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

[stewfox]

I assume you are new to all this then? Trust me, the past few weeks are really nothing in terms of inconsistent model output. There has been no real strong signal yet to a direct route to cold. Yet. There are plenty of positives that simply weren't there 3 weeks ago however and it will be from this that the building blocks to a proper (not transient) cold spell will be built upon. Only once we get the first credible signal to real cold show up on the charts and start to edge closer will you see the forum rollercoaster in full on action. Not a place for the faint hearted!

 

Not seen much inconsistancy in the model output and the general 'trends' in recent weeks

 

People jump on favoured output way out in FI then get disappointed when it doesn't happened and that causes the 'inconsistancy'.

 

In fact Christmas weather was fairly well pinned down by early December. At the moment seems we are fairly sure via the models where we will be till at least mid January.

[Methuselah]

f.

 

Oh and the met office agree with me as well they are saying zonal to at least the end of Jan. Like CC says lets keep it real.

 

 

And the MetO is absolutely never wrong! IMO, it's too soon to be counting your chickens? 

[nick sussex]

This is like watching paint dry! even with the PV in bits all over the place the sum total is zip!

 

A very uninspiring ECM operational run, the most excitement was a bit of trough disruption at T168hrs, after that it leaves a shortwave waiting to phase with the upstream low!

 

It's all rather bland but given the dismal lack of continuity between outputs and especially the ECM recently which is fast turning into the GFS lower resolution past T144hrs hopefully this run can meet the shredder!

 

Indeed what the ECM does with the main chunk of PV over Canada looks suspect, if and when any snow does arrive then coldies in here certainly deserve a medal for  stamina because its certainly becoming a lesson in patience!

[Continental Climate]

I know I am no expert but the ECM looks to be zonal and westerly throughout here are some examples 24hrs http://www.wetterzentrale.de/pics/Recm241.gif!! 120 hrs http://www.wetterzentrale.de/pics/Recm1201.gif and finally 240hrs http://www.wetterzentrale.de/pics/Recm2401.gif!! As I say I am no expert but that run looks entirely zonal to me

[nick sussex]

I know I am no expert but the ECM looks to be zonal and westerly throughout here are some examples 24hrs http://www.wetterzentrale.de/pics/Recm241.gif!! 120 hrs http://www.wetterzentrale.de/pics/Recm1201.gif and finally 240hrs http://www.wetterzentrale.de/pics/Recm2401.gif!! As I say I am no expert but that run looks entirely zonal to me

Theres another word for it but the swear filter is in operation! To use an analogy it initially promised something and delivered nothing, a bit like those chocolates where you think great and bite in and realize its one of those horrid licquer things!

 

Just read the upstream thoughts of NOAA they're expecting temps below 0 Fahrenheit in the ne USA about -18c as daytime highs for some areas! Whilst here the BBC weather have called COBRA to advise them of a bit of frost on the grass and are airlifting in those window scrapers for car windscreens!!!

 

They're calling it a meridional event so the low around 144hrs may well carve a bit more sharpness ahead of it in term of the low near the UK.Overall its a messy looking picture not helped by the models inability to decide on what happens to the PV over Canada in the extended timeframe.

[Vorticity0123]

Based on the model trends on the last few days, I'll try to give a broad view of a trend currently showing up on the different models and ensembles.

 

The GFS ensembles are showing a mid- to upper-level trough to be positioned directly to the north of the UK, which could be the precursor of a pattern change.

Looking at the situation, the GFS ensembles at T72 show a marked trough to the west of the UK:

 

GFS ENS T72.

 

Also note the low geopotential heights dipping south toward the northwest of Spain (the green colors).

 

However, at T+240 (though still quite far away), the dip in the geopotential heights has moved significantally eastward, toward italy. Moreover, the average lowest pressures are located directly to the north of the UK, in contrast to the western position at earlier timeframes.

 

GFS ENS T240.

 

The change in general weather above the UK will be quite slim, with temperatures perhaps decreasing toward average values.

 
The aforementioned change is also noted by the technical discussion of the long range forecast (up to 15 days out) of the KNMI (the Dutch national weather center, equivalent to the UKMET) stating that:

 

 

There is a fair chance that the steering low might move toward over Holland, which could result in a colder type of weather to develop.

http://www.knmi.nl/waarschuwingen_en_verwachtingen/extra/guidance_meerdaagse.html

 

Depending on how amplified the pattern will become, the upper trough could be located south (or east) of the UK, resulting in a chillier NW flow to develop.

 

As a result of the repositioning of the trough, the average 850 hPa temperatures also decrease below 0*C. This is nowhere close to freezing cold, but it once again justifies a possible turn to more average temperatures.

 

Sources:

http://www.knmi.nl/waarschuwingen_en_verwachtingen/extra/guidance_meerdaagse.html

http://www.wetterzentrale.de/topkarten/fsenseur.html

[Bristawl Si]

I know I am no expert but the ECM looks to be zonal and westerly throughout here are some examples 24hrs http://www.wetterzentrale.de/pics/Recm241.gif!! 120 hrs http://www.wetterzentrale.de/pics/Recm1201.gif and finally 240hrs http://www.wetterzentrale.de/pics/Recm2401.gif!! As I say I am no expert but that run looks entirely zonal to me

Agreed...but that is only 10 days CC.With Meto mentioning chance of "something significantly colder" for later in January i'm pinning my hopes on that.

[nick sussex]

Model of the evening in terms of cold potential goes to the JMA at T192hrs:

 

 

Its not an implausible scenario given higher pressure to the ne, the ECM may well have looked better if it hadn't stuck a lobe of lower heights over northern Greenland, this reduced the forcing on the pattern.

 

 

You need that circled in red to take a hike!

 

Putting my optimistic head on if we're to see a dramatic development it will happen around the 144 to 192hrs timeframe.

 

 

 

 

 

 

[ANYWEATHER]

And another small but vicious low for around the turn of the year, gfs keeps on developing this shortwave and bringing it quicker to the new year events, hope this does not happen, some New year celebrations will definitely be cancelled   Ive highlighted the concern in the graph below with this small potentially nasty disturbance! Its not even been born yet , but gfs is good in modelling this ......

[Continental Climate]

Agreed...but that is only 10 days CC.With Meto mentioning chance of "something significantly colder" for later in January i'm pinning my hopes on that.

I entirely agree with you about something wintry developing later on but like I said earlier I don't think it will happen until at least the 20th of jan simply because this pattern is entrenched and will be difficult to break, I think our weather is becoming more extreme and the uk will experience more extreme months like dec,10 and march 2013 in the future and hopefully feb 14 could be one of those months

[lassie23]

New years eve could be one for staying indoors.

[SMU]

Much to be resolved over the next few days- with that low coming off the states-

 

The ECM 12z V its 00z is much better at 192

 

12z

http://www.meteociel.fr/modeles/ecmwf/runs/2013122812/ECH1-192.GIF?28-0

 

00z

http://www.meteociel.fr/modeles/ecmwf/archives/2013122800/ECH1-192.GIF?00

 

Note the 12z pulls the pattern back a long back- but not enough to save the day. 1 more step back like that & were in business.

 

Don't write this off the fat lady is still munching on the boxing day turkey...........

 

S

[Tom Quintavalle]

The essence of the importance of the Pacific Ridge and how it might impact the patterns this January is documented in some valuable analogue material in the stratosphere thread relating to major warming events during a westerly QBO.

 

January 2009 being the case in point

 

Strong poleward anomalies then over the Eastern Pacific promoted wave 2 activity with favourable flux that were the precursor to major warming that led to the cold spell and easterly at the end of January and into February. As Chiono says, if i recall correctly from that thread, the 100hPa heat flux should be monitored closely this coming month.

 

In this sense then the Pacific ridge this January, is entirely relevant to this +QBO 'solar maximum' winter. So far so good it seems in this respect - hence the longer game that is being played here

 

 

Picking up on this earlier post from Tamara, another late December/January that featured outbreaks of poleward ridging in the Aleutian/Alaska area, from a Pacific high, was the Winter of 1990/91. This Winter also featured a major warming in January/February and as we know eventually led to blocking over Scandinavia and bitter easterly winds spreading across the UK, during the second week of February, with much snow in places.

 

The salient point being that this Winter, like 2008/09, occurred during a westerly (+) QBO phase. The example given by John Holmes earlier, of the  Winter 2009/10 was during an easterly (-) QBO phase and although an easterly QBO phase is more likely to give an increased risk of high latitude blocking during the Northern Hemispheric Winter, may I respectfully suggest that any HLB attained during either of those 2 QBO phases may well have quite a different looking synoptic profile, from one another, over the Northern Hemisphere.

 

I should also make the point that, as stated in some excellent and informative posts on here and the Stratospheric Thread, that any change in the current synoptic pattern towards one that would be more conducive to any cold, wintry weather reaching our shores, is likely to be a rather drawn out process.

 

Tom.

Edited December 28, 2013 by Kentish CZ

[SMU]

Anyone reading my posts Tamara / Kentish

 

The Kumchatka ridge is the same as the above post ^^^

S

[Mucka]

Model of the evening in terms of cold potential goes to the JMA at T192hrs:

 

JN192-21.gif

 

Its not an implausible scenario given higher pressure to the ne, the ECM may well have looked better if it hadn't stuck a lobe of lower heights over northern Greenland, this reduced the forcing on the pattern.

 

ECH1-168.gif

 

You need that circled in red to take a hike!

 

Putting my optimistic head on if we're to see a dramatic development it will happen around the 144 to 192hrs timeframe.

 

That's twice now Nick that I have come back to the thread, read through, made some observations and considered what I was going to post only to read you had written much the same thing as I got to the last few posts.

 

I alluded to this earlier, that the distribution of energy over the 5 to 8 day period is nowhere near agreed upon.

The ECM simply sends more energy northeast than the JMA from the 5 day mark the negative impact  of which can clearly be seen by day 7 in comparison charts but there is at least agreement for the trough to sink South day 6 across the output which is where things could get interesting.

 

 

 

JMA is more in line with how I have been thinking things might progress with the residual PV energy out of Canada dropping further SW around day 8/9 though I would hope for signs of trough disruption and the heights to the East to be further NW. I'm not sure the JMA 192 chart has a strong enough ridge to get the low to disrupt SE enough to set up a cold zonal flow for the second week of Jan but would like for the other models to head in that direction.

 

If ECM is correct my thoughts for cold zonal and snow falling to low levels in the North in the first half of Jan seem unlikely to verify but if JMA is the way forward then a few tweaks would have me quite excited about snow prospects IMBY in the second week, if only transient episodes.

Either way the idea of a more blocked second half of January looks quite plausible.

Edited December 28, 2013 by Mucka

[Tom Quintavalle]

Anyone reading my posts Tamara / Kentish

 

The Kumchatka ridge is the same as the above post ^^^

S

 

Exactly Steve, Kamchatka, Aleutians, Alaska, pretty much the same and importantly looking through the archives from those years mentioned above, it's easy to see that poleward ridging taking place, a few weeks in advance of HLB occurring. Obviously that's only a couple of years to go on. Steve, have you looked at other Winter's with similar teleconnecting factors?

 

Tom.

[nick sussex]

That's twice now Nick that I have come back to the thread, read through, made some observations and considered what I was going to post only to read you had written much the same thing as I got to the last few posts.

 

I alluded to this earlier, that the distribution of energy over the 5 to 8 day period is nowhere near agreed upon.

The ECM simply sends more energy northeast than the JMA from the 5 day mark the negative impact  of which can clearly be seen by day 7 in comparison charts but there is at least agreement for the trough to sink South day 6 across the output which is where things could get interesting.

 

 

 

JMA is more in line with how I have been thinking things might progress with the residual PV energy out of Canada dropping further SW around day 8/9 though I would hope for signs of trough disruption and the heights to the East to be further NW. I'm not sure the JMA 192 chart has a strong enough ridge to get the low to disrupt SE enough to set up a cold zonal flow for the second week of Jan but would like for the other models to head in that direction.

 

If ECM is correct my thoughts for cold zonal and snow falling to low levels in the North in the first half of Jan seem unlikely to verify but if JMA is the way forward then a few tweaks would have me quite excited about snow prospects IMBY in the second week, if only transient episodes.

Either way the idea of a more blocked second half of January looks quite plausible.

In terms of the ECM if you're going by the ensemble mean it does give you a chance of that cold zonal flow, the ECM operational run is once again going against the main cluster of its ensemble suite, indeed if you look at the mean its almost a carbon copy of the pattern expected by NOAA in their anomaly map done yesterday.

 

The ECM is making far too much of high pressure in southern Europe, its been doing this for several days now. In terms of a window of opportunity as some energy digs se around 168hrs that would be where we might get some movement from the NWP.

Edited December 28, 2013 by nick sussex

[bluearmy]

Going anticlockwise as we look at the NH - Kamchatka, Aleutian, Alaskan. If we all use the same refs then we all know what we're about.

ECM, having managed to be reasonable against its ens mean this morning, loses it again this evening. Beginning to get concerned about the Azores ridge in all this but I suspect ens will prove to be right with trough over us by day 10.

Thereafter, we can look to see where the jet goes and the various nuances, timings etc. bit of patience required I'm afraid.

[Nick F]

And another small but vicious low for around the turn of the year, gfs keeps on developing this shortwave and bringing it quicker to the new year events, hope this does not happen, some New year celebrations will definitely be cancelled Ive highlighted the concern in the graph below with this small potentially nasty disturbance! Its not even been born yet , but gfs is good in modelling this ......

Yep, more troublesome Atlantic systems on their way through next week, though they aren't looking as severe wind-wise as earlier this week ATM, with rain probably likely to be more of a worry. After a lull this weekend, the jet shows signs of cranking up again, as another surge south of bitter cold air over E Canada meets warm conveyor up from the Carribean to fuel another 200 knot+ jet streak to race eastward towards the SW of the UK. The first effects of the jet's return on Monday, as an active cold front sweeps east, with gale or severe gale force southerly winds ahead of it. Then risk of waves developing into secondary lows moving east across UK mid to late week to watch out for.

Record cold stratosphere likely fuelling this unusually protracted stormy spell characterized by the classic +ve NAO/AO combo. However, it does look like the PNA (NE PAcific) ridge is aiding in the formation of an arctic high/cross polar height rises evident on medium range modelling, hence the -ve AO forecast despite cold stratosphere. Combine this with a strong Russian/siberian High - there is potential for wave-breaking to change the stubborn pattern as we head through early Jan, this without a SSW. The wave breaking and presence of the arctic high may not guarantee a route to cold and snow for us, but there are increasing signs there to put the breaks on the stormy and mild onslaught. So it seems IMO that we may not need a sudden strat warming to help reverse the H500 pattern, but it could speed up the process!

Edited December 28, 2013 by Nick F

[Mucka]

In terms of the ECM if you're going by the ensemble mean it does give you a chance of that cold zonal flow, the ECM operational run is once again going against the main cluster of its ensemble suite, indeed if you look at the mean its almost a carbon copy of the pattern expected by NOAA in their anomaly map done yesterday.

 

The ECM is making far too much of high pressure in southern Europe, its been doing this for several days now. In terms of a window of opportunity as some energy digs se around 168hrs that would be where we might get some movement from the NWP.

 

Agreed. I was specifically talking of the ECM Op regarding cold zonal remark and as I suggested I am expecting something closer to JMA to verify for day 7/8

[nick sussex]

Just looking at the ECM De Bilt ensembles, they do turn colder towards the end of the extended range ,  the operational run is backed by the control run in terms of trough disruption with some energy heading se and pulling in a temporary east and se flow over the there.

 

They both however bring another low pressure in as can be seen by the temps edging up again, in terms of this trough disruption theres not a great deal of support in terms of the wind ensembles but this often can be the case with their lower resolution.

 

http://www.weerplaza.nl/15daagseverwachting/?r=midden&type=eps_pluim

 

 

You can also see there the spread widens towards the end with more easterly and se options although these are still in the minority, for the timebeing!!!

 

Just to add having had a closer look at those, the control run does bring some trough disruption earlier than the operational and does have some support for that, its the operational which really is not supported.

 

PS  Theres about 4 members which go cold and stay cold! it would be great if we saw a sudden change in the outputs, I remember many moons ago we were sat here and the GEFS ensembles were all cold bar one member which stuck out much milder, and of course the curse struck and the operationals trended that way, it would be great to have that in reverse here.

 

I even remember SM talking about it as just typical sods law, although of course you could write a book on the amount of tragic near misses we've suffered in here!

Edited December 28, 2013 by nick sussex

[johnholmes]

Is this what you are trying to show?

 

 

 

 

thanks for posting that but no-it was the 8-14 day 500mb NOAA chart issued 1 January 2010.

In answer to Tamara I am still not convinced but maybe best we leave our differences and move on.

If anyone, unlikely, is interested enough then the post No was 44 issued 1 January 2010 with my ideas of what the weather might do out to 21 January. It is somewhere in the Net Wx files I suppose.

[bluearmy]

The ECM control brings a stocking MLB stretching mid Atlantic across to Russia, slowly ingesting arctic air into it. Not consistent with its previous offerings at all.

Very tenuous at the moment but the beginnings of a slow march west of the block to our east evident on the extended ens anomolys. IF that does happen, then all we need is low heights over Europe and it we could get a continental feed east of south in a battleground as the Atlantic slams into a wall. Long way off in modelling terms and I have only noticed it looking at the 11/15 day output gefs and ECM ens from today's 12z's.

[Cecil Hogmanay Melchett]

The ECM control brings a stocking MLB stretching mid Atlantic across to Russia, slowly ingesting arctic air into it. Not consistent with its previous offerings at all.Very tenuous at the moment but the beginnings of a slow march west of the block to our east evident on the extended ens anomolys. IF that does happen, then all we need is low heights over Europe and it we could get a continental feed east of south in a battleground as the Atlantic slams into a wall. Long way off in modelling terms and I have only noticed it looking at the 11/15 day output gefs and ECM ens from today's 12z's.

Thanks for the continuing excellent analysis BA

Patience definetely the buzzword this winter,hopefully we will be rewarded.

[nick sussex]

Just looking upstream for any trends before the GFS 18hrs run comes out:

 

Operation New Year Cold Miracle has this to offer!

 

It might not amount to much but heres the NAM  18hrs run jet out of the USA at T84hrs compared to the GFS 12hrs at T90hrs, the NAM has made a correction south and is further south than the GFS:

 

NAM

 

 

GFS

 

Edited December 28, 2013 by nick sussex