air -

Would be a good bet for snow for the Pennines & Northern areas-

 

heres the snowline

http://www.meteociel.fr/modeles/ecmwf/runs/2013121612/ECF0-216.GIF?16-0

humber to central wales

 

 

If I was punting a bet on a white xmas I would go with Glasgow as it stands....

 

 

S

Edited December 16, 2013 by Steve Murr

[Gibby]

Hi everyone. Here is tonight's look at the 12 noon outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Monday December 16th 2013.

 

All models continue the unsettled and often windy theme with High pressure to the South and very deep Low pressure to the North and NW. The next 24 hours will see the High to the South throw a ridge across England and Wales tonight and tomorrow with the rain belt here currently clearing away East overnight. Some mist and fog will develop with a fair day tomorrow before gales and heavy rain sweep back over the UK on Wednesday with colder still windy and showery weather on Thursday with wintry showers in the North. The end of the week and weekend sees strong winds and rain never far away from the UK as the status-quo synoptically is maintained though milder conditions will be featured more than the slightly colder and showery weather over the weekend.

 

GFS then shows the run up to Christmas as very unsettled and often wet and temperatures will slowly lose their mild status as lower uppers associated with deep low pressure dig in over the UK. With a powerful jet stream still evident close to the UK some powerful storm systems look possible over the Christmas Holiday with severe gale or storm force winds possible with a lot of rain too at times mixed with spells of wintry showers, especially over the North. A short spell of colder northerly winds is shown by the operational tonight as we move towards the New Year but it is very short-lived as milder, windy and changeable conditions return over the New Year period with rain at times.

 

UKMO shows a broad Westerly flow across the UK next Sunday with showers or longer spells of rain moving swiftly East in the flow with fluctuating temperatures ranging from rather chilly early in the day and milder by Sunday night as the next Low approaches.

 

GEM also indicates a very volatile run up to Christmas with strong and often mild SW winds and spells of rain blowing through on the wind with some rather chillier and more showery conditions over the North at times. Christmas shows a very unsettled period with Boxing Day tonight looking particularly wild and wet with storm force winds and heavy rain followed by squally showers.

 

NAVGEM too shows a very unsettled start to next week with a strong WSW wind delivering spells of rain in largely mild conditions.

 

ECM shows deteriorating conditions next week with mild and wet weather on most days culminating a in colder and even deeper unsettled conditions over the Christmas period with spells of rain falling as snow at times over the hills along with the risk of severe gales with damaging gusts as surface temperatures fall close to or a little below average.

 

The GFS Ensembles tonight show a continual period of average uppers over the UK made up from members showing alternating days of milder then chillier conditions without ever becoming particularly cold. With regard to precipitation there is copious amounts of rainfall shown throughout the period and at times this could fall as wet snow at times as polar maritime air crosses over Britain on occasion, especially later.

 

The Jet Stream remains the focal point for the continuation of this mobile and sometimes stormy setup. It continues to flow rapidly across the Atlantic and over the UK throughout the run with the axis slipping further Southward in Week 2 whilest losing none of it'ss strength and dominance.

 

In Summary the weather remains unchanged tonight with only day to day variations within a very static patern of strong West or SW winds between very deep Low pressure to the North and High pressure well to the South. The Christmas period looks particularly stormy with heavy rain, gales and even a little snow all possible over the holiday period with little noticeable improvement or release from the pattern even up to the New Year. So it's a case of watching the skies for wind, rain and gales rather than snow and ice that will occupy us weather observers over the coming 10-14 days.

[draztik]

the GFS and Canadian ensembles from their 12z runs show considerable troughing to our NW at the day 11-15 period. With no apparent let up in terms of unsettled weather to come.

 

GEFS & GEM Ens -Height anomalies Day 11-15

Edited December 16, 2013 by draztik

[ANYWEATHER]

A lot of meat to get your teeth into tonight, albeit, details will change dramatically from one run to another. The lead up to Christmas,will provide some stormy weather along with some colder weather with snow turning up briefly in one or two surprise places! The Big day itself, looks very interesting ,with potential stormy and colder weather on offer. Looking forward to the days ahead and  what the models will be showing!!!  Both ecm and gfs generally agree on a similar evolution on that far away and of course unreliable timeframe. But nonetheless Fascinating model watching, and at least the weather wont be dull and non-descript!  

[Stuie]

The jet stream finally gets South of the UK on boxing day. It is over a week away but makes sense of the stormy conditions currently shown by the ECM.

[Frosty.]

For the first major cold snap look no further than P6 GEFS 12z...sensational snowfest charts for almost a week and freezing cold for many areas with the PFJ ending up across north africa..this run would bring a very merry christmas for all my fellow coldies...BANK 

[UV-RAY]

For the first major cold snap look no further than P6 GEFS 12z...sensational snowfest charts for almost a week and freezing cold for many areas with the PFJ ending up across north africa..this run would bring a very merry christmas for all my fellow coldies...BANK 

Would be an absolute belter that Frosty, proving you can make a silk purse from a sows ear if it was to come off that is.

[forecaster]

Sub 520 in fact.

 

Those aren't thicknesses. Just 500hpa heights it looks like.

[R.P. McMurphy]

Would love to bank this run now for Christmas. ECM going for a White Christmas for most Northern areas, from the 24th and the 25th running into the 26th.

[Methuselah]

For the first major cold snap look no further than P6 GEFS 12z...sensational snowfest charts for almost a week and freezing cold for many areas with the PFJ ending up across north africa..this run would bring a very merry christmas for all my fellow coldies...BANK 

Similarities, though not to be taken too seriously, with the wet-snow event on Xmas Day 1968? If the model-predictions anywhere near approach reality, that is... 

[Swave Snow]

http://www.meteociel.fr/modeles/ecmwf/runs/2013121612/ECH1-216.GIF?16-0

 

The odd glimour of hope for some for Xmas- the above chart aligns the jet into a classic scenario where an area of rain moves across the UK engaging with the cold air -

Would be a good bet for snow for the Pennines & Northern areas-

 

heres the snowline

http://www.meteociel.fr/modeles/ecmwf/runs/2013121612/ECF0-216.GIF?16-0

humber to central wales

 

 

If I was punting a bet on a white xmas I would go with Glasgow as it stands....

 

 

S

 

 

And Aviemore maybe too

[bluearmy]

Something to look out for over the next few days - the extended ECM ens have played with a mid Atlantic ridge post Xmas. Looks like its just an amplified transient ridging but we know what the fi ECM op is prone to do with this type of signal.

[R.P. McMurphy]

Really ! Bit premature to say that. I rather doubt the 00z will repeat the output.

 

You wrote it off last week !

Edited December 16, 2013 by Glenn W

[Frosty.]

Good signs from tonight's Ecm 12z ensemble mean, the jet alignment slowly trending towards enabling a progressively colder feed of air although even with the strong wsw'ly flow the mean shows for most of the time, the air originated in the high arctic as you can see when you follow the isobars back to their source, strongly modified by the long atlantic route but still cold enough to bring snow to hills and notice how the PFJ trends further south. I think some of us are going to have a white christmas.

[bluearmy]

 

You wrote it off last week !

I thought you were referring to the inflated scandi ridge ukmo showed on that days 12z run and digging trough. Clearly you must have been referring to the met office? Sorry if I misunderstood you.

[nick sussex]

Just dealing with Xmas Day itself and this low moving east with very strong winds on the southern flank. You can see from the De Bilt ensembles the two marked jumps in precip , one from the operational run and one from the control run  close together.

 

 

The interest with the control run is that it has an easterly then quickly nw, the operational and control run are both developing depressions but on a different track and timing by 24hrs.

 

 

The operational has the low further north, the control run further south, you can see from the wind  direction that De Bilt control run stays on the cold north flank of the low.

 

With the set up these fast moving lows are always likely to occur on the southern flank of the controlling upper trough and the question for the UK is how much cold will be ahead of one of these as it tracks eastwards.

 

In the set up because we're not dealing with an easterly set up the snow chances for Holland can be viewed more comparatively with the UK. So I think for those seeking a White Xmas some interest, of course these forecast lows might change track or not verify but just a little bit of interest to look out for:

 

 

The standard ensembles show the snow chance over there:

Edited December 16, 2013 by nick sussex

[R.P. McMurphy]

I thought you were referring to the inflated scandi ridge ukmo showed on that days 12z run and digging trough. Clearly you must have been referring to the met office? Sorry if I misunderstood you.

 

Ahhh, I see, No sorry at the time I was referring to the predicted storm which it seems to pick up very weel, even a week in advance.

 

No need to apologise Nick, just mis-communication.

[Paul_1978]

Cold zonality yes is rare but you can't sustain it without some blocking to the n/ne, maybe if the PV chunk goes east and stays there that might open up an opportunity.

Like January 1984?

[nick sussex]

Like January 1984?

That had a PV chunk quite far south helped by a negative AO which eventually moved to blocking to the ne, cold zonality is often mentioned in here but its a difficult thing to achieve. Certainly if it happens its full of interest especially for northern areas.

[Summer Sun]

Meteo Group and MetDesk have tweeted these pictures of ECM for Christmas day

 

 

 

Michael Dukes, MetDesk Director of Forecasting said: "It looks very much like it won’t be a white Christmas for most of us, with the possible exception of northern hills and mountains.

 

"It's still a little too far off for much in the way of detail, but current indications are that the Christmas period will very unsettled and often wet/stormy with the risk of high winds as our weather continues to sweep in from the Atlantic.

 

"Temperatures will be mostly above average for the time of year, but it may be cold enough at times for some wet snow over northern hills and mountains.

 

"We are watching that risk of high winds with interest, but we won’t be sure if it’s actually going to happen or how bad it will be until five or six days out. Heavy rain in the days before Christmas last year caused severe flooding in some areas.

 

http://news.sky.com/...e-wet-and-windy

Edited December 16, 2013 by Summer Sun

[AWD]

Something to look out for over the next few days - the extended ECM ens have played with a mid Atlantic ridge post Xmas. Looks like its just an amplified transient ridging but we know what the fi ECM op is prone to do with this type of signal.

Agreed:

[draztik]

The 16 member ensemble forecast for the cfsv2 keen on building a ridge to our west into week 4. Will be interesting to see the EC32 later tonight, and where it sees us post new year.

week 4 cfsv2

[bluearmy]

Meteo Group and MetDesk have tweeted these pictures of ECM for Christmas day

 

 

 

http://news.sky.com/...e-wet-and-windy

 

well they're not from the ecm 12z op run gavin. that tells a different tale re a white xmas. however, likely it will be a different story tomorrow.

[Barry12]

-4 uppers for the majority of the UK on Friday morning