Model Output Discussion 17th Dec.2013-12z onwards.

[ICETAB]

GEFS, members 3, 6, 9 & 19 all look good to me 3 being the best. I also note that the PV wants to migrate east on a good few runs which should make it easier for heights to build around Greenland further down the line.

 

GEFS mem 3;

 

[Severe Siberian icy blast]

Poor runs this morning all round. Firstly and most importantly the Xmas eve storm has if anything intensified on the overnight runs, followed by another severe storm at the end of week.Secondly for coldies there is a big step backwards this morning, the tentative signs of trough disruption have disappeared. Yes there are some heights over the pole, but they are not helping to advect any deep cold towards us and if anything during the back end of gfs the vortex is intensifying over Greenland and we have hgh pressure building to our south.ECM ends with a little bit of interest, but it's verification at day 9 and 10 has been average at best this winter so far in my view, and only yesterday it was suggesting trough disruption at 168, which soon went on the next runs.Sorry for the rather downbeat post, please don't shoot the messenger Cheers

Considering what we have been forced to watch for the entire month of December these charts are so much better than what we'v had , granted we have lost the trough disruption , but the polar profile is about to undergo a pattern change , we can expect the period of transition to polar blocking to be period where the models play with different possible solutions , a transitional period brings even more chaos to the models than normal , so expect to see lots of different runs , but considering how mighty strong the vortex has been , I welcome these charts with my arms wide open .It's what Iv been searching the models for since November ! With polar blocking and the vortex shredded we have a much better chance of cold and snowy weather , so let's hope these charts move closer to the reliable timeframe because once they do we can realistically start looking for deep cold to effect our shores. On a separate note I'm off to Poland on the 3rd for 4 nights , and I really hope things the weather becomes more seasonal over their rather than been 6c , that would be Sod's law ! Edited December 22, 2013 by Severe Siberian icy blast

[Captain Shortwave]

Well the ECMs poor form continues, getting a low at day 5 completely wrong, even the GFS was more on the ball here. In fact most other models including the lower ranking ones were closer to the mark. Of course the models might change here but the others have been very consistent in developing this low over the past couple of days.

The rest of this year will be seen out by some very deep lows crossing the Atlantic and ploughing into north west Europe bringing strong winds and rain, temperatures will be around or just below average so there is always the chance of wintry precipitation, especially over higher ground.

There is evidence that the polar vortex will weaken, contract and move westwards slightly which might give an opportunity for better weather to effect the UK, but whether it is a high latitude block or the return of the Euro high remains to be seen. Of course the models might be underestimating the PV in the later output but the GFS ens do show some sort of trend and specifics aside it is pretty good at spotting when the PV is going to shift (it spotted the transfer from Siberia to Greenland/Canada very well a few weeks back).

In the more reliable timeframe, tomorrow looks dreadful

75-85 knots (up to 95mph) gusts in the evening rush hour for the south east potentially here  

Edited December 22, 2013 by Captain shortwave

[The Northern Ramper]

Of course the stats will show the ECM as leading the pack when it comes to verification stats, it's just that it keeps getting the key things wrong in comparison to the lesser models (Gfs)

[bluearmy]

Of course the stats will show the ECM as leading the pack when it comes to verification stats, it's just that it keeps getting the key things wrong in comparison to the lesser models (Gfs)

 

hmmm - not sure thats completely fair.  it was the only model that deepened the system to begin with. the others followed suit, having shown a weaker feature. yesterday morning it threw out a wrong run re that depression.  i think the problem on here is too much attention is paid to op fi charts when the ens are not in any kind of agreement. this morning, we see the ops less excited re a disturbed polar profile - yet the ens, as pointed out earlier, remain similar to yesterday. therefore, no need to get too bothered about the fi ops if you are seeking a hemispheric pattern change after new year.

 

and it probably does need saying - there could be a huge vortex split and cold spread far and wide into the mid lattitudes, yet our eastern canadian friend could sit there and fire up the atlantic for the next 8 weeks - its happened before.

 

extended ecm ens are headed in a better direction for january cold - nothing dramatic (yet) but a developing theme of getting the surface trough to our east.

Edited December 22, 2013 by bluearmy

[Gibby]

Good morning everyone. Here is this morning's look at the synoptics for the UK over the run up to Christmas, Christmas itself, run up to the New Year and into the first days of 2014 data supplied from the midnight outputs from the NWP for Sunday December 22nd 2013.

 

All models show a showery WSW flow today which will deliver scattered showers and breezy weather to all areas with some heavy and wintry showers over the hills of the North. Tonight shows winds backing SW as a rapidly deepening depression in mid Atlantic moves NE towards the NW of Scotland tomorrow with a very wet and windy spell for all with severe gales and potentially storm force winds in the NW for a while. Clearer and more showery weather will reach the West and North by dusk. Christmas Eve then shows all areas in a very windy and showery WSW flow again with showers, turning progressively wintry on Northern and Central hills through the day. Any remaining rain from the previous day will clear the SE. Christmas Day and Boxing Day shows isobars opening up over the UK giving much less windy days with as a result many inland areas staying dry and bright in rather cold winter sunshine. However, Western coasts and hills will be peppered with showers and where these are allowed to drift inland on prevailing winds they could be heavy and wintry. Late on Boxing Day winds will back SW and freshen again markedly with Friday seeing another very deep depression close to NW Britain with another area of very strong winds and rain followed by showers the order of the period as we approach next weekend.

 

GFS then show the rest of the period between Christmas and the New Year as remaining unsettled and windy with showers and periods of rain. Though rather chilly at times in the North under the more showery interludes the South looks like it could turn milder as pressure builds over Europe. Into the first days of the New Year a brief colder and drier interlude is quickly squashed away South as Westerly winds return though with pressure staying high not far from the South all areas will become quite mild with rainfall much more restricted to far Northern and NW areas.

 

UKMO closes it's output for next Saturday with deep Low pressure up to the West of Scotland with a strong to gale WSW wind blowing everywhere with further rain or showers in very average temperatures.

 

GEM shows pressure building over Europe next weekend and while this period will be still influenced by Low pressure North of the UK with attendant rain and showers with time the worst of the weather will transfer more towards the North and West while Southern and Eastern parts slowly turn less wet and rather milder.

 

NAVGEM remains very unsettled next weekend with Low pressure still covering sea areas North of Scotland with strong and blustery West or SW winds over Britain with heavy rain at times in largely very average temperatures.

 

ECM keeps the unsettled and windy theme going throughout the post Christmas period and up to the New Year with Low pressure close to northern Britain throughout. As a result there will plenty more wind and rain though the threat of damaging winds should steadily diminish. Temperatures look like holding close to average for all.

 

The GFS Ensembles today show virtually no chance of any significant cold weather developing on a natuionwide scale at all over the last week of this year nor the first week of the New Year. Instead uppers are locked solid at average levels as far as the eye can see and with plenty of rain spikes from all members at times the Atlantic remains in complete control of this seasons UK Winter so far. The damaging winds of the current period do look like becoming less of an issue as we reach the New Year but rainfall amounts could continue to be a problem on flood plains and other susceptible low lying areas.

 

The Jet Stream continues to pump actively out of the States for the duration of this morning's output. It oscillates between a position over and to the South of the UK over the next week in response to the ebb and flow of the low pressure systems to it's North. In Week 2 a temporary weakening of strength is short lived as a new surge is shown crossing the Atlantic towards the UK later in week 2.

 

In Summary the weather remains locked in an Atlantic pattern which looks like refusing to lie down. There are plenty more active and powerful Low pressure areas between now and the New Year each producing their own version of gales, heavy rain followed by showers with the chance of wintry showers over the hills at times, largely in the North. In Week 2 there are some signs of pressure rising over the Meditteranean Sea and pulling the Jet flow more NE towards Scandinavia and as a result sucking milder air across the South and East while maintaining quite unsettled but less stormy conditions however, this all looks tentative at the moment. The one constant between all the models being that not one shows any excursion into anything cold and wintry so we are left stuck looking at wind and rain events for the foreseeable and staring at the computer models outermost limits for seeking any embryonic signs of change. I think the 240 hr mean chart sums up our problem for cold weather fans this morning considering this is a chart for 10 days from now.

 

http://www.wetterzentrale.de/pics/Reem2401.gif

Edited December 22, 2013 by Gibby

[shedhead]

Still struggling to see any signs of a pattern change within the model suite, in fact the charts are starting to look all to familiar, with HP either over Europe or the Med. The deep PV continues to sit precisely in the wrong spot for UK cold and even as we move into the New Year it's very much as you were...

 

No doubt some will manage to put a +ive spin on things, but it still looks like being a very long road to a genuine cold pattern from here.

 

Edited December 22, 2013 by shedhead

[Summer Sun]

UKMO showing another spell over gales next Saturday after a brief respite mid week

 

 

After going a different route for a fun runs ECM is back in line with UKMO and GFS now

 

 

GFS

 

Edited December 22, 2013 by Summer Sun

[Mucka]

I certainly haven't been overly enamoured by this mornings runs but then I expected the signal for blocking chances into January to wax and wane through the Xmas period so not time to panic either.

As a generalisation the Euro trough is modelled a little shallower and we have more energy pushing NE through Scandinavia which would certainly lessen our chances if it became a trend. We need to stall energy as much as possible and a link up of heights through Scandinavia with the Arctic high would be a big help. For me this is really the first step in maintaining a more amplified pattern behind, if it doesn't happen the pattern could well flatten out with the Atlantic quickly overriding any transient ridges thrown up and the dreaded Azores high becoming more of player, slowly returning the jet North.

 

Back to the here and now, plenty of wet and windy to get through with the best chance of snow falling to low lying areas on Xmas eve morning in Northern and Western areas.

The jury is still out on Xmas day but currently it doesn't look like anywhere away from high ground or the far North will have much prospect of seeing snow falling - still time for a surprise or two there though.

 

The biggest concern for severe weather at the moment (other than some possible localised flooding and high winds Christmas eve morn) is the storm modelled for the 27th.

The track and intensity of a storm that has such potential for explosive cyclogenesis is difficult to pin down even 48 hours out so not worth trying to second guess the magnitude of this yet, just something to monitor.

 

GFS 06z so far, incoming!

 

 

Also it continues with sending more energy NE rather than SE but the Arctic high looks a little better.

[TSNWK]

Still struggling to see any signs of a pattern change within the model suite, in fact the charts are starting to look all to familiar, with HP either over Europe or the Med. The deep PV continues to sit precisely in the wrong spot for UK cold and even as we move into the New Year it's very much as you were...

 

No doubt some will manage to put a +ive spin on things, but it still looks like being a very long road to a genuine cold pattern from here.

 

Sadly I agree. I posted this morning that I thought the situation was poor for coldies and the best challenges to my remarks were that some ensemble members at the back end of GFS were looking cold, granted they did - but I think it testament to how poor things are at the moment for coldies when we start wheeling out hand picked ensembles members from the back end of GFS.

[Captain Shortwave]

Round goodness who knows of wheelie bins vs Atlantic storm machine setting up next weekend

B&Q are going to have a bumper boxing day sales I think, many a fence panel will be lost during this period.

Edited December 22, 2013 by Captain shortwave

[shedhead]

Sadly I agree. I posted this morning that I thought the situation was poor for coldies and the best challenges to my remarks were that some ensemble members at the back end of GFS were looking cold, granted they did - but I think it testament to how poor things are at the moment for coldies when we start wheeling out hand picked ensembles members from the back end of GFS.

Yes indeed TSNWK.   I know very few take any notice of what I say on here, but for those who do I still think we are in for a very interesting 2nd half of Winter, especially Feb....

[Mucka]

Sadly I agree. I posted this morning that I thought the situation was poor for coldies and the best challenges to my remarks were that some ensemble members at the back end of GFS were looking cold, granted they did - but I think it testament to how poor things are at the moment for coldies when we start wheeling out hand picked ensembles members from the back end of GFS.

 

I really wouldn't go writing off January's chances all over again on the back of a couple operational runs TSNWK.

It may be the Atlantic wins out completely or it may not.

Personally I think we will see something in between with enough amplification to bring possible 48h cold snaps intermixed with milder spells for the first half of Jan, still rather unsettled but nothing like as stormy with weaker lows being forced South by transient ridges.

I wouldn't want to call it though. We will have a better idea after Christmas. 

 

BTW 06z better out to 144 so fingers crossed it is a better FI - if just to raise spirits.

 

Edited December 22, 2013 by Mucka

[draztik]

Still struggling to see any signs of a pattern change within the model suite, in fact the charts are starting to look all to familiar, with HP either over Europe or the Med. The deep PV continues to sit precisely in the wrong spot for UK cold and even as we move into the New Year it's very much as you were...

 

No doubt some will manage to put a +ive spin on things, but it still looks like being a very long road to a genuine cold pattern from here.

 

 

Yep, I couldn't agree more. The synoptics shown atm do not lend themselves to anything very cold. The ext ecm ensembles continues with the idea of troughing to our NW, and as long as this is the case, it looks like staying fairly unsettled with fairly average conditions overall. The MetO in the their latest long range assessment agrees stating

 

"Current indications are that the very unsettled weather that is expected to dominate into the New Year. Spells of mild, wet and windy weather are likely to alternate with brighter, colder, showery periods, though the risk of any significant snow or prolonged wintry weather looks low except on high ground in the north. Further into January, the most probable scenario is for the unsettled conditions to ease somewhat with a greater chance of drier weather, whilst frost becomes a little more likely."

 

So, more of the same.... and of course, this is not what the majority in this forum want. but its what we have and its what the models are suggesting.

 

ext ecm ens day 10-15 heights

Edited December 22, 2013 by draztik

[cooling climate]

Still plenty to be encouraged by this morning. ECM t240 looking full of promise.

I think people need to remeber we are looking at post Jan 7th for cold pattern to

set up so there will be ups and downs from the models.

[bluearmy]

not much point posting a day 12 low res op and using it to illustrate how grim things will look on that day. (Tbh, there is a fair bit to put a positive spin on that chart anyway). no matter, It won't look like that come the 3rd jan anyway. martin's ens mean more relevant but again, that shows the 528 dam line across central Scotland and the jet over France. We've been in far worse places for cold in winters past than this come the Xmas output.

[Captain Shortwave]

A major problem here is when the jet starts to ease across the Atlantic it seems to want to encourage the Azores high to push northwards back into Iberia and put us back in a west/south westerly flow.

we really need to keep this little blighter from getting back in.

[Iceaxecrampon]

Ouch!

 

 

Meant to be in Ambleside  - Grasmere on a visit Christmas Eve will have to see..... that is a serious LP .

 

Was going to take the sledge for Kirkstone on the way back home but maybe a kite will be more suitable - or both? 

 

Striding Edge anyone?

 

Ian

[cooling climate]

The building blocks for a potential east/northeaterly type feed as we go into the second

week of Jan start as early as t168 with the Arctic high migrating towards Spitzbergen.

Confidence level of this happening is growing daily.

[Mucka]

A major problem here is when the jet starts to ease across the Atlantic it seems to want to encourage the Azores high to push northwards back into Iberia and put us back in a west/south westerly flow.

we really need to keep this little blighter from getting back in.

 

We do but we will always see it being modelled trying to ridge back in, so long as we have Southerly jet it should only be temporarily. 

Still it will be a constant thorn until such time we have strong enough blocking we can get low pressure digging South further West, then we can use it to force WAA up toward Greenland/Iceland - in a perfect world of course. 

[Iceaxecrampon]

 

 

 

 

 

Why such a contradiction between the Jet and UK Wind Direction charts?

 

Jet showing NW direction on Boxing day UK showing SW?

 

Ian

[Captain Shortwave]

We do but we will always see it being modelled trying to ridge back in, so long as we have Southerly jet it should only be temporarily. 

Still it will be a constant thorn until such time we have strong enough blocking we can get low pressure digging South further West, then we can use it to force WAA up toward Greenland/Iceland - in a perfect world of course. 

Yeah very true, just call me a cynic I guess

My major gripe with the type of pattern suggested by the GFS this run and the GEM 

Is that this is the same pattern we had for a good part of October..... which brought mild and wet weather overall

You are right about one thing (related to yesterday), the key place to look is not for a raging vortex over Greenland, or a magical block over Greenland or Scandi. It's the pressure pattern south of the UK which is key because if pressure is high there then we are not going to be cold and vice versa.

I do wish that we could nuke the polar vortex though, unfortunately.

In Soviet Russia. Polar vortex nukes you!!! 

At least the strat looks rather promising

Not really polar vortex, more polar hotdog 

I think my sanity has left and taken shelter already.

Edited December 22, 2013 by Captain shortwave

[Mucka]

Yeah very true, just call me a cynic I guess

My major gripe with the type of pattern suggested by the GFS this run and the GEM 

Is that this is the same pattern we had for a good part of October..... which brought mild and wet weather overall

You are right about one thing (related to yesterday), the key place to look is not for a raging vortex over Greenland, or a magical block over Greenland or Scandi. It's the pressure pattern south of the UK which is key because if pressure is high there then we are not going to be cold and vice versa.

I do wish that we could nuke the polar vortex though, unfortunately.

In Soviet Russia. Polar vortex nukes you!!! 

 

The air is a lot warmer in October than January though. 

 

Seriously though, if that is the way things turn out, that type of pattern can give some very heavy snowfalls, it all depends on the mixing of air masses and with such marginal situations there is no way to predict if we will see more rain or more snow. Likely we will have periods of both, snow more especially in the North.

Also from an optimistic point of view it opens up more possibilities of some sustained blocking later in January.

 

Of course until we have a better idea of how amplified the pattern will likely be in January it is all just speculation but it keeps my inner, snow loving, geek happy seeing such possibilities open up at least. 

[Troubleatmill]

Ouch!

 

h500slp.png

 

Meant to be in Ambleside  - Grasmere on a visit Christmas Eve will have to see..... that is a serious LP .

 

Was going to take the sledge for Kirkstone on the way back home but maybe a kite will be more suitable - or both? 

 

Striding Edge anyone?

 

Ian

Haha! Sharp edge would be fun! High dive to scales tarn! Perhaps thats how AW said you could it! Enjoy

[Chris K]

We heard this kind of thing ad nauseum at the start of Dec, but here we are closing in on Xmas and the the charts are looking exactly the same...if not worse for sustained cold.  We all know charts 12 days hence will not verify as shown, but they can and often do give very good pointers to the overall pattern at that time and given what I can see now any positive spin is precisely that...spin!

But at the start of December we were staring at the prospect of a sceuro blocking high, so the charts are not exactly the same shed.....look how they changed in a matter of a few days...Quite frankly my focus is on this coming week, with potential of severe weather over the Christmas period looking likely now. My search for cold and snow can wait on the backburner.