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

[Cheshire Freeze]

5 minutes ago, booferking said:

I thought the Atlantic powering up would reset the setup but i beginning to think i am so wrong very frustrating..

It's not a proper Atlantic power up though, that's the issue- merely a temporary few days where things get a bit more lively. The issue is there's no way low heights can sustain in Europe where we need them because of that monster HP that is rooted all the way down into Africa as I've already said. If this was summer we'd be breaking heat records with that HP sat there pumping up plume after plume. It's the type of pattern that can last a season.

I think we all know when the N'lys will start.

Edited December 19, 2016 by CreweCold

[Northern Sky]

9 minutes ago, CreweCold said:

Look where the high has its foundations...it's been the same for a while now. Not a chance that is changing unless something comes along to completely change the set up. The optimism that initially looked to be there on the run up to the new year has all but dissipated. There's no dressing this up anymore. I'm beginning to wonder whether lowland southern UK will actually see snow before Feb.

This shows how grim the situation is...look where the high is rooted to...yes, Africa

A hot summer pattern in winter....

Hi Crewe, what is it that is causing this high to be so persistent? And, more importantly what needs to happen to get rid of the blasted thing?

[January Snowstorm]

The Ecm is performing very well this year. It was the first to pick up on the euro high yesterday. The gfs as per usual over egging low pressure systems.

[Cheshire Freeze]

1 minute ago, Northern Sky said:

Hi Crewe, what is it that is causing this high to be so persistent? And, more importantly what needs to happen to get rid of the blasted thing?

In laymans terms there is absolutely nothing churning the atmosphere. We're stuck in the doldrums as it were. At this point it'd be better to have a stronger ENSO signature either way as it would, at least, allow for some diversity from the current set up. We just have no forcing from anywhere at present and until this changes we will not see a change in our fortunes. 

All we're seeing at present is a flattish jet running over the top of mid latitude features (one of which happens to be knocking around our shores). Every time the HP tries to gain some amplitude, the jet just rolls it back over again. Rinse and repeat. It can do this for as long as it wants and whilst it happens, our weather remains static.

[snowbunting]

The meto office has issued us with a yellow be aware warning for lightning and wintry showers wed into Thursday for the western Isles. Any idea how severe it is likely to be?  From the charts the Western Isles is about to get all flavours of weather over the next few days.

[stewfox]

6 minutes ago, LRD said:

Thanks Ian

Got to say that's a horrible update for someone like me who wants something resembling a winter. It sounds very 1988-89. Mild and dry. The worst winter weather possible. No cold but a lot of nothingness

I thought that positive anomalies to the west of the UK might give us colder temps though. Or is it HP sitting pathetically just to the west and SW and so tropical atlantic air is moving over the top of it?

In the reliable we have a lot of PM around with max temps below freezing on Christmas eve in parts of Scotland and potential storm force or above winds for Christmas day when folk sit down to their Christmas dinner in Scotland. I don't call that nothingness ? . FI T168

 

 

[Man With Beard]

3 hours ago, booferking said:

The last 3 charts have the slug wrote all over them...

I ain't so negative about this EC monthly update. I suppose what you're hoping for is Week 1 to be spot on, week 2 to be fairly close and then an ever increasing envelope for error at week 3 and onwards - so that week 3 gives a very general idea of the pattern from a hemispherical point of view, and week 4 simply the hope that anomalies will still be there by week 1 in the same ocean or continent!! 

With that as a mental guide, well, I would call the week 3/4 charts as being "options open" charts. A positive height anomaly over the UK - well, that could be accurate (perhaps 1 in 4 recent EC monthlies at week 3 have been as accurate as this :0), or heights could be up to a 1000 miles south, east, west or north. So in other words, my translation of weeks 3-4 are "anything is possible". I accept that the strength of the PV means proper HLB is unlikely, but, had the height anomaly been say over Spain or France, I'd say we'd be in a much less hopeful position of getting a favourable tweek.

So not a fantastic position, but no write-off either.

EDIT - of course, the caveat being the ensemble clusters  - a 50/50 split between HLB and Iberian heights would produce the same mean - hopefully Ian will be able to comment on this later...

Edited December 19, 2016 by Man With Beard

[Chris.R]

19 minutes ago, Northern Sky said:

Hi Crewe, what is it that is causing this high to be so persistent? And, more importantly what needs to happen to get rid of the blasted thing?

Perhaps an expansion of the Hadley cell, maybe  caused bye climate change.  Only a dramatic pattern change my get rid of the high for a time. 

https://en.m.wikipedia.org/wiki/Hadley_cell

[swilliam]

7 minutes ago, CreweCold said:

It's fact, based on what we're seeing being modelled in front of us. Don't know what you want people to say? 

It is not fact in that this is NWP for 9 days away - we will have to see what the actual fact is. What is fact is that climatology tells us that the normal/average/most common situation is for us to have high pressure to the South and low pressure to North (not sure why this question was asked). This will be shown more often than not in most winters with SW winds. So moaning about it when it is shown seems rather pointless to me. Much more interesting is to see what changes could occur as shown by several of the ensembles (and the ECM yesterday). Often this will get watered down to something less favourable but that is because this is the norm. The actual chart you showed was not that bad as far as I can see as it was reasonably amplified providing the opportunity for something more interesting later. If it was completely flat then we would continue with the zonality with mostly mild, wet windy weather with some Pm incursions in between. In fact the benefit of the amplification  is shown at 384 with a move towards retrogression of the high that does form with some potential.

All this is FI of course but show potential which at that range is all that we can ask. Moaning does not help at all.

[Cheshire Freeze]

Just now, swilliam said:

It is not fact in that this is NWP for 9 days away - we will have to see what the actual fact is. What is fact is that climatology tells us that the normal/average/most common situation is for us to have high pressure to the South and low pressure to North (not sure why this question was asked). This will be shown more often than not in most winters with SW winds. So moaning about it when it is shown seems rather pointless to me. Much more interesting is to see what changes could occur as shown by several of the ensembles (and the ECM yesterday). Often this will get watered down to something less favourable but that is because this is the norm. The actual chart you showed was not that bad as far as I can see as it was reasonably amplified providing the opportunity for something more interesting later. If it was completely flat then we would continue with the zonality with mostly mild, wet windy weather with some Pm incursions in between. In fact the benefit of the amplification  is shown at 384 with a move towards retrogression of the high that does form with some potential.

All this is FI of course but show potential which at that range is all that we can ask. Moaning does not help at all.

I'll repeat, it's a fact that we are discussing what we see in front of us. It's a fact that the NWP modelling is showing less than desirable synoptics through into the new year and it's a fact that it's more than a touch hypocritical that you slate someone for posting a day 9 chart only for you to go ahead and post a day 16 chart and try to use it as evidence of 'potential'.

It's also a fact that there is nothing on the horizon at present which could even begin to change the pattern that we're locked in.

[Guest]

WINTER 2016/17 FULL REPORT No. 4 WITH DECEMBER 19TH 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 Monday, December 19th at 2200), some of the charts may already have updated. My comments relate to what the charts showed at the time of this posting.

Forum Behaviour:

Before I go through my usual routine and give my take on the overall model output and a broad outlook over the next few weeks, I must make another attempt to persuade everyone to be respectful of each other’s opinions. It would be great if the season of goodwill could apply to our model thread and throughout the whole year as well. I have thought long and hard about this and will address some of the issues in a slightly different way and I hope that all the moderators take note too. I will never name and personally criticise individuals and I only name other posters when I have something complimentary to say. We have the “report a post” button if we wish to alert the moderators to unacceptable comments. This should not be confused with making a direct reply to another post. Everyone is entitled to their opinion and also to disagree with anyone else – it is the manner in which this is done that causes so many of the problems.

I feel that during the rest of the year, outside the Winter season, there is far more harmony and mutual respect on this site and the moderators have a much easier time. This is largely due to the much smaller number of posters and readers during these seasons. Then as we approach Winter the level of interest explodes into life. The vast majority (myself included) are coldies and snow lovers. Many members avidly join the chase for deep Winter cold but, unfortunately, too many seem to seek almost instant gratification. The mood swings in line with the model output. Excitement and optimistic expectations are quickly followed by disappointment and desperation and this is repeated over and over again as the signals fluctuate. An indication of a colder outlook takes the forum to fever pitch and many posts are ramped up. The professionals and more seasoned and experienced amateurs usually try to manage expectations choosing their words very carefully but sometimes even a “hint of something more interesting” is seen as it might well happen and a “higher probability” is read as “almost certainly will happen”. A predicted “blocked pattern” is often interpreted as bringing certain cold but as we have witnessed in the last few weeks if the blocking is in the wrong position it may be settled but often not cold at all.

A sudden change in the outlook to something less cold or a mild spell is often met with disbelief and horror. Then all hell breaks loose. Moaning and bickering turns into blatant criticism of the models, the forecasts, the background signals and finally into some posters insulting their fellow posters who were behind those forecasts and “shooting the messenger”. Comments like “complete fail” and “100% wrong – fact” get banded around and are usually very wide of the mark and thoroughly misleading causing confusion and even greater unrest. Many explanations aimed at defending these “alleged” culprits are simply shot down or ignored. Suggestions that “I will write-off this Winter, so see you next year” are quite extraordinary and no one has ever been able to justify such a remark made so early in the season. Anyway, if they really meant what they said, why do they return several weeks later with exactly the same comments? Those who have taken the time to post something more meaningful (and there are many excellent contributions from our resident experts as well as a whole array of interesting posts from many other members) simply become swamped by the sheer number of posts with critical remarks without any reasoned arguments, the crude one-liners and some completely off-topic statements. This makes the thread very difficult to wade through and complaints about these start to crop up regularly. The moderators remove many of the most offensive and most irrelevant posts but I, for one, would like to see them take some much tougher action.

There is a real danger that the Winter model thread will match some of the worst examples of communication seen on other social media like Facebook and Twitter. This year we have seen some worrying divisions opening up in the world. We have Brexit with many Remainers and Leavers still at each other’s throats six months after the referendum. A similar divide has been exposed in America and this seems likely to spread across much of Europe and into other countries. There seems to me a similar divide across this model thread between those criticising the long range forecasts, background signals and even the whole science of meteorology and those defending it.

It does NOT need to be like this and I feel that the vast majority of us are really decent people most, if not all, of the time. We “all” have a responsibility (readers, posters and moderators alike) to ensure that this is a friendly place for airing opinions with respectful comments and criticism. There was an outstanding post yesterday by “Trom” (see page 147 of this thread). He directed us to a Wikipedia link which gives a “List of Cognitive Biases” and covers every form of behavioural bias and there are far more than I believed with examples of almost all of them showing up every day on this thread. I strongly encourage “everyone” on this thread to read this. I repeat the link now:

https://en.wikipedia.org/wiki/List_of_cognitive_biases

Every one of us can relate to many of the forms of behaviour shown whether we are newbies, occasional visitors, seasoned posters, experienced amateurs, professionals or even a moderator! Just take a step back and think of your own pattern of behaviour. The “bandwagon effect” (or herd mentality) applies to all those who take one side of an argument against another group who take the other. I put my hands up and fully admit that I have been guilty of many of the traits listed. Even if one can start to understand them or see it in oneself or in others, it is still a question of how one addresses these traits.

So far “Trom” has only had 12 “likes” which suggests to me that many readers either missed his post or did not appreciate its significance. If you agree that we can all learn from this, please give due credit to “Trom” and take the time to go back to his post on page 147 and “like” it. He was very subtle with his brief comments but I make no apology for being far more direct!

The Models and Possible Future Pattern Changes:

Following yet another week of wild swings in much of the model output, they have started to become much more consistent for the 5 day outlook (which they should) with a broad pattern change to much more unsettled and even disturbed conditions. Christmas itself is still out at D5 and D6 with the finer details still not nailed down yet and “nailed-down” may start to take on a more literal meaning if those gale to storm force winds do hit our shores. There are enough short term updates posted on here with a full range of coverage and comments and I cannot add much to this. I will focus more on the period after that.

After Christmas, through the New Year period and into early January we start to see greater diversity again. There has been a recent trend developing showing a recovery to a more blocked pattern again with perhaps this change being suggested as the slightly more probable solution. In fact some of the longer term model output has been indicating this for a while but it has rather been overlooked with so much focus on the Christmas holiday and possibly some disruptive stormy weather. It has got to be said that there is still considerable uncertainty as to the extent of these changes and the timing of them. The MetO medium term outlook does seem to increasingly reflect this more blocked pattern and was suggesting just a hint of the high pressure building to our west during early January. Whether this “might” lead us to some HLB with a more meridional set-up and possibly an arctic outbreak more in our vicinity rather than the MLB we have seen for so many weeks is very much open for debate. There had also been a hint at Greenland and Scandi heights building but at the very time that I am writing this I see that the very latest longer term releases are downgrading the blocking to a much more mixed picture. From what “Fergie” tells us, GloSea5 is pointing more to MLB with the higher pressure to our south again where we do not really want it and a stronger PV maintained. Consequently that means higher temperatures and possibly one or two colder interludes during the next month. ECM have moved recently from less blocked to much more blocked but this evening’s EC32 release posted by “Gael_Force” seems to suggest a slight positive temperature anomaly for the next 4 weeks. There is  continuing uncertainty with very weak signals and I would be very surprised if we do not see more swings in these outlooks. Even small changes might be sufficient to get the blocking into more favourable positions. There is a “chance” of something colder on the horizon but at this stage a greater chance of temperatures averaging out slightly above normal. There is still plenty of time for things to change and Judah Cohen’s Tweet yesterday suggested that the “crunch point” might come in early January. It is 2145 and his latest weekly update has just been published – see next part. I am afraid it is not good news.

I will be looking out for any signs of these changes. I am sure the likes of Knocker and John Holmes with their excellent mean ensemble charts will tell us if there are any hints of any changes as soon as their charts start to show it. In my last few reports I have looked at some of the factors that might drive these changes. I always point out that I am very far from being a teleconnections expert and I need to keep things simple for myself and in order to convey my thoughts.

We have seen an extraordinary change in the strength of the Polar Vortex from a prolonged period of almost record weakness during November and into early December to amongst one of the strongest on record right now. Even so, the pattern still looks different to last Winter when the PV consistently kept the cold locked up in the high Arctic. We have been seeing the well forecast widespread very cold snap in North America although this was not quite the record breaking cold that had been indicated and it has eased somewhat in the last couple of days. This has fired up the Jet Stream and, for the first time in weeks, we are seeing a much more mobile Atlantic just about to push in across the country, finally displacing the high pressure that seems to have been here for an eternity.

How long will this last for? The PV could weaken again just as quickly as it strengthened or it could split. There has even been talk of it fragmenting due to the pressures and strains from the stratosphere – this is the bit that is rather beyond my abilities to understand and explain, I just try to follow the guidance from our much more knowledgeable posters. There has been mention of a Sudden Stratospheric Warming event (SSW) at some time in the first half of January. If these events happen it can take anything from about 10 days to 6 weeks to show signs of impacting on the surface (if at all) although several experts have suggest that given the unusual state of the stratosphere if we were to see an SSW soon (within the next 3 to 4 weeks) it could possibly propagate down to the surface much more quickly than usual. Other factors might prevent this. Even if none of these changes transpire, the PV and the broad pattern could still move into a more favourable position to deliver something more interesting to our shores. In my view, there is still plenty to be “hopeful” about and to look out for. We have been going through a highly unusual sequence of events and we should keep an open mind as to how this Winter might unfold.

Dr Judah Cohen’s Latest Arctic Oscillation Report:

Here is the link to Judah Cohen’s latest update published at 2145 on December 19th.

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

Now I copy his summary and impacts below.

"...Summary

The Arctic Oscillation (AO) is currently positive and is predicted to first trend positive towards strongly positive and then trend negative back towards neutral.  However the models do not predict a negative AO in the foreseeable future.

The positive AO is reflective of mostly negative pressure/geopotential height anomalies in the Arctic and mostly positive pressure/geopotential height anomalies across the mid-latitude ocean basins. With negative heights over Greenland and Iceland, the North Atlantic Oscillation (NAO) is currently positive and is also predicted to remain positive over the next two weeks. 

The persistent positive AO will likely result in a mild pattern over western Eurasia, especially Northern Europe.   Cold air currently over Western Asia will be shunted further east into East Asia over the next two weeks.

North American weather will be more sensitive to the circulation in the North Pacific.  A return to more zonal flow this week will bring an end to the cold pattern.  However a new ridge/positive geopotential height anomalies centered near the Aleutians will help amplify a trough/negative geopotential height anomalies downstream over Western North America and a return to colder temperatures across Alaska and Western Canada heading into the new year.

The polar vortex (PV), which has been relatively weak since the end of October is predicted to transition to relatively strong this week and remain strong the next two weeks.  This is consistent with the model forecasts of a relatively milder pattern across the Northern Hemisphere (NH) especially northern Eurasia.

The strengthening PV is related to predicted below normal poleward heat flux over the next week.  However in my opinion there are signs that the poleaward heat flux will turn more active in the coming weeks that should result in further perturbations of the PV.

Impacts

It is my opinion that any atmospheric response to extensive snow cover across Eurasia in the month of October has now ended.  The most direct impact of the extensive snow cover was a weakening of the PV, which resulted in cold temperatures first across Northern Eurasia in November followed by cold temperatures across northern North America in December.  With the conclusion of that cycle, the PV is recovering and is predicted to swing into the stronger than normal category.  This will likely result in an overall milder patter as we close out the month of December.  I did think that the cold pattern might persist just a little longer but that idea is not supported by the latest polar cap geopotential height anomalies (PCHs) shown below.

With the signal from the extensive snow cover ending, there is much uncertainty in any long-range predictions, at least for me.  Instead I am relying more heavily on sea ice extent anomalies in the Barents-Kara Seas for predicting variability in the PV.  Sea ice extent was likely record low in the Barents-Kara seas earlier this fall but the sea anomalies don’t look as impressive to me this week.  Still based on low sea ice in the Barents-Kara Seas, I anticipate further perturbations to the stratospheric PV this winter.  Also the atmospheric circulation looks to me more favorable for increased poleward heat flux than it has for the past several weeks.

We run daily at AER an experimental 30-day forecast model of the strength of the stratospheric PV.  The model is predicting a significant weakening of the PV during the second week of January.  The model is known to be overly sensitive to PV weakenings, but last winter it did anticipate the timing of PV weakenings even if it did predict the amplitude incorrectly.   Also I did inquire more about the quasi-biennial oscillation (QBO) while I attended AGU last week.  The QBO is clearly in its westerly phase this winter.  Also a westerly QBO favors a relatively stronger PV and inhibits sudden stratospheric warmings (SSWs).  Therefore a full reversal of the zonal winds might be difficult this winter (referred to as a major mid-winter warming), and instead might favor more of a PV stretching or elongation as occurred earlier this month and occurred repeatedly in the winter of 2013/14, also a QBO west winter.

An elongation of the stratospheric PV often promotes cross-polar flow into both North America and Northern Asia.  This circulation configuration would favor cold temperatures in parts of Canada, the US and Siberia but not probably Europe as the wind direction often remains westerly, a mild wind direction.  Also I anticipated that negative sea ice extent anomalies would become fully focused in the North Atlantic side of the Arctic favoring cold temperatures in Eurasia.  However negative sea ice extent anomalies remain in the North Pacific side of the Arctic favoring cold temperatures in North America.

Finally an alternative but plausible possibility is that a troposphere-stratosphere-troposphere coupling event is underway that favors a positive AO and strengthened PV both in the stratosphere and troposphere.  In that scenario we would have a mild pattern in the NH possibly interrupted by a colder pattern before transitioning back to a mild pattern for much of the duration of the remainder of the winter.  If the Wave Activity Flux (WAFz) either remains relatively quiet or directed towards the equator this scenario becomes much more likely….”

BRIEF COMMENT:

Unfortunately this speaks for itself and is a further downgrade on Judah’s last few reports and does not make particularly good reading for coldies. At least it does explain some of the things that went wrong. I was really hoping to post something a little more encouraging. I’m only the messenger but I can see myself being shot to pieces! Right everyone – chins up, things have been so topsy turvy, we could still see some unexpected changes for the better. I will keep looking for any more positive signs.

Arctic Sea Ice News and Analysis:

The last full monthly report was published on December 6th but please note that the ice extent map and the comparison chart to the mean are updated daily and are of some interest. 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 very strong recovery during December and it’s now only just shy of the previous low set during Winter 2012-13. The Baring Sea and Kara Sea ice extent on our side of the Arctic has also started to recover much more quickly but is still well below average. The recovery is also evident across other parts of the Arctic, particularly the ice extent in Hudson Bay and around the Canadian islands which has increased very rapidly due to the North American very cold snap. 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 in the part of the Arctic nearest to us. 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 and snow cover extent.

Arctic Oscillation (AO) 14 Day Ensemble Charts (updated December 19th): 

The Arctic Oscillation, which had been negative until last week, is now positive and is trending strongly positive during the next week before peaking and turning down again strongly. Almost all of the 11 ensemble members trend down continuously around the turn of the year and half are close to neutral again by then. So we need to watch this trend – it could be just one indication reflective of a possible change to greater HLB in early January. 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 19th):

The NAO is mostly positive but some of the ensemble members move back towards neutral around the turn of the year. 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 19th). 

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:  The UKMO (shortest forecasting period) is now showing the MJO emerging from the COD (Circle of Death) in phase 5 at low amplitude. The ECM is quite different. It generally keeps the MJO in the COD but close to phase 6 and onto phases 7 and 8 by next week. There is a wide scattering of the ensemble members and some do get into the key phases 7 and 8 at slightly more amplitude The NCEP/GEFS is more encouraging. It starts off in phase 5 like the UKMO and re-enters the COD re-emerging in phase 8 around the turn of the year but it ends around the phases 8 and 1 boundary at considerably higher amplitude, This may well change again but it is the sort of output that we need if we want a stab at greater HLB and is the best indicated for many weeks. The JMA is a halfway house between the NCEP/GEFS and the ECM. The overall picture underlines the current uncertainties but 3 of the 4 models are more encouraging.

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 you can change the speed and pause on any particular day. These are brilliant, very informative charts and great to play around with. I’ve have re-set the links below to show the last 2 weeks from December 4th to December 18th:

a) Animated Northern Hemisphere Snow Cover Changes (updated by NOAA December 19th):

https://www.ncdc.noaa.gov/snow-and-ice/snow-cover/nh/20161204-20161218

b) Animated Europe and Asia Day Snow Cover  (updated by NOAA December 19h):

https://www.ncdc.noaa.gov/snow-and-ice/snow-cover/ea/20161204-20161218

COMMENT: There continues to be well above average snow cover over northern Asia. Much of Scandinavia continues to have decent snow cover (the high plateaus usually have pretty complete snow cover for most of an average Winter) The snow cover currently extends to eastern and north-eastern Europe and partly into central Europe. Unfortunately this may well be the maximum extent that we see in Europe for quite some time. North American snow cover has increased significantly due to the  very cold snap. The Arctic ice sheet has expanded quite quickly during the last few days (as described earlier). The Hudson Bay has gone from almost ice free to completely ice covered during the last week.

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 (19th 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 to my previous readings on December 11th in brackets:

North Pole:  -20c to -28c (-16c to -24c).

Barents Sea/High Arctic:  -4c to -16c  (0c to -16c).

Scandinavia: south 0c to -4c (little change); north 0c to -4c (-4c to -16c).

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

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

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

Greenland: -20c to -36c (-4c to -32c).

Canadian Arctic: mostly -12c to -28c (-12c to -32c).

Alaska: -8c to -24c (0c to -16c).

Western USA: -4c to -12c (-12c to -24c).

Central USA: 0c to -8c (-12c to -20c).

Eastern USA: -4c to -8c (-8c to -20c).

Please note:  For land masses I have tried to focus on readings away from the coasts and away from any mountainous areas.  At the time of posting this link it was showing 1900 GMT on Monday, December 19th. I will always try to show the 1900 GMT (2000 BST) 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 1900 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 20th  -3c;    December 24th   -8c;    December 28th  -10c.

North-West Svalbard – Ny-Alesund:  

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

December 20th  -5c;    December 24th   -10c;    December 28th  -15c.

Central South Svalbard – Sveagruva:   

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

December 20th  -4c;    December 24th   -10c;    December 28th  -16c.

The “maximum” temperatures fell to between -20c and -25c  during the second week of December and then recovered to around 0c for the last few days but are set to fall back again considerably from Wednesday onwards.

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 in early December  which is the longest period of below average temperatures for about 3 years! The coming week will see maximum temperatures just above their means but much lower than right now.

Final Comment:

Most of the models, indicators and forecasts continue in a very uncertain state and so does Judah Cohen! I still believe that things can change for the better during January and I will continue to look for any more encouraging signs. Please note that I am trying to put a brave face on things but with so many uncertainties there is no call for either extreme pessimism or extreme optimism. Perhaps things will become clearer as we move into the new year.

Just before I sign off, I would like to say a big thank you to all our regular posters, especially those that put so much thought and preparation into their updates. The minority that keep on posting throughout the whole year through thick and thin deserve a special award and have my utmost respect – thoroughly appreciated.

I wish everyone a very Happy Christmas whatever the weather. Let’s hope that early 2017 brings at least some much more seasonal weather and something for the many long suffering coldies.

Next Update:

If there are no major imminent pattern changes indicated from early next week onwards, I will probably not submit a report next week and will leave it until around or just after Monday, January 2nd.

 

Edited December 20, 2016 by Guest

[Singularity]

When the MJO moves through phases 5-6-7 in Dec it's common to see a blocking high develop over Europe, edge up through the U.K. and then become a HLB.

Trouble is, most models are seeing some phase 5 MJO activity but with little appetite to take it on through 6-7. So the Euro high is pumped up but sees little impetus to gain much latitude.

GEFS have become very keen on a move to phase 8/1 MJO week 2 having taken it through 6-7 in 'stealth mode' I.e. With little activity to force the patten. This route sees forcing trying to move our HP west of the UK and then perhaps build it north but only if the atmosphere stays away from a La Niña state (still possible IMO).

ECM ens share the direction of GEFS but are slower and weaker with the activity. This links to the faint suggestion of moving HP west of the U.K. but a lack of ensemble consensus for any gain in latitude.

Given that this MJO forcing is also a good way to drive attacks on the lower stratospheric vortex to avert disaster via the upper beast propagating down, it feels like we're waiting for the DJ to start the party when they're not even through the door yet and nobody is sure whether anyone got around to hiring them in the first place!

[chessfiend]

18 minutes ago, Chris.R said:

Perhaps an expansion of the Hadley cell, maybe  caused bye climate change.  Only a dramatic pattern change my get rid of the high for a time. 

https://en.m.wikipedia.org/wiki/Hadley_cell

 

I thought climate change was supposed to make NW Europe cooler? There has always been climate change, always will be (until we are Masters of terra and meto-forming).

What I see ATM is our old visitor the Bartlett High (respect there as always) and honestly it doesn't matter whether it is El Nino, La Nina, NAO, SSW or the kitchen sink, our global position (large ocean, prevailing winds) will nine times out of ten give us very predictable maritime mildness. So watch the models, understand their bias and tendency, and enjoy what we get in this unique island off the west coast of Europe.

And chasing snow is one of the reasons why my second home is Colorado  and, guess where I will be in February?

[Scandinavian High.]

Winter is not over high looks to moving north west all in F1 but we have to start somewhere. We have January-February-march- to come yet im not giving up on this winter just because a long range model says no to cold . 

[booferking]

There it is in all its glory now we just need to get it shown at 00hrs

Edited December 19, 2016 by booferking

[Man With Beard]

2 minutes ago, abbie123 said:

Winter is not over high looks to moving north west all in F1 but we have to start somewhere. We have January-February-march- to come yet im not giving up on this winter just because a long range model says no to cold . 

Quite a good cluster on the GEFS going for high pressure centred in the Atlantic for the new year onwards, with obvious risk of a minor topple from the north.

[Summer Sun]

So that's GFS and ECM going for a better boxing day after an unsettled Christmas day 

 

[West is Best]

1 hour ago, January Snowstorm said:

The Ecm is performing very well this year. It was the first to pick up on the euro high yesterday. The gfs as per usual over egging low pressure systems.

It didn't even have the low pressure systems on the charts until today. Very very poor.

[swilliam]

31 minutes ago, CreweCold said:

I'll repeat, it's a fact that we are discussing what we see in front of us. It's a fact that the NWP modelling is showing less than desirable synoptics through into the new year and it's a fact that it's more than a touch hypocritical that you slate someone for posting a day 9 chart only for you to go ahead and post a day 16 chart and try to use it as evidence of 'potential'.

It's also a fact that there is nothing on the horizon at present which could even begin to change the pattern that we're locked in.

Well the point I was trying to make was that the chart you posted was not so bad as an evolution from the current predicted zonal pattern. This is highlighted by for example P8 which is a similar chart at the time you posted

and the situation a couple of days later looks even worse and would no doubt induce a lot of moaning

 

but only a few days later goes to this

 

All speculation of course but shows the potential from the chart you posted  which was the point I was trying to make  - that the chart was not so bad. Most of the HP for MLB and HLB comes from amplification of HP to our S. So as long we get some amplification there are possibilities - as shown by P8 and P2 (even more closely matching the op which you showed) which goes from this

to this

 

 

 

 

 

[Paul_1978]

Well based on Ian's update, it might be just me but I can think of worse places for HP to be than west of the U.K.  

This winter's not over by a long stretch, and there is bound to be some eyebrows raised (in terms of cold weather) over the next few weeks I'm sure. 

Edited December 20, 2016 by Paul_1978

[SMU]

Evening All-

So as we head into the festive period & peoples breaks - the weather sadly is taking a turn for the worse, the vortex initially displaced NW by around 500 miles will wobble back SE & take a westerly swipe at the UK with 1 maybe 2 atlantic storms rolling in-

In terms of a white xmas,Glasgow is the main favourite with maybe Belfast a moderate outside bet as its close to the colder flow- It appears that 'snow' in heavier showers later in the day as the coldest uppers move in would be the best shot- 

unfortunatly the wobble of the PV is set to retreat back NW as the quasi stationary high pressure to our SE develops & moves north again- 

Whilst this is favourable for the UK in terms of keeping the wind & rain away we must not link this with the overall NH pattern changing- quite the opposite infact-

looking at the zonal wind along 60N @ 10HPA we are not at peak yet, peak date is around the 23rd Dec @ about 60M/S ( remember climo for this time of year is around 35M/S ) - so we are the thick end of double the climo norm-  what this actually means is theres very unlikely to be any trop > Strat disconnect & the 200mb jet will follow a very sinuous flow along ~ 60N -

* Teleconnection AO/NAO couplet  expected to be top 10 positives ever recorded with AO close on +5

* Strat signature reminicent of 2013 & 2015

* Recovery time to AVERAGE metrics in the stratosphere ( & net teleconnections ) - 2 weeks, 3-4 post propergation.

* Chances of a greenland high are near on zero for at least 4 weeks.

* Chances of a Scandi high are near zero for 2 weeks

* Chances of a mid atlantic high - low for next 10 days, possible slight amplitude thereafter.

January expectations: 

The worst ( warmest ) Jans post 1979 are as follows 

2007- 7.0   2008 - 6.6 1990 -6.5  1989- 6.1

we see the following Merra zonal wind data-

 

* Sadly our closest match is 88/89 ATM-note the zonal wind never really gets below climo across Jan with no warmings ( remember our start point will be around 50M/S which is very close to the above 4 start points-

conversely our coldest months

1979 - -0.4 1985 - 0.8  2010 -1.4 1997 -2.5 we see the following maps-

The top 3 all have significant warmings reducing the zonal wind - 

Also I have looked at the specific dates of the top 3 in terms of when the warming started (commencement of zonal wind deceleration )to see of these were trop lead - 

1978/79 occured on 14th January

& the 500mb anomalies 5 days prior to the warming - we have a big wave 1 pacific high ( -EPO)

1984/85 occured on the 17th December - 

& the 500 height anomalies 5 days prior to it - we have a big wave 1 Russian High- (-POL)

2009/10 occured on 10th Jan 

& The 500mb height anomalies that preceeded the warming- note the very strong 2 wave pattern over the atlantic & Greenland -

 

so in terms of SSW linked into cold jans looking at the zonal wind V the 500MB plots the trop response to a trop induced warming was instant - the the zonal wind slowed down & reversed 

So its pretty clear that our start point isnt good heading into Jan- 

The indications are that there will be a peak ( as mentioned ) around 23rd/24th dec with a decline to the 3-5th down to about 45-50 M/S thereafter we have 2 junctures-

1) No strong wave activity enough to break strat PV down- leading to an above average zonal index for Jan @ 60N - no significant wave amplitude so no Greenland High- only real chance of cold from scandi -

NAO/AO loaded positive- trending towards neutral-positive (IE not quite as bad) 

2) A trop induced wave (2) SSW in week 2 -3 of Jan, similar to 2009/10 where we saw results quickly - it was also a WQBO year as well -

So in a nutshell, The early 'form' leading us to the conclusions of a front loaded winter have been replaced by a structured vortex on a par with 2015- 

We are now preying on a trop lead SSW to backload the winter in our favour.

No SSW is 'likely' to mean winter is already over in terms of HLB- leaving the scrum for a MLB locating favourably for the Uk & we all know thats a very difficult block to support any snow for the UK.

* This could be the worse winter since 1989 ...

S

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[Interitus]

1 hour ago, Singularity said:

Given that this MJO forcing is also a good way to drive attacks on the lower stratospheric vortex to avert disaster via the upper beast propagating down,

Too late, or maybe the flux is actually up from the troposphere, because of the six levels in the MERRA data, it is the 150mb and then 100mb levels which rank first and second with regard to their timeseries. The forecast for the 150mb wind speed on 26/12 is 41st on the all-time list (13883 days) and a couple of m/s faster than anything last winter.

The stronger periods at 150mb have been -

Dec 80, Jan 83, Jan 84, Jan 89, Feb 90, Mar 90, Feb 93, Mar/Apr 97, Jan 00, Nov 13

[Mucka]

There will be a window of opportunity as the pattern amplifies again end of Dec early Jan for blocking to take hold again.

If there is a signal that would lead to cold prospects then it is for the PV to set up further east and for a deep trough to drop through Scandinavia. maybe right into Central Eastern Europe early January.

That would displace the Azores high West somewhat and cause a strong pressure rise to our S/SW. How deep the trough digs and how far West it sets up will determine what type of blocking we get.

We are due a break so instead of a boring West based UK high with the jet riding over the top I quite fancy the Atlantic ridge scenario and a cold pattern setting up before end of first week of January.

ECM ensembles show a bit of split developing

I think the cold members from around 28th are a bit over zealous, probably have low pressure diving SE into the continent, but the ones falling away around New year are likely responding to trough to our NE digging South and might be onto something.

A bit far out yet so it will be a case of seeing if the signal strengthens as usual and if we can get an Atlantic ridge modeled within the 10 day output.

 

[Interitus]

45 minutes ago, Steve Murr said:

 

2) A trop induced wave (2) SSW in week 2 -3 of Jan, similar to 2009/10 where we saw results quickly - it was also a WQBO year as well -

 

Do you mean Jan 2009?

This was a massive wave-2 SSW, 24/01/09 -

whereas the SSW of 09/02/10 was predominantly wave-1 -

edit: Also to add, the actual wind reversals of SSW of 1979 and 1985 were at later dates on 22/02/79 and 01/01/85 and were both largely wave-2 as shown in the plots below and which can be confirmed by looking at the geopotential waves in the MERRA data -

Despite what some posts suggest, it isn't always clear from surface and 500mb charts what the actual dominant stratosphere wave pattern will be.

 

Edited December 20, 2016 by Interitus

[Geordiesnow]

3 hours ago, CreweCold said:

It's not a proper Atlantic power up though, that's the issue- merely a temporary few days where things get a bit more lively. The issue is there's no way low heights can sustain in Europe where we need them because of that monster HP that is rooted all the way down into Africa as I've already said. If this was summer we'd be breaking heat records with that HP sat there pumping up plume after plume. It's the type of pattern that can last a season.

I think we all know when the N'lys will start.

You don't know for certain the high will come back into play after this potential stormy period, it could end up with the jet stream being nearby and the UK still under the influence of lower pressure.

Either way there IS a pattern change to more unsettled Atlantic based weather and how long it lasts for is open to alot of doubt.

Regarding the 18Z, then the GFS still hints the 2nd deep low will have more of an impact than the first one, do hope the GFS is wrong on the first deep low, as I say earlier, it will be typical on my point of view if those Euro heights deflect those storms further North.