Stravaiger
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Posts posted by Stravaiger
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GEM's gotta be the pick of the bunch from this evening's deterministics.
At Day 10 (yes a long way off) that high over Scotland is only heading in one direction....northwest.
If it can get properly established up that way, cold uppers will eventually swing in down it's eastern flank and for southern UK, where pressure will be lower, Atlantic incursions might produce some interesting battleground events.
We can but hope, eh?
At the very least, some dry, settled weather with nightly frosts depending on where the stratocumulus ends up drifting.
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@Penrith Snow - totally agree.
I think the bottom line is that the impacts of CC are manifesting in the increased frequency of certain weather patterns in the winter, as @Catacol alluded to.
My simplistic understanding is that GHGs stop heat escaping from the troposphere into the strat, cooling the strat, which in turn gives us a tighter sPV and tPV, with the polar jet pulled poleward, which allows HP to ridge north into southern Europe.
Fascinating discussion though and just hope the tropical forcing comes to our aid soon.
Thanks all!
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28 minutes ago, Penrith Snow said:
I a not sure Singularity is correct about the Iberien High being a response not a cause, its chicken and egg.
Check out a 100 years of historical data pre 1988 and you won't find such a massive and persistent Iberain/Mediterranean High as we see modelled now, it just didn't happen and of course the current persistant Bartlett is only the latest in a long line since the 1999's.
IMO, the Iberian High dominance is due to the expansion of the sub tropical Hadley Cell in response to a warming world, the expanse forces the Jet Stream north preventing the PV leaving its natural home ie Greenland, it happens occasionally of course like last week but any change is pushing againt the new normal and is quickly crushed.
This I feel is the over riding factor and overwhelmes other natural signals that might encourage Northern Blocking, hence the late January early February forecast debacle.
Watch the MJO if you like but it will make little difference
Andy
This - 100%. So often climate change isn't looked at as a driver but it has fundamentally changed the game. Expansion of the Hadley cell, GHG and CFC-induced stratospheric cooling leading, etc., all of these factors are uniting to increase the likelihood of strong, coherent PVs and a northward push of the sub-tropical high into Southern Europe during winter.
Of course there will be times when other drivers can override these factors and we get pressure in Europe to fall - we've seen it a few times since November - but the winter season is fundamentally changed by the increased likelihood of long periods where really high heights to our south effectively block any cool or cold air from covering the British Isles.
The way I think about it is that we're playing the same game but the cards in the deck are different now, with many more leading to anomalously mild conditions. We'll still occasionally get to play great hands but the odds of them appearing have lengthened considerably.
Original post: https://community.netweather.tv/topic/99814-model-output-discussion-22nd-jan-2024-onwards/?do=findComment&comment=5022916-
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28 minutes ago, Penrith Snow said:
I a not sure Singularity is correct about the Iberien High being a response not a cause, its chicken and egg.
Check out a 100 years of historical data pre 1988 and you won't find such a massive and persistent Iberain/Mediterranean High as we see modelled now, it just didn't happen and of course the current persistant Bartlett is only the latest in a long line since the 1999's.
IMO, the Iberian High dominance is due to the expansion of the sub tropical Hadley Cell in response to a warming world, the expanse forces the Jet Stream north preventing the PV leaving its natural home ie Greenland, it happens occasionally of course like last week but any change is pushing againt the new normal and is quickly crushed.
This I feel is the over riding factor and overwhelmes other natural signals that might encourage Northern Blocking, hence the late January early February forecast debacle.
Watch the MJO if you like but it will make little difference
Andy
This - 100%. So often climate change isn't looked at as a driver but it has fundamentally changed the game. Expansion of the Hadley cell, GHG and CFC-induced stratospheric cooling leading, etc., all of these factors are uniting to increase the likelihood of strong, coherent PVs and a northward push of the sub-tropical high into Southern Europe during winter.
Of course there will be times when other drivers can override these factors and we get pressure in Europe to fall - we've seen it a few times since November - but the winter season is fundamentally changed by the increased likelihood of long periods where really high heights to our south effectively block any cool or cold air from covering the British Isles.
The way I think about it is that we're playing the same game but the cards in the deck are different now, with many more leading to anomalously mild conditions. We'll still occasionally get to play great hands but the odds of them appearing have lengthened considerably.
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Fantastic to hear this - thanks for the updates MIA - and to see ice forming in places we haven't seen it for a while. Bit further south but almost looks like the Odden ice tongue is emerging once again to lick at the Greenland Sea.
Proper old school winter in Scandinavia, too, might even see the Gulf of Riga ice over if this winter keeps on going. Would be great to hit 14K km2 before Feb this year, maybe even an above 15K maximum is on the cards.
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How about this for a November snow extent? We've come a long way since September.
Best start to the European winter I've seen for a long time...the question is, will it last?
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Although it doesn't look great on the face of it, I'm really encouraged by the GEM evolution on today's 12Z.
It ends up with the heights/cold in Scandi holding firm, forcing energy from the Atlantic to disrupt SE into C. Europe, which will ultimately open the door to heights in the north retrogressing and, at the very least, giving us coolish zonality without the awful Iberian / Bartlett high that has plagued recent winters.
Plausible outcome and preserves the awesome Scandi cold pool - we could do worse!
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1 hour ago, Midlands Ice Age said:
Not done an update for 3 or 4 days...
Mainly because the sea ice has been so variable (on the whole negative) , and the snow is only slowly moving into Europe. I have also been busy looking after young Grandkids all weekend. NIce, but not good at 80 years old.
However I believe 'things they are a changing'. (especially written here for me and Meth and some ol'timers)....
Very apt really (see below) -
Firstly, NH snow situation -
Today
Friday
A slow steady haphazard movement westwards into Europe, rather than a dramatic blizzard - probably best describes it. We could see the blizzard happen to Europe later this week as the low drives into central European areas . I can also see a few pixels into Scottish Highlands today. However on the US side - no real changes.
Meanwhile sea ice has stagnated for 4 or 5 days now -
and is no longer in the top 2 positions.
Losses of -56K, +43k, +58k, and yesterday -12K have left the extent unchanged, and slipping down the league table to 5 -7th lowest in the last 18 years according to Jaxa - (ASIF).
not by any means disastrous, but after 6 days with little change it doesn't look as strong.
So why might this have happened.? My thoughts are that 3 things have impacted this.
1) the central Arctic basin is now just about full, and the chart above shows that normally in early December the ice extents seem to merge somewhat, before outer areas are cold enough to freeze
2) We have had a very rapid refreeze this year and most of the 'available; ocean is now frozen.
3) In the last 5 days the weather over the Polar regions has changed, What were easterlies have become westerlies, This has stopped the ice progress in the Barents, but it is still to affect the Bering Sea because it was blocked by the Aleutian low pressure. The outer areas are also 'in limbo'.
The most striking of the events this year has been the cold pool developing in Scandinavia. This has not shown in the Baltic sea ice graphs yet, but it is probable that ice increase will occur this week.
Also, the early Scandy cold has not been seen for a decade or two really, Apart from 2010 - but that was remarkable in its cause. It used to occur fairly regularly back in 'my day'. Lets hope that it is omen for this winter in the UK, as easterly winds in the UK always (or so it seemed) brought snowfall.
All for now
MIA
Yeah the Scandi cold is really noteworthy this year...started early and has been sustained for a long time now. Very old school, as you say MIA !
Temps currently below -30C in parts of Lapland and that cold air will be sucking heat out of the Gulf of Bothnia incredibly fast, leading to further expansion of sea ice in the northern and coastal parts of the Baltic.
If the pressure anomalies persist and keep pressure low in Central Europe this cold spell could go on for a while yet. I think an eQBO is partly responsible for this set-up but doubtless there are other factors...
In any case, been a good long while since I've seen a November chart that is so devoid of of warm air at 850hPa on both sides of the Atlantic. Great for the alpine ski resorts - long may it continue!
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We're about to see a big expansion of snow cover across central and even parts of western Europe. Some bits of the alps exposed to the north winds will see over a metre of snowfall in the next 48 hours.
Not bad for autumn and likely to push NH snow cover extent above average again - just in time for the start of meteorological winter !
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2 hours ago, Midlands Ice Age said:
Following on from the above posts about ANTARCTIC ice and there not be a similar thread I will supply the correct info...
Thanks to the ASIF
Extent
and Area -
2 to 3 months ago we were running at lows but there has been a recovery (against anomalies) recently .
So 'doomster' reporters are somewhat out of date.
I strongly 'suspect' that this drop in the Antarctic ice is caused by the H20 put out by Hunga Tonga. (time will tell). It is being researched right now.
Perhaps what is of more significance is the overall sea ice totals -
which have been performing strongly recently due to the Arctic sea ice performance (see late today for details.).
MIA
Really interested that you look at the total sea ice area chart and see that as "performing strongly".
When I look at it, I see that, yes, the negative anomaly is decreasing but we're still currently 2 million km^2 below the 1990s average for total sea ice area...
That's an enormous loss of sea ice.
I'm not trying to be doomster at all...I'm delighted the Arctic ice is doing ok this autumn, esp. pleased to see it doing better in the Barents than in previous years, and I'd love for there to be evidence that these decadal trends are starting to reverse. But we need to be eyes wide open about where we're at in relation to even just 30 years ago so we don't lose perspective on how our cryosphere is changing.
Sorry if that brings the mood down in this thread - not my intention! I get as excited about the boreal autumn's expansion of snow and ice as the next man, which is partly why I mourn the losses.
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Good to hear the ice is rebounding quickly up north this autumn, would be great to see ice extent hitting 1980-2010 mean levels again. It's been solidly below average for years now.
The situation across the cryosphere as a whole is pretty dire, though. NH snow extent is now back to being below average and Antarctic sea ice continues to chart a new course of record low extents for the time of year.
The crumb of comfort for us in Blighty is that Scandinavia is having a cold and very snowy autumn, with persistent low temps since October now. If we can tap into that pool of cold air or, better still, draw it across the still warm North Sea, we might see some good amounts of snow and ice ourselves
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Quite remarkable lack of snow for the time of year in Canada, as this anomaly chart from Rutgers University shows.
It will all change in the next week, as polar air sweeps southeastwards on Monday and Tuesday but notable to see at the current time.
Likely to see some colder air getting into Western Siberia in the next week too, helping to boost snow cover across that swathe of Russia and bring Eurasia up closer to average levels for the time of year.
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26 minutes ago, stodge said:
Evening all
24 hours later, 16 pages later and one sense of deja vu later - I'm still none the wiser.
Wednesday-Friday looking very complex and messy across the models - some bring back milder air quickly especially for the south while others keep colder conditions going or return colder air after a brief milder incursion.
The fact is these type of cold outbreaks don't usually last - the energy which creates them rapidly dissipates and we are relying on a strong Greenland ridge to keep the jet stream and Atlantic systems crossing over or just to the south of southern Britain. A strong build of Iberian heights tilts the trough further positive and pushes the milder boundary north.
Beyond the immediate snap/spell, GFS quickly dissipates the Iberian heights allowing the Atlantic LP to move in and the trough sets up across southern Britain keeping plenty of cold air over northern Britain - indeed, I'd argue the GFS 12Z OP is a stellar run for Scotland especially the higher ground.
Just seen the ECM 240 - a very quiet Atlantic and heights to north and south - a very different evolution certainly compared to GEM and JMA at the same time.
It's probably fair to argue the models are still to converge on a clear resolution and even at T+96 we have some considerable divergence.
Yeah I would 100% bank the GFS run for snow up here, esp. over the hills where it is sorely needed after a mild and snowless February.
Problem is, betting on Iberian heights dissipating seems a tall order given how this winter has been. Much as I’d love to be wrong, I’d bet those heights will be more bullish than first reckoned on and drive a more positive tilt to the angle of Atlantic attack, allowing milder air to get further north, for longer between successive low pressure systems.
Time will tell and there is still scope for the GFS solution to come good. Lord knows we deserve it !
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Well done the 06Z...it's pulled the @nick sussex Holy Grail out of the bag!
Cut-off high to the north, with energy (low heights) going underneath. Shame the succeeding pattern doesn't hold.
Encouraging to see this sort of output nonetheless - I would pay 100 English pounds for the first 330 hours to verify as per that run.
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52 minutes ago, Met4Cast said:
AAM tendency continues to rise as the MJO marches westwards creating +ve frictional torque further initiating a rise in overall GLAAM. In theory everything is coming together rather well.
Favourable MJO triggering a rise in AAM with an SSW occurring aloft. In theory this all suggests an increased likelihood of high latitude blocking as we progress into early March.
One fly in the ointment is the continued lack of consistent poleward flux being modelled, equatorward flux looks to continue for the time being, this essentially blocks the initial warming from downwelling & impacting the troposphere.
The second round of warming could perhaps be more favourable but currently the jury is out & there’s a lot of changing between runs. Yesterdays runs for example showed very little in the way of poleward flux & a continued disconnect between the strat & trop.
It’s plausible then to suggest that any blocking before March is tropospheric led and the SSW may not enhance this blocking into March at all. This does hinge on the above GFS charts being right, of course. There’s no consistent trend in either direction at the moment.
Thanks for this post - really informative and it seems like this disconnect will be key to any impact the SSW has!
Do you expect the SSW to impact the troposphere ultimately? Or is it possible the disconnect will mean this event never downwells below the tropopause?
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10 hours ago, Stravaiger said:
Surprised there isn’t more chat about the GEM this evening.
It ends up in a good place, with the core of high heights finally retrogressing and allowing a NW-SE aligned jet, bringing PM air masses over the UK and helping pressure to finally drop over Europe.
It has good support from the ECM operational too, albeit the latter is slower to bring in the cold NW’ly.
I for one would be very happy to see the core of the tPV’s low heights dragged eastwards and a reloading mid-Atlantic high bringing seasonal fare until the SSW shows its hand.
A trend to watch over the next 24/48 hours for sure…
Mmm hmmm…what did I tell ya
But seriously, kudos to the GEM for picking this up. Seems like the MJO is helping to put our limpet heights into a much better position for cold, with the flow mostly north of west for a change.
Still a fair way to go to realise these synoptics but hopefully the SSW then obliterates the tPV to the northwest and our high continues to retrogress opening the door to a southerly tracking jet and all the goodness that will bring.
Lord knows the mountains of Europe (and Scotland) need a snowy March if the snowpack is to survive what will doubtless be another anomalously hot summer.
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Surprised there isn’t more chat about the GEM this evening.
It ends up in a good place, with the core of high heights finally retrogressing and allowing a NW-SE aligned jet, bringing PM air masses over the UK and helping pressure to finally drop over Europe.
It has good support from the ECM operational too, albeit the latter is slower to bring in the cold NW’ly.
I for one would be very happy to see the core of the tPV’s low heights dragged eastwards and a reloading mid-Atlantic high bringing seasonal fare until the SSW shows its hand.
A trend to watch over the next 24/48 hours for sure…
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13 minutes ago, Don said:
It has been suggested perhaps something more akin to March 2008 could be a possibility which had some cold/snowy weather, but nothing on the scale of 2013 and 2018.
I’m praying for March 2006.
I recommend treating yourself to a scroll through that month’s charts on the archives if you want to remember what low heights and cold 850s look like
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Delighted to see the 18Z brings the tPV down to our neck of the woods from Day 8 onwards.
I’d give my right arm for that run to verify and winter to resume in our snowless hills.
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2 hours ago, mushymanrob said:
Cheers Mushy...who creates these anomaly charts? Are they not a composite of model output?
2 hours ago, Quicksilver1989 said:Not sure I really get that logic. If we can't get cold and snowy weather, might as well be nice enough for the outdoors.
6C and rain or 20C and sunny weather?... I know which one I'd pick at this time of year, especially in the strengthening solar input.
Might not be as mild as what the GFS 06z OP is going for but the EC OP ain't too bad either.
Really mild weather at this time of year is terrible news for wildlife. It messes with the timings of plants, insects, amphibians and birds, often leading to mismatches in when species and their prey breed. We always want closer to average weather, because that's what our ecosystems evolved to cope with.
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I'm interested in what the ECM's picked up on the last 12 hours. As I feared, the forecast lowering of heights as a lobe of the tPV moved towards us from the NW has been replaced by a renewed surge of heights from the south. But why? What signal has it picked up on that's caused a complete reversal of yesterday's output, which also had support from the GEM.
Hoping it will flip back, but expect that it won't. The AGW curse of relentless high heights will take some breaking.
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Latest output all converging on the idea of lower heights moving into the UK from the NW in 8 or 9 days time.
Atlantic feed so it won’t be cold, but close to average with plenty of snow over high ground in the north if it verifies.
The dream would be for this cool zonality to be pushed away by heights building out of the north as the forecast SSW perhaps takes hold.
Either way, after a pleasant, settled spell for the south of the UK, I’ll be ready for lower heights to return and cloak Scotland’s mountains in snow again
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1 hour ago, Drifter said:
Take it you haven’t seen the awful day 7
Can someone tell me what the route to (non-surface) cold is from there? Looks terrible, with more unstoppably high heights pushing in from the south.
@Eagle Eye are you still expecting heights to rise near Greenland around the 15th and pressure to fall over Europe?
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17 hours ago, Stravaiger said:
I honestly don't like this set up one bit. It's got disappointment written all over it given the strength of the jet going over the top of the high.
I'd take a period of proper, stormy, coolish zonality over this any day. Kick the jet and the Azores high well to the south, with a raging PV moving east over time to be just to our north. It feels like we can never remove high heights from being close to the south of the UK these days and with that, we kill the prospects for even average uppers unless the spectacularly unlikely happens.
This kind of garbage just eats up the precious weeks of low solar heating.
As expected...the GFS backtrack begins with the high unable to get as far north due to the energy running across the top of it. The run still ends up being ok because high pressure sits close to or over the UK, which is always nice, but the risk of an ECM 0Z solution, where long-fetch southwesterlies are never far away, is palpable.
Still want the PFJ kicked well south and for pressure to fall on the continent. Instead it's running across the north of Scandinavia !
We'll wait and see what the second half of February brings.
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Snow and Ice Northern Hemisphere - Winter 23 /24
in Spring Weather Discussion
Posted
Amazing to see the sea ice surround the Svalbard archipelago for the first time in a long while.
Beautiful images coming off the webcams around Longyearbyen, showing how influential all the snow and ice is on the albedo of the High Latitudes at this time of year:
BOREALIS LIVECAM PORT OF LONGYEAR 360 (kystnor.no)
When you consider how jaffa cakes poor the UK's "winter" has been, it's encouraging to know that Scandinavia and the most northerly extremes of Europe have still managed to get some goodly cold in.