Model Output Discussion 1200 hrs 15/11/14

[BlueHedgehog074]

Just a fairly brief post, but have decided to rate the 240+ hour models out of 20 with regards to their cold weather potential. (Note: with the odd exception of the 12Z GFS, which has just been let loose, this will mostly be the 00Z/06Z runs).

GEM (00Z): This model shows an interesting evolution with Low Pressure from the North-West late next week swinging down towards Eastern UK. Significant amplification occurs to the West and North-West with the Vortex becoming stamped out over Greenland. The UK becomes affected by a chilly Northerly and North-Easterly flow during next weekend as a result of this. However, -5*C 850 hPa temperatures only start becoming pulled towards Northern UK at the end of the run, with snow likely to be restricted for high ground. But perhaps some sleety stuff for lower levels should we see heavy enough precipitation. There's also some milder air getting pulled Northwards towards Greenland on the amplified High Pressure system's Western flank, although there is a possible risk of the pattern breaking down as Low Pressure systems to the West of the blocking High try to break back through further East. Nevertheless, with Low Pressure sitting over Southern UK, then it could help to prop up the collapsing ridge to our North. Rating: 14.7/20

(18:40 update: GEM 12Z goes for a Northerly toppler during next weekend with some high ground wintry showers possible, mostly especially towards the coasts. But the blocking High to the West quickly gets pushed out towards the East as Lows start coming back through from the West. No strong heights over Greenland on this GEM run. But a trend for a Northerly is their. Rating - 11.5/20).

ECMWF (00Z): Exhibits some similar traits to the GEM model. It shows Low Pressure again swinging down from the North-West late next week, with the Azores High becoming amplified to our West. A Northerly swamps the UK during next Saturday with the -5*C hPa temperatures spilling Southwards through the UK. Wintry showers possible towards Eastern, and some Western, coasts. The amplified High to the West, however, is not quite as significant in comparison to the 00Z GEM with strong heights failing to reach Greenland. Low Pressure to the North-West flattens the Mid-Atlantic ridge somewhat during Sunday. But... as this Low Pressure system starts tracking East/East-South-East, it shows the possibility of the High to our West re-amplifying with another Northerly reload possible. Rating: 13.7/20

GFS Operational (06Z): Mostly free from cold North-Westerly and Northerly flows with the pattern generally quite flat with periods of Mid Latitude Blocking Highs (which, to be fair, could help aid frost and fog potential at night time, and something that's possible on other models, too) and more unsettled Westerly flows. Near to the end of the run, the GFS becomes bored of this and decides to provide us with amplified High Pressure to the West of the UK with a couple of quite potent Polar Maritime flows and a chance of wintry showers for places, especially towards the North-West. Since this is in deep FI, it will affect the score I give to this model. Rating: 10/20

(Edit: the 12Z GFS is not too different from the 06Z run. Still no signs from this model for a Northerly to occur next weekend with cyclonic conditions quite invasive to the North and North-West. Therefore still not buying into the 00Z ECMWF and 00Z GEM's more amplified solutions. It does however show a chilly Northerly in deep FI. Rating: 9/20

GFS Parallel (06Z): Again, mostly quite flat, with quite a mobile, Westerly Atlantic pattern, but with some periods of ridges of High Pressure affecting the UK at times giving some possible drier, frostier weather. It does go for quite a chilly Polar Maritime flow for next Sunday. And then, closer to the end of the run, it looks as though the Jet Stream becomes orientated from North-West to South-East with Low tracking East-South-East into mainland Europe with further cold Polar Maritime flows affecting the UK. No strong blocking, though. Rating: 11.2/20

(Edit: The 12Z GFS Parallel does still go for some kind of Polar Maritime flow for places next Sunday with a bit of amplification to our West. Chance of wintry showers for the North-West. But doesn't last long as the ridge to the West becomes flattened, although we see variable flow of less-cold Westerlies and cooler North-Westerly flows towards the end of the run. Some fairly decent looking Mid-Latitude Blocking Highs over the UK for next week, as well, with frost and mist opportunities (though some spells of wet weather could affect the far North at times). Rating: 10/20

NOAA 8 to 14 Day 500mb Anomaly Chart (issued 27th November): Probably not the best idea to give these anomaly charts a rating for cold potential, really. It does, however, appear some higher than average heights are likely to be dominant to our West, with low heights occupying the North of the UK. Maybe that possibly we could see some potent Polar Maritime and/or Arctic Maritime flows, with maybe signs of High Pressure amplifying to our West to turn the less-cold Westerly flows into something more chillier. Some higher than average heights over the Pole area, which could signify Arctic/Pole High Pressure possibilities. This of which could help keep the blue and purple 'monster' (Polar Vortex) to our North, disorganised. Rating: 13/20

Additionally, it looks likely a cold front will slip through the country during Monday as Low Pressure moves Eastwards through Northern UK. This of which could bring heavy rain for places with colder air tucking behind from the North-West for a time.

Maybe some possible temporary wintry showers towards North-Western coasts before the Azores High slowly ridges Eastwards through the UK from the West bringing some settled conditions.

Edited November 28, 2014 by DiagonalRedLine
Correcting odd mistake where I rated a couple of model runs out of 10, instead of out of 20.

[Steve C]

Not often the 06z and 12z GFS ops churn out a very similar evolution out at T+360 right towards the end of the run, I know it's 6 hrs difference, but both have a strong cold Nly flow on Sat 13/12 as the flow amplifies:

 

06z T+360

gfs06z_360.png

 

12z T+360

gfs12z_360.png

 

Sheer coincidence at that range, but what's possible if we see a wave amplify and slow upstream over Ern N America, provided we see the core of low heights shift off Greenland more.

That's an ugly storm surge potential chart. Cold is nice, but North Sea flooding not so. I hope the evolution is somewhat different.

[Andy Bown]

12Z UKMO expands the low to the south until end of the run at T+144 holding the southern portion of the country in a NE'ly. Consequently the ridge is held further north. Looking up wind it looks like it could get pretty cold fairly soon with lower dewpoints already into parts of the low countries.

http://www.meteociel.com/modeles/ukmo2.php?ech=6&carte=1021

Your link seems to go to a chart for Friday 6th June 2014!!

[carinthian]

The UKMO 12z is a major upgrade for a cold outlook imo. For once I suggest people view this on the Europe view as opposed to the northern hemisphere one. Now compare this run with yesterdays 12z and the first thing you will notice is the air still comes in from the continent in todays run, whereas yesterday, the theme was for the azores ridge to be dominant. The change brought about by today's run is the low over southern Europe being a bigger player than previously anticipated - The importance of which Carinthian has been at pains to point out these last couple of days. This draw from Europe should make it easier for the high in our locale to retrogress and join forces with the high off the eastern seaboard and then hopefully complete the retrogression and bring our northerly.

Yes Blizzard, maybe too much attention to whats going on further field and into he longer term outlook. Certainly I am encouraged in the shorter latest UKMO 12z output and as you say a better chance shown for the High to retrogress for a colder outlook. We will have our latest view on developments in the morning when I get the portal numerical predictions for Central Europe with a added insight for the UK.

C

[bluearmy]

The extended GEFS anomolys falling in line closer to ecm re how far into europe the troughing gets in our vicinity. that means not as far south.  also, as early as day 3/4, the ecm is at odds with gfsp re heights over scandi.  not sure that will make a big difference in the mid range butit could change the movement of the arctic high re fi

[Gael_Force]

That's an ugly storm surge potential chart. Cold is nice, but North Sea flooding not so. I hope the evolution is somewhat different.

 

Indeed, striking similarity with the chart from last year, when major flooding issues were concern for here and the Low countries.

 

2013 

GFS forecast chart.

 

        

[Duane S.]

The charts now starting to reflect how we should expect December to proceed. Getting very gradualy cold as the month progresses. But I think more patience will be required and although it could get quite (very) frustrating in the next week or 2, I am becoming more confident that the wait is going to be worth it.

 

I am starting to change my mind with how a cold spell will form. I think what we will see is repeated attempts to ridge up into GL from our growing Mid Atlantic high but too much energy still overhead and every attempt will likely topple (although bringing in cold shots of PM air as it does so) then I wonder if we should watch to the East?? Our old lingering friend the Sceuro/Scandi/Russian high could play a BIG part in 10-14 days, I could envisage a giant WAA shot heading north east through the UK to create a completely different HP beast then with high anomalous heights over the pole likely to still be remain in place, retrogression will naturally occur with an initial Steve Murr Sausage High then full retrogression into proper GL high, low heights established to our south =  Actic floodgates open!

[Tamara]

Major amplification on the ECM tonight with a connection opening to the arctic High. This would sure accelerate the feedback processes..if it happened

 

 

 

 

We know that ECM is prone to over amplification but this is exactly the type of evolution we are looking for further down the road to lead us to the important next step to a colder pattern - and with wave breaking feedbacks in the atlantic sector.

 

To illustrate this further, see how at day 10 (if we assume at face value the ECM operational verified) the heights are building again over Scandinavia.

 

 

 

Pattern re-cycle following the transfer of energy across the pole as modelled this week - and much as I mentioned in my post a day or two back

 

 

Its a case of if/when this happens. Very arguably not when ECM suggests here, but it does show the template for the way ahead as we go through December.

Edited November 28, 2014 by Tamara תָּמָר

[nick sussex]

You've had my more Guardian type posts now for something a little more tabloid!

 

Tonights headlines.

 

Europe warmth set to break as winter finally arrives.

 

Upstream model chaos leads to  mass confusion in the UK.

 

The GFS and GFS P apart from well into FI are dire for coldies

 

GEM drops outlandish cold scenario and replaces it with something a little more believable.

 

UKMO promises some cold treats at T144hrs but will it deliver?

 

As we come to post some late breaking news from the ECM, best upstream at T144hrs delivers tasty chart to warm coldies hearts at T168hrs.

 

More news later once  I can find something hopefully from NCEP that rubbishes the GFS and GFS P which are horrid!

[radiohead]

Major amplification on the ECM tonight with a connection opening to the arctic High. This would sure accelerate the feedback processes..if it happened

 

 

Yes, very interesting chart! Though we do know how the ECM is prone to amplification sometimes.

[Buxton Codge]

Well after a very mild weekend, it will feel cold next week! Maybe some possible wintry showers in the far north for a time too. Later next week, the Azores High will bring a return to settled weather and it will feel milder again. No signs of any widespread snow in the 0-14 day range

[Timbo]

Well after a very mild weekend, it will feel cold next week! Maybe some possible wintry showers in the far north for a time too. Later next week, the Azores High will bring a return to settled weather and it will feel milder again. No signs of any widespread snow in the 0-14 day range

Think you need to take a look at the ECM!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[nick sussex]

Well after a very mild weekend, it will feel cold next week! Maybe some possible wintry showers in the far north for a time too. Later next week, the Azores High will bring a return to settled weather and it will feel milder again. No signs of any widespread snow in the 0-14 day range

So you're happy with this call even though there are huge disagreements between the GFS/P and the ECM and UKMO?

[Buxton Codge]

Think you need to take a look at the ECM!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

ECM has been all over the place recently at 168+ . Lets see if its still there tomorrow. I doubt the GFS will be far off

[Boro Snow]

BANK loving this chart from the ecm -6 / -8 850s across the majority of the UK and Surely Snow for a few

 

[IDO]

Yes Blizzard, maybe too much attention to whats going on further field and into he longer term outlook. Certainly I am encouraged in the shorter latest UKMO 12z output and as you say a better chance shown for the High to retrogress for a colder outlook. We will have our latest view on developments in the morning when I get the portal numerical predictions for Central Europe with a added insight for the UK.

C

 

Unfortunately UKMO has a bias for lowering heights on the eastern seaboard and therefore creating the impression that heights will build towards Greenland:

 

 

So when I see the T144 chart I have a look at the GFS ensembles to test it; there is practically no support. In the circumstances I expect it to resolve in later runs towards the GFS:

 

 

The ECM also has a tendency to model a small feature north of the Azores, an upper level low, that tends to act as a block so heights build north over the top of it. So by T168 there is a clear bias for height rises towards Greenland:

 

D6:  D7: 

 

A few of the GEFS members have this feature but only two are even close to amplifying like the ECM and both are rather poor relatives in comparison. 

 

IMO with the Greenland PV lobe still potent around D7 then any heights will just topple from the next wave of energy. I think we need to wait till after D13. Mid December still remains of interest but the setup is very fluid at the moment as to where the heights will build.

[bluearmy]

Anyway, I see the ecm has pulled one from the top shelf this evening. Not impossible but I suggest it's showing what could happen with more amplification than we will probably get.

Edited November 28, 2014 by Polar Maritime
To remove off topic reverence.

[gottolovethisweather]

Well after a very mild weekend, it will feel cold next week! Maybe some possible wintry showers in the far north for a time too. Later next week, the Azores High will bring a return to settled weather and it will feel milder again. No signs of any widespread snow in the 0-14 day range

 

You've obviously not viewed the latest ECM and this afternoon's GFS P amongst others, as your statement is far removed from current projections.   The only mild day away from the far West and Northwest at times perhaps during the next working week is likely to be Thursday and even then, Temperatures would be unlikely to reach double-digits in most places. Tonight's ECM continues where yesterday's 12z left off, a thing of beauty it is, for those who admire the cold in its rightful season. Snow would be possible at D4 for parts NW and more especially over the hills. D7 - D9 also offer opportunities for more widespread snow, but at that range, it should taken with a truckload of salt.

 

Slightly cold beyond the weekend and trending colder with perhaps some snow in the early stages of FI (as alluded to above and in other posts) is a more accurate viewpoint IMHO. 

Edited November 28, 2014 by gottolovethisweather

[Polar Maritime]

Well after a very mild weekend, it will feel cold next week! Maybe some possible wintry showers in the far north for a time too. Later next week, the Azores High will bring a return to settled weather and it will feel milder again. No signs of any widespread snow in the 0-14 day range

 

A few charts to at least try and back up your mild posts of late would be welcome Buxton Codge, And can you please read your Pm's.

 

PM.

Edited November 28, 2014 by Polar Maritime

[Summer Sun]

We might not be far off some snow IF ECM is correct with some strong north to NE'ly winds for a time we could be looking at blizzard like conditions over high ground

 

 

A much better position that we were in last year thats for sure

 

Edited November 28, 2014 by Summer Sun

[blizzard81]

Yes Blizzard, maybe too much attention to whats going on further field and into he longer term outlook. Certainly I am encouraged in the shorter latest UKMO 12z output and as you say a better chance shown for the High to retrogress for a colder outlook. We will have our latest view on developments in the morning when I get the portal numerical predictions for Central Europe with a added insight for the UK.C

Hi Carinthian, yes, quite a change short term that has major ramifications down the line as can be seen with tonight's ECM op which agrees with the UKMO op. I always like it when these two models agree. Look forward to your update tomorrow.

[blizzard81]

The UKMO 12z is a major upgrade for a cold outlook imo. For once I suggest people view this on the Europe view as opposed to the northern hemisphere one. Now compare this run with yesterdays 12z and the first thing you will notice is the air still comes in from the continent in todays run, whereas yesterday, the theme was for the azores ridge to be dominant. The change brought about by today's run is the low over southern Europe being a bigger player than previously anticipated - The importance of which Carinthian has been at pains to point out these last couple of days. This draw from Europe should make it easier for the high in our locale to retrogress and join forces with the high off the eastern seaboard and then hopefully complete the retrogression and bring our northerly.

Well as we all know now, following on from my post earlier, the 12z ECM op agrees with the UKMO 12z and it is these changes in the T96 period that brings the massive changes later on.

[tinybill]

http://www.meteociel.fr/modeles/gfse_cartes.php?mode=2&ech=204

 

deep f1  is looking  good  for the coldies at the  moment  we  could  see  some cold weather  about after  DEC 12  it might change  and  it will!!!

[carinthian]

Hi Carinthian, yes, quite a change short term that has major ramifications down the line as can be seen with tonight's ECM op which agrees with the UKMO op. I always like it when these two models agree. Look forward to your update tomorrow.

Yes Blizzard, UKMO AND ECM latest numericals look in tandum. So quite an upgrade to a colder scenario next week especially after such a mild flow over the UK and France this weekend.

Should have an update tomorrow morning .

C

[mcweather]

Major amplification on the ECM tonight with a connection opening to the arctic High. This would sure accelerate the feedback processes..if it happened

 

 

 

 

We know that ECM is prone to over amplification but this is exactly the type of evolution we are looking for further down the road to lead us to the important next step to a colder pattern - and with wave breaking feedbacks in the atlantic sector.

 

To illustrate this further, see how at day 10 (if we assume at face value the ECM operational verified) the heights are building again over Scandinavia.

 

 

 

Pattern re-cycle following the transfer of energy across the pole as modelled this week - and much as I mentioned in my post a day or two back

 

 

Its a case of if/when this happens. Very arguably not when ECM suggests here, but it does show the template for the way ahead as we go through December.

Interesting ECM as you say Tamara and certainly what we need to see happening as a precursor to where us coldies want to be come months end.