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

[nick sussex]

I think the GEM remains an outlier solution when you view the rest of the models. The problem is really how it moves a chunk of the PV eastwards much further north than any other output and develops a split in the PV to allow the high to ridge north. At the same time its more amplified with the main PV and this digs south into the mid Atlantic.

 

It's not that this is totally implausible but it really needs to have backing from the other models. Given the timeframes involved I think tonight will settle this issue, if theres a clear signal to develop the GEM trend then it should show up across the big 3 on their 12hrs outputs.

 

In terms of the ECM ensembles for De Bilt the main clustering for wind direction is between east and sw and given the model trends you can see this makes sense as its all to do with the positioning of the high.

 

 

 

In terms of the ECM ensembles spread just a quick word about two things that caught my eye, two clusters one ot the nw and another regarding the shortwave running down the Baltic, you can see that some members take this shortwave further west and  a cluster over the ne Italy at 144hrs:

 

 

Now on the chart below you can see those two spread clusters, there is some support for high pressure in a much more favourable location both in terms of bringing some surface cold into the UK and going forward holding the high further north as that chunk of the PV moves east to the north.

 

 

I've drawn in the implied synoptics for that as you can see the high is much better placed than on the operational run.

 

Remembering here that going forward the evolution can look a lot different from changes within the normally reliable timeframe, so instead of looking into FI we take a different view here, small changes earlier could make a large difference later.

 

I still think its a long haul to get to an easterly with cold upper air within T240hrs, I think more realistically its seeing whether the UK can hold onto a cold surface flow off the continent especially as the models move the PV chunk eastwards.

 

Changes to the block in terms of orientation and position north are hugely effected by event between 96 and 144hrs, we'll see tonight whethers theres any further interest in that front.

 

 

[shedhead]

Glenn you should know by now what effects  Southern England effects all of us.

 

Back to the model output or shall I say lack of interesting things to talk about. I still can't see heights becoming established over Scandinavia within the next 10 days at least, the weather really does look very benign for the foreseeable but one thing it doesn't look is mild except perhaps NW Scotland and Ireland, average at best and below average for the SE.

 

Typical daily maxima range from 5.5c in the far north to 8.5c in the far south in early/mid Dec SI.

 

Here are the predicted max from GFS between Sun -Thu next week. What is clear from these is the mildest weather is likely early next week, when all areas are shown to have above average maxima.  As we get into midweek there is a clear cooling trend, but even come Thursday temps are average at best across the UK as a whole.

 

Given the predicted airflow there will be areas in the north and west that see temps higher than those shown due to local effect, similarly there will be areas in the east that due to local effects are on the cool side, but given these charts your contention that temps will be average at best and below in the SE is flawed.....unless you have data to prove the contrary of course ??

 

Sun

Mon

 

 

Tue

 

Wed

 

 

Thu

Edited December 5, 2013 by shedhead

[Radiating Dendrite]

GFS 6z looks like groundhog day.

 

I am still optimistic that we will see a pattern change soon, but am well aware that another Feb 1998 could occur also

 

Fingers crossed for a colder outlook soon.

[carinthian]

Morning,

 Its a good job the snow came last week in abundance. Euro -High for the next 10 days. Hate that scenario than any other. I suppose we have been spoilt over the past few winters. Anyway still early days yet. Lets see if any other trends appear before Christmas ? UK not well placed , especially the NW for any cold in the immediate outlook. Keeping my fingers crossed for you guys, we are now almost in the same boat over here as it can take a long time to move the high thats due to settle in the ( wrong place ) for at least the next 5 days or so.

C

Edited December 5, 2013 by carinthian

[Frosty.]

The Gfs 06z op run is easy to sum up, a northwest / southeast split with lower heights to the northwest bringing an increasingly unsettled and breezy outlook with temps close to average across northwestern britain, the southeastern half of the uk becomes generally anticyclonic with temperatures just on the cold side of average with frost and fog patches.

[Severe Siberian icy blast]

Morning all having looked at the GEM as already said its on its own but there is "some" backing from the ecm ensembles. I said the other day that by the weekend I think we will see some change in the output and I stand by that. If we can see a move tonight by the mods toward the gem then its really giving us a different outlook over the next 10days more akin to what ones thought would be the case 2 or 3 days ago. Lets not forget the ukmo is a lot better than the ecm/gfs although not as good orientation on the high as the gem , but as steve said the other day if the ukmo isnt on board then it's not reliable. So although the ukmo isnt amazing it does scream potential and I would prefer to have the ukmo standing alone (although in reality it has the gem as support which is statistically more reliable than gfs) than the gfs .

All eyes on the 12z )

Ps sorry to the ones who felt I was argumentative yesterday the weather has this thing that has the power2 wind me up and I should not take it out on hear . . . Pls forgive my pettiness

Edited December 5, 2013 by Severe Siberian icy blast

[forecaster]

The Gfs 06z op run is easy to sum up, a northwest / southeast split with lower heights to the northwest bringing an increasingly unsettled and breezy outlook with temps close to average across northwestern britain, the southeastern half of the uk becomes generally anticyclonic with temperatures just on the cold side of average with frost and fog patches.

 

That's maximum temperature occurring in the 00Z-06Z overnight period. Doesn't look cold even in the SE!

[Frosty.]

That's maximum temperature occurring in the 00Z-06Z overnight period. Doesn't look cold even in the SE!

[fergieweather]

That's maximum temperature occurring in the 00Z-06Z overnight period. Doesn't look cold even in the SE!

The models will struggle with boundary conditions at that range and so hard to judge temperature in SE especially other than broad-brush. Latest UKMO analysis sees "... little or no signs now..." of any deeper cold incursion from E into 10-15d trend period with flow diagnostics continuing a story of between SE to SW in lead-up to Christmas (& EC ENS signal being even less backed now). EC32 update awaited tomorrow with interest.

[TSNWK]

The models will struggle with boundary conditions at that range and so hard to judge temperature in SE especially other than broad-brush. Latest UKMO analysis sees "... little or no signs now..." of any deeper cold incursion from E into 10-15d trend period with flow diagnostics continuing a story of between SE to SW in lead-up to Christmas (& EC ENS signal being even less backed now). EC32 update awaited tomorrow with interest.

Thank you for the above Fergie. Rules out the GEM solution.

Edited December 5, 2013 by TSNWK

[fergieweather]

Thank you for the above Fergie. I think that kind of rules out the GEM solution.

No: it merely makes it unlikely, not wholly discounted. But it does look ever more isolated...

[Barry12]

The models will struggle with boundary conditions at that range and so hard to judge temperature in SE especially other than broad-brush. Latest UKMO analysis sees "... little or no signs now..." of any deeper cold incursion from E into 10-15d trend period with flow diagnostics continuing a story of between SE to SW in lead-up to Christmas (& EC ENS signal being even less backed now). EC32 update awaited tomorrow with interest.

 

I really hope it's the SE and not the SW!

[TSNWK]

No: it merely makes it unlikely, not wholly discounted. But it does look ever more isolated...

 

Thanks for the response, a tiny little carrot to dangle I guess for this afternoon.

[nick sussex]

I think realistically for coldies at the moment its a case of seeing if we can get some nice sunshine and frosty nights out of the set up, which IMO is infinitely better than horrible dank mild sw'erly mush.

 

If theres to be no snow then at least a bit of hoar frost and some sparkling sunshine will put everyone in a more festive mood. As much as I'd like to see the GEM solution verify its an outlier for the timebeing.

 

In terms of the outlook much will be decided quite early on, so look out for that shortwave energy running se towards the Baltic and whether we see lower heights developed towards northern Italy.

 

This is within the T144hrs mark, because of the movement of that chunk of the PV eastwards after this point this will place more pressure on the high so the further north you can have this and better orientated at the outset the better chance you have of holding onto a colder surface flow from the continent.

[Barry12]

It's so frustrating that when the models show signs/signals of blocking to the north/north east that it won't happen but you can bet your bottom dollar that when the further outlook shows 'milder' options it happens! The ec32 will show a different story tomorrow and I bet it occurs but yet when it showed cold blocking it simply doesn't Sod's law.

 

Someone in Siberia will be thinking the same except the other way round

[Ian Brown]

The latest METO update reflects what Ian F is saying though I think the Atlantic will make incursions before the METO indicate, the recipe is certainly for an intense HP to the South and very low heights to the NW, meaning a progressively long draw SWerley is likely for the second half of the month.

[Great Plum]

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

I'll have the light blue line please...

[mountain shadow]

Very poor models for coldies, no two ways about it. Dare I say, December is looking a write off for widespread snow already?

 

I had a wee look at the MJO forecast and there is no help there with the orbit stagnating around the origin. With a dominant Polar Vortex our only hope is the continued Alaskan High which may distrupt the vortex from time to time allowing a shot at a toppler.

[Gavin Hannah]

No: it merely makes it unlikely, not wholly discounted. But it does look ever more isolated...

 

 

If the energy diving south into the Atlantic amplifies enough, it should help promote the GEM solution.  The fact that the GEM hasn't back away from it means that it's still up for grabs. Some models will present a solution for a run or two before falling back in line with the majority.  The longer the GEM goes against the grain, the more hope I will cling on to.

[nick sussex]

It's so frustrating that when the models show signs/signals of blocking to the north/north east that it won't happen but you can bet your bottom dollar that when the further outlook shows 'milder' options it happens! The ec32 will show a different story tomorrow and I bet it occurs but yet when it showed cold blocking it simply doesn't Sod's law.

Yes frustrating but not really sod's law, milder solutions are always more likely to verify than colder ones and that's part and parcel if you live in the UK. It's for this reason that the most model variability we see is generally with colder patterns because these go against the prevailing weather patterns for the UK during winter.

 

As we've seen in recent winters we can still get decent cold spells but these are still the exception rather than the rule, I think it's part of the fun in terms of this thread anyway because if it was a simple countdown to cold it would be rather boring and also would this thread have many visitors if it was Canadian based.

 

It's the rarity of those wintry spells that makes them all the more enjoyable when they come.

[Barry12]

Dare I say, December is looking a write off for widespread snow already?

 

November was written off too as a mild month, the models at very best can only forecast 7 days in advance accurately, so what happens after that is anyones guess. Far to much importance is placed on the PV, it would be easy to forecast the weather if all you did was look at the pv...

Edited December 5, 2013 by Barry95

[snowmadchrisuk]

Bom is closest to Gem I can find, so the idea not totally dead , although with a P/V that strong I would have thought SW'ly's could have about a 50% chance also of effecting us in 10-15d period. 

 

Edited December 5, 2013 by snowmadchrisuk

[karlos1983]

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

I'll have the light blue line please...

 

Yikes, pattern looks pretty much nailed to mid month based on that set, start to see a bit more spread after the 15th, but nothing jaw dropping.

 

Would like to point out I am not writing winter or December off, we have all seen how quickly things can change recently.

Edited December 5, 2013 by karlos1983

[Weather Boy]

November was written off too as a mild month, the models at very best can only forecast 7 days in advance accurately, so what happens after that is anyones guess. Far to much importance is placed on the PV, it would be easy to forecast the weather if all you did was look at the pv...

 

Absolutely.  Is it ever possible to "write off" (or indeed the opposite, expect hoped-for weather) a month on its fifth day?  Even in the shortest month, February, that's making an assumption as to the weather pattern over the next 3 weeks and 2 days, way beyond our current capabilities (apart from guessing at the broadest of trends, which guesses could be completely wrong).

 

So, I say the answer is no, one should never make an assumption as to the entire month's weather until the middle of that month at the very earliest.  Any post suggesting that a month is a 'write off' at such an early stage is just silly, I'm afraid.

 

That's particularly so when based on a couple of uninspiring runs.  Two days ago, the ECM wanted an easterly.  GEM hangs on to that.  Who's to say that the ECM (or, stranger things have happened, the GFS!) won't want one tomorrow or the next day?

[Trickster]

Looking at the latest GFS and longer term CFS charts today, I'm starting to get really worried that we maybe looking at a late 1990's style winter.  High pressure staying over France and South/South Westerly winds constantly over the UK.

Edited December 5, 2013 by Trickster