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Model Output Discussions 06z 04/11/16

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4 minutes ago, knocker said:

I thought we were already going in the right direction :cc_confused:

gefs_t2ma_5d_eur_51.png

It'll be coming from the right direction by mid Dec Knocker , About half 2 on that map!!

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2 minutes ago, knocker said:

I thought we were already going in the right direction :cc_confused:

gefs_t2ma_5d_eur_51.png

You know that is GFS Knocks with jet over the top and even the 12z Op was a lot cooler than that.

You might want to save those charts to show just how wrong GFS anomaly charts can be rather than to prove their worth. :wink:

FI is 144 for now.

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5 minutes ago, knocker said:

I thought we were already going in the right direction :cc_confused:

gefs_t2ma_5d_eur_51.png

Still too many runs resolutely driving the jet NE having missed the possible split - the resulting 2m temp anomalies are so far above normal (particularly by night) that the few precious colder outcomes are overwhelmed.

Not surprising given theoretical scope for a Euro High precursor pattern as discussed earlier. im still prepared for the possibility of a very mild spell in 2nd week of Dec - but considering the probability to now be lower than I did a couple of days ago.

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2 minutes ago, frosty ground said:

Could you say what you actually mean rather than a putting it in a cryptic way

Surface temps warming by the 7-12 period.

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2 minutes ago, knocker said:

Surface temps warming by the 7-12 period.

I gathered that but isn't that a better way of getting your message across.

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Could be about to enter a period of quite prolonged below average temperatures at the surface anyway. 

ECM temperatures from tonight's run looking below average for all for the next week. 

An example is for the London area, ECM going for maximum of only 1/2c Tuesday, and possible lows of -6/-7c tuesday night.

A very cold night for some, -9c Tuesday night in some spots!!

 

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A very anticyclonic outlook for the foreseeable with little rain. Indeed the complete opposite to what we normally see at this time of year, and that is usually a raging jet and rampant southwesterlies - last year being an extreme case in point, but how very different things will be compared to early Dec 2015 - thank goodness!

Not expecting much change in the models in the coming days, only slow evolution, but as I keep saying the key player is likely to be the N pacific ridge which is likely to ridge into the Pole, temporarily it will push a trough in towards west greenland, and have the downstream affect of pulling a more SW flow around the 5/6 Dec, but longer term it is likely to have the effect of forcing the trough down through scandi, allowing the mid atlantic heights to build NW, this is how I see things panning out through the first half of Dec.

As others have said, upper temps at this time of year, can be very deceptive when sat under high pressure, as this week just gone by over Scotland and N England has shown, here it has been significantly below average, snow has remained thick on the fells, and we have had a run of air frosts with temps dropping down to -5 degrees, and maxes up until today struggling to get above 4 degrees. It has been a very cold week in general.

Edited by damianslaw
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6 minutes ago, frosty ground said:

I gathered that but isn't that a better way of getting your message across.

It was actually just meant as a light hearted reply to the previous post which said:

Quote

Looking forward to the 18z from GFS. Big things (in the form of continued small steps in the right direction) are expected...

I wasn't trying to make a profound point or getting any message across. When I do that I normally supply a little more detail

And in any case one picture is worth a thousand words

Edited by knocker
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Just now, knocker said:

It was actually just meant as a jocular reply to the previous post which said:

I wasn't trying to make a profound point or getting any message across. When I do that I normally supply a little more detail

I see you used 12z data to highlight the lack of changes in the as yet unreleased  18z output.

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1 minute ago, frosty ground said:

I see you used 12z data to highlight the lack of changes in the as yet unreleased  18z output.

If you say so.

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Oh come on, anyone actually fancy discussing the, you know, 18z output that's rolling out other than playing mind games with each other?

I'll give you a start @t132..

12z gfsnh-0-138.png?12 18z gfsnh-0-132.png?18

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1 minute ago, Ravelin said:

Oh come on, anyone actually fancy discussing the, you know, 18z output that's rolling out other than playing mind games with each other?

I'll give you a start @t132..

12z gfsnh-0-138.png?12 18z gfsnh-0-132.png?18

12z maybe slightly more amplified, but to be honest I think we need to focus towards mid month.

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4 minutes ago, Ravelin said:

Oh come on, anyone actually fancy discussing the, you know, 18z output that's rolling out other than playing mind games with each other?

I'll give you a start @t132..

12z gfsnh-0-138.png?12 18z gfsnh-0-132.png?18

Just for the sake of comment then.

The low that is heading South, to the West of Portugal, doesn't do us any favours as it just helps extend an Azores ridge toward us which deflects the jet further North.

If it does develop we could do with it pushing SE rather than S.

 

Edited by Mucka

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Thinking the 18z has stopped the little steps in the right direction  for coldies, circa 135 heights a little lower to NW and the low pressure to south west of Greenland is on more positive tilt hopefully a little stutter.

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Not happing this time on 18z just getting more and more painful watching  it unfold.

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1 minute ago, TSNWK said:

Thinking the 18z has stopped the little steps in the right direction  for coldies, circa 135 heights a little lower to NW and the low pressure to south west of Greenland is on more positive tilt hopefully a little stutter.

As a back up plan (assuming GFS is right which I don't) it will be interesting to see how long it maintains A W/SW flow - it was very brief on the 12z before the pattern reamplified.

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2 minutes ago, Mucka said:

As a back up plan (assuming GFS is right which I don't) it will be interesting to see how long it maintains A W/SW flow - it was very brief on the 12z before the pattern reamplified.

Even with that flow the 850s ain't exactly scorching hot. This at t180 is the 'worst' so far.

gfs-1-180.png?18

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MY FIRST “WINTER 2016/17” REPORT WITH NOVEMBER 27TH 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 (Sunday, November 27th at 2200), some of the charts may already have updated. My comments relate to what the charts showed at the time of this posting.

Hello folks, I’m back! I have been exceptionally busy running my business and will only manage occasional reports and updates this winter. I have followed the model thread for the last 2 months as well as an array of other analyses and expert reports. I will go through some of my usual focuses such as Dr Judah Cohen’s latest Arctic Oscillation report, Arctic Sea Ice News, Asian and European snow cover, Arctic, Northern European and Northern Asian temperatures and what I’ll be looking for in the models and current model analysis. Please remember that I do not claim to be an expert and I’m certainly not a scientist but I have taken a keen interest in the weather for nearly 60 years.

Seasonal Forecast Uncertainties for Winter 2016/17:

The overwhelming majority who follow this model thread are “Winter Coldies” (including myself). My main message is that we all need to be patient. We have seen three mild Winters in a row and 2015/16 was probably the most frustrating of all. We have an extremely different set up for 2016/17 and El Nino has subsided and we appear to be oscillating between neutral and weak La Nina conditions. We have seen an extended period with a very weak polar vortex, a mostly weak and often undulating jet stream, some early stratospheric warming, a fairly but not completely blocked pattern in the mid latitudes, generally warmer than average conditions over much of North America and the Arctic and mostly colder than average conditions over central and northern Asia, Siberia, northern Russia, north-east Europe and northern Scandinavia.

Although there is some great “potential” for at least some decent cold spells and possibly more prolonged cold from mid-December, the path to possible Winter cold is very uncertain. I will give my views on this in the next part of my report. The much anticipated full Winter forecast (available here on the Netweather site) was published last week with the authors, Tony Wells and Matt Hugo, underlining the considerable uncertainties. In fact they have decided to change the way they present these forecasts and we will see at least monthly updates as the season progresses with any changes or major shift in emphasis being highlighted. I believe that this is an excellent way to approach this in any event and particularly when so much is at stake.

My View on the Current Model Output and What I am Looking Out For:

During the last few days, we have seen huge swings in model output beyond a week or so out and often considerable disagreement between the models. This has caused similar swings in emotions, particularly by those seeking a cold and snowy Winter. There has been the usual friction between some of the posters. As some have been reminding us, “Winter hasn’t even started yet” - so it is unwise to get either overly optimistic or overly pessimistic at this stage. Very few of our severest Winters get going properly much before Christmas, eg: 1946/47 was the 3rd week in January,1962/63 was just before Christmas, 1978/79 was late December and 1981/82 was mid-December. Perhaps the memories of 2010 starting in the 3rd week of November are a little too recent. That was the earliest and coldest start since 1890.

Back to the models and what most of them seem to agree on is no full on Atlantic surge. Yes, several models such as the recent GEM output, show a period of milder southwesterlies in a week or so but we are still largely under the influence of nearby high pressure. As long as this “mid-latitude” high pressure block prevents the Atlantic sweeping in across northern Europe, we remain on course for something colder eventually. This should allow a cold pool to settle over Europe. There is plenty of cold further east and northeast and Judah Cohen (see later for more details) states that this will be re-enforced in Siberia during the next 2 to 3 weeks.. In fact, with the Arctic so warm and ice-free (see later sections), we need the source of any meaningful cold more from an easterly quarter rather than an Arctic airstream, at least for the first half of Winter.

If it happens, it might take until after mid-December until the European cold pool might become established. Then it could become self-sustaining. The mid-latitude blocking then needs to shift further north but it may take a little longer than some would wish. Several of the models hint at this and the Met Office are halfway there in their longer term outlook but are likely to continue to hedge their bets for at least the next week to 10 days, especially due the huge uncertainties. GFS get there on some runs only to pull back on the next.

I do not wish to mislead or over excite anyone but the general build-up so far to this Winter is not that different to that of 1962-63. A couple of early cold snaps in November (snow fell in London on 2 days), some cold and foggy days in early December. Then slightly milder with continuing high pressure nearby in mid-December and progressively colder towards Christmas with the first big snowfalls on Boxing Day. Of course that was the beginning of an epic Winter. In December 1970 we had 3 weeks of fairly mild conditions under mostly high pressure. Then this built northwards and finally northeastwards to produce a 10 day cold spell from the east with much of the country having a white Christmas.  There are quite a few other examples.

So, I’m looking for dominant high pressure over the next 2 to 3 weeks to give us a much better shot at some proper Winter cold thereafter. May be the models will start to show a more definite trend within a week or so. As we all know, nothing is certain but there is everything to play for and seemingly, the best chance of proper cold since March/April 2013. Some posters have alluded to that memorable cold spell, probably in part as it was the most recent. This was a particularly late severe spell triggered by a very strong Sudden Stratospheric Warming (SSW) event. I prefer to focus on early Winter comparisons.

Arctic Sea Ice News and Analysis:

The last full update was on November 2nd with the next one due in early December. The ice extent map, however, is updated daily. Here’s the link:

http://nsidc.org/arcticseaicenews/

This highlights the record low overall Arctic ice extent during October and the very slow recovery since then. There is still practically no ice in the Baring Sea and Kara Sea on our side of the Arctic and ice build-up in all other parts of the Arctic is either below or well below average.

Dr Judah Cohen’s Latest Arctic Oscillation Report:

Judah Cohen last updated his AO report on November 21st. This Winter he is aiming to update this site every Monday. Here is the link:

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

I copy the first part of his last summary below.   

....“Summary

The Arctic Oscillation (AO) is currently slightly negative and is predicted to remain on the negative side of neutral through the first week of December.  I continue to expect large model volatility due to challenges predicting downward propagation of circulation anomalies related to the ongoing weak polar vortex (PV) event and upward propagation of energy.

The current negative AO is reflective of mostly positive pressure/geopotential height anomalies in the Arctic. With positive heights over Greenland and negative heights in the eastern North Atlantic, the North Atlantic Oscillation (NAO) is currently also negative and like the AO, the NAO is predicted to remain mostly negative over the next two weeks.  

The large pool of cold air sitting over Siberia the first half of November has discharged into Central and East Asia.  But with the AO predicted to remain negative, cold air should rebuild across the Northern Hemisphere (NH) continents.

With the main polar vortex (PV) center predicted to slide from the northern North Atlantic into Siberia, cold air is predicted to become re-established over Siberia the next two weeks.  With cold air once again becoming extensive across Siberia, Europe and especially East Asia remain at risk for cold air outbreaks.

North America has been near record warm for most of November but that pattern is predicted to change.  With the most recent PV weakening/sudden stratospheric warming (SSW) geopotential heights are predicted to build across Alaska and Northern Canada in the stratosphere.  This should favor similar positive pressure/geopotential height anomalies across much of the North American Arctic and negative pressure/geopotential height anomalies across the United States.  This pattern is potentially a prolific snowfall producer across Southern Canada and the Northern US but may also promote the pooling of Arctic air in Western Canada.

The stratospheric PV remains weak due to an early split of the PV and as of yet no meaningful recovery is predicted.  In fact the models are predicting further weakening of the PV through the end of the month.  The ongoing weak PV is likely to elevate the risk of wintry weather across the NH continents, especially Siberia but also including East Asia, Europe and the US during much of December. 

Eurasian snow cover was observed to be well above normal across Eurasia for the month of October. Also Arctic sea ice extent remains well below normal especially in the Barents- Kara seas where sea ice is likely at or near record low extent.  High Eurasian snow cover and low Arctic sea ice in the Barents-Kara seas favor first, a strengthening Siberian high and then a weakened polar vortex (PV) in winter.”....  

There is a more detailed look at the “Impacts”, a look at the near term and further out and plenty of supporting charts and diagrams. Judah sums up the current uncertainties by saying:

... “We have overlapping PV weakenings, downward propagation and upward energy transfer that constructively and destructively interfere with each other.  This has not only made it difficult to discern the signals that I like to monitor but has made it difficult for the operational weather models to accurately forecast the weather patterns and atmospheric circulation in the medium range.  I expect the forecast challenges to continue in the near term.  But regardless the extensive Eurasian snow cover, the reduced Arctic sea ice and the stronger than normal Siberian high all indicate at least one significant PV weakening event/SSW during the winter months followed by an extended period of severe winter weather across the NH continents including East Asia and/or Europe and/or the Eastern US.”...

Judah does not definitely suggest that the severe cold will extend into Europe and the UK but there is huge potential. We will have to wait and see but it will be an extremely exciting period for model watching.

AO Ensemble Charts: 

Right, now on to my usual indicators to see if there is any clue as to how things might pan out in the next few weeks. The Arctic Oscillation is currently negative.  During the next 7 to 14 days, half of the ensemble members go into positive territory and half into negative territory. This precisely demonstrates the current uncertainties which is evident across all the models. A negative AO would reflect greater high latitude blocking. We need to get much closer to the end of this period to see which direction we are likely to go in. Here’s the link.

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

MJO Ensemble charts:

Here are today's MJO ensemble charts for the big 4 (all updated on November 27th). 

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:  All 4 start the MJO off in phase 2 to 3 but moving into the circle of death (COD) during the next 3 to 5 days. Then we have some interesting divergence. The UKMO (shortest forecasting period) keeps it inactive in the COD. The ECM attempts re-entry into phase 1 but at very low amplitude. The NCEP/GEFS and the JMA both predict the MJO to re-emerge in phase 8 and phase 1 around next weekend at reasonable amplitude. This should assist greater high latitude blocking. It will be interesting to see if UKMO come on board with this reactivation. The overall mixed picture merely underlines the current uncertainties beyond 7 to 10 days.

Northern Hemisphere Snow Cover:

I was having difficulty in accessing the 31 day animations for snow cover changes. These are produced by the US National Ice Centre (NIC) and by the National Ocean and Atmospheric Administration (NOAA).

Update November 28th 0900: I have just added the excellent NOAA animated charts (see c and d below). When you go to their site you can change the date range and look at the Autumn and Winter seasons:

a) Whole of Northern Hemisphere Current Snow Cover  (updated by NIC November 26th):

http://www.natice.noaa.gov/pub/ims/ims_gif/DATA/cursnow.gif

b)  Asia and Europe Current Snow Cover  (updated NIC November 26th):

http://www.natice.noaa.gov/pub/ims/ims_gif/DATA/cursnow_asiaeurope.gif

c) Animated Northern Hemisphere 31 Day Snow Cover Changes (updated by NOAA November 27th):

https://www.ncdc.noaa.gov/snow-and-ice/snow-cover/nh/20161101-20161127

d) Animated Europe and Asia 31 Day Snow Cover  (updated by NOAA November 27th):

https://www.ncdc.noaa.gov/snow-and-ice/snow-cover/ea/20161101-20161127

There is well above average snow cover over northern Asia and much of Scandinavia. The snow cover currently  extends to eastern and northeastern Europe.

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 (27th November). 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 for comparison:

North Pole –  around -24c.

Barents Sea/High Arctic – around -8c to -12c.

Scandinavia – mostly around -8c.

Northern Siberia - around -28c to -40c.

North West Russia - around -16c to -24c.

North-east Europe – around 0c  to -4c.

Please note:   At the time of posting this link it was showing 2000 BST on Sunday, November 27th. I will always try to show the 2000 BST (1900 GMT) charts for a consistent comparison. The charts are automatically updated 4 times a day, so the temperatures shown will be different to those I just mentioned above. We can follow the trends by looking at the latest data at any time from now on. It is vital to note the time of day to take account of daytime/night time variations. So for like for like comparisons, for example the 2000 charts for each day should be available to view from the 12z (T+6) updates which are published around 1600 to 1700 or about 4 to 5 hours later. This also applies to some of the other charts I link to in this post.

Svalbard Daily “Maximum” Temperature Forecast for 10 Days:

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

Central/West Svalbard – Longyearbyen 28 m asl:   

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

November 28th  -5c;    December 2nd   -9c;    December 6th  -9c.

North-West Svalbard – Ny-Alesund:  

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

November 28th  -4c;    December 2nd   -14c;    December 6th  -14c.

Central South Svalbard – Sveagruva:   

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

November 28th  -4c;    December 2nd   -15c;    December 6th  -14c.

The general trend is for the “maximum” temperatures (which have been above 0c for much of November to fall well below freezing during the next few days and then to remain at these much lower levels.

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 latest trend is, however, more encouraging with temperatures falling to only slightly above their long term averages. If this trend continues, then we should start to see new sea ice forming much more quickly in the coming weeks. In the meantime, it does mean that a northerly airstream from the high Arctic might have slightly more of an edge to it and could be the difference between rain and snow over lowland Britain given a marginal pattern. I still feel that we need to look to the east for any pronounced and more prolonged cold during December and into January.

Final Comment:

Most of the models, indicators and forecasts are in a very uncertain state. I feel that the next 2 to 3 weeks might be decisive and the path to Winter cold (or otherwise) will become much clearer.

Next Update:

I’ll try and manage a full update to this report in 2 week’s’ time.

 

Edited by Guest
Added animated snow cover link"

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Here we go, the pattern already reamplifying.

gfsnh-0-204.png?18

Edited by Mucka
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The high is hanging on for dear life and only gives up the ghost towards T174hrs, normally these go south much more quickly. Some very cold conditions likely especially towards the se where the flow is likely to remain from the Continent for the longest time.

Remembering here that even if the upper air warms up the surface will remain cold until you get that mixed out. One of the most notable inversions came a few Febs ago with upper air at I think +5 but some places didn't get above freezing with a few places recording maxs around -3.

Whether the GFS is correct with this sinking of the high time will tell but events between T120 and T168hrs could still lead to some bigger changes in the medium term.

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Worst perhaps shorter term but to be honest if that is all the Atlantic can throw at us in terms of zonal as far as I am concerned it is still game on mid December.

hgt500-1000.png

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