Model Output Discussion 1200 hrs 15/11/14

[BLAST FROM THE PAST]

Things are moving slowly aren't they, however are we seeing early signs in FI that our first real cold shot if we get one will start from a northerly due to ridging in Atlantic [towards Greenland/Iceland and an advancing arctic HP] behind a trough that gets to our E but sets up shop in North Sea/Norway due to Siberian block preventing any further E progression?  An evolution looking possible? and one I'll be keeping eyes on.  Risky route though as if Atlantic ridge gets broken through its 'westerlies'!!!

 

 

 

So deep FI though...

 

 

BFTP

Edited November 25, 2014 by BLAST FROM THE PAST

[Buxton Codge]

18z keeps it dry next week but increasingly cloudy and mild

[Nick F]

Even if the mid-latitude high sinks south a bit next week and the lows plough on eastwards to the north of the UK ever deeper into Scandinavia, there's still a good chance, based on the way the upper westerlies have been behaving beneath the disturbed Polar Vortex, that another wave will come along in the jet and amplify HP north and northeast to rebuild a Scandi high like the end of the parallel run. The deep cold pool over NW Russia/western Siberia is ready and waiting for such an opportunity to head SW.

 

Now I'm not implying, by any means, that whatever evolutions that the models throw at us, there's always a route to cold - but with the the upper flow behaving rather differently than this time last year over Europe, with help of a much less organised polar vortex, it may be a matter of time when the waves eventually fall in the correct place and buckle the right way to allow deep cold this way.

Edited November 25, 2014 by Nick F

[Man With Beard]

www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php

knocker has already posted this NOAA anomaly chart above - not for the first time, Knocker, I'm going to disagree with you! About this chart, you say "no cold in sight" - but I see the potential there for a Scandi High and an Iberian/Italian Low which equals potential easterly for us - though it may not quite reach us. The cold is most certainly "in sight" though!

(I will concede though, Knocker, the last time we disagreed ... you were right!)

[Nouska]

It's hard to credit that a region as small as the UK and Ireland could have such a diversity of temperature anomaly given as an average over 3 months. Looking also at France (cold east, milder west) and Spain, I wonder does it indicate a complex situation with HP often near the NW of these islands, low pressure over Spain and France, with bursts of east winds bringing cold across England. But not sustained or widespread?

Or a settled scenario with alot of blocking close or over these islands and the east of England getting any colder air much more often than other areas. It certainly doesn't indicate much in the way of any cold northerlies. Maybe it also indicates HP over north and east Europe, but not Greenland, jet going around the high, coldest air in these islands in England from east winds making it that far west sometimes. Western, and northern areas not getting the cold penetrating

 

The temperature forecast on the Cohen map is very similar to the one from the NOAA sea surface temperature analogues. I'll post both the height anomaly and the temperature anomaly as it gives a better idea of how circulation patterns contribute to the temperature shown.

 

These would also tie in with the OPI forecast in that they show a very southerly jet stream making inroads well into Europe and setting up a return easterly flow. Western France would be mostly milder in that set up with the maritime influence as the flow comes ashore. The fact N. Scotland is positive on the Cohen forecast may indicate periods of split jet stream where they also come under usual westerly flow. 

 

Charts courtesy of Huug Van Den Dool.

 

http://www.cpc.ncep.noaa.gov/products/people/wd51hd/

 

 

[Nick L]

Just removed a bunch of off topic posts. This thread is for model discussion, not Met Office forecast discussion.

[Mucka]

Sort of as you were this morning but with the chances of an Easterly slightly lessened perhaps. I still think that our first cold spell will come with high pressure to our W/NW rather than to our E/NE though so I have no problem with that.

A lot will depend on how sharp the trough into Scandi is around day 7/8 should the output continue to move that way and I would like to see disruption f low pressure have a more SE tilt than plow E as it meets the arctic ridge as this would help define the Scandi trough and amplify the pattern upstream.

 

So the next real potential for cold for me excluding any easterly potential would be a trough dropping through scandi into central-Eastern Europe and a ridge forming to the West of that. How far West we can back such a pattern and how well defined the trough is will determine how strong the ridge is behind and I will be hoping to the pattern far enough West with enough amplification that we strong Atlantic ridge with WAA toward Greenland at last as the PV is allowed to shift East.

 

UKMO has the disruption pretty much straight East which would lead to a slower evolution and probably a less well defined trough into Scandi eventually, it may also allow the AH to ridge in which would be another fly in the ointment.

 

 

 

GFS has a slightly more SE tilt to it which would be better IMO and leads to quicker troughing into Scandi though I would still like to see a sharper angle of attack and better disruption, we still need some blocking further East to stop everything pushing through and flattening out.

 

 

As a less well defined trough will allow the AH to ridge in strongly.

 

 

 

And though this pattern is not far enough West or amplified enough in th end because of this I think we can see the potential in such a pattern change.

 

 

Essentially if we don't get the easterly we will likely have a shot at a Northerly  down the line but if we want more than a toppler we will need to see improved charts over the earlier time frames int he areas I described.

At leas that is my take on the most likely course of the output over the coming 10 days but I still wouldn't rule out big changes in the medium term that increase the possibility of an Easterly once more or more likely a UK high forming.

Edited November 26, 2014 by Mucka

[MR EXTREMES]

Interesting P this evening as from T144 onwards it has the low and Azores ridge moving east in tandem bringing a very marked warm.cold split over Europe. Not going to plan here.

Charts courtesy weatherbell.com

It depends who it's going to plan for ??????

All I can say is it's a good start to winter and confidence is higher than last week.

But then one chart don't tell the whole story.

But I wouldn't bet against a rather strong Greenland block through December at some point or both Greenland and Scandinavia block.

The weather don't make plans it's does what it wants.

One chart don't make the weather any different to the broad agreement the models suggest average to slightly below for now which I might add is fantastic and once cold air gets trapped under heights then it's a bugger to remove.

Great start to winter

[Captain Shortwave]

Same trend as yesterday really, heights building in towards the UK from day 6 onwards

Decent pattern to have as finally the low heights over Greenland can move one way towards Siberia whilst we remain fine and chilly. 

I suspect once the high gets over us then it might be here for quite a while. It does give us time to probe the evolution afterwards. But with low heights receding to our north west then maybe retrogression of the UK high into the Atlantic with a North-west/northerly burst might be an option as we head towards mid December.

Edited November 26, 2014 by Captain shortwave

[MR EXTREMES]

Yep as some suggested yesterday tetis special could progress from here I've seen this pattern emerging in winter and what a beaut it could be.

Northerly moving on to a northeasterly after uk heights shifts west out into the Atlantic door shut can't retrograde East as low heights dropping into Scandinavia heights then a retrograde to Greenland where pattern could settle........

Edited November 26, 2014 by emotional rollercoaster

[Duane S.]

As you were the 00z suite. Mini Easterly setting up I the medium term, lowish heights into Europe. Jet riding over the top so unlikely to be reinforced and so the Azores high likely to exert more influence. The Azores high itself yet to declare whether it will be a hindrance or a help as we head deeper into FI.

I am liking the look of the ECM at D10

Would be nice to see it kick on from here but I'm not sure sure the teleconnections, right now, support much more amplification.

[knocker]

I suppose one could say the upper anomaly is somewhat volatile looking at this morning's GEFS.

The pole/Scandinavian HP has weakened and moved west.  Low Labrador and intensification of the Atlantic HP. Plus upstream a low Pacific and HP north America. So surface analysis has an HP dominate Atlantic with slightly below temps in UK from a westerly flow.

 

 

At T312 amplification upstream and a broad area of very slack LP Europe. The Russian vortex has gone and along with it the Scandinavian block. On the surface this leaves a broad area of low pressure Canada east with still HP dominating the Atlantic bringing a westerly slightly cool flow to the UK. I'm not placing any bets on a cold incursion on this evidence. But of course the caveat is this is one run, one model so punters are urged to stick to a low dose Diazepam.

Charts courtesy weatherbell

Edited November 26, 2014 by knocker

[joggs]

Well imo i dont buy into a greeny high anytime soon.The vortex over canada/w,s and central greeny is just orientated wrong for

me and if its modelled to move we always seem to have residual lower hights there.The outcome for me in the 2wk timeframe is mlb somewhere in our locale and maybe unsettled weather at times from the west/north west later.

Edited November 26, 2014 by joggs

[BLAST FROM THE PAST]

 

 

Hmmmm, is this the way forward? 

 

 

BFTP

[bluearmy]

The vortex still looking beat up as we head into winter proper. now that the scandi ridge looks to be taking a holiday (brief or sustained?) , we look elsewhere for a bit of amplification. (And given the arctic high, there will be amplification). would be a great point stratospherically, to get a mid Atlantic ridge pumping some WAA into the greeny region, even if it were only for a day or two. thereafter, we wait for what goes up from the trop to come back down from high up!

[Nick F]

Plenty of potential this morning from the models for the pattern to eventually evolve to bring a better chance of deep cold air towards the UK.

 

There's a good chance that a belt of mid-latitude high pressure from the Atlantic across the UK and on into eastern Europe will hang around through much of next week. In the meantime, alot of energy spreading east above the HP belt with lows ploughing east into Scandinavia. But, models are indicating a wave coming out of N America later next week or weekend which could amplify sufficiently over the Atlantic to allow height rises north then northeast to allow a cold northerly then perhaps eventually a cold easterly. A fair few 00z GEFS members heading in this general direction..

 

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=240

 

Though we are relying on crucial amplification upstream ... but the polar vortex is so unstable atm, there seems to be plenty of waves developing upstream and working through to the Atlantic sector.

Edited November 26, 2014 by Nick F

[bluearmy]

Well imo i dont buy into a greeny high anytime soon.The vortex over canada/w,s and central greeny is just orientated wrong for

me and if its modelled to move we always seem to have residual lower hights there.The outcome for me in the 2wk timeframe is mlb somewhere in our locale and maybe unsettled weather at times from the west/north west later.

I agree jogs- a sustained one anyway. A transient one is possible. I think we may well have to look beyond first third December for anything really wintry to emerge. wondering yesterday if expectations of the Canadian vortex's demise week 2 could be a bit premature? However, beginning to see signs of some vortex establishment towards Alaskan sector of the polar field. That would be of interest if it draws the Canadian lobe that way.

[MR EXTREMES]

 

 

Hmmmm, is this the way forward? 

 

 

BFTP

Of course blast I think bit nippy comes to mind.

I'm glad I'm not the only one who has faith in the possible outcome what a thing of beauty that chart u posted.

[Captain Shortwave]

I agree jogs- a sustained one anyway. A transient one is possible. I think we may well have to look beyond first third December for anything really wintry to emerge. wondering yesterday if expectations of the Canadian vortex's demise week 2 could be a bit premature? However, beginning to see signs of some vortex establishment towards Alaskan sector of the polar field. That would be of interest if it draws the Canadian lobe that way.

The ECM this morning was way too quick. But I am certainly please with the Atlantic/Euro pattern coupled with the Arctic profile. That should encourage the very low heights of Greenland to drain towards Russia and Siberia, though I suspect we won't remove them entirely. I would feel that some form of amplified Atlantic ridge developing from mid-December would be a fair bet. So possibly quiet and settled with some frost and fog followed by some wintry weather (albeit not deep cold).

Pure conjecture though at this point.

Edited November 26, 2014 by Captain shortwave

[Polar Maritime]

Once again the GFSP is showing a nice Northerly around the 9th.

 

Edited November 26, 2014 by Polar Maritime

[Blessed Weather]

I suppose one could say the upper anomaly is somewhat volatile looking at this morning's GEFS.

The pole/Scandinavian HP has weakened and moved west.  Low Labrador and intensification of the Atlantic HP. Plus upstream a low Pacific and HP north America. So surface analysis has an HP dominate Atlantic with slightly below temps in UK from a westerly flow.

 

 

At T312 amplification upstream and a broad area of very slack LP Europe. The Russian vortex has gone and along with it the Scandinavian block. On the surface this leaves a broad area of low pressure Canada east with still HP dominating the Atlantic bringing a westerly slightly cool flow to the UK. I'm not placing any bets on a cold incursion on this evidence. But of course the caveat is this is one run, one model so punters are urged to stick to a low dose Diazepam.

Charts courtesy weatherbell

 

Hi Knocker. Hope you don't mind but I'd like to put a positive spin on the sentence I've highlighted. We've all been moaning about lack of real cold in Europe to tap into, and on a number of occasions in FI the GFS has teased that the Siberian PV might drop a lobe down into Europe but it's never materialised.

So I was taken with your chart as, IMO, it shows the reason the Siberian PV seems to have disappeared is that it's drained down into Europe, finally bringing that much needed cold air? So this could be good news for coldies, but your final sentence "one run" is noted!

 

I've marked the chart:

[IDO]

We were getting nowhere with the block to our east and my call has always been to get a spell of Atlantic driven weather and with the PV not organised, as it normally is, this should give an opportunity for heights to reposition in our region. An Atlantic ridge is looking a possibility (probably transitory) on this morning's runs but we have a period (5-7 days) of high pressure in our locale to bide our time as the Atlantic slides over the top of the UK. Best of both worlds; we get a reset and we miss the zonal flush.

 

It is no coincidence, looking at the charts, that in GEFS FI, an Atlantic ridge develops. During the next 12-14 days the Atlantic High train keeps the pattern mobile (to our north thankfully) before it slackens again and we get the opportunity for the resident NH high pressure systems to settle down, enabling a more meridional flow.

 

The D10 charts from the main models all show a similar long wave pattern and the variations are more to do with upper level lows (ULL) complicating the Atlantic (ECM & GEM). ECM therefore allows the Atlantic high at D10 to throw some WAA towards the Arctic. GFS does not have that ULL so cannot give us an early taste of amplification:

 

 

 

 

 

As for the GEFS at the end of FI; the good news is that the mean Russian vortex has pushed east, though at the moment the trend after next weeks mobile flow is for Greenland again to become the location for the other mean PV lobe:

 

 

Thats not where we want it to land when the music stops but has support from the CFS monthly mean for December:

 

 

So no cold spell looks likely for the next two weeks at least and this ties in with all the LRF, MJO and other signals. How cool the high is next week is difficult to know but I suspect December will put a halt the above average CET anomaly; London 2m temps:

 

 

 

 

 

 

 

[SMU]

Plenty of potential this morning from the models for the pattern to eventually evolve to bring a better chance of deep cold air towards the UK.

 

There's a good chance that a belt of mid-latitude high pressure from the Atlantic across the UK and on into eastern Europe will hang around through much of next week. In the meantime, alot of energy spreading east above the HP belt with lows ploughing east into Scandinavia. But, models are indicating a wave coming out of N America later next week or weekend which could amplify sufficiently over the Atlantic to allow height rises north then northeast to allow a cold northerly then perhaps eventually a cold easterly. A fair few 00z GEFS members heading in this general direction..

 

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=240

 

Though we are relying on crucial amplification upstream ... but the polar vortex is so unstable atm, there seems to be plenty of waves developing upstream and working through to the Atlantic sector.

Morning Nick -

Agree with those sentiments & all the while its developing its cold & generally dry here.

For newer members its a pattern we havent seen for a long while :

A relative mild negative AO circa -2 driven by the arctic high, followed up by a sharp modality change of the PNA pattern from generally mild positive driving that cold snowy pattern like last year to a very steep negative PNA ridge -

The eastern us goes through a significant of warming which may bear fruit for the UK !

Regards

S

[knocker]

Worth reading MH's tweet on trough disruption this weekend.

 

Brilliant examples of trough disruption, or anticyclonic trough disruption to end the week this morning.

https://twitter.com/MattHugo81

[IDO]

Looking at the D10 means and the ECM op tease has no support (taken as given of late):

 

 

 

I was also reading the Twitter and Matt also reiterated that the UKMO LR Winter forecast takes into account the possibility of an SSW, so I don't know what the strong signal is that is suggesting milder than average DJF? Should be interesting ECM/UKMO -v- the stratospheric undercurrent.