Altostratus

Yup was a nice surprise this morning! Radar suggests the shower came in around 4am and it seems we were in one of the sweet spots. Took me well over and hour to get into the city this morning and there is barely a dusting here on the coast.

Was not expecting rain this morning...temperature and dew points are good..must be some warmer uppers in the flow...been the story of the winter so far for this part of the world! A standard toppler is more productive than this...at least it brings in colder uppers directly from the North rather than this modified flow from the NW.

It appears all models are picking up a general signal for flattening the pattern, although the key to this outcome lies in what happens over N. America circa T96 – T120. Given this is at the limit of model ‘accuracy’, it would only take a slight amplification to result in energy being sent south rather than east - even if this delays the westerly onslaught it would be good as it buys more time for pressure to build over Scandi. At the same time, the ridge extension from the Russian/Arctic high could be being underplayed too. Both are long shots, but we shouldn't dismiss anything just yet, although granted, odds currently favour a switch to a more zonal pattern. Without the assistance of high level blocking (lacking all winter!), the Atlantic ridge was always going to be temporary affair. If there is to be any slight increase in upstream amplification, we better hope this starts getting reflected in the ensemble data ASAP.

Nothing here, as expected. Currently sunny but noticeably windier than this morning.

Agreed. There are far too many variable and complex interactions to draw any meaningful conclusions from teleconnections in isolation. Statistically they may be useful as one of an array of inputs into complex seasonal models, however even the UKMet model hasn't proven it's worth yet. Whilst I understand people’s frustration re transitory ridges, far worse charts could be shown. Agreed that NWP do not appear to be picking up on a signal for a major shift in global waves just yet, but perhaps the driver for a pattern shift could be the progged trough over central Europe and pressure building in across Northern Scandi. As Steve alluded to, the PV chunk over Baffin hasn’t really moved all winter and therefore any chance of a pressure rise over GL would therefore have to come from a ridge backing west from Northern Scandi/Arctic area. On the plus side, at least there is no consistent Euro high forecast with the jet flattening and stampeding Russia…best case scenario from what I envisage would be for a Jan 1985 type evolution....anyway let's see what the next few days bring.

Gone very dark here...heavy looking shower is imminent. Will find out what the PPN is in a few mins... Up to 4C now so not looking too good but we shall see... Turns out it was a wintry mix here on the coast...started as graupel, then rain and currently sleet.

Agreed. According to latest met office observations, the temperature in town is 3C, so touch and go. Further inland and with a bit of height should be ok for snow I would have thought.

Some tasty looking showers out in the North Sea...and they appear to be heading in this general direction. Worth keeping an eye on as the day progresses...

Amazing the difference a few miles makes. When I left Kingswells/Westhill area this morning, there was a good 2 inches of snow cover. That's the problem with these isolated showers...it really is pot luck.

Woke up to 2cm of fresh snow this morning...looking at the radar, it looks as though a heavy shower passed through around 5am. Nightmare journey into the city this morning...total gridlock in places.

First complete snow cover of the season yesterday evening...probably about 2" on the ground at home, although much less in the city. Currently cold, crisp and sunny. Will be interesting to see how low the temps dip overnight.

Dusting of snow here after a moderate shower.

Fantastic snow shower passed over....really heavy with low visibility at one point. We finally have a covering of snow in the city!

First proper snow shower for some time here...unfortantely it went as fast as it came...

Waste of time here - complete wash out. We had colder temperatures and more snow back in Halloween! Very disappointing...

Nice shower passing over here...no signs of sleet or rain thankfully

Impressive temperatures this morning...the temperature dropped again as the cloud cleared between 7-10am. Aboyne was back down to -10C @ 9am!

Woke up to a nice covering of snow here - prob a couple of cms. WIll be looking to add to that throughout the day though.

Just had a moderate to heavy shower that left a dusting in the city

Had a snow shower about 50 mins ago. Not much settled but still nice to see. Hopefully some beefy showers will feed down soon...radar looks encouraging.

Some of you are talking absolute nonsense tonight. All models are showing potential for a cold to very cold spell – this is pretty much a certainty now. This run is just another variation on this theme. There is good reason to be optimistic. Why all the negative posts, I’m not sure. It is a developing situation as per normal. There is high confidence for the cold air backing up into the UK. This is all we need for now - what happens after this, is open to debate. The first hurdle is cleared however. This has often been the achilles heel in recent years. With good foundations, the final piece of the jigsaw will likely fall in place.

Blast, please don’t take this personally, but your over-confidence is bordering on arrogance at times; particularly when the weather in question has not happened. I'm not just referring to this post by the way. We are all entitled to make predictions/forecasts and that in part makes the forum an interesting place, but your implied confidence at that range is rather misleading. Your forecasts might well prove to be correct. If that’s the case, perhaps we should all take note of your methods. As always, the proof will be in objective assessment after the events. I agree that this evening’s outputs are excellent. With better cross-model agreement we have taken a massive step in the right direction - the odds seem to have swung in favour of a cold spell for now. Taking an averaged look across the big three, I wouldn’t be surprised to see the cold spell upgraded with subsequent runs, with the possibility for even tighter gradients. Let’s not carried away though – let’s concentrate on getting that cold air flow established. Having said that, it looks like quite a fast moving pattern, with the cold air and instability arriving almost simultaneously – as usual, the timing and coincidence of these events hold the key to any snow potential.

This degree of uncertainty is unprecedented in the internet era. It’s a guessing game right now. Having glanced over the model outputs, it still looks 50:50 to me. The evolution to cold is fraught with danger. However, it is often these risky situations that go on to lead to some of the biggest snowfalls. I’m sure some of the great snowstorms of the past e.g. Feb 1978 and Dec 1978 were equally as difficult to forecast. A more predictable transition to long lasting cold like in Feb 86, whilst very cold, was also very dry. To get decent widespread snow events, an Atlantic influence is usually required. IF the cold air can get established across the UK, the ingredients seem to be in place for an attack from the Atlantic, giving the potential for widespread heavy snow. Things appear to be so finely balanced that I wouldn’t rule anything out just yet. From a neutral viewpoint, this period of model watching has been fascinating. Even though I'm not in the UK, I would love to see the cold air win out. A decent blast of cold air would surely be the icing on the cake for this winter; firmly cementing it as the best winter in a generation.

The 216hrs chart sure is a thing of beauty – slider low allowing the shortwave to back up and open the flood gates – textbook stuff. Obviously subject to change but it’s nice to see such an evolution be churned out.

Good run from the ECM if you like cold. It was obvious where this run was heading given the T+144 chart. A lot can and will change between now and then so no means a done deal. Something to boost morale if nothing else.