Model output discussion - 20th Feb onwards

[chris55]

4 minutes ago, snowray said:

I like the way the Arpege has it further East, virtually Nationwide snow there.

Very nice from Arpege!

[I remember Atlantic 252]

24 minutes ago, snowray said:

I like the way the Arpege has it further East, virtually Nationwide snow there.

similar setup to 16-17 Jan this year? saw lying snow at low level then, was modeled west but moved further east than modeled, infact a bit too East for me

[Walsall Wood Snow]

2 hours ago, chris55 said:

After all, statistically we are more likely to see a white Easter than a white Christmas.

 

It surely must also depend on how early or late Easter is. Easter's in late March such as this year would have more chance of snowfall than those that occur in late April. Christmas on the other hand is on a set date so it's hard to judge conclusively I would imagine. From personal experience though I don't ever recall seeing snowfall or lying snow on Easter Sunday, whereas i've seen both of these on Christmas Day on a few occasions.

 

[Singularity]

At this point a less organised Atlantic trough would make a big difference with the jet powering on into Europe rather than angling NE.

Yet actually I can see where a height rise across Europe might fit in provided the MJO does lose amplitude from this point forward as the models are projecting; I have often seen it as a precursor to SSW impacts, with the Euro High jumping up to the high latitudes as the AO turns negative.

After all, March 2013 had a warm day early on thanks to a high to the SE/E of the UK - reaching the high teens in the south. Okay, I'll get me coat 

 

At least you can see the jet digging way south in the Atlantic as per the 00z. A consequence of the trop. vortex unraveling - something recent GFS det. runs have struggled to get to grips with, producing a hint here and there - late in the 12z being a good example - but without cutting out the westerlies quite as much as should be the case.

Cold imports by around mid-month look likely to be from between NNE and NNW. Could be a real case of a 'false dawn' for the spring this year. Unless the MJO remains more amplified through phase 8, in which case the NW-SE jet is favoured to continue with little interruption.

[Weather Observer]

2 hours ago, nick sussex said:

Thanks. Its always fun looking back at notable snow events and colder spells during March and how they developed. March is one of those months that can give you some notable extremes from a taste of early summer to mid winter. March 2013 was exceptional and the depth of cold very rare and of course there was that amazing blizzard for the Channel Islands and northern France. That's not on the cards but certainly there could be a lot more interest than for the whole winter.

Quite by chance, I was looking at past charts for March today to see how extreme the cold could be. Came up with these two. I am not remotely suggesting we have anything like that on offer but nothing wrong in wondering what it was like.

If I am honest, it was not by chance. I do this quite a lot.

[stodge]

Evening all

Another evening, another set of thoughts on the 12Z output beyond the interest of the immediate:

1) GEM keeps the cold longer than the other models once again.

2) ECM finishes on a spring-like note but its an evolution that doesn't have a lot of support as yet. I argued for the possibility of a "false spring" spell a few days ago based on past El Nino springs which go, in effect, cold, warm, cold through March and April. We had 21c at Cheltenham a few years back and ECM is pointing toward something pleasant.

3) GFS, as always, makes all the headlines. The OP gets there in the end with a retrogressing HP as the PV is completely destroyed.  The Ensembles make hugely interesting reading with as strong a signal for HLB as I've seen for a long time. I would say 50% of the members show HP to the North of the British Isles at T+240. That's a strong signal and not to be ignored. The orientation of said HP is variable - some scenarios would be warm, most wouldn't.

4) Post Monday, next week still seems very uncertain to this observer. The Azores HP is of course the key factor - some models have it ridging across the southern UK while others keep it further SW allowing some limited Atlantic activity.

[Guest]

This post follows on from yesterday’s post (on page 48 of this thread). In part 1 I looked at the broader pattern  and factors that might influence pattern changes in the next few weeks. I briefly covered some of the issues and I concluded that we really seem to be in unchartered territory in respect of the interaction and impact of the mature El Nino, a major Stratospheric warming event (both close to or exceeding any previously recorded), the predicted negative Arctic Oscillation and the Madden-Julian Oscillation currently in Phase 8 at decent amplification. For the MJO, in the last 24 hours the NCEP/GEFS has joined UKMO and ECM in showing reduced amplification and moving closer to the dreaded “0”. Kyle MacRitchie remains much more bullish. If you go to the links in yesterday’s post you can click on them and you will see that they have all automatically updated to March 2nd charts.

PART 2 - COLDER SCENARIOS

In this part I shall be making an assumption that we will see a lot of colder weather during the next 6 weeks and even consider the possibilities of the UK having a prolonged cold spell. Of course the broader pattern could change and, as some models currently show (including the NOAA anomaly charts posted by the likes of John Holmes and Knocker with their excellent analytical comments), there “could” be a flatter pattern with some milder or even quite warm interludes later next week and towards mid-March before, perhaps, a return to a much more blocked pattern after mid-March. Even with those patterns, the longevity, strength and axis of ridges and positioning of adjacent troughing would be critical in determining weather conditions and types for the UK. We are told by Fergie (at least up to the time of my writing this post which I started last night) that the signals from Glosea5 and EC-32 are for very frequent blocking and “predominantly colder than average conditions right through March and into April”. I understand the usual caveats and that this is a “broader” expectation of the mean predictive set-up and very short-term milder interludes and day to day variations away from the “mean” are quite possible.

Overall, given the combination of the ENSO / SSW / MJO that I referred to in part 1, we should be looking forward to some highly unusual weather. I will be looking for a HLB pattern being reflected in the AO indices around mid-March with it trending strongly negative then. I think “expect the unexpected” should cover it! Like the majority of posters on this thread, I am a “coldie” and crave for snow but I also like extremes and love following very unusual set-ups like we have now. Whatever happens, the next 6 weeks or so should be a wonderful period for model watching and analysis and I expect this thread to be buzzing.

COLDER PATTERNS AND THE “RIGHT” SYNOPTICS:

I believe that there are two possible “general” colder scenarios. We could see a continuation of what’s on offer from the current menu with a mixture of rather cold or even cold periods with some less cold or very briefly mild interludes. On the other hand, could everything fall into place for something considerably colder for an extended period? I will focus on the latter scenario but, as you will see, much of what I outline would still be important even for some rather cold weather to continue or some cold snaps with occasional snow events.

Given that we are now in meteorological Spring, it would surely be almost impossible to achieve a protracted “cold” spell with temperatures far below average for a few weeks. Even if we get the right synoptics, so much else has to fall into place. Will there be sufficient cold to tap into from the high Arctic or from northern or central Europe (or further north-east)? Will there be any snow cover over Europe to off-set the ever increasing solar energy during March? We will also need the source of the cold to become really frigid and then Scandinavia and/or Europe to become very cold and rapidly develop a snow cover. I shall now go through all these variables.

Just what are the “right” synoptics. In mid-winter an airstream coming from anywhere between north-north-west, through to north-east (broadly Arctic Maritime) or from north-east through to east and even south-east (broadly Polar Continental) might deliver a very cold set-up. In Spring, we are much more limited on the sources that might deliver. I think we can rule out anything from a north-west to north-north-west direction. Even though Greenland has seen some decent cold this winter and there is still that curios cold-pool in the north-west Atlantic, the airstream would be highly modified over the long sea fetch before it reaches our shores. A straight northerly coming from the high Arctic is a possibility and I will examine this below. Perhaps better, from a similar source but traversing Scandinavia, before reaching us on a north-north-easterly might deliver deeper cold with only a short sea crossing across the north North Sea. Better still, a straight north-easterly from eastern Scandinavia or north-west Russia would have an even shorter sea crossing across the south North Sea. Alternatively, a true Siberian blast delivered on a very long fetch east-north-easterly or a direct easterly might do the trick.

THE POSSIBLE SOURCES OF COLD:

For any of the synoptics outlined above to deliver we need to tap into a cold or, ideally, a very cold source. This must be from the high Arctic, northern Siberia or anywhere in between. Before I go any further, let’s take a look at current surface temperatures in all these areas.

GFS – Northern Hemisphere Current Temperatures:

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=6&code=0&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 today (Tuesday, 2nd March***). As this is T0 to T6 hours, it should be accurate! In the Arctic, temperatures around the North Pole are around -28c to -32c. In “our” part of the high Arctic (around the Barents Sea) temperatures are much higher – around -4c to + 4c. Most of Scandinavia is around -8c and much of northern Siberia is currently between -20c and –36c.

*** Please note:   At the time of posting this link it was showing 1900 on Wednesday, March 2nd. 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/nighttime 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 or about 4 hours later. This also applies to some of the other charts I link to in this post.

Another link to Arctic temperatures, this time from “weather-forecast.com”:                                                                                                        

http://www.weather-forecast.com/maps/Arctic?symbols=none&type=lapse

I like this surface pressure/temperature map – very easy on the eye. There is a facility to take one through the forecast changes for the next 10 days. I have no idea how reliable these forecasts are. Please can one of you fellow posters give an insight into this. At least the “current” temperatures can be relied upon.

Many of you will be well aware that much of the Arctic and particularly our sector, has had an exceptionally warm winter. Last week, I posted some charts from Svalbard as I feel that this is a good place to focus on (see my post on Page 41 of this thread). I linked to an observation station at Longyearbyen. Here it is again.

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

Temperatures have been well above the 30 year mean for each of the last 13 months. In fact, fellow poster “Interitus”, responded to my post (see page 42) tells us that the last month to see a below average temperature was way back in November 2010! I am sure that the main reason for this anomalous warmth is due to the sharp decline in the polar ice cap in the north Barents Sea (in particular). The Arctic has been warming up but this part of the Arctic has suffered particularly badly. The strong south-westerly jet that brought us our record December warmth drove right up into that part of the high Arctic. It is very timely that the NSIDC (The National Snow & Ice Data Centre) provided their monthly update this morning. Here is the link.

NSIDC Arctic Sea Ice News and Analysis:                                                                             

http://nsidc.org/arcticseaicenews/

So, we see the record low ice extent continue for most of February. The last 10 days has seen the ice extent rising. In most years it peaks around mid to late March – so not much time left for any significant recovery, although growth can continue through April, especially from exceptionally low winter levels. This is all very worrying for the longer-term but my post is focusing on the next 6 weeks. If we need to rely on a feed from the high Arctic we need surface temperatures to fall considerably there. With the impending –AO reflecting HLB patterns, it is entirely possible that we shall see some of the deeper cold from around the pole and on the opposite side of the Arctic transfer to our side of the Arctic. So back to Svalbard as a good indicator.

In my Svalbard post, I wanted to look at forecast temperatures. The same link as above does contain a further link with an 8 day forecast. For convenience, here is the direct link:

Central Svalbard – Longyearbyen 28 m asl:   

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

This should also update automatically several times a day. I wanted to look further ahead and I found a 2 week temperature forecast with hourly updates. I will not post that link again as “Interitus” kindly pointed out to me that the data did not come from the Norwegian Met Office (who produce the data referred to above) and was utterly unreliable. In fact the forecast temperatures shown changed markedly even hour by hour! He also drew my attention to 2 other stations on Svalbard and for a good consensus, I provide links to both of these.

West Svalbard – Ny-Alesund:                                                            

http://www.yr.no/place/Norway/Svalbard/Ny-%C3%85lesund/forecast.pdf

South Svalbard – Sveagruva:                                          

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

Fellow poster “High Ground” (on page 41) feels that all the temperature forecasts for that part of the Arctic are quite variable and not very reliable. He and I wonder why this is so. Anyway, we need to focus on the general trends. Overall, the next week is still looking far too warm. Temperatures tomorrow (March 3rd) around 0c gradually trending down towards -8c to -10c early next week. I think we need to see -15c to -20c or lower to give us the chance of tapping into to any decent Arctic cold. If Judah Cohen’s predictions (see part 1 and earlier post of mine referred to there) are anywhere near accurate, with the polar vortex extending down from the Arctic towards central Europe then we may well see the much lower temperatures develop in the source region quite quickly. We need to watch out for this in all the models from around March 10th onwards (or currently T+ 180). I will keep an eye on the Svalbard forecast temperatures and provide brief updates from time to time.

*** Please note:   At the time of posting the links to the 3 Svalvard stations the forecasts were prepared at around 1500 on Wednesday, March 2nd. They are automatically updated up to 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.

The Northern Hemisphere surface temperature chart (with the link I posted above) needs to be monitored and updated. Obviously on this thread, we can all look at the main models for predicted temperatures which I will not go into now (with all the short-term uncertainties). We will be able to judge if the surface temperatures start to fall significantly across Scandinavia or whether the low temperatures in northern Siberia start to move westwards as predicted by Judah Cohen.

ESTABLISHING A COLD POOL ACROSS SCANDINAVIA OR EUROPE TO TAP INTO:

Again we can all look at current and forecast European surface temperatures as well as the 850s. For those not used to accessing this information, here’s a link to one site:

ECM - European Temperatures now:                                                                       

http://www.meteociel.fr/observations-meteo/temperatures.php?region=eur2

Far too warm right now (the chart for 1200 on Wednesday, March 2nd was showing at the time of writing but will update automatically twice a day) and can we get enough cold air into Europe to develop a cold pool? Perhaps if the current “rather cold” pattern across the UK can move into Europe, it will be good if central and northern Europe can get some significant low level snowfalls. Any cold air that does arrive (from any of the sources I referred to above) will need to be maintained and a deep snow cover is required. This will reflect the increasing solar energy (the “albedo” effect) and, given slacker pressure patterns, would allow the cold pool to stagnate. It is still very uncertain that this will occur at all, let alone become entrenched. In recent weeks snow cover has declined in much of Asia and Scandinavia and has been absent from low lying parts of Europe for a long time. There has been a recovery in the last few days across north-west Russia and a hint of snow cover developing in north-east Europe. Note that much of Norway and extreme western Sweden are on quite high plateaus and generally maintain decent snow cover even in mild winters. Here is the latest snow cover chart from NOAA.

NOAA - Northern Hemisphere Current Snow Cover:                                                   

http://www.ncdc.noaa.gov/snow-and-ice/snow-cover/nh/20160229

You can put in the dates and run the pattern from January 1st through to March 1st. This will update every day for the latest chart. Definitely one to watch very closely. I would say “rather” encouraging recent developments. Update: 2300, March 2nd - excellent progressive today with March 2nd chart just out and showing snow cover extending further into Europe.

WHAT I SHALL BE LOOKING FOR IN ALL THE FREE TO VIEW MODELS OVER THE NEXT 2 WEEKS:

Now that I have gone through many of the key factors, just what are the chances of us getting everything falling into the right place to produce a prolonged cold spell? Impossible? Highly unlikely? Far too late to get any decent cold to stick around?   I think we need a huge amount of luck to get anywhere near it. We are in this highly unusual set-up. Could all the ENSO / SSW / MJO influences come together to produce something extraordinary? I would like to think so and I would love Judah Cohen’s predictions to verify. Let’s make some meteorological history this month.

Within a week to 10 days, I will be looking for the HLB becoming dominant (and reflected in AO indices trending strongly negative) and the polar vortex (or a substantial lobe of it) to shift down into Europe. Then we can get the high Arctic sourced airstream. I also would like to see the cold deepening in Europe and a cold pool becoming established. Then a big westward push from Siberia with the airstream veering to the north-east. Snow cover increasing and becoming widespread across Russia, Scandinavia and central and northern Europe. Then the synoptics might just deliver!

More realistically, if we get any of these factors impacting on the UK we should at least see something much more wintry than we are likely to get this week.

I have designed the layout of this post to make it easy for me to provide much briefer updates. Most of the links to charts that I have provided, update automatically, so anyone can check for the latest developments. In fact, as I always say, I am extremely busy running my online business from home. My obsession with the weather is stronger than ever and I need to get back to prioritising my working time! I will be very happy if one or more of you wish to pick up the mantle and provide updates and comments on any of the key areas that I have identified.

Edited March 7, 2016 by Guest
grammar, spelling, missing words + several updates

[feb1991blizzard]

1 minute ago, Weathervane said:

Quite by chance, I was looking at past charts for March today to see how extreme the cold could be. Came up with these two. I am not remotely suggesting we have anything like that on offer but nothing wrong in wondering what it was like.

If I am honest, it was not by chance. I do this quite a lot.

In some ways that 1931 chart is one of the best ive ever seen, The high is further North  so would have given massive North Sea snow convection to a wider area than some of the other stellar Easterlies, even Scotland perhaps.

[Speedway Slider]

1 hour ago, Singularity said:

At this point a less organised Atlantic trough would make a big difference with the jet powering on into Europe rather than angling NE.

Yet actually I can see where a height rise across Europe might fit in provided the MJO does lose amplitude from this point forward as the models are projecting; I have often seen it as a precursor to SSW impacts, with the Euro High jumping up to the high latitudes as the AO turns negative.

After all, March 2013 had a warm day early on thanks to a high to the SE/E of the UK - reaching the high teens in the south. Okay, I'll get me coat 

 

At least you can see the jet digging way south in the Atlantic as per the 00z. A consequence of the trop. vortex unraveling - something recent GFS det. runs have struggled to get to grips with, producing a hint here and there - late in the 12z being a good example - but without cutting out the westerlies quite as much as should be the case.

Cold imports by around mid-month look likely to be from between NNE and NNW. Could be a real case of a 'false dawn' for the spring this year. Unless the MJO remains more amplified through phase 8, in which case the NW-SE jet is favoured to continue with little interruption.

Are these charts ever viewable in fluid state? I mean like in motion (time) as a moving scenario? So you could see the lows/highs/fronts/jet, moving through time/dates...? Would that be better than stills, or would it (pardon the pun) cloud the facts?

Cheers

Speedway Slider.

 

[Faronstream]

45 minutes ago, Weathervane said:

Quite by chance, I was looking at past charts for March today to see how extreme the cold could be. Came up with these two. I am not remotely suggesting we have anything like that on offer but nothing wrong in wondering what it was like.

If I am honest, it was not by chance. I do this quite a lot.

Can you show me where to find 2m temp charts for 1902?

[ricey076]

What a season it has been, what does it take these days to have proper winter weather at our latitude.. Looking forward to reading all the posts later this year.. 

[winterof79]

Plenty to keep one interested from the updated Faxes

Snow for some.

[ukpaul]

1 hour ago, snowray said:

I like the way the Arpege has it further East, virtually Nationwide snow there.

With these 850s very much a northern event moving into East Anglia, the European view isn't detailed enough to show that though.

It would bring in some colder air away from the west and snow showers later though.

  

[I remember Atlantic 252]

GFS 18Z has it further East!

[snowray]

If anything Arpege usually under cooks uppers. 

Everything a bit further east on the again on the GFS this evening, a white mothers day maybe for some.

[knocker]

The 6-10 anomalies tonight are all on the same page. Canadian vortex with trough SE into the Atlantic, ridge in the close proximity to the UK and trough down into southern Europe with Russian HP into the Pole. Depending on the precise orientation of the surface high we are probably looking at a brief interlude of more settled weather under the influence of the HP although becoming more unsettled later in the period particularly in the north. Temps rising but remaining below average.

The 10-15 period becomes more interesting as the transition takes place, The trop vortex and trough establishes eastern Russia with height rises Scandinavia/Greenland and trough mid Atlantic the upper flow backs westerly heralding general periods of unsettled weather although the temps will be nearer average. This is the script according to the GEFS and EPS but NOAA is reluctant to relinquish the ridge in proximity to the UK.

So all in all at the moment we look like entering into a more zonal regime  but there can be no high confidence in this resolution at this stage.

 

 

Edited March 2, 2016 by knocker

[Weather Observer]

37 minutes ago, Faronstream said:

Can you show me where to find 2m temp charts for 1902?

Faronstream, sorry to say that 2m temp charts are not included in the meteociel archive. But Sweden under -20 uppers at the end of March. One can only imagine.

For 1902 read 1901?

Edited March 2, 2016 by Weathervane

[fergieweather]

26 minutes ago, knocker said:

So all in all at the moment we look like entering into a more zonal regime is the percentage play but there can be no high comfidence in this resolution at this stage.

 

 

The very polarised distinction between 1st two EC clusters exemplifies why that period in March is proving exceptionally tricky and with low predictability, particularly as models toy with SSW effects further into the month. 

[snowray]

latest fax charts 

[bobbydog]

40 minutes ago, I remember Atlantic 252 said:

GFS 18Z has it further East!

if you want more detail, there is a zoom feature-

 

[stodge]

7 minutes ago, fergieweather said:

The very polarised distinction between 1st two EC clusters exemplifies why that period in March is proving exceptionally tricky and with low predictability, particularly as models toy with SSW effects further into the month. 

Indeed, the first cluster is strongly represented in the GFS 12Z Ensembles while the latter is the ECM 12Z OP at T+240. I'd say Cluster 2 was more akin to a west-based negative NAO while the former is a more traditional east based scenario.

[Nouska]

1 hour ago, Faronstream said:

Can you show me where to find 2m temp charts for 1902?

There are a few stations recorded for that date - link set to it.

http://www.infoclimat.fr/cartes/observations-meteo/archives/temperature-minimale-journaliere/25/mars/1901/00h/france.html

 

 

[Cheshire Freeze]

I'm not sure the operational modelling is in the ball park for the mid range yet. Just the slightest hint from the 0z GFS that the mid range modelling may be about to sniff heights around the Svalbard area (perhaps to be an accelerating trend as models continue to synthesise SSW). 

Small tweak from the 18z but heights a smidgen higher and LP shows just the slightest hint of disruption to our N

As opposed to the 18z

You have to wonder whether another snow event will pop out from the woodwork here. We could be seeing the magical scenario unfolding of disrupting low after disrupting low.

Edited March 3, 2016 by CreweCold

[knocker]

A quick look at the GEFS anomalies this morning. No change with the previous 6-10 assessment but towards the end of the 10-15 it retrogresses the Russian vortex/trough and Atlantic HP so they reside respectively over N. Russia.Scandinavia and ridging into Greenland. The questions are will the ecm follow along and if so what will be the evolution from here? At the moment it's looking like a return to zonal as the HP weakens but there are other possibilities. Way above my pay grade I'm afraid.

Edited March 3, 2016 by knocker

[knocker]

Further to the above