Model Output Discussion 29th December - Into mid-Winter.

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WINTER 2016/17 FULL REPORT No. 8 (PART 1) WITH JANUARY 15TH INPUT

Please note that some 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, January 15th at 1900), some of the charts may already have updated. My comments relate to what the charts were showing at the time of this posting. I am just starting to learn how to cut and paste charts into my posts so please bear with me as I increasingly use these in future reports.

This is part 1 of my weekly report which will usually appear on a Sunday evening (from now on). It contains all my usual features except Judah Cohen’s latest Arctic Oscillation report. This will appear in part 2 of my report shortly after it is published, which is usually between 2300 and 2330 on each Monday evening.

Reacting To The Model Output – A Dose of Reality:

There seems to have been just a little activity on here since my last full weekly report (on page 179 of this thread) which was six days ago! We are not far off 100 pages since then and the last 24 hours has been pretty quiet. We had the short Arctic cold snap and many of us saw at least some snow including Londoners (just a few flakes down here in Exmouth). Most of us on here (including me) are obsessed with snow but it seems that some of you were so busy worrying about how quickly it would end and looking for the "easterly" that you did not seem to stop to enjoy it while it lasted!

The mood has changed from one of pure excitement and joy to one of utter disappointment and despair. I usually try to manage everyone’s expectations during the former and rally the troops during the latter. The reality is that both types of mood during the last week were overreactions. Not everyone gets caught up in this emotional roller coaster, especially the tiny minority that do not like the cold! With such an intense period of model watching, I fully understand that some of us are suffering from model fatigue and a few days away helps one to recover one’s sanity and perspective on the real world.

The "pessimists" will make comments like: the models only verify when they predict a mild pattern; any half decent output will disappear on the next run; the mild ensemble outlier will verify; you cannot trust the GFS (or the ECM or UKMO) or whichever one is the most bullish at the time; this model has been dreadful all Winter; the op or the control run is not representative of the current output; anything beyond D3 is FI; FI is only correct when it is not showing cold; models only ever downgrade when a cold pattern is predicted, they never upgrade; we only really ever get zonal; the PV never gets into a favourable position for the UK; the jet stream always blasts away anything remotely cold; I can only see mild crud or mush; the “euro-slug” never moves away; the HP supporting the northerly will always topple; easterlies are almost impossible to achieve these days; faux cold is not real cold and we may as well have a zonal flow; long range forecasts are always unreliable or wrong; then one liners start to get very critical and usually without any constructive argument presented; moans start to predominate when the output is downgraded; teleconnections science is a waste of time; those making the forecasts or using teleconnections have no idea what they are talking about or are idiots (from the tiny really nasty fringe); this Winter is over; I am leaving the forum, see you next Winter (but they never leave!).

Apart from mostly the opposite comments from the pessimists, the optimists can make comments like: look at perturbation 15 on the GFS 18z for T+300 – if that verifies we will be have a raging blizzard across the whole country; when showing a cold pattern – this model has been the most reliable recently; so and so has said that the pattern is almost identical to that of 1946-47; that chart (showing cold) is almost certain to verify; the ens or almost all the members show a cold pattern is probable (when the op shows mild) or vica versa; tweets supporting a cold or snowy pattern are posted, usually with no comments added; well considered comments are misrepresented or taken out of context leading to a huge ramp;   

I could go on. In reality, depending on the fluctuating model output, many of us could fall into either camp at any particular time. If one avoids being overly optimistic then there should be less despair when things take a turn for the worse. If you can manage the excitement then that’s fine as long as you can manage the disappointment. I am almost always an optimist but not naively so and I try to get the right balance into my posts.

The trouble is that the changing emotions often lead to misleading posts and comments. Identical charts can have polar opposite comments. How often do we see a post from a newbie or someone just trying to learn and understand the subject say, “I am completely confused by what people are saying “, when two different conclusions are expressed. There is nothing wrong with well explained comments but throw away one liners can be thoroughly misleading.

Let’s drop this snow obsession just for a short while. Many on here enjoy the “chase”, looking for early signs of the next cold spell. This winter’s patterns have been so unusual that almost anything is possible during the next few weeks and there is plenty still to chase. There should be many more opportunities and I’m really confident that something will emerge to really excite the coldies before too long.

In fact, even the next week still has some interesting possibilities. I felt the need to make several short posts (by my standards!) during the week to bring some life into the recent sombre mood. A few posts have been drowned out by the critical one-liners. At least this morning, with the thread so quiet, several great posts of encouragement were made. For example, if you haven’t seen them, look back to at least the two from @bobbydog and @stewfox. I thoroughly endorse these views and I will elaborate on them in the next section of this report.

Overview Of The Current Model Output and Looking Ahead:

In my last weekly report (see page 179) I looked at four broad alternative scenarios that might develop following the conflicting, fluctuating and very uncertain model output beyond around D5 to D7. I still believe that my colder scenario iii is the most probable and that we nearly made it to the coldest scenario iv. Yesterday, I produced a short post (on page 257) where I felt that we would be entering a transition period to a “continental” flow between today and Tuesday and this would be the first critical period for the models. I often prefer to look at all of the six main models (+GFS ensemble means) to see if there is any cross model consensus. I  posted up the charts for D3 (now D2) to demonstrate that all the models showed the milder air coming in from the west and coming up against the cold block to our east as well as the receding Arctic cold that had been over us. There is usually a messy transition especially when the Atlantic fails to make proper inroads and the incoming fronts stall right over or just to the east of us.

Whatever the fine detail is for today into Monday (a “nowcast” nightmare for forecasters) the position by late Tuesday is “more or less” agreed upon by all the models. The fronts are predicted to stall and be pushed back westwards and fizzle as they do so. We will be left with high pressure building over us and a very gentle east or south-easterly drift. The area of rain (with a little sleet and snow in the east) initially moved from north-west to south-east but has now slowed down and the precipitation is now edging southwards and not eastwards (I am writing this bit at 1500 today). The MetO fax chart below shows the position (just updated):

            12z - valid 1800 Sunday                        12z - valid 1200 Monday                       12z - valid 0000 Tuesday

   

Occasionally, when we see this type of stalling pattern, the push of milder air completely loses its impetus and gets steadily squeezed out at the surface and the colder air takes over much more quickly. I make this point, as this is something that might be very interesting to follow later this evening and into tomorrow.

UPDATE: Here are the current surface temperatures posted at 0848 GMT (0948 French/Meteociel time) on Monday, January 16th (note that this updates automatically, so you can follow the changes):

 

This shows the cold moving back in more quickly. The NetWeather radar has just started to show some wet snow developing just west of Ipswich. The cold over eastern France , the Benelux countries and Germany seems to be edging westwards. If this continues, expect the MetO to update their short term forecasts.

The more likely scenario will be the one I mention below (written 18 hours ago prior to my update).

The models broadly agree on the HP moving over us although there is some disagreement on the extent of the colder air pushing back north-westwards during the early part of this week. Although much of Europe has now lost the extreme cold conditions experienced a few days ago, there is still widespread cold extending over much of the continent as can be seen in the charts below:

GFS 12z T+6 current Euopean surface temps                   GFS 12z T+6 current European 850s

                                

Please note: Unfortunately, I am still copying across incorrectly some of my charts. The left one above is frozen but the right one keeps updating. What am I doing wrong - please help!

Unfortunately, it was this first transitional period that was recently modelled (up to 2 to 3 days ago) to be the gradual move towards a proper easterly flow developing across the whole country (or at least the southern half). Some of the severe cold (of a week ago) over Europe looked like it might be advected into the UK with cold to very cold surface conditions and very low uppers too. The cold has been substantially modified and the uppers have mixed out to some extent but we may well see some sharp night-time frosts in the south-east (initially). With the dry continental influence and low dew points there may be some decent diurnal ranges with maximum temperatures in any sunshine briefly getting close to average before dropping quickly after sunset. The air may well stagnate with much lower daytime maxima later in the week.

Whilst a full on easterly now seems a low probability (at least at this stage), the position of the high pressure may be critical around next weekend. I feel this is the next important phase if there is to be a transition to generally colder conditions in week two. The models really start to diversify beyond D7. Even in a normal winter, the output for this longer term period is usually far less reliable and inconsistent as the models start to explore various options. In this winter with the often weak and conflicting signals we have witnessed some amazing swings even in the D5 to D7 period. Anything beyond that has been very difficult to predict with any real confidence. So, I shall speak in more general terms.

There is a useful little chart that gets posted up quite regularly on the MOD by the likes of @karlos1983. This is the ensembles for the surface temperature. I show the 0z chart for London below.

London 2m Temperature Ensembles 0z 15th to 29th January

This shows the brief milder interlude for today with temperatures already falling back below 5c during tomorrow and closer to 0c in the following few days. After D4/5 the ECM mean shows slightly less cold conditions while the NCEP falls further and the mean remains in the 0c to 5c band. This pattern continues until towards D10 when the NCEP mean suggests another milder interlude. There are a wide spread of ensemble members from D3 onwards and particularly in the less reliable period from D10 to D17.

The model output during week two is very uncertain and we may see further substantial swings during the next few runs. I do not feel that a “prolonged” (over a week or longer) period of zonal (with full on Atlantic) is likely. Several models hint at a brief spell of westerlies or south-westerlies but this is well into week 2 and FI (update: while writing this, I see that this is partly indicated on the GFS 12z and slightly more progressively in the GEM 12z  output). There is also a hint of the high pressure remaining closer to us. Much would depend upon its precise position with anything from the dreaded euro-slug, to right over us or ridging northwards which might allow another Arctic outbreak and even an easterly! I believe that we are still in a period of transition (for how long I hear you ask impatiently!). Following the evolution during the latter part of January should make for yet more fascinating and, perhaps, very exciting model watching but do expect some more wild swings.

I have not yet even mentioned the now quite strongly anticipated Sudden Stratospheric Warming (SSW) event. Although this can take many weeks to propagate down properly to the surface (like last winter), it can also be much more instantaneous. Several posters (who are much better qualified than me to comment on this area of the subject) suggest less than two weeks this time from the start of the warming event. If this does materialise, it will have an impact. This usually (but not always) leads to much of the cold air in the Arctic being released towards the mid-latitudes with HLB and much more meridional patterns being established. It does depend just where the HLB sets itself up but, more often than not, western Europe and the UK do see a decent cold spell developing. A SSW can also interrupt the patterns in a way that might be less favourable for us in this part of the world (like moving the PV to a bad location). So fingers crossed for a strong SSW with fast propagation and positive (cold) impacts heading directly to us!

Even without a SSW event we can still have further colder snaps or cold spells later in the winter. The highly unusual winter continues. I do not believe that we could go through two (or even three) months with a very blocked Atlantic and very few cold incursions. I want to believe that the recent Arctic snap was simply a precursor to a more prolonged cold spell. January could well be heading to be a below average month. Just how cold and how snowy it might get is still very much up for grabs, as is February.

Arctic Sea Ice News and Analysis:

The last full monthly report was published on January 5th. This is a fascinating read and includes a review of the whole of 2016. Please note that the current ice extent map and the comparison chart to the mean are updated daily and are always of interest. Here’s the link for the latest updates:

http://nsidc.org/arcticseaicenews/

This chart shows the current extent of the sea ice (as on January 14th) in relation to 30 year means.

The “rate of recovery” during December was very close to a record but, despite this, the overall ice extent is still at record lows and remains just below the previous low set during Winter 2012-13. Overall ice growth stalled during the last few days but is to the resume this week (at least in the Baring and Kara Seas which should see some rapid growth due to some severe cold setting, as is demonstrated later in my Svalbaard temperature review).

Arctic Oscillation (AO) 14 Day Ensemble Charts (updated January 15th): 

The Arctic Oscillation is trending positive in the next 2 days and then back neutral with a split after D5 with some members trending negative, some neutral and others going positive again during week 2. This is particularly mixed and reflects the very uncertain model output.

Note for newbies: The AO index reflects the amount of HLB in the Arctic. A positive +AO reflects very little HLB and a strongly +AO reflects no HLB anywhere in the Arctic. A negative –AO reflects some HLB and a strongly –AO reflects substantial HLB with more intense high pressure and/or more extensive HLB in various parts of the Arctic. This index produced by NOAA is based upon GFS model output and will fluctuate in line with that. Although ECM produce similar data based upon their own output this is not one of their “free-to-view” charts for public consumption.

Here's the link:

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

...and here’s the current chart:

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif

 

North Atlantic Oscillation (NAO) 14 Day Ensemble Charts (updated January 15th):

The NAO is currently trending from slightly positive to slightly negative later this week before returning to around neutral (with some members still slightly negative and some slightly positive) during week 2. Again a mixed picture reflective of the rather uncertain GFS modelling.

Note for newbies: A neutral NAO index reflects the close to average state of the mean sea level pressure patterns or the “climatological” norm in the North Atlantic. This would equate to the anomalous high pressure in the south, particularly around the Azores and low pressure stretching from off the eastern USA seaboard in a wide band running north-eastwards to the east of Newfoundland, east of Greenland and through Iceland. A positive +NAO occurs when these patterns are stronger than usual (eg: the Azores high is more intense or more widespread and/or the Iceland low is deeper or more widespread than usual). A negative –NAO reflects a weak Azores high and/or less intense Icelandic low pressure. A strongly –NAO would reflect a reversal of the normal patterns with relatively low pressure in the Azores and high pressure further north towards Iceland. A “west based –NAO” (talked about recently) is when the pressure is higher than usual in the western Atlantic such as around the Newfoundland area). An “east based –NAO would indicate higher pressure than usual in our part of the Atlantic. This index produced by NOAA is based upon GFS model output and will fluctuate in line with that. Although ECM produce similar data based upon their own output this is not one of their “free-to-view” charts for public consumption

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

...and here’s the current chart:

 

MJO Ensemble charts:

Here are today's MJO ensemble charts for the big 4 (all updated on January 15th) with the live links below should you wish to check any future changes. 

                UKMO   (7 day forecast):                      ECM (14 day forecast):                    NCEP/GEFS (14 day forecast):                       JMA (9 day forecast):          

        

COMMENT:  A rather mixed picture yet again but slightly more encouraging signs with all 4 models bringing the MJO to life again. The UKMO with it’s shorter forecasting period moves the MJO out of the COD (the "Circle of Death" - the relatively inactive area in the centre of the chart) today and into phase 1 at steadily increasing amplitude and even reaches phase 2. The ECM goes for the same route but then goes back through the COD and is set to break out again this time into phase 6 with a fairly wide spread of ensemble members but in broad agreement. The GEFS is a little different, emerging from the COD in phase 8 at low amplitude and on into phase 1 at good amplitude and then does an about turn back into the COD (remaining just inside the phase 8 and 1 borders) with the ensemble members mostly following a similar trend. The JMA is similar but then keeps the MJO signal in phase 1 at mostly good amplitude.

Please Note: Depending upon how much emphasis each model builds in the MJO signals (which I believe is one of the automatic parameters) and to what extent this conflicts with other signals, should be reflected in that particular model’s output. The phases 7, 8 and 1 at good amplification (as at last shown now) is supposed to assist with greater HLB. I have read a few conflicting reports on this with this winter’s unusual patterns and weak signals highlighting some of the possible problems. Some who support the merits of using the MJO as an important forecasting tool have suggested that the signal has been “masked” by other more dominant factors. It does seem odd that the MJO remained inactive during the brief period of HLB and last week’s Arctic outbreak while as soon as the HLB subsides we see the MJO come to life! I see that another argument is that the MJO signal is not as useful as first thought particularly in the winter months when there are so many other strong forces at play.

This is beyond my limited understanding but I have been following the debate this month between several of the more seasoned regular posters on the MOD. In particular (in no specific order) I have enjoyed the active discussion between @Nick F, @nick sussex and @Singularity. I highlight your names as I also noted that you have debated the use of Kyle MacRitchie’s specialist MJO predictions and I have some input that you guys might find very useful and I would imagine might stimulate your discussions somewhat further!

Last winter I included Kyle’s charts in these reports and used to show these with a cautionary note below wondering why his charts were usually quite different in what the others showed. I had read on Kyle’s old website that his main research "was" on studying the tropical/equatorial forcing mechanisms and particularly the ENSO. His MJO charts (based on raw data drawn from CFS) was an attempt to modify this with the other signals. Following a direct message exchange with Kyle over the summer I decided to suspend showing his charts. I added a brief standard note about this under this section in all my reports for this winter. I feel that I should state Kyle’s full reply now:

…”I am happy for you to use my charts in your reports but you must be aware that a full comparison could be misleading. Some of my work is still experimental, particularly where I apply the “modifiers” (for sake of a better description). I have also been rather lazy with the frequency of my updates!....”

I was just getting the impression that he wanted to move on into other areas of the subject. Then, just a few days later around last April (hence the "was" above) Kyle closed his old website and opened a new one. This is called "Weather For Vines". I read what he was doing (on his site) and contacted him again. Whilst he will continue his research into tropical forcings and still have some new and regular input on his new site, he now has a new focus. He was always interested in growing vines and the climate parameters required for this. He is now researching the optimum conditions and how things will change through global warming impacts. I think that he also feels that he can make this into a more commercial/profitable business by providing special seasonal as well as shorter-term forecasts for vine growers as well as helping those considering going into that industry. So, I can only imagine him studying the MJO while having a glass or two of some high quality vintage wine!

@nick sussex - thank you for your interesting response (in your post below this one) particularly with what you say regarding the assisting of a SSW with the MJO progressing through phases 6,7 and 8 rather than emerging from the COD directly into phase 8 or 1. This may be something to look out for and might the ECM just be factoring in this possibility? Their MJO chart is different to the others from D10 to D14 showing the dive back into the COD and quickly re-emerging towards phase 6 (with most of their ensemble member spread heading in that direction). This might be a pure coincidence and it is well into FI. If they stick with this signal, their D10 model should start to get interesting by mid-week. Just a glimmer of hope but one to monitor. With this in mind, I shall re-introduce Kyle's charts for the next few weeks - here's his current one:

   and the link:  https://weatherandvines.com/?page_id=140  + his explanatory notes and further guidance: https://weatherandvines.com/?page_id=128

It is closer to progressing towards phase 6 and the red ensemble member gets there but not until mid-February. As his charts are slow to update and the SSW signal has only become clearer in the last few days, perhaps his next full update might show a faster progression. Again, just a "possible" scenario but with plenty of interest. Over to you (and others in the know) to use your other sources to see if their is any more supporting evidence.

Just to start this "chase within a chase" here are the ECM 0z D10 charts which are probably still a few days too early. They are quite different to the GFS and GEM 0z charts which show a zonal flow. I wonder if any of the ECM ensemble members will provide any hints. I have broken one of my golden rules by going into FI territory but let's have a little fun for a few days! 

ECM 0z January 16th T+240 - Pressure:       ECM 0z January 16th T+240 - 850s:

       

 

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 go back over 10 years. 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 January 1st  to January 14th but you can change these again on the site:

a) Animated Northern Hemisphere Snow Cover Changes (updated by NOAA January 14th):

https://www.ncdc.noaa.gov/snow-and-ice/snow-cover/nh/20170101-20170114

....and here is their current chart:

 

b) Animated Europe and Asia Day Snow Cover  (updated by NOAA January 14th):

https://www.ncdc.noaa.gov/snow-and-ice/snow-cover/ea/20170101-20170114

....and here is their current chart:

BRIEF COMMENT: 

Just look at the rapid build-up of European snow cover during this period (which peaked a couple of days ago). There continues to be well above average snow cover over northern Asia and this has continued to expand southwards and south-westwards. Scandinavia is once again fully snow covered, including the south (the high central plateaus usually have pretty complete snow cover for most of an average winter). Meanwhile, the extensive snow cover over North America has declined sharply due to the much milder conditions there.

 

Current Arctic Regional Surface Temperatures:

GFS – Northern Hemisphere Current Temperatures for January 15d 1900 (12z – 1300 T+6):

and here’s the link to live charts if you wish to view future changes (updated 4 times a day):

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

Here is my selection of Arctic Regional Temperatures:

The the previous readings from my last full report are shown in brackets alongside

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

Barents Sea/High Arctic:  -4c to -20c (-4c to -24c).

Scandinavia:  south -4c to -8c (no change);  north -8c to -12c (-12c to -16c).

Northern Siberia: -28c to -40c and below (-32c to -40c and below).

North West Russia:  -28c to -40c (-20c to -32c)

North-east Europe: -8c to -12c (-8c to -20c).

Greenland: -16c to -40c (-20c to -40c)

Canadian Arctic: mostly -12c to -36c (mostly -12c to -40c).

Alaska: -12c to -28c (-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.   You 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.

Svalbard Daily “Maximum” Temperature Forecast for 10 Days:

Here are the links to the 3 Svalbard stations that I am monitoring together with a summary of D1, D5 and D9 values:

Central/West Svalbard – Longyearbyen 28 m asl:   

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

January 16th   -1c;    January 20th  -12c;       January 24th  -13c.

North-West Svalbard – Ny-Alesund:  

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

January 16th   +2c;    January 20th   -14c;      January 24th  -19c.

Central South Svalbard – Sveagruva:   

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

January 16th   -3c;     January 20th   -17c;      January 24th   -22c.

Please note that the links above 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 quite short range. 

BRIEF COMMENT:

After the temperatures rise to near or just above freezing tomorrow with some snowfall, they fall back dramatically after that and end up around their lowest levels seen this winter (matching the 2 to 3 days in early December) and down to or even below their 30 year means which has rarely be seen in the last 3 winters! This injection of severe cold should help the Arctic sea ice extent to quickly resume its growth in the Baring and Kara Seas where it is still at record lows right now for mid-January. 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.

Final Comment:

An interesting period of model watching ahead with all sorts of possibilities.

Next Update:

Part 2 of this report with Judah Cohen’s latest update should posted around 2330 tomorrow (Monday) evening.

My next full weekly report should be on Sunday evening, January 22nd.

@Buzz  Thank you for your kind comments (even though the moderators removed it for being off-topic!) - it makes it all worthwhile!

 

Edited January 16, 2017 by Guest
To ensure that all the charts are showing, the links are working properly and to correct any typos

[nick sussex]

Thanks BB for that info re Kyle and the MJO and also your great post. I read the research that he and Roundy  conducted into the MJO and I think it does have  merits. I think what peaked my interest in the current differences between his MJO forecast and the normal Wheeler Hendon was the progression of phases 6,7 and 8 as statistically significant signposts for a SSW given the time period of that progression. Whereas the others are skirting phase 8 then into phase 1 which is less correlated with a SSW.

The issue with the WH forecast is the interference from Rossby waves and Kelvin waves and the odd cyclone thrown in for good measure, the last global tropics hazards outlook doesn't see cyclone formation in week 2 so this should be one less factor to worry about. I think if we're to see changes in the NWP then it will come quickly without much warning if the MJO does impact the NH pattern especially as going by the WH we would have gone from an MJO lying on the sofa for the last month to getting up and running a marathon!

 

[TomDav]

Record breaking in terms of zonal winds but too late in the season to have much impact

[bobbydog]

5 minutes ago, More Snow said:

with everybody now pining there hopes on this SSW it is worth remembering that an SSW does not always mean cold and snow for the UK.. didnt we have an SSW last winter that failed to deliver until it was to late in April/May... well maybe not to late for our Scottish friends but to late for most of us..

Actually last winter we had a very late SSW which was the 'final warming' which led us into spring. Unfortunately, we didn't have any before that which could have given us cold weather. Final warmings are common. This one forecast is well before that timeframe so hopefully it could give us something decent. Despite what some say, the timescales of this one (which of course hasn't happened yet...) are very similar to 1991. It's not "straw clutching" as they are not exactly frequent events during winter. They don't guarantee snow but they do greatly increase the chances. As always, things can change literally overnight but fingers crossed.....

[booferking]

4 minutes ago, TomDav said:

Record breaking in terms of zonal winds but too late in the season to have much impact

Have you chart above that shows last full SSW during a winter period.  what site is it you get these charts Thanks

[TomDav]

3 minutes ago, booferking said:

Have you chart above that shows last full SSW during a winter period.  what site is it you get these charts Thanks

https://ozonewatch.gsfc.nasa.gov/meteorology/wind_2015_MERRA_NH.html

Last technical SSW in mid winter was Jan 2013:

[Polar Maritime]

Some posts have been hidden, Just a reminder that there are moaning/winter threads already open for discussion and chit chat.

Please continue discussion on what the Models are showing, Thanks. 

Edited January 15, 2017 by Polar Maritime

[nick sussex]

Looking at the ECM ensembles for De Bilt, still a strong cluster of solutions keeping that area in an east/ne flow for an additional 2 days compared to the op. The longer range do signal a more unsettled picture but before then it could be a messy picture.

In terms of any support for the GFS op well the spread does show some energy heading se'wards. I've done the rough synoptics given the spread from the mean, I still think the ECM/UKMO are more likely to verify given they agree but stranger things have happened.

 

 

 

[nick sussex]

The GFS 18hrs run so far just about manages to hang onto its previous trend although upstream it started to backtrack to the Euros. It ejects a shortwave east, the Euros have the same shortwave but that hangs onto the mothership and this whole system heads ne over the top with them.

If somehow the GFS was on the right tracks the interest really would be the surface flow ahead of any fronts moving in from the west.

It's all very slow motion stuff from the GFS, not exactly exciting but it looks to turn slowly colder during the week for the UK as a colder continental flow heads nw,  the ECM/UKMO solutions look cleaner in terms of evolution but even they could slip into a more messier picture if they take a bit more energy se'wards.

 

Edited January 15, 2017 by nick sussex

[Nouska]

Some posts looking at the similarity to a SSW in 1991. The current and historic charts may look similar at face value but don't tell an important aspect of the '91 event.

The first warming took place end of December/beginning of January. Not replicated this year.

The second phase - middle of January to early February.

The important factor, IMO, was the split that isolated a connection to western vortex segment and allowed a mega Scandinavian high to develop.

Z 500 anomaly

I don't want to rain on anyone's parade but perhaps better to be aware that current modelling is not showing a '91 redux at the moment.

All historic images from here.

http://ds.data.jma.go.jp/gmd/tcc/tcc/products/clisys/acmi.html

[bluearmy]

Even though the GFS and FIM continue to eject some jet se, there appears to be no stopping the Atlantic heading in on a sw/ne axis in week 2.  I was hoping that this se push of the jet may encourage a wedge of heights  to build but seems that boat has now sailed aswell. Not many spoilers left to derail this zonal truck.  we could generate a block high enough to keep the south uk away from the worst but to be honest, I'd rather we 'took our medicine' with n Europe under low heights in general than build another euro block which may hang around for several weeks again. 

[chris55]

1 hour ago, TomDav said:

https://ozonewatch.gsfc.nasa.gov/meteorology/wind_2015_MERRA_NH.html

Last technical SSW in mid winter was Jan 2013:

And this SSW caused a cold blocked pattern to set up from about 10th Feb 2013, that was the last widespread lowland snowfall for much of England and Wales. The blocking pattern remained for a while and even into march on and off.

here is the chart for that snowfall, a nice south easterly element from the slider meant that even though 850s were nothing special, snowfall was guanenteed.

 

[Seasonality]

GFS continues to offer surface cold for continental Europe within the reliable and increasingly for the UK moving to next weekend. Not the most inspiring chart in some ways, but raging Euro high it is not.

 

[Seasonality]

Later on our old friend Azoroslug returns.

[IDO]

Not much to add to yesterday's thoughts, apart that the remnants of January are firming up. D10 GEM and GFS charts say it all:

Before then maybe a few drier days the further SE you are, The GFS op right out till the start of February is full on zonal, though in the latter stages colder rain than before it (TBC).

If a SSW event does occur the forcing from that will not show up in the models this month IMO, despite others musing that it will be effecting the trop now; this winter the general consensus has been a disconnect between trop and strat so far; any trop forcing has not been forced by strat developments.

So a case of getting through a rather usual winter couple of weeks and hope that the SSW occurs, no done deal yet, and then of course the blocks have to sit in the right place, and bearing in mind the Azores spoiler profile this winter, that is no done deal either.

Strange as it may seem the CET for Jan is currently +1.5c above average, similar to December, so this promising NH pattern has in fact been very unkind to the UK so far.

 

[mb018538]

Nothing much to add this morning, other than a slow descent into a period of zonality appears ever more likely.

[mcweather]

Sadly the 00z Gfs continues the much advertised return to a mobile Atlantic based theme fo the final week of January.  Beyond that who knows. 

[That ECM]

47 minutes ago, mb018538 said:

Nothing much to add this morning, other than a slow descent into a period of zonality appears ever more likely.

I am still not sure that we are heading for a period of Atlantic zonality. Most  of the charts that show this are on gfs t168 plus. This from the ecm doesn't look zonal. Agreed fro a cold perspective it isn't great but not sure it is zonal and not sure it would lead to zonal.

Edit This is for the 26th. Bit early to write Jan off I think!

Edited January 16, 2017 by That ECM

[bluearmy]

There is your glimmer of hope on the latest ec op. At day 8 a wedge of higher heights opens up ne caanda/Greenland - not much but enough to force the big Atlantic depression onto a more southerly trajectory as it fails to link up to the lower heights to our north  - heights over Europe stay lower than previously predicted though last op run was also less than enthused about that rise to our south. 

Probably just the ramblings of the op late on but it's a straw and it's really the only one coldies have at the moment before Feb arrives! 

[mb018538]

Not looking 'traditional' zonal for sure - the main chunk of the PV has been shoved away from Greenland and the pole across to Siberia thanks to that building high over Arctic Canada. Net result is cold zonal for the UK for now....after this, we could have a shot at something from the North.

[bluearmy]

17 minutes ago, mb018538 said:

Not looking 'traditional' zonal for sure - the main chunk of the PV has been shoved away from Greenland and the pole across to Siberia thanks to that building high over Arctic Canada. Net result is cold zonal for the UK for now....after this, we could have a shot at something from the North.

The consistent agreed  ens route forward is the quick return of a big chunk of vortex back again to ne Canada/nw greeny 

hence the mobility we see in the Atlantic 

i can't see how that mobility can be avoided which is why I've been saying we need to change the mean features this side of the Atlantic  or we will be under a broad wsw flow 

[jvenge]

You can almost tell what the models will be showing based on the number of posts here on a morning. GEFS showing quite mild from the 24th onwards for the UK and much of Europe. In the reliable? No, but the ensembles aren't churning out favorable outcomes for those with a preference of cold.

[Kentish Snowman in Yorks]

5 minutes ago, jvenge said:

You can almost tell what the models will be showing based on the number of posts here on a morning. GEFS showing quite mild from the 24th onwards for the UK and much of Europe. In the reliable? No, but the ensembles aren't churning out favorable outcomes for those with a preference of cold.

Yes having been keeping an eye on the models for the last few days it seems that the countdown to the Atlantic has been moving nearer like clockwork with no drama whatsoever.  Now why can't the same be said when a cold spell is shown in FI?!  

[ArHu3]

10 hours ago, bobbydog said:

Actually last winter we had a very late SSW which was the 'final warming' which led us into spring. Unfortunately, we didn't have any before that which could have given us cold weather. Final warmings are common. This one forecast is well before that timeframe so hopefully it could give us something decent. Despite what some say, the timescales of this one (which of course hasn't happened yet...) are very similar to 1991. It's not "straw clutching" as they are not exactly frequent events during winter. They don't guarantee snow but they do greatly increase the chances. As always, things can change literally overnight but fingers crossed.....

This year the warming seems about a week earlier than last year, last year's ssw only gave us a crappy cold spring, this warming is about 3-4 weeks too late if we had a cold north sea and baltic (and for us in the Netherland ijsselmeer) things could have been different, much more wintry like 2013 but now, I doubt it

Edited January 16, 2017 by ArHu3

[Seasonality]

13 minutes ago, Kentish Snowman said:

Yes having been keeping an eye on the models for the last few days it seems that the countdown to the Atlantic has been moving nearer like clockwork with no drama whatsoever.  Now why can't the same be said when a cold spell is shown in FI?!  

Because the UK has a mild maritime climate as the norm. Mild Atlantic weather is much more common than cold weather so of course it appears to "verify" more but really it is more like having a die marked with five ones and only one six and then marvelling how often one comes up when you throw it. *nb know your post is tongue in cheek but it is a sentiment I see expressed a lot here which should be addressed