A Winter's Tale

Thursday is looking quite promising for heavy snow showers and it’s always good to see the met office mention significant accumulations - though I wonder what the threshold is for depths to be classified as significant according to the met office. This month has already had a number of polar maritime incursions bringing spells of wintry weather. Up to now these spells haven’t produced much more than some wet snow/sleet so hopefully Thursday will be more like early last month which produced 2 inches or Jan 2015 and 2018 which saw falls of 7cm or more. It’s difficult to gauge how much snow could fall in the Glasgow area but looking at the charts I think there’s a decent chance of accumulations in the range 2-6 inches. Certainly the western highlands (mainly Argyll, the Trossachs) look set to be in the firing line for heavy snow showers. Whilst fewer heavy showers will make it to the east coat I think some eastern parts of the central lowlands could still see an inch or two with some heavy showers reaching the Firth of Forth.

A slushy covering here as expected. It’s a pity the front couldn’t be 20 or 30 miles further south.

Tomorrow looks set to be an action packed day for much of the British Isles. A potentially historic storm for parts of England and Wales and fur parts of Scotland the most significant snow event of an uneventful winter for snow. I’ve been following this for a few databanks hoping the front will be north enough for central Scotland to experience prolonged heavy snowfall but not too far north to be on the wrong side of marginality. In the past 10-15 years frontal snow has rarely delivered much to central Scotland. The last one to produce more than 2 inches was Jan 2018, before that Feb 2013, 2009 and of course March 2006. We are long overdue a decent frontal snowfall. I think for areas in central Scotland under 100m I struggle to see much more than an inch of wet snow. I’m hoping for at least 2 inches - which would be the second 2 inch snowfall of the winter which would equal 10/11, 14/15 and exceed 12/13, 20/21! Some charts show the potential for 4-6 inches of snow in central areas but I suspect that would be above 150m. That could be enough to warrant an amber warning but for now I think the yellow warning is adequate. Some places further east - especially the eastern Grampian highlands - could see more sustained heavy snowfall. 15cm+ could be quite widespread and maybe one or two places could get close to or exceed 30cm. An amber warning could be issued for parts of the north east away from the coast. Thankfully for the north set it won’t even wind causing problems. It has been a dismal winter in terms of the lack of snowfalls during December and January (this month has resembled more normal winter weather) if we could end up having a couple of decent snowfalls and maybe one significant fall that wouldn’t be a bad outcome. Personally I’d prefer a winter that delivers at least one snowfall of 2 inches + than a winter with more snowfalls that fails to produce a fall of more than an inch.

Lots of travel disruption including reports of abandoned vehicles in East Dunbartonshire. Almost reminiscent of 6 Dec 2010 with surprise snow during rush hour. At least 5cm falling between 5-8am is bound to cause disruption. Cars stuck on motorway as snow causes disruption across Scotland WWW.BBC.CO.UK Motorists are facing treacherous driving conditions with heavy snow falling across many parts of Scotland.

If the line of the snow showers currently south of Glasgow was a little further north then I’d think an amber warning would be a possibility with the potential for more than 10cm of snow. I’ve got to say I’m surprised by this event given how brief this cold interlude is and how wet the ground was after the rain of yesterday. It just goes to show what a polar westerly can deliver and ironically a mobile westerly has delivered more this morning than any of the failed blocking opportunities since late November.

A better snowfall than the 4cm in early January last year - making this the best snowfall here in the first half of January for some time. I was expecting maybe a cm or two at best so quite pleased to have up to 2 inches. Some photos:

Nice snowfall this morning with about 4-5cm causing some travel disruption. Polar westerlies can be a reliable source for decent snowfalls in the Glasgow area.

Well after the terrible ribs esrly this morning we have seen somewhat of a recovery today - especially UKMO 12z and GFS 18z. The uncertainty at such close range is unprecedented so tomorrow we should hopefully sed more consensus. It still looks likely that Christmas will be cold with a chance of some snow in the east and it looks like staying cold until the 29th. The GFS 18z has a battleground snowfall around the 29th before mild air arrived from the south west. It looks like high pressure in Iberia will be a bit of a pain but and will probably bring a spell of mild weather around New Year but it’s cold air not too far away and some heights still persisting to the north west we could still find ourselves on the margins of colder air (a potentially high risk/high reward set up for snow). It’s possible that high pressure to our south could develop in a Scandinavian high so there are still opportunities going forward but despite some cold weather over the festive period it’s looks like this December won’t be much better for snow than the previous 10. We’ve still got two months+ of winter and in the past decade most of our snow opportunities have been from mid Jan onwards. Before today’s downgrades even yesterday’s charts were underwhelming after the promising charts of previous days. Despite achieving heights to out north west and having uppers below -5C for several days the set up not as conducive for snowfall as we would have hoped with the best chance of widespread snow during the breakdown (which is still the case). The best set up is stronger heights in Scandinavia, Greenland/Iceland with colder uppers to spreading south and west and lower heights to the south and east of the block. This would increase the chances of disturbances and convection bringing more better opportunities. I’m no expert about reading charts and but it seems to me the set up of having a wedge of high pressure to the north can be very rewarding but more often than not is incredibly risky. If the set up is right you can probably get some decent snowfalls from the fronts or easterly winds but there’s the risk of being too far north (dry) or south (marginal/wet). I think the last occasion we had a similar set up was January 2013 which did produce a two week cold spell but I recall much of Scotland missing out on a lot of the main snowfalls and much of the snow that fell in the Glasgow area was too wet to settle - a very frustrating spell. Hopefully we see some incremental improvements of the length and depth of the cold spell and we get some chances of decent snowfalls.

The models have been remarkably volatile - a very unimpressive performance to say the least. I think it will take another day or two to clarify Christmas Day. A lot of the charts today (except ECM 12z) show cold air from the east over most of Scotland during Christmas. At the moment much of Scotland is likely to be north of the front (GFS 18z shows the front reaching the very far south) with any frontal snowfall likely to be somewhere between the Midlands and Northern Ireland - I must admit I’m not sure how much snow would settle at low levels. It wouldn’t take much of a shift north to bring southern and central Scotland into play but at the moment it looks like best chance of a white Christmas for some will come from snow flurries. I think it’s almost certain that most of Scotland won’t snow on the ground on Christmas morning but some areas further east could have a covering by the end of the day. The uppers look pretty cold so I’m hoping this could enhance shower activity but at the moment I’d say snow flurries along the east coast is likely. It still looks likely that the cold spell spell will last to at least 29-31 Dec. The past couple of days have shown a variety of options for this period including largely dry, snow showers from a variety of wind directions and battleground snowfalls. In the next few days we should hopefully have a better idea about what this cold spell might deliver in terms of snow and low temperatures and whether it might last into the new year. Whatever this cold spell brings it looks like being one of the better December cold spells of the last 10 years. I hoping we can have a few days of winter sunshine, daytime temperatures little above freezing, some sharp frosts and enough snow for a covering. I would love the cold spell to be prolonged with some ice days and lying snow of at least a couple of inches.

GFS is very snowy for much of Scotland for Christmas Day. It stays cold until breaking down around 30/31 Dec with some leading edge of snow. ECM interestingly shows frontal snow on the 23rd Dec. Largely cold and dry until the 27th with frontal snow in southern Scotland. It remains cold to the end of the run. Christmas remains very uncertain with regards to where that front ends up. We should have a decent idea by Wednesday. It looks like staying cold until the 30th at least. It remains to be seen what the period between 25th-30th will offer in terms of weather conditions. Very cold and dry with some snow showers in coastal areas, or some disturbances in flow brining snow to wider areas or even convective snow from an easterly. If it stays predominately dry then there should be opportunities for battleground snow if the Atlantic makes a return. Both GFS and ECM are a little disappointing in FI in terms of the strength of blocking to the north west compared to previous runs. This makes the longevity of cold less certain but it’s too far away to be concerned (models normally underestimate blocking in the long run). Even if heights weaken a little to the north west there’s still a strong possibility of recurring episodes of cold - potentially very snowy. It’s a high risk/high reward scenario and I believe some of the notable periods of winter weather in the past occurred with slight heights to the N/NW. A solid Greenland high is the best option but not the be and end all.

For Glasgow: Max 2C Min -3C AM - patchy cloud cover, slight easterly breeze PM - mostly clear and calm

Looking drier for Christmas Day but still a decent chance of a white Christmas for eastern parts of Scotland. The GFS 12z has the front reaching southern Scotland but much weaker than previous runs. ECM 12z has the front in southern England. It looks very likely we are heading for the coldest spell of weather in December since 2010. Potentially very cold - especially ECM 12z after Christmas. It’s looking mostly dry away from the the east coast but there’s always the chance of features coming out of nowhere brining the risk of more widespread snowfall.

I’m no expert but I’d say we should have a decent grasp of the general situation at 72-96hrs. Of course with snow it’s often a nowcasting event. I think early next week we’ll have a decent idea of where any frontal snowfall will be. Given we are already seeing low pressure moving south (as expected) I think much of the potential frontal snowfall will end up somewhere between Manchester and the English Channel - possibly further south than that if the trend continues. As for Scotland we would likely be looking out for snow showers (most likely from the east). It’s uncertain whether we’d end up with proper convective snowfall or just flurries. Regardless, if the atmosphere is cold enough for snow there’s always the chance of surprises popping up at short notice (as was the case in late November).

GFS 00z shows a shift north for Christmas but still showing a white Christmas for many - though we can’t afford another shift northwards. A very good run 28th December onwards. The ECM on the other hand shows a southward shift which has raised the spirits of members south of the border in the model thread. Still showing a white Christmas for much of Scotland away from the south west with estimated depths generally in the range of 2-5cm. The main snow risk for Christmas in the Midlands. The easterly also returns from the 24th-26th. It remains cold and blocked to the end of the run with the potential fur very low temperatures with slack heights during day 9/10.

GFS 18z is an upgrade with a chance of significant snowfall across large parts of Scotland between Christmas Eve and Boxing Day. A cold Northerly follows until a battleground snowfall on the 30th. Turning milder around New Year but very impressive northern hemispheric profile with a very much diminished polar vortex (which doesn’t guarantee cold and snow but increases the likelihood of the ebbing and flowing of cold in January). Model watching doesn’t get much more exciting than this. The upcoming period is certainly the most promising for December cold and snow since 2010 and probably the best chance of a prolonged cold spell since then. The period between 24th-27th December has the potential to produce not only a white Christmas (and it looks likely that somewhere should see a technical white Christmas) but a snowfall on the magnitude of 28 Feb 2018, 6 Dec 2010, 12 Mar 2006. Unlike the beast from the east which was a convective snow event this would be a frontal snowfall and there haven’t been too many notable frontal snowfalls in the last decade. This is very much a high risk/high reward scenario. A shift north and most would end up with cold rain/hill snow. A shift south and we have dry, cold conditions with perhaps some snow showers. If things stay as they are now we could see a significant snow event and if the GFS 18z is correct Christmas Eve into Christmas morning could be very snowy. It’s a long way off and a lot will change between now and then but it will be fascinating to see how things progress. The upcoming cold spell may not yet be 2010 levels in terms of severity and longevity but I would very happily take a one off large snowfall or a week of proper winter weather. I do think as we get closer to Christmas we might see upgrades in terms of blocking and longevity of cold and if the PV continues to be diminished as charts are currently showing then January could be very interesting.

Some similarities with the cold spell of late December 2000: 21 Dec 2000 21 Dec 2021 22 Dec 2000 22 Dec 2021 23 Dec 2000 23 Dec 2021 24 Dec 2000 24 Dec 2021 25 Dec 2000 25 Dec 2021 26 Dec 2000 26 Dec 2021 27 Dec 2000 27 Dec 2021 That cold spell started around Christmas Eve and lasted to around New Year’s Eve. It wasn’t as prolonged as many of the classic cold spells but it was quite a notable period of weather. Temperatures at Glasgow airport: 24th 4/1 25th 2/-2 26th -3/-5 27th -1/-6 28th -1/-9 29th -3/-10 30th -3/-11 31st 4/-6 The period between 26th-30th Dec 2000 saw the joint most consecutive days of maximum temperatures -1C or lower (equal to Dec 2010) in records since 1973. There was quite a notable snowfall around the 28th with depths around 15-20cm+ in the Glasgow area. The weather during that period would not have looked out of place in 2010. Looking at the archives the main difference between 2000 and 2031 is the shape of the low pressure system in the Atlantic (elongated in 2000, bowling ball in 2021). The potential snowfall in the Christmas period also reminds me a little of 26 Feb 2001.

Latest ECM very snowy for much of Scotland after Christmas Eve. Despite a significant shift north it’s still looking good for snow prospects during the Christmas period but it’s a very fine margin between significant lowland snowfall and cold rain/hill snow. We can’t afford for another shift north or we risk missing out. With the tropospheric polar vortex looking fragmented and the likelihood of heights to our north/north west we should have a chance of further shots of cold and snow going forward. But higher pressure to our NW doesn’t mean we will have a continuous supply of cold air - especially if high pressure moves too far north and west - but as shown on today’s charts Scotland has a better chance of being on the right side of marginality.

The chances of cold and potentially snowy weather between the 23rd and 28th December has increased. Reading the model thread it seems a number of members are concerned about the blocking high being positioned too far north for snow south of the midlands. In such a scenario I’d expect Scotland to stay on the cold side but in my experience of following the models usually in a scenario such as this we see southward adjustments which increases the snow risk for parts of England and Wales whilst Scotland remains cold but generally drier.It will be very interesting to see things evolve in the next week. At the moment I’m keeping expectations low but I feel it’s quite likely we’ll end up with a cold few days with the possibility of either marginal frontal snowfall or snow flurries from an easterly. It’s quite possible we could end up with significant frontal snowfall or convective snow showers and perhaps a more prolonged cold spell. It’s refreshing to see this sort of potential in the charts considering the lack of cold and snow in December in the last decade. Already this season we’ve seen some promising charts fail to materialise and there’s always a danger of ending up with less snow with missed opportunities in a set up conducive to blocking than a more mobile, westerly regime. I’m hopeful our luck might change in the next couple of weeks and if not we should see further opportunities in the new year.

It looks like we have the sequel to ‘That ECM’ from 2012. If we end up with Synoptics like that for Christmas it would be spectacular. So too will be the reactions in the model thread if we end up with something a lot less appealing. The outlook for Christmas is incredibly uncertain with so many possibilities. At the moment I’d say we might end up with drab, overcast, drizzly conditions and temperatures in the range of 4-9C but hopefully we get wintry weather for Christmas and beyond.

Maximum/minimum temperature at Glasgow airport: 24th 4/1 25th 2/-2 26th -3/-5 27th -1/-6 28th -1/-9 29th -3/-10 30th -3/-11 31st 4/-6 I was four at the time and I can remember some snow showers on Christmas Eve. I woke up to a covering of snow on Christmas morning and I can remember snow lying on the ground up to about New Year. There was a large snowfall around the 28th - being so young at the time I can’t remember specifically how deep the snow was but at least 6-8 inches of snow fell in the Glasgow area. As a four year old I thought it was just normal Christmas weather and in the following 20 years only 2004, 2009 and 2010 had snow on the ground on Christmas Day. It was certainly a very ideal period of festive weather. A snow depth of more than 15cm, 5 consecutive ice days, a maximum of -3C and a minimum of -11C would not have looked out of place in the major cold spells of Dec 2009-Jan 2010 and Nov/Dec 2010. Obviously the cold spells in 2010 were more prolonged and had more widespread impacts but December 2000 like the Beast from the East in 2018 are examples of relatively short but sharp cold spells which can produce impactful and memorable weather without being exceptional in terms of length. I would prefer a potent cold spell no longer than 7 days to an uneventful period cold up to 2 weeks or more. I would rank Dec 2000 up there with the more notable and memorable cold spells I’ve experienced.

First covering of snow of the winter - hopefully the first of many. Looking at the radar it looks like the precipitation is heavier further south and east so I imagine some places should have a decent covering of snow.

Looking forward to the first taste of winter during the coming days. It looks like parts of eastern Scotland are in for some interesting weather with potentially strong or even damaging winds aswell as some. In the west winds should not be as strong and I’m not expecting much in the way of snow other than scattered showers. After such a mild and benign autumn it’s good to have seasonal weather just before we enter winter.

First taste of winter after what has felt like a long summer. How common is October snow where you are and is it any less frequent than it used to be? I know snow in late Spring in northern Scotland isn’t unusual - I’d imagine more common than October. South of Aberdeen snow in October is fairly rare - maybe once in every 5-10 years or so with the first snowfalls normally occurring in latter part of November.

Glasgow airport reporting a temperature of 21C at 10.20pm which is pretty remarkable for the 8th September.

28C at Glasgow airport which is the highest autumn temperature since the records began in 1973.