Blizzardo

Its actually snowing quite heavily just to the east of Glasgow just now but I'd agree with you that most showers that get through should be light today down here today.

Still very light snow falling here but sky brightening up. Not sure if that was just a rogue shower or if there could be a few surprises today. A light covering left on roofs and grass. A lot of shower activity to the north but will any more reach the central belt?

Light snow falling in Glasgow. I'm a bit surprised that the showers have not disintegrated from the north but not complaining.

More good model output this morning although some on the model discussion thread will be nervous about the evolution the GFS takes - a low dropping north to south introducing a north easterly before probably getting to the easterly in the end. The northerly has pushed in and should be with us over the weekend and probably through Monday before the Atlantic tries to push in. For me, after the weekend is where it starts to get interesting as we have cold air across us, introduced from the north, a strong block to our north east that would like to move west and Atlantic fronts trying to move east. The GFS has a bit of battleground situation going on with heavy snow early in the week. This is how it looks on the fax chart.

I saw that one, its a cracker. I think there may be a few excellent charts popping up over the next couple of days. PS Met Office advisory of blizzards for the North of Scotland now for both Saturday and Sunday.

I'm going to blame it on that 12z ECM run the other night that showed a seriously cold and snowy spell a la 1947. The problem with getting a run like that is that some people start comparing all future runs against it and it seems that what are perfectly good runs are downgrades. I think patience will be needed when viewing the models over the next week as there will be a few ups and downs. It will create some funny posts and a bit of heated debate which is always good.

Really quite remarkable ensemble agreement this morning on quite a lengthy cold spell. There is not a lot of spread at the end of the runs and its basically saying - strong northerly influence followed by a few possible evolutions towards a cold easterly but in the end we will get there and it will be cold. Personally I'm still a bit wary because of the timescales involved and the different stages that still have to happen but really encouraging signs if your looking for another cold and maybe very cold spell.

Very good ensembles from the GFS 12z with the mean for my area at or below -5c all the way. Much better trend for cold than this mornings. I think the key period is around 2nd/3rd Feb. If we can slip quite seemlessly from northerly to easterly then its game on. If you look at this time period there is quite a clear spread between very cold solutions and relatively mild although the general trend is for cold to win out in the end.

First advisories out. Widespread ice for Scotland Friday morning then this one for Highland, Grampian, Orkney and Shetland:- There is a moderate risk of a severe weather event affecting parts of north and east Scotland on Sunday. Frequent heavy snow showers affecting northern and eastern Scotland on Sunday are likely to bring significant accumulations of snow in places. Strong winds may also lead to drifting of snow and blizzard conditions, especially over high ground. Issued at: 1115 Wed 27 Jan

This Met Office fax for Sunday looks to be going for a prolonged period of snow for parts of Scotland. We are sitting between the 528 and 510 dam line with a little low slowly dropping North to South down the East coast. This is how it looks 6 hours later on the GFS.

Some amazing model runs tonight with all going for potent Northerlies followed by strong Easterlies, albeit how they get from Northerly to Easterly differs a little. The ECM run is almost a perfect run with not a hint of mild and if it was to verify there would be some heavy and widespread snowfall for much of the UK. The GFS is slightly less dramatic compared to the ECM but would still deliver a cold spell of weather loads of snow opportunities. There will undoubtably be some ups and downs over the coming days but it it looks like a another cold and wintery period of weather is on the way.

Cold and snowy looking GFS 0z with the mid atlantic high slightly further west and north maintaining the northerly a bit longer than on previous runs. A very brief milder interlude followed by a strong easterly.

Lowest GFS ensemble temperature mean for me for a couple of weeks. At or below -5 from 28th Jan all the way through.

My own view is ignore any comments such as "it will be a mild February because of stratospheric blah blah...." or "it was a good ECM but it wont happen because GP said such and such". I'm not saying that what the experts say is irrelevant and I do keep this at the back of my mind but I sometimes think it takes takes away a lot of the wonder and excitement from watching the weather and following what the models are showing. Personally. I very much doubt this mornings ECM will happen exactly as shown but the trend is good in that its showing a better Northerly flow and the possibility of then drawing in some more cold from the North East or East. Thats good enough for me. Anyway, I dont know whats wrong with a 3 day Northerly toppler, for Scotland its better than a feable Easterly that only gives a bit of sleet or a few snow grains in the South East of England.

Very good Northerly on this mornings ECM. More potent and longer lasting than previous runs.

It looks to me as though there will be some changes next week with more of a North Westerly then maybe Northerly influence later in the week. ECM showing this tonight and UKMO was getting there at T144. The GFS has been hinting at this for days but the positioning of HP on its 12z was always in the worst possible position. I know that it goes out longer but its strange how often the GFS picks a new trend then drops it, plays about with things for a couple of days then comes back with similar charts at a later date.

Just to add my own view on the ensembles to Catch's very good explanation. I think they can be a good trend spotter as they measure the probability of a certain forecast actually happening by running a number of different forecasts each with a slightly different scenario. Each day throughout winter I normally have a quick check of the ensembles and my focus is on the 850 temps (the temperature at approximately 1.5 km) and then air pressure. For me the air pressure gives a clue to a pattern change and the 850's tell how cold it may be. I tend to focus on the ensemble mean (average) which gives an indication of the most likely forecast from that model run. At the moment, using the GFS 06z for example the ensemble trend is for pressure to start building from around 23rd (Easterly) and and then fall away after a couple of days (probably Polar Maritime North Westerly influence as the temperature doesnt rise much). There is reasonable agreement for the initial rise is pressure but a bit less for the pressure drop from the 26th.

The 6-15 day Met Office forecast looks a bit colder than recently and seems to indicate that they believe that the Easterly as shown in some models this morning will be brief with more of a Polar Maritime influence afterwards. Its a bit vague and covers a few bases but in general it does look as though they feel the trend is towards a colder spell. UK Outlook for Sunday 24 Jan 2010 to Tuesday 2 Feb 2010: Rather cloudy for many parts, with showers or longer spells of sleet or snow likely in the east and over high ground at first, with outbreaks of light rain further west. From Wednesday (27th) wintry showers are expected to ease in the east, with rain, sleet or snow developing across western and northwestern parts. Temperatures are expected to be below normal, and perhaps very cold in the east, with overnight frosts likely and an associated risk of ice in places. There is a lot of uncertainty regarding the end of the period, but a continuation of unsettled weather is likely with spells of rain, sleet and snow, and a risk of strong to gale force winds mainly across western parts. Temperatures probably remaining below normal. Updated: 1226 on Tue 19 Jan 2010

Todays GFS 0z in the short term has snow risk on Wednesday night mainly for North West Scotland. The Atlantic does push in briefly on Thursday and Friday but the block fights back and by Sunday there is an Easterly influence with a snow risk, especially for the South East by Monday. Big changes compared to yesterday mornings GFS.

Some quite heavy rain moving in from the Atlantic. GFS has this moving in a little bit quicker than the ECM so ECM shows more opportunity for slightly colder uppers to make progress from the East. The fax chart over the last 2 days has also seen the 528 dam line edge a little further West with each update which is good. At the moment GFS showing sleet for low ground of Scotland but GFS can sometimes be a bit progressive in bringing in the Atlantic so the cold upper air may make it a little further West than its showing. Uppers looking about -3 or -4 for most during the window and max temps of about 3c when the heaviest precipitation around so may be enough. At the moment I'd say rain/sleet turning to wet snow for my location but still time for further upgrades.

Early Met Office warning out for South West Scotland for Wednesday for heavy snow that gives an indication that its not a straighforward situation this week of the Atlantic pushing in and blowing away the block to the North East. Sometimes a knife edge situation can produce the heaviest snowfall i.e. when a relatively warm moist air meets cold dry air and it would be nice to get a rain to snow situation this week. It still looks to me thats there is a reasonable chance of the cold air from the North East pushing back towards us but even if not there is a lot of cold air to our North West that might soon come into play. Loads of possibilities, more cold than mild.

I like the ECM tonight from a cold and snow prospects viewpoint. I know its a bit away but there is a train of lows running under the UK at 168 hrs and from then on low pressure seems to be doing its best to drag the cold air towards us.

Only one run from one model but the GFS 06 hrs has potentially a lot of snow forecast for some parts of Scotland as the big Siberian High speads a little westward. Where this meets the Atlantic influence there could be heavy snow. Likely to change but one to watch around the middle of next week.

Dont know if you read this thread yesterday as there was a bit of talk about the snow depths at the ski areas (Cairngorm in particular) which might be of interest to you. I think skiing might be a bit of a struggle with the winds this weekend but should hopefully be a bit more managable next week. Have a great time!

A light covering in Bishopbriggs this morning - maybe 1-2cm - on top of the ice pack.