Model output discussion - 5th December 2016 - Into Winter we go

[Newberryone]

1 hour ago, knocker said:

He's hoping it hangs on in there against the onslaught from the vortex but he has his doubts. I think he's had an early look at the ext ens

Sounds like we can deduce from this that the PV will have possibly strengthened significantly enough in the latter stages to bring us flashbacks of last winters continuous Atlantic onslaught. However, if given a choice between the now all too familiar Euro Slug scenario or an active zonal train, give me the ferocity of Mother Nature and everything associated with a zonal train any day.

[Man With Beard]

Can't anyone else see how close this is to a very good winter chart? Is there really zero chance of our weather being an acceptable variation on this chart which may allow a draw from the cold east? A little trough disruption in our favour and we could end up with that weird cold pool a few GEFS op runs have toyed with? Deep uppers not needed off the continent in the depths of winter.

[mulzy]

Poor ECM eps day 10 mean chat.

 

Extended eps not much better with broadly the same pattern persisting right through to day 15.

[feb1991blizzard]

Just now, mulzy said:

Poor ECM eps day 10 mean chat.

 

Extended eps not much better with broadly the same pattern persisting right through to day 15.

Any decent clustering?

Edited December 11, 2016 by feb1991blizzard

[mulzy]

3 minutes ago, feb1991blizzard said:

Any decent clustering?

Haven't got access to clustering sadly, but just looking at the strength of the anomalies, I would hazard a guess that most members would show a SWly airstream over the UK in the day 8-12 period.

Edited December 11, 2016 by mulzy

[feb1991blizzard]

Just now, mulzy said:

Haven't got access to clustering sadly, but just looking at the strength of the anomalies, I would hazard a guess that most members would show a SWly airstream over the UK in the day 8-12 period.

Thanks, yes guessed the 12d period - prob 15d.

[Nick L]

6 minutes ago, feb1991blizzard said:

Any decent clustering?

The clusters are a bit of a horror show at D10, frankly. All west-southwesterly.

[bluearmy]

10 minutes ago, mulzy said:

Poor ECM eps day 10 mean chat.

 

Extended eps not much better with broadly the same pattern persisting right through to day 15.

Actually, following on from the day 10 op which joined the Russian surface high with our sceuro fellow into one large feature, the control goes on to do similar and subsequently extends the Atlantic trough towards Iberia which strengthens the se flow across the uk as the Russian high extends itself nw into Scandinavia . Not often I take much note of the control but it does fit quite well with the mean/anomoly and  takes on the theme of the operational. 

Given the apparent upcoming standoff between the Atlantic trough and sceuro ridge, perhaps the intervention of the Russian high to bolster the ridge  may tip the battle in favour of the block and force the jet into Iberia. 

[feb1991blizzard]

Just now, Nick L said:

The clusters are a bit of a horror show at D10, frankly. All west-southwesterly.

Thought so - so there will be a lot more mild clustering on the London ens at 1130 than on the 0z I presume. I have to say I saw this coming a mile off.

[bluearmy]

I would suspect the 10/15 clusters revert to a split of sorts with continental flow fighting back 

[knocker]

The 6-10 anomalies tonight are still not in complete agreement although the end result vis the weather regarding the UK should not differ hugely.

The disagreement upstream is still with us and specifically to do with the orientation of the vortex and associated troughs across North America and to the south east over the Atlantic between the GEFS and EPS. This difference continues downstream as the EPS has the trough being slightly more influential in mid Atlantic which ensures that the strong upper north easterly flow is pushed a tad south east forcing the Azores ridge and the connected HP to our east to make similar adjustments. Net result whereas NOAA and the GEFS have the surface high cell adjacent to our E/SE the EPS has it not so well defined and further south east suggesting that the Atlantic will gain more ingress to the UK than the other two. Nevertheless certainly a dry and settled period for all except maybe Scotland.

The later anomalies are no help at all in getting a handle on the way forward. Both NOAA and the GEFS are weakening the Atlantic trough to the NW, thus an upper flow that has backed a tad, and the HP slipping slowly SE and not quite so influential. The EPS on the other hand has the vortex/trough still going great guns and the trough is SW of Iceland running south at the end of the run. Ergo a westerly upper flow with the HP in eastern Europe. In very simple terms it's the vortex/trough v the HP. Place your bets...........

[Weather Observer]

14 minutes ago, bluearmy said:

Actually, following on from the day 10 op which joined the Russian surface high with our sceuro fellow into one large feature, the control goes on to do similar and subsequently extends the Atlantic trough towards Iberia which strengthens the se flow across the uk as the Russian high extends itself nw into Scandinavia . Not often I take much note of the control but it does fit quite well with the mean/anomoly and  takes on the theme of the operational. 

Given the apparent upcoming standoff between the Atlantic trough and sceuro ridge, perhaps the intervention of the Russian high to bolster the ridge  may tip the battle in favour of the block and force the jet into Iberia. 

That would be a great call. One of my favourites from the archives is December 1938 when a high migrates from  around Nova Zemyla to Scandinavia over a week or so. Unforeseen then and I wonder how well it would have been forecasted today?

[bobbydog]

AAAAAGGHH! flicking between LandyZone and netweather, forgot which one I was on for a moment! Sorry guys!!

[blizzard81]

24 minutes ago, bluearmy said:

Actually, following on from the day 10 op which joined the Russian surface high with our sceuro fellow into one large feature, the control goes on to do similar and subsequently extends the Atlantic trough towards Iberia which strengthens the se flow across the uk as the Russian high extends itself nw into Scandinavia . Not often I take much note of the control but it does fit quite well with the mean/anomoly and  takes on the theme of the operational. 

Given the apparent upcoming standoff between the Atlantic trough and sceuro ridge, perhaps the intervention of the Russian high to bolster the ridge  may tip the battle in favour of the block and force the jet into Iberia. 

What an uplifting post. Thanks BA for many of us don't have access to this data. I really was wondering what the control run showed when I saw how cold it became on the debilt ens. Lets hope this becomes the trend on tomorrows runs.

[supernova]

15 minutes ago, Weathervane said:

That would be a great call. One of my favourites from the archives is December 1938 when a high migrates from  around Nova Zemyla to Scandinavia over a week or so. Unforeseen then and I wonder how well it would have been forecasted today?

 

32 minutes ago, bluearmy said:

Actually, following on from the day 10 op which joined the Russian surface high with our sceuro fellow into one large feature, the control goes on to do similar and subsequently extends the Atlantic trough towards Iberia which strengthens the se flow across the uk as the Russian high extends itself nw into Scandinavia . Not often I take much note of the control but it does fit quite well with the mean/anomoly and  takes on the theme of the operational. 

Given the apparent upcoming standoff between the Atlantic trough and sceuro ridge, perhaps the intervention of the Russian high to bolster the ridge  may tip the battle in favour of the block and force the jet into Iberia. 

What an insightful contribution guys. Great knowledge and enthusiasm combined. *watches with interest*

[Scandinavian High.]

Cold easterly for the south end of December no doubt it won't verify but you never no with the weather. Cherry picking 

Edited December 11, 2016 by abbie123

[Summer Sun]

6 minutes ago, abbie123 said:

Cold easterly for the south end of December no doubt it won't verify but you never no with the weather. Cherry picking 

 

Saturday's 00z too so it's rather outdated now

[radiohead]

Just look at that cold pool over Eastern Europe on the CFS! Uppers off the charts.

[karlos1983]

When the forum has its quiet periods like it has this afternoon / this evening, you really do get some fantastic posts, very informative. A real joy to read. 

[radiohead]

Some significant differences on the 18z GFS with the handling of that low around Newfoundland at 96 hours. Whether it makes any difference down the line remains to be seen.

[Nick F]

2 hours ago, Man With Beard said:

Can't anyone else see how close this is to a very good winter chart? Is there really zero chance of our weather being an acceptable variation on this chart which may allow a draw from the cold east? A little trough disruption in our favour and we could end up with that weird cold pool a few GEFS op runs have toyed with? Deep uppers not needed off the continent in the depths of winter.

The NOAA prognostic 8-14 day 500mb HGHTS/anomalies bears some resemblance to the 11-15 day 00z EPS 500mb mean below.

They both actually  advertise a pattern change from day 10 with the removal of the ridge over the Aleutains and replacing it with lower heights and a trough over the Gulf of Alaska and Western Canada (+EPO) - so we actually see the deep cold over northern U.S. and eastern Canada retreat west and a SE ridge develop. This *may* relax the jet downstream over the Atlantic heading NE to allow the Euro high to ridge further north. But we still need more energy/troughing to undercut over SW / S Europe - aka -NAO, something that seems to be increasingly hard to attain in winters these days.

But the fact that there is this pattern change upstream indicated, not just by EPS, but GEFS too, plus tropical forcing is pretty active over the maritime continent (SE Asia) despite the incoherent and conflicting MJO forecasts from many models, there is a glimmer of hope that we may see changes later in the month to shake up the stagnant pattern.

Edited December 11, 2016 by Nick F

[johnholmes]

As Nick F points out the major change on NOAA anomaly charts is in the far west, from marked ridge and +ve heights shown (quite high values) to a trough. No change shown yet in the far east with ridging and +ve height centred in about the same position +/- 1 degree or so, similar on the 8-14. Nevertheless some change seems probable as the overall wavelength must shows some reaction to what is predicted to happen in the far west. The outcome is far from clear but worth watching over the next couple of days or so.

[Guest]

WINTER 2016/17 FULL REPORT No. 3 WITH DECEMBER 11TH INPUT

Please note that most of the charts that I refer to in this post are through “live” links which update periodically. So, if you are reading this a few days or even hours after publication (on Sunday, December 11th at 2230), some of the charts may already have updated. My comments relate to what the charts showed at the time of this posting.

My normal intention is to time these updates for my full weekly report to include Dr Judah Cohen’s latest Arctic Oscillation report (usually produced in the late evening each Monday). Judah will be attending a conference early this coming week and states that his blog is likely to be delayed and interrupted. Given that everything remains on a knife edge, his latest views will make for essential reading. So I will proceed with the rest of my report now (excluding the Judah Cohan update)  and then produce an interim update during the week focusing almost entirely on Judah’s next update.

Why Are The Models Continuing To Struggle?

It has been yet another extraordinary week of wild swings in almost all the model outputs with very little consistency from one run to the next with lurches between blocked and mobile solutions beyond about D6. Yes, there is broad agreement in the very short term regarding this week’s mild spell and slightly less settled pattern, particularly in the west (high pressure never too far away) but from next weekend the real fun and games begin.

In my last report (see page 13 of this model thread) I went through an overview of some of the factors involved and what we should look out for. I always try to keep my reports straightforward and easy to understand, partly to appeal to the majority of readers who (like myself) are not experts but mostly due to my rather limited knowledge of the more complex science behind the teleconnections! I leave that for the experts to explain and try to learn all the time (as I have been doing for 60 years!). There have been some fascinating contributions from many of them during the last few weeks and some excellent updates in recent days. Their posts are so much appreciated by “most” of us but there is a minority who seem to moan and complain if they do not like what the messenger is delivering or explaining!. It really would make this place better for everyone if the moderators carried out more of their warnings to suspend the worst and most persistent offenders – not just remove the posts. I appreciate that the mods have a difficult task and emotions can swing just as wildly as the models do! We must do our part and show complete respect for each other and any rudeness is totally unacceptable. The criticism by some posters of the long range forecasts (and even the forecasters) has been harsh and occasionally outrageous. Constructive comments are fine and to be encouraged but not a blanket dismissal just because they have appeared to fail or one is not happy with the current predictions or model output shows a different outcome to what had been expected.

Tamara made an outstanding and thoroughly balanced post earlier today explaining why there continues to be so much uncertainty. She, as well as a number of other experts including some of the professionals like Fergie, Nick F and GP (to name a few) have tried their best to tell us how unusual the current set-up is and why we should continue to expect further swings in the model output during the coming days and perhaps even weeks until some of the issues are resolved. Yes, I am a true coldie but I find this great uncertainty intriguing and try to focus on this. For example, rather than get into a complete frenzy if the chances of a white Christmas or a very front-loaded Winter seem to disappear (not completely judging by some of this evening’s output!), I take pleasure in trying to understand why things have changed, what went wrong and how might things improve again before too long.

Just because we have seen a strong recovery in the strength of the Polar Vortex, the cold snap in North America firing up the Jet Stream, a more mobile Atlantic and a mild south-westerly for the first time in many weeks does not mean that we are about to see a repeat of last Winter. In fact, things are still very different this Winter. Last Winter, we saw a near record breaking El Nino, a record strength Polar Vortex and record December warmth. The SSW - Sudden Stratospheric Warming (seemingly a very likely event later in a typical El Nino Winter) expected for late January was delayed for some weeks or struggled to fully propagate down to the surface until late March and then we ended up with a very delayed start to Spring. Some of the experts felt that the El Nino forcing was almost too strong and interfered with some of the normal responses..

Moving into this Winter we have seen the change to ENSO neutral conditions, bordering on a weak La Nina state but not quite getting there (at least so far). We have just had a record weak Polar Vortex during November. Yes it has strengthened with a strong lobe moving into Canada producing a very cold snap in North America right down to the central and parts of the lower states. This in turn builds up a stronger temperature contrast between the US mainland eastern seaboard and the western North Atlantic which produces a much more powerful Jet Stream. The question is whether this a major change that will dictate weather patterns for some weeks to come or a temporary interruption to the pattern that was established during the last few weeks. Is it a problem with timing the change and/or will we see another equally dramatic change.

Last week Judah Cohen more or less repeated what he had forecast previously (it's possible that he may revise this in his next update) with a temporary weakening of the European cold, a temporary increase in the strength of the Polar Vortex especially in north-east Canada (as opposed to Siberia), a temporary very cold snap moving down into North America, a stronger Jet Stream but still likely to split as it hits the Western Europe/UK high pressure block (which he describes as highly anomalous and persistent), followed by a re-strengthening of the much more dominant Polar Vortex lobe in Siberia, with the deep cold in Siberia expanding again and, in time, moving back towards Europe. During this week, he produced a tweeted comment (someone posted it on this thread) drawing attention to enhanced cold moving into Europe (he did not state whether this would be limited to eastern and central Europe or spreading towards us too – we’ll need his next full report for that detail). He based this on rather more successful propagation dripping down to the surface from the stratosphere. Please note, that I am not trying to ramp this up to mislead anyone, things may change but I do have huge respect for Judah’s forecasts and his research into the relationship between north Asian Autumn snow cover extent, Arctic sea ice build- up (or lack of it) and SSW events, likely to impact on HLB reflected in the AO.

So, I will continue to focus on these drivers and impacts and look to see if there are indications signalled in the models. I have been fascinated and a little confused by the supposedly somewhat difference in opinions between two of our excellent resident posters regarding the anomaly charts. These are “Knocker” and “John Holmes” who seem to have great mutual respect for each other and usually sing from the same hymn sheet. I fully appreciate that any differences in timing, the period referred to and which model output is used can make a difference but why is John rather more bullish about the blocked pattern (particularly on the 10-16 day charts) than Knocker is? It would be most welcome if one or both of you could pick up on this point (differences noted particularly on your Saturday posts).  

Now my personal take on this for what it’s worth. There are indeed indications on “some”  models that the Polar Vortex lobe in north-east Canada may well weaken again from later next week (caution: some other models do show the complete opposite!). Several posters have drawn attention to this earlier this evening. Consequently, the cold snap in North America may fade later on. In fact, it does look like the greatest and longest extent of the cold will become more restricted to the western states. There seems to be quite persistent higher pressure close to or just off-shore from south-eastern USA. All these factors might well help to weaken the Jet Stream again which will make it even more likely to meander and/or split and together with at least decent mid-latitude blocking in our vicinity ought to divert the Jet well away from our shores. So, I do not see a return to a strong zonal pattern, at least not until the New Year and perhaps not until much later in the Winter. This does not rule out short periods of mild Atlantic conditions. I strongly sense that everything is still very much up for grabs. I fall into the camp that feel that we need to tolerate the current mid-latitude high pressure block for a while longer in order to give us a chance of dragging in some decent cold uppers. Of course “meridional” can mean southerly as well as northerly. I will still be looking to the east for some proper cold.

Dr Judah Cohen’s Latest Arctic Oscillation Report:

Please refer to my note at the top. No update right now but I will provide a separate report on here when it’s published later this week. In the meantime, here is the link to his previous report from December 5th:

http://www.aer.com/science-research/climate-weather/arctic-oscillation

Arctic Sea Ice News and Analysis:

The last full update was published on December 6th. Here’s the link:

http://nsidc.org/arcticseaicenews/

This highlights the record low overall Arctic ice extent during October and the very slow recovery during November. There has been a strong recovery during the last 10 days but it’s still below the previous low set in 2012. The Baring Sea and Kara Sea on our side of the Arctic have started to recover but still have well below average ice build-up and in all other parts of the Arctic the ice extent is either below or well below average. I would expect a decent recovery to continue on our side of the Arctic from a very low base. Last Winter, the record strong Polar Vortex sent a roaring Atlantic Jet Stream right up towards the high Arctic which greatly restricted ice build-up for weeks on end. So far this Winter, this has not been the case, although other factors are also at play. See later for my analysis of current Arctic surface temperatures..

.Arctic Oscillation (AO) 14 Day Ensemble Charts (updated December 11th): 

The Arctic Oscillation, which had been negative until last week, is now positive and looks to trend even more positive during the next 5 to 7 days before moving sharply lower after that with 8 of the 11 members trending negative from around December 20th.This continues to demonstrate the current uncertainties which is evident across all the models. A negative AO would reflect greater high latitude blocking and there remains some evidence of this towards the end of the 14 day period. Here’s the link.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao_index_ensm.shtml

North Atlantic Oscillation (NAO) 14 Day Ensemble Charts (updated December 11th):

The NAO has been negative and is currently close to neutral. About a third of the ensemble members go positive and stay there (but not strongly so) with another third going negative again within 5 to 7 days and the rest close to neutral. With this 3-way split, I feel that it only serves to reflect the extreme uncertainty beyond D6 and it would be dangerous to infer anything else other than “confused”!  Here's the link:

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.sprd2.gif

Please note that both the AO and NAO charts I show are based on GFS ensembles so are indicative of their modelling and not the ECM and UKMO output.

MJO Ensemble charts:

Here are today's MJO ensemble charts for the big 4 (all updated on December 11th). 

UKMO (7 day forecast):  

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ukme.shtml

ECM (14 day forecast): 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ecmm.shtml

NCEP/GEFS (14 day forecast):

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ncpe.shtml

JMA (9 day forecast):  

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/jman.shtml

Please note that last Winter I reported on Kyle MacRitchie’s specialist MJO predictions which seemed to always differ somewhat from the big 4. I have been in contact with Kyle during the summer and he feels that his charts are not adjusted frequently enough and should not be compared to the others. So, unless Kyle improves his updating standards, I shall discontinue reporting on his predictions for the time being.

COMMENT: This has improved somewhat during the last few days. All 4 start the MJO off in the circle of death (COD) but close to the phase 4 boundary and then re-enter the COD. The UKMO (shortest forecasting period) has it moving towards the phase 7/8 boundary but at minimal amplitude. The ECM attempts re-entry at phase 7 in about 5  to 7 days but the mean returns to the COD but there is quite an ensemble spread with some members remaining in phase 7, several spread into phase 6 and phase 8, at slightly increased amplitude. The NCEP/GEFS is similar to the ECM but with more members in phases 7 and 8 and mostly at reasonable amplitude. The JMA is also similar but in phases 8 and 1 rather than 7 at low to moderate amplitude. The overall picture  underlines the current uncertainties and the higher degree of optimism from all 4 models in respect of the MJO coming to life in the important phases 7, 8 and 1. We do need the recent trend to continue and to evolve with greater amplification before it is likely to have much of an impact.

Northern Hemisphere Snow Cover:

I show animations for snow cover and sea ice changes. These are produced by the National Ocean and Atmospheric Administration (NOAA).  When you go to their site you can change the date range and look at the Autumn and Winter seasons and set the date ranges. These are brilliant, very informative charts and great to play around with. I’ve set the links below to show the last 2 weeks from November 27th to December 10th:

a) Animated Northern Hemisphere Snow Cover Changes (updated by NOAA December 11th):

https://www.ncdc.noaa.gov/snow-and-ice/snow-cover/nh/20161127-20161210

b) Animated Europe and Asia Day Snow Cover  (updated by NOAA December 11th):

https://www.ncdc.noaa.gov/snow-and-ice/snow-cover/ea/20161127-20161210

COMMENT: There is well above average snow cover over northern Asia which has continued to expand and spread southwards and westwards in the last few days. Much of Scandinavia continues to have decent snow cover (the high plateaus should have snow cover for most of an average Winter) The snow cover currently extends to eastern and northeastern Europe but not quite so far westwards. North American snow cover has increased due to the current cold snap. The Arctic ice sheet has expanded quite quickly during the last few days but is still below the 2012 level (the record low year). The ice extent in the east of the Kara and Baring Seas has grown rapidly in just the last few days (there was a period of below average temperatures there for a few days – see later).

Current Arctic Regional Surface Temperatures:

GFS – Northern Hemisphere Current Temperatures:

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=6&mode=9&carte=1

The link to this chart updates 6 hourly with each GFS run. At the time of writing it is showing a chart for 1900 GMT today (11th December). As this is T0 to T6 hours, it should be pretty accurate. Here is a summary of the temperature readings that I will be following in future reports with comparisons for the previous reading on December 5th in brackets:

North Pole –  -16c to -24c (-28c to -32c).

Barents Sea/High Arctic – 0c to -16c (-16c to -20c).

Scandinavia – south 0 to -4c (+4 to -8c); north -4c to -16c (-12c to -20c).

Northern Siberia - -28c to -40c with a wider area now below -40c  (32c to -40c).

North West Russia - around -16c to -24c.(no change)

North-east Europe – -4c to -16c (-4c to -8c).

I shall add Greenland some North American temperatures from now on (inland, not coastal):

Greenland: -4c to -32c.

Canadian Arctic: mostly -12c to -32c.

Alaska: 0c to -16c.

Western USA: -12c to -24c.

Central USA: -12c to -20c.

Eastern USA: -8c to -20c.

Please note:   At the time of posting this link it was showing 2000 BST on Sunday, December 11th. I will always try to show the 2000 BST (1900 GMT) charts for a consistent comparison. The charts are automatically updated 4 times a day, so the temperatures shown will be different to those I just mentioned above. We can follow the trends by looking at the latest data at any time from now on. It is vital to note the time of day to take account of daytime/night time variations. So for like for like comparisons, for example the 2000 charts for each day should be available to view from the 12z (T+6) updates which are published around 1600 to 1700 or about 4 to 5 hours later. This also applies to some of the other charts I link to in this post.

Svalbard Daily “Maximum” Temperature Forecast for 10 Days:

Here are the links to the 3 Svalbard stations that I am monitoring.

Central/West Svalbard – Longyearbyen 28 m asl:   

http://www.yr.no/place/Norway/Svalbard/Longyearbyen/forecast.pdf

December 12th  -16c;    December 16th   -1c;    December 20th  -4c.

North-West Svalbard – Ny-Alesund:  

http://www.yr.no/place/Norway/Svalbard/Ny-Ålesund/forecast.pdf

December 12th  -12c;    December 16th   -2c;    December 20th  -8c.

Central South Svalbard – Sveagruva:   

http://www.yr.no/place/Norway/Svalbard/Sveagruva/forecast.pdf

December 12th  -15c;    December 16th   -4c;    December 20th  -8c.

The “maximum” temperatures fell to between -20c and -25c  during the last 2 days which is their lowest levels for several years. The trend for this week is for a temporary recovery to close to 0c with some snowfall before they fall again later on but not as low as last week (for a while at least). The recent very cold snap is reflected in the rapid ice growth in the last few days but this may slow again.

These links will update automatically at frequent intervals throughout the day. They are the Norway met office’s predictions. We need to be aware that these are only a forecast that is subject to change and I am told that the Arctic surface temperature forecasts are not completely reliable even at short range. 

To put the above figures into context, here is a link to the main Longyearbyen site:  

http://www.yr.no/place/Norway/Svalbard/Longyearbyen/statistics.html

 This shows monthly means, and actual highest/lowest temperatures recorded during this winter and goes back further. Svalbard has been seeing “maximum” temperatures often running at 8c to 10c above their long term average throughout most of 2016. This has been the pattern for several years and is reflective of the warming Arctic and record low sea ice cover. The very recent trend was more encouraging with temperatures falling to slightly below their long term averages for 4 days. The longest period of below average temperatures for about 3 years! Sea ice may continue to grow more quickly in the coming weeks. It could mean that a northerly airstream from the high Arctic might have slightly more of an edge to it and could be the difference between rain and snow over lowland Britain given a marginal pattern. I still feel that we need to look to the east for any pronounced and more prolonged cold during late December and into January.

Final Comment:

Most of the models, indicators and forecasts continue in a very uncertain state. I still feel more optimistic than most and many of my indicators support this to a degree. Perhaps things will become clearer as the month progresses.

Next Update:

I’ll try and manage another full update to this report in a week’s’ time with the Judah Cohen report in between.

 

Edited December 12, 2016 by Guest
Correct typos and ensure all the links work

[fergieweather]

Incidentally, after such a prolonged period of close broadscale agreement between runs of GloSea5 and ECMWF Seasonal, you'll note now how they finally bid each other farewell in their respective Dec updates and ride their own separate ways into J-F-M. Glosea fits with previous thinking (a marked switch away from -ve NAO 2nd half of winter); ECMWF continues similar to before. Of course, the combined 3-monthly means mask detail of how the journey unfolds, but it'll be intriguing to watch.

[Sawel]

Do the Met Office put more credence in GloSea5 than they do the ECMWF Seasonal model? Like, say they were the only 2 models that existed and they're showing completely different scenarios.