Thundery wintry showers

Long range forecast team
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About Thundery wintry showers

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    Cumulonimbus Incus
  • Birthday 06/22/1984

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  • Gender Male
  • Location East Exeter, Devon
  • Interests Weather (of course!), chess, music, computer gaming, social events, football, tenpin bowling, environmental issues
  • Weather Preferences Sunshine, convective precipitation, snow, thunderstorms, "episodic" months.

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  1. The 4th April 2000 even had a covering of snow at Hastings early in the day.  The period 2nd-4th April 2000 saw falling sleet or snow almost everywhere.  It was a very marginal and persistent frontal setup and so many lowland places saw no lying snow, but high ground plus some low-lying areas saw large accumulations.  The fronts cleared away south-eastwards during the 4th, followed by a mix of sunshine and scattered sleet/snow/hail showers.
  2. I looked at the temperature anomalies for January 1984 over at the NOAA/NCEP reanalysis site and they were fascinating.  Exceptional anomalies of -10 to -15 degrees near the east coasts of North America and Canada, and this cold air kept blowing right across the North Atlantic to the British Isles.  To the south of the north Midlands, there were marginal/wet snowfalls interspersed with mild interludes, due to the long sea track and the frequent intervention of secondary lows bringing tropical maritime air.  Further north, the dominant polar maritime incursions and deep lows brought repeated heavy snowfalls.  It was particularly snowy around the 21st to 25th, when this cold Atlantic regime faced opposition from fairly cold continental air, resulting in a frontal stalemate not dissimilar to that of 5-7 February 1996.   A phenomenal month, but having looked over the Wetterzentrale charts back to the 1870s, the persistence and intensity of that setup appears to comfortably exceed anything that was seen since the late 1800s.  Indeed, I haven't been able to find many near-approaches to the cold zonal March of 1995 (the nearest approach that I lived through, and I often reminisce favourably about that month), which often had a watered-down version of the setup that dominated most of January 1984.  January 1952, January 1978 and December 1982 are a few that do stick out, plus Decembers 1993 and 1999 in the north. As Weather-history alluded to in a post a few days ago, while many people complain about us being too far west, the main reason why we don't get much snow from westerlies is that we are too far east.  If the British Isles was about 500 miles further west, "westerly" snowfalls would probably be quite common.  Indeed, with that persistent cold anomaly in the North Atlantic combined with a persistently zonal pattern, the winters of 2014/15 and 2015/16 would both have ended up pretty snowy.  But with the UK being where it is, the days of widespread lowland snowfall from westerlies are rare, and their existence probably endangered.
  3. I think the nearest UK equivalent would be a generally north-easterly regime with a strong Greenland/Icelandic anticyclone and a deep low pressure system moving east through the English Channel and then turning northwards up the North Sea.  The main issue would be marginality since the low would have warm air wrapped within its core.  A setup similar to this occurred on Boxing Day 1927.  I remember potential for a setup like that in late November/early December 2010 (the GFS's overblown low to the south that it had moving north-eastwards up the North Sea) but thinking that the projected temperatures looked conducive only to sleety stuff at low levels. Of course there are different setups that can bring blizzards to individual regions- a strong to gale-force easterly from Russia for eastern Britain, polar lows and northerlies for Scotland and Northern Ireland, and frontal battleground scenarios for the west and south, like the blizzards in the south in January 1881 and February 1978.  
  4. I am thinking that this February is looking very likely to be another mild month... It may well be that March and April end up as the snowiest months of the winter, which was also true in some parts of the country during the similarly insane El Nino of 1997/98.
  5. I think it was February 1994 that had the fortnight of really cold weather- February 1995 was a mild month apart from a brief northerly around the 8th/9th.  However early March 1995 had widespread snow for much of Ireland, from a lesser version of the setup that brought big snowfalls in mid-January 1984. There are hints on the model outputs of potential for some cold polar maritime blasts in the next couple of weeks, but they probably won't sustain for long enough to bring widespread snowfall.
  6. I tend to think of the British climate as being near the back end of the top 20% of the world's most interesting climates.  We are capable of getting pretty much every type of weather that exists on the planet, but on the other hand, the "mundane" weather types (dull with persistent moderate rain, dry and cloudy, dry with some sunny intervals, moderately mild in winter, moderately cool in summer) occur far more frequently than the weather types that tend to generate excitement.   That last detail is why I think we're "near the back end", not helped by the issue that some of the higher-up climates are on our doorstep in continental Europe.  But it's easy to forget that some climates feature the same weather type and the same temperatures every day and most of us would probably quickly miss the relatively variable British climate after a spell spent in those areas.
  7. I had a theory that the world's nearest thing to my "ideal" climate might be the Munich area- more continental, more prone to extremes than the UK, thunder-prone in summer due to the nearby mountain range, but not generally prone to the highly destructive level of extremes that are common in parts of the USA. Thus, I've started following Munich's weather via webcams.  They had lying snow throughout the past week with generally dry bright conditions, but the snow is now thawing due to the arrival of milder air from the west.
  8. As Nouska mentions, the SST anomaly is a factor.   Also, it may be that cold air from eastern Canada and Greenland heads south into the area to the south-south-west of the UK, causing below-average temperatures there.  Meanwhile, that area is typically our warmest possible airmass source in winter, with average temperatures of around 15C, so one or two degrees down on the average won't stop it from bringing uneasonably warm weather to the UK.
  9. Winter 2015/16.

    Must be very frustrating for you when you hear talk of "improving weather", in reality meaning changes to anticyclonic/tropical maritime regimes and dry and warm (and, in the summer half-year, often sunny) weather for the majority of the country, but grey drizzly conditions in the Lake District.  It's hard for me to imagine how wet it's been in Cumbria in the last couple of months.
  10. Looks about right to me, based on the latest model output.  I think there's a fair chance of that cold continental air extending further west and reaching Scandinavia, but I doubt that it will penetrate as far west as the British Isles.
  11. The mild winter of 1987/88 also had a cold end of February/beginning of March, with widespread snow showers in the east on 24/25 February 1988 in particular, with lying snow penetrating to parts of the southeast, although it tended not to stick around for long. Also, how about 1994/95, in that case it was western and midland areas that were particularly hit in early March.  
  12. The above scenario happened in late-November 2010 when Scandinavia suddenly cooled down and we had a north-easterly blowing straight from Scandinavia, but North Sea temperatures were still quite warm.  It is harder to get a plentiful supply of snow showers off the North Sea when the sea surface temperatures are lower, but given sufficiently deep cold, it can still happen well into March. Northerlies seem able to generate widespread showery activity throughout the winter half-year, probably helped by the long sea track, though in the absence of troughs and polar lows, the showers often end up confined to coastal areas. Conversely, in frontal scenarios with milder airmasses colliding with cold ones, I find that high SSTs are mainly a hindrance for snow because frontal setups are often very marginal and the warm sea can make the difference between a dumping of snow and sleety rain.  These observations help to explain why North Sea areas rely a lot on North Sea convection for a dumping of snow whereas central and western areas tend to be more dependent on frontal scenarios.
  13. The Greenland High cold/snow setups tend to have a lot of warm air advection up the western side of Greenland, resulting in anomalous warmth in western Greenland and northern Canada, while the Svalbard/Franz Josef Land sector of the Arctic sees close to or below-average temperatures, resulting in potent cold blasts from the N and possibly NE.  This was the prevailing setup during the winter months of 2009 and 2010. The Scandinavian High setup tends to see unusually warm temperatures pumped into the Svalbard/Franz Josef Land area, while northern Canada and, most importantly for us, continental Europe, ends up very cold.  Hence the potential for very cold air to come across from the east. The point being that, for cold snowy weather, we are looking for significant poleward inputs of warm air to affect parts of the inner Arctic Circle but with colder air on the other side of the block that then comes our way- having anomalous warmth across the whole Arctic doesn't particularly help because it means that none of our blasts originating from a long way north are likely to be particularly cold. That said, the recent period has had unusually cold temperatures over Scandinavia, so if we'd been able to get a draw of north-easterlies, it could have been a major snowfest for eastern areas with the high SSTs around the UK and the deep cold Scandinavian air creating very vigorous convection over the North Sea.  But instead we've had north-westerly and northerly winds pulling air down from around the Svalbard area, which has been about 10 degrees above the normal for the time of year.
  14. Most of the Arctic has been 10 to 15C warmer than the long-term average since Storm Frank pumped exceptional warmth up as far as the North Pole at the end of December.  Combined with the high sea surface temperatures around the UK after the record-breaking warm and wet December, it's not surprising really that this relatively cold snap is proving to be somewhat tame.
  15. Far North Of England - Weather Chat, July 4 and on...

    I was watching Neil Bradshaw's webcam earlier today- Marsden appeared to have a lot of sleet and wet snow with the wind off the North Sea sometimes lifting the temperature to 2-3C, but they had a brief dusting at around noon.