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

[BLAST FROM THE PAST]

 

 

I'l take that if it happens.....here's hoping!!!

 

BFTP

[Gibby]

Hi everyone. Here is the report on the 12 midnight outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Monday December 23rd 2013.

 

All models show Low pressure deepening explosively over the Atlantic as it winds up to be West of Scotland later today pushing very strong winds, gale, severe gale or even storm force winds into the NW later. In addition a spell of persistent and heavy rain extends NE across England and Wales this morning and on to other areas soon after. Rain will be heavy and prolonged with some flooding issues possible in the South and SW through the day. Later on clearer, colder and more showery weather will spread across Northern and Western areas reaching the SE on Christmas Eve with a windy and showery day with some showers heavy with hail, thunder and sleet or snow over the hills. On Christmas Day and Boxing Day the weather will become quieter with showers more likely towards Southern and Western coasts and hills where they may be wintry and heavy in places. Some inland parts may stay dry and bright with some weak winter sunshine especially in the East.

 

GFS then shows another powerful storm sweeping gales and heavy rain NE again over the end of the week and next weekend. Further flooding and structural damage is possible with wintry showers over Northern hills once the main frontal activity has passed. The rest of the run tonight indicates further rather windy and wet weather at times as further depressions sweep wind and rain followed by showers across the UK with temperatures close to average at first but becoming rather colder from the NW later.

 

UKMO early next Sunday shows a strong WNW wind delivering sunshine and showers ahead of a ridge of High pressure drying things up briefly later in the day, in turn followed by another Atlantic depression to begin next week.

 

GEM today keeps the train of Low pressure from Scandinavia to Canada going late next weekend and into the New Year week with rain at times on a blustery and strong West or SW wind though not as stormy as recently.

 

NAVGEM closes next week and weekend off with plenty more rain at times, some heavy as Low pressure remains well established over the Atlantic to Northern Europe. Winds will slowly become less strong but still reaching gale force at times as the West or SW flow over the UK remains dominant.

 

ECM today maintains unsettled weather on the run up to the New Year with Low pressure trundling across the Atlantic. However, late in the period pressure rises from the South over the Atlantic and it looks possible that the procession of low pressure will end soon after the New Year with maybe somewhat colder and drier conditions as pressure rises over the UK under a Northerly towards the end of next week.

 

The GFS Ensembles for the first time trend down towards the end of the output with some members going into rather colder weather as we move into the New Year, especially the Control run. There are still some windy and rainy options on the table too, including the operational but overall things may become rather drier and brighter into the New Year with some frosts possible at least for a time.

 

The Jet Stream continues it's slow movement South to blow East to the South of the UK over the Christmas period. It's position then sets up a pattern much less biased towards SW to NE motion taking it on a more of a West to East track with it's position much further South over Continental Europe in Week 2.

 

In Summary the weather remains distinctly unsettled and potentially stormy over the next week with a Christmas lull in the stormy activity over Christmas and Boxing Day though still with showers, wintry on hills. With some colder air over Britain at times up to the New Year the heavier showers could lead to some wintry weather over the hills almost anywhere but most likely over the North. Longer term the risk of stormy weather recedes but the pattern remains largely unsettled as shallower Lows and fronts continue crossing the UK into the New Year though there are some small changes indicated this morning which could lead to a pattern change soon after the end of this morning's output to something rather colder and drier.

[Cecil Hogmanay Melchett]

As previously stated the ECM op looks an outlier with respect to the Arctic High migrating to the conus.

 

The mean at T240 (strong polar high anomaly) :   EDH1-240 (1).gif

 

This also shows a slacker zonal flow to the N/NE so opportunity for heights to build given the right ingredients.  Compare to the T168 chart which has a zonal flow (low heights anomaly) to our north:  EDH1-168.gif

 

Its a waiting game and may take several shots before the cold seeps south and to where?

Not sure the 240ecm mean is anything to 'write home about'  http://www.wetterzentrale.de/pics/Reem2401.html.

Again,looks a long way to cold from there.

Whilst its brazen to write off chunks off winter this much is true,its been a rotten December virtually snowless for 99% of the UK and the 1st week of January looks a write off as well.

I really hope Jan and Feb do deliver....

[Jason M]

I wouldn't worry about the ECM mean at that range as you would be better off reading tea leafs :-). I really think the mean charts are totally misleading in most situations.

Just look at the ensemble members for trends at day 10 and beyond. It seems to me that it's just scatter this morning with the GEFS so pretty much anything can happen. Given how rock solid the pattern looked a few days ago this should be welcomed as major progress.

Jason

Edited December 23, 2013 by Jason M

[IDO]

I wouldn't worry about the ECM mean at that range as you would be better off reading tea leafs :-). I really think the mean charts are totally misleading in most situations.Just look at the ensemble members for trends at day 10 and beyond. It seems to me that it's just scatter this morning with the GEFS so pretty much anything can happen. Given how rock solid the pattern looked a few days ago this should be welcomed as major progress.Jason

 

 

Yes I would agree, lots of permutations, but thats what the 10 day mean is for, looking for patterns, and in this case there is a strong polar anomaly. With this in place we can reasonably assume that there is a trend towards blocking. The mean at D10 still verifies better than the op, so probably the best tool still at that range:

 

Mean:  OP:  

[Purga]

I know we've got some pretty potent stormy weather to contend with but there looks to be some serious snowfall due over the Alps on Boxing day!

 

Not to mention rain over the Riviera.

Trouble is with the volatile cold / mild regime there could be some nasty avalanche conditions developing.

[Grimsby Snow Lover]

The GFS 0Z ensembles caught my eye this morning. The fact that the London ens in FI have colder 850s than the Manchester ens suggests to me a continental feed could occur as we head into the first few weeks of January. I know there is little showing from the GFS op at the moment that suggest this, but is one I will be keeping an eye on.

http://www.wetterzentrale.de/pics/MT8_London_ens.png

http://www.wetterzentrale.de/pics/MT8_Manchester_ens.png

The AO forecast http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif has to be a positive as well as the forecasted NAO http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.sprd2.gif which seems to be heading negative as well as we enter January.

Edited December 23, 2013 by Grimsby Snow Lover

[bluearmy]

trending to drop heights to our south on both naefs and ecm extended. with mid atlantic ridging and eastern european ridge intact, that is beginning to 'wet my whistle' from a cold perspective.also, how appropriate that you recently changed your name happy days !!!

[Cecil Hogmanay Melchett]

trending to drop heights to our south on both naefs and ecm extended. with mid atlantic ridging and eastern european ridge intact, that is beginning to 'wet my whistle' from a cold perspective. also, how appropriate that you recently changed your name happy days !!!

Change of name,change of fortune hjopefully BA

Not so sure i like the sound of the Eastern European ridge though.Unless of course it becomes a scandy ridge..

[Cecil Hogmanay Melchett]

MUCH better gfs06z run with Atlantic systems taking a more southerly route..

Yes 06z would be a very welcome change in the pattern with Lp finally becoming established across southern Europe.

All eyes on the 12z runs to see if GFS has picked up on a pattern change.

Edited December 23, 2013 by Cecil Hogmanay Melchett

[That ECM]

MUCH better gfs06z run with Atlantic systems taking a more southerly route..

Indeed and the far reaches of fi are very interesting, a model gift at this time of year or dud of a present? Time will tell.The height rise to our north are a welcome site. Long may this continue, then we can call it a trend. Edited December 23, 2013 by That ECM

[shaky]

And once again that area of little low pressure shows up for Christmas evening but this time on the 06gfs!!gota keep an eye on that could give a surprise or two snowfall wise.

[bluearmy]

 

MUCH better gfs06z run with Atlantic systems taking a more southerly route..Yes 06z would be a very welcome change in the pattern with Lp finally becoming established across southern Europe.All eyes on the 12z runs to see if GFS has picked up on a pattern change.

 but this is already showing in the extended ens (see my earlier post) so how would it be gfs op picking up a pattern change ?

[Frosty.]

Cyclogenesis is continuing to deepen rapidly as the next storm roars in off the atlantic today, this could be a historic storm which leaves a trail of devastation in it's wake, not just the winds which will be gusting between 60-80 mph (some areas will see lower / higher values) but also the torrential rain on already saturated ground leading to more flooding with up to 60mm rainfall in the next 12-24 hours. The models are in a frenzy with the jet stream powered up to 280 mph and the stormy weather looks like coming back with a vengeance later this week after a relatively calmer few days over christmas.

[snowmadchrisuk]

Where's the p/v gone lol ..... Nice setup that would be , plenty of Cold air and plenty of Low pressure. 

 

[Altohumorous]

Two extremely powerful storms this week, haven't seen the likes in about 20 years. Also I don't recall the last time a low pressure of CBP less than 930mb has come so close to these shores. Northwest Ireland and much of Scotland, especially the west, and the northern islands are going to get a  fierce battering tonight and tomorrow.

The friday storm looks like giving the south west and west of these islands a real pounding then too. Models still unsure on possible further storms in FI, though surely not as bad as these two. Alot of heavy rin to come in places, I fear the south and west of Ireland are in for some bad flooding.

[karyo]

The 6z is looking promising in FI but does it have any support from the ensembles?

Karyo

[Purga]

Happy New Year!

 

[Mucka]

GFS 06z FI shows something akin to what I have suggested might happen but hasn't really been modelled before. 

We have transient ridges, weak high pressure to the North and low pressure to the South, not a classic cold set up by any means as any cold air being pulled in from the North is constantly being mixed out from the SW as disrupting troughs run NW/SE across the UK. 

It is the classic cold zonal set up which would provide some heavy widespread snowfalls. A lot would depend on the track of the low pressure systems with the snow line moving North and South accordingly, rain turning to snow, snow turning to rain on the boundaries. Northern England is often best placed in such set ups because too far North and you don't always get the ppn and too far South you will more often see rain.

Still that is quite a rare set up but interesting to see it being modelled at last as just about everyone would likely see a decent snowfall before the pattern changed to more blocked or more mobile.

 

Posted for illustration not as a forecast.

 

 

 

 

 

Okay so that is a long way off and may never happen but it is worth illustrating because it also ties in with the idea that troughs may well disrupt more than generally modelled past the mid term and hopefully the nasty looking storm of the 27th will be the last bad storm we see for some time. (You can quote me on this )

 

As long as we continue to see a Southerly jet and displaced Azores high we will continue to see more blocking opportunities, especially as the Atlantic driven weather begins to meet more resistance from high pressure to the North and East.

Disruption, disruption, disruption.

 

ECM Op was quite disappointing this morning wasn't it?

But at 240 we still have a Southerly jet modelled and the disappointment should also be tempered by looking at the unlikely way energy is handled from the mid term to our NE - I'm trying not to say that word, but it is lacking. I don't think we can ignore it as a possibility but it is definitely on the pessimistic side of the possible scenarios.

 

Both ECM and GFS 00z ensembles show a cooling trend as we go onto January with a few more colder options and one or two less mild options turning up.

We need for that trend to continue because things are very much still in the balance, we certainly haven't reached a tipping point where we can say January will be below average and feature more blocking but I would say that if you live in the North of England your chances of seeing a decent snowfall in the first half of January are significantly higher than they were a few days ago when EC32 was showing Westerly flow and no cold signal for that period. I would think there is still no cold signal on EC32 but with more scatter.

 

So, two more storms to get through and then come the 28th we will have a more definitive view of wintry prospects for January - I think we may just have a peek at 1 or 2 model runs between now and then though.

Edited December 23, 2013 by Mucka

[chris55]

Some improvements wrt colder scenarios this morning. Lets hope it continues as we head through Xmas.

 

Some decent building blocks from GFS 06z as we head into 2014,

 

[UV-RAY]

GFS 06z FI shows something akin to what I have suggested might happen but hasn't really been modelled before. 

We have transient ridges, weak high pressure to the North and low pressure to the South, not a classic cold set up by any means as any cold air being pulled in from the North is constantly being mixed out from the SW as disrupting troughs run NW/SE across the UK. 

It is the classic cold zonal set up which would provide some heavy widespread snowfalls. A lot would depend on the track of the low pressure systems with the snow line moving North and South accordingly, rain turning to snow, snow turning to rain on the boundaries. Northern England is often best placed in such set ups because too far North and you don't always get the ppn and too far South you will more often see rain.

Still that is quite a rare set up but interesting to see it being modelled at last as just about everyone would likely see a decent snowfall before the pattern changed to more blocked or more mobile.

 

Posted for illustration not as a forecast.

 

 

 

 

 

Okay so that is a long way off and may never happen but it is worth illustrating because it also ties in with the idea that troughs may well disrupt more than generally modelled past the mid term and hopefully the nasty looking storm of the 27th will be the last bad storm we see for some time. (You can quote me on this )

 

As long as we continue to see a Southerly jet and displaced Azores high we will continue to see more blocking opportunities, especially as the Atlantic driven weather begins to meet more resistance from high pressure to the North and East.

Disruption, disruption, disruption.

 

ECM Op was quite disappointing this morning wasn't it?

But at 240 we still have a Southerly jet modelled and the disappointment should also be tempered by looking at the unlikely way energy is handled from the mid term to our NE - I'm trying not to say that word, but it is lacking. I don't think we can ignore it as a possibility but it is definitely on the pessimistic side of the possible scenarios.

 

Both ECM and GFS 00z ensembles show a cooling trend as we go onto January with a few more colder options and one or two less mild options turning up.

We need for that trend to continue because things are very much still in the balance, we certainly haven't reached a tipping point where we can say January will be below average and feature more blocking but I would say that if you live in the North of England your chances of seeing a decent snowfall in the first half of January are significantly higher than they were a few days ago when EC32 was showing Westerly flow and no cold signal for that period. I would think there is still no cold signal on EC32 but with more scatter.

 

So, two more storms to get through and then come the 28th we will have a more definitive view of wintry prospects for January - I think we may just have a peek at 1 or 2 model runs between now and then though.

Excellent post Mucka and highlights the potential wintry synoptics as we head into the New Year, I expect lots of inter model agreement and upgrades on a potentially wintry spell of weather post xmas. 

[itsnowjoke]

Excellent post Mucka and highlights the potential wintry synoptics as we head into the New Year, I expect lots of inter model agreement and upgrades on a potentially wintry spell of weather post xmas.

Hope your right :-)

[Weather Boy]

GFS 06z FI shows something akin to what I have suggested might happen but hasn't really been modelled before. 

We have transient ridges, weak high pressure to the North and low pressure to the South, not a classic cold set up by any means as any cold air being pulled in from the North is constantly being mixed out from the SW as disrupting troughs run NW/SE across the UK. 

It is the classic cold zonal set up which would provide some heavy widespread snowfalls. A lot would depend on the track of the low pressure systems with the snow line moving North and South accordingly, rain turning to snow, snow turning to rain on the boundaries. Northern England is often best placed in such set ups because too far North and you don't always get the ppn and too far South you will more often see rain.

Still that is quite a rare set up but interesting to see it being modelled at last as just about everyone would likely see a decent snowfall before the pattern changed to more blocked or more mobile.

 

Posted for illustration not as a forecast.

 

 

 

 

 

Okay so that is a long way off and may never happen but it is worth illustrating because it also ties in with the idea that troughs may well disrupt more than generally modelled past the mid term and hopefully the nasty looking storm of the 27th will be the last bad storm we see for some time. (You can quote me on this )

 

As long as we continue to see a Southerly jet and displaced Azores high we will continue to see more blocking opportunities, especially as the Atlantic driven weather begins to meet more resistance from high pressure to the North and East.

Disruption, disruption, disruption.

 

ECM Op was quite disappointing this morning wasn't it?

But at 240 we still have a Southerly jet modelled and the disappointment should also be tempered by looking at the unlikely way energy is handled from the mid term to our NE - I'm trying not to say that word, but it is lacking. I don't think we can ignore it as a possibility but it is definitely on the pessimistic side of the possible scenarios.

 

Both ECM and GFS 00z ensembles show a cooling trend as we go onto January with a few more colder options and one or two less mild options turning up.

We need for that trend to continue because things are very much still in the balance, we certainly haven't reached a tipping point where we can say January will be below average and feature more blocking but I would say that if you live in the North of England your chances of seeing a decent snowfall in the first half of January are significantly higher than they were a few days ago when EC32 was showing Westerly flow and no cold signal for that period. I would think there is still no cold signal on EC32 but with more scatter.

 

So, two more storms to get through and then come the 28th we will have a more definitive view of wintry prospects for January - I think we may just have a peek at 1 or 2 model runs between now and then though.

 

Great post, which is this forum at its best, if I may say so.

 

It seems to me that the signs in the model output are extremely subtle and therefore it is possible that we are making too much out of them.  Time will tell.  However, it's really good to have the experienced and slightly less experienced on this forum to interpret the subtle signs that the truly amateur such as myself might well miss.

 

However, the thrust of the output is that the flat-as-a-pancake, zonal, Atlantic-driven, Bartlett, call it what you will, will, with a soupcon of luck, be a thing of the past from the output in the near future, and then we can get down to some more interesting model watching, and who knows, maybe enjoy some wintry weather too?

[Frosty.]

This is what me and all my fellow coldies are waiting for..the Gfs 06z during early January is showing exactly the type of charts I want to see, gradually less emphasis on the stormy and more on the wintry with snow becoming more likely and widespread frosts, even a chance of ice days. I have a feeling we are in for a more pronounced wintry spell early next year, not just based on this run but based on what the models have been hinting at in recent weeks with the jet going south..keep the faith guys.

[Tim Bland]

Meto long range not buying into the latest model changes unfortunately