Thundery wintry showers

Snow is starting to lie in South Shields for the first time: Today's Weather WWW.SOUTHSHIELDS-WEATHER.CO.UK

Yes, it would be frustrating living in Norwich (where I did some of my studies earlier) as the band of heavy snow has stalled just to the south of Norwich for the past 6 hours or so, leaving Norwich with just light flurries. The north-east also isn't getting much, plenty of flurries of light snow and graupel but not generally heavy enough to settle. I expect the north-east and Lincolnshire to get rather more on Monday and Tuesday as convection kicks off more over the North Sea, but there is certainly a chance of the Norwich area largely missing out, not unlike what happened there on 30 November to 2 December 2010. At this rate it looks like the most likely reason for disappointments in this region on Thursday/Friday is the frontal systems fizzling before they get here, rather than a quick arrival of mild air from the SW, except perhaps in west Cornwall.

I'd be interested to know the Darcy equation for the precipitation moving in off the North Sea tomorrow.

The models have shunted Tuesday's low back southwards again this afternoon, so less chances of anything significant from that, though maybe some snow showers clipping the English Channel coast as the wind briefly turns more south-easterly. It's still not too late for northward corrections at three days out, but for now the odds are looking against again. But as AWD mentions there is an increasing chance that Thursday/Friday will have snow for at least some, with the fronts getting in but not pushing the cold air away quickly, and possibly not pushing it away at all for the N and E of the region. From a local perspective at least the Netweather model outcome would give Exeter some of the white stuff rather than an all rain event or just sleet on the leading edge, though it would only stick around for long in the north and east of the region.

I'd say definitely increased chances for this area of the region on this morning's runs. I still doubt that it will be quite cold enough tonight, but increased chances of some sleet or snow tonight if it stays heavy enough while getting this far west. Tuesday's low is on a knife edge with some runs having it over most of the region and others having it just to my south, but overall I'd say another slight northward shift from yesterday's 12Z runs, so if the trend keeps up, some of us will probably get something. Increasing chances of the frontal attack on Thursday bringing a South West battleground event followed by a cold dry regime, rather than pushing the mild air north and east. It could still be that either Devon and Cornwall get rain and the snow is confined to the N and E of the region or the systems don't even make it in, considering that it's still five days away, so there are no guarantees, but certainly increased potential.

Just picking up on another part of this, I don't think I was ever "very sure" that it was all going to France, just stating that in my experience these lows tend to get revised southwards near the time (due to models often overdeepening the lows), but there are certainly exceptions. I'd only be very sure about it if it was being modelled to be well south of the English Channel at this time range, or if the GFS and ECMWF were sticking to current outputs at 1 day out.

I'm not discounting them at all, just commenting on what the latest GFS run is showing. The latest trend on the GFS/ECM has been to inch it a little further north, so if that trend is repeated in tomorrow's runs they should end up more or less in line with what ICON is currently showing. Also 12Z ECM had a snow streamer breaking out on the system's northern flank (albeit mainly just near the coast), GFS 18Z disappointed me in that respect as it is a dry run for Tuesday but even that has some snow breaking out to the east of the frontal system on Thursday mainly over Devon. Thus, I'd say definitely somewhat greater potential for Tuesday and even to some extent Thursday as things stand today than was the case yesterday. I'm also keeping an eye on the system moving in through Saturday night into Sunday. 850s don't look cold enough to me, but that's not the only variable that governs the rain/snow chances and some runs have certainly had some of that turning to snow.

The 12Z ECM today and now the GFS 18Z are picking up on a possibility that after the frontal attack on Thursday/Friday we might well move into a cold and dry regime, rather than a mild and wet one. NOAA's 8-14 day outlook is also inching in that direction - a couple of days ago it had a low height anomaly right over Britain, but it's now out to the west: Climate Prediction Center - 8-14 Day 500mb Outlook WWW.CPC.NCEP.NOAA.GOV

GFS 18Z has the low on Tuesday just missing the majority of the southern coastal strip but clipping south-west Cornwall, hence the GFS's prediction of a couple of centimetres in the far south-west. Thursday now has an area of light snow hitting a large part of Devon before the main band comes in, which is still predicted to bring rain to the south and west of this region, but snow for the north-east of the region. In this run the mild air doesn't really penetrate far beyond the south-west, so I see that northern parts of Central S England are down as holding onto their lying snow for a while on this run. I'd say the chances are growing that after the frontal attack on Thursday/Friday we may move into a cold and dry regime, rather than a mild and wet one.

Given your join date I guess you must have been "lurking" 2-3 weeks before joining the forum. I still have that run saved somewhere on an external hard drive. Amusingly its setup wasn't dissimilar to what is forecast for the next five days or so!

Looking back at that 19 February 1996 forecast, I remember that despite the ridge of high pressure coming in and forecasts that the showers would increasingly be limited to the SE corner, a cluster of snow showers developed over north-east England on the evening of the 20th and topped up the snow cover in many areas. I recall that after significant accumulations on the 19th, a thaw had set in along the Tyne and Wear coast overnight into the 20th so there wasn't much lying there on the 20th, probably due to a mix of sublimation and the strong wind off the relatively warm North Sea, but plenty by the morning of the 21st. I can't remember which forecast it was (it might be out there on YouTube, not sure) but there was one in early February 1996 referring to the possibility of significant snow coming in off the North Atlantic where John Kettley said, "The weather might run off the rails!"

My name comes from all the way back in 2002 when I joined the BBC Snow Watch boards and named myself after the weather type that the Tyne and Wear area had during the northerly outbreak of 8/9 November 2001 and more locally from the northerly of 22 December 2001. I thought it was a good way of combining the three types of weather that I tend to get excited by the most - thunderstorms, snow and convection.

The frontal attack from the SW doesn't even reach the east of this region on the ECMWF 12Z run tonight - I have mentioned a few times that the models often place these things further south, but it's also true that when they underestimate a cold block they also tend to place systems further west with successive runs. It's an unusual evolution from cold easterlies to mild southerlies without any significant frontal precipitation in between, but in many ways better than a switch to mild wet and windy weather and consequent flooding. And yes, the ECMWF has joined the other runs in pushing Tuesday's low a little further north - I can see strong hints of a Channel streamer on its northern flank while the frontal system makes it into the far south-west. A bit further north still, and some of the region could get a fair amount of snow from it, although admittedly that may increase the marginality in the south of Cornwall.

Yes, although in my experience these things correct south more often than not, it doesn't always happen, and certainly if that system nudges just a smidgeon further north on subsequent runs, those of us close to the English Channel coast would have a near-guarantee of a decent covering prior to the more marginal push from the south-west on Thursday. For Thursday this GFS run has the scenario swebby mentioned earlier with the milder air pushing in from the south before the precipitation reaches us, resulting in nothing more than transitionary snow to rain for the north and east of the region. The latest UKMO run might have the same issue on Thursday but it, too, looks closer to delivering for near the south coast on Tuesday with the low to the SW deeper and closer than on earlier UKMO runs.l

The Met Office outlook looks similar to the ECMWF ensemble mean, with a slow breakdown from the south but the milder air arriving in the south and south-west relatively quickly, a much slower breakdown in the north and then southerlies with high pressure staying put to the east, which definitely has potential to bring back colder air. Still, by that point we're out at day 10 and I don't think the ECMWF ensembles have that strong a track record past day 7 (though the ECM is on average the most reliable at 5-7 days out). I don't think the update necessarily means that confidence is high, just that they think it's the most likely scenario as things stand.

Although I wasn't there at the time, I remember seeing reports that the Exeter area got a big dumping on 20 December 2010 (the Monday before Christmas, rather than the preceding weekend) with over 20cm in places, and with lying snow out to the sea front along the south coast of east Devon, though not as much in west Devon and generally nothing in low-lying parts of Cornwall. I remember there being a lot of uncertainty over that one in the days leading up to it with some model runs (notably the GFS as per usual) deepening the low and sending it further north, which would have brought the dumping of snow further north but rain into the areas that ultimately got snow from it. It was a very different kind of setup though (a northerly followed by a lobe of the polar vortex being stuck over Britain for a few days).

Yeah, I hadn't really thought of that possibility (the cold air being mixed out and then cold rain), probably because I haven't lived in this area of the UK for that long (January-June 2009 and October 2014 to present) and don't remember experiencing any instances of that in this period. I'm aware that the region missed out on potential frontal battleground snowfalls around 13 January 2010 and at times in January 2013, when snow accumulated over Dartmoor but not here.

Yeah, come to think of it, it would be somewhat more of a kick in the teeth if I was in Lincoln this winter and Lincoln stayed in a dry slot between the snow showers further north and the organised snow further south, and Exeter actually got more, especially if Thursday's Atlantic attack does end up further south and slower to break through the cold block than modelled and Exeter gets a snow event from that. I remember Norwich (and for that matter Abingdon) lay in such a dry slot in late Nov/early Dec 2010, though I didn't miss out altogether living in Norwich as there were snow showers there on 25-29 November before the easterly set in. Living in Exeter on the other hand we don't normally expect much off the North Sea from an easterly and the breakdowns often (but not always) push too far north too quickly, so expectations from this type of setup are necessarily lower. I'm remembering that at one point (I think it was March 2006, just before Abingdon got hit in February 2007) Abingdon had such a snowless run of winters that I produced a map of expected snow depths and had a tiny area centred on Abingdon down as having "definitely nothing". Actually, here it is:

Yeah that's true, it seems to be showing Lincolnshire in a dry slot in between showers to the north and the more organised activity to the south, and it has the latter extending across to Devon. I remember when I came to Exeter for the first time in January-June 2009, the easterly on 2 February actually brought more and longer-lasting snow to Exeter than to the Tyne and Wear coast, as a snow shower came all the way across from the North Sea that afternoon and the trough that came in from the SE was an all snow event in Exeter but turned to rain along the north-east coast. The long-term averages indicate that the odds are against though. I just have to hope that this ends up as one of those easterlies that bucks the long-term averages.

Low-lying Devon, especially south Devon, has always been on average one of the least snowy regions of the UK, albeit prone to occasional severe snowstorms as per 1 and 18 March 2018. As we're seeing with the predicted frontal attack from the SW next week, it relies on the low pressure and fronts aligning favourably, but on rare occasions it does work out. In some ways it is frustrating being in lockdown down here while this easterly is happening, for I expect to be in the Lincoln area next winter which is more guaranteed to get snow showers off the North Sea in an easterly and so it doesn't matter so much there if the breakdown is a snow to rain or all rain event, but there are no guarantees of anything like this happening next winter. I agree that if Tuesday's low was a little further north much of this region could see an all snow event from it, but in my experience if these things get revised, more often than not it tends to be a southward correction, which is why I see more potential from Thursday.

Tuesday's low increasingly looks like missing us to the south, so probably a dry spell for the west of the region up until Thursday, maybe the odd flurry as others have mentioned, maybe up to a few cm in places in the east of the region. Thursday's breakdown is still "up in the air" as far as I can see. GFS and ECMWF have a snow to rain event in the north and east of the region with an all rain event for much of Devon and Cornwall, but the UKMO at T+144 (which so far has been verifying well) has the frontal attack further south, which might well result in more substantial snowfall for this region instead of the Midlands. Also, it's not unusual for the models to revise this kind of setup further south with successive runs (like they did with Tuesday's low, which ironically looks likely to go too far south as a result).

Considering years since 1950, 1968 and 1969 stick out as two years when this period had particularly notable snow events. In 1968 there was a heavy persistent frontal event which brought heavy snow for some and therefore very large depths, while others had rain/sleet. In 1969 there was an exceptionally cold northerly accompanied by a couple of polar lows which brought snowfalls a long way inland. I can't think of anything much during the following 15 years, but 5-8 February 1986 was one of the snowiest spells of that very "easterly" month. In the 1990s, 7-8 February 1995 was snowy in north-east Scotland but the cold air struggled to make it much further south, giving a few wintry showers near the north-east coast of England and some light wet snow to the north-west. The northerly blast in February 1999 caught the end of this period, with frequent snow showers for NE Scotland and East Anglia on the 7th and 8th, frontal snowfall across an area of England and Wales on the 8th, and then snow showers developed more widely near the east coast on the night of the 8th/9th, so snow cover was quite widespread on the 9th. In the 2000s, there was a heavy snowfall in Scotland and parts of northern England on the 4th February 2001 which stuck around for a while in parts of Scotland but melted in northern England. I can't think of anything else of note other than 2007 and 2009, In the 2010s, 5 February 2012 was snow covered for a large part of eastern England from Durham southwards after a frontal system on the 4th brought rain, freezing rain and ice pellets to the north and west but turned to snow as it headed towards the SE. In some areas, certainly Lincolnshire and East Anglia, the snow stuck around throughout the period, but there was no further snow of note until the 9th, which was similar to the 4th. Nothing else sticks out though. 2018 may have had modest snowfalls for some in the north and east.

Yes, I see a slider missing us to the south on Tuesday and then a quick snow to rain event on Thursday/Friday followed by cold air hanging on in the north, milder air in the south, and the cold air building back south/west at T+240. I think there's a good chance that the Thursday/Friday event, being a week away, may get revised further south. Ideally I would like the Tuesday low a bit further north though, and expect that one possibly to also end up a bit further south. But the GFS 12Z does have a bit of precipitation over the SW to its north nonetheless.

Aye, the slider on Tuesday largely misses us (though some light precipitation shown for the SW to the north of it) and then a swift snow to rain event on Thursday. However, only a minor revision south would put our region in the firing line and sometimes these setups do shift southwards as we get nearer the time. I remember the unexpected South West snowfall of 31 January 2019 was forecast to be over the Midlands about 4-5 days before the event before being modelled further south with successive runs.

The synoptic outlook for next week reminds me of the third week of February 1978, which had more or less the scenario that I envisaged above, and it looks like one of a range of realistic possibilities for mid to late next week. I wasn't even born when this event happened but as far as I'm aware it was intense and affected most of this region of the UK. Of course that's practically the snowiest-case scenario from here and something rather less snowy than that or even non-snowy is probably more likely, but it's noteworthy to even be able to consider it as a realistic possibility.