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Thundery wintry showers

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  1. Regarding the London sunshine stats, remember that Heathrow moved to an electronic Kipp-Zonen sunshine sensor in September 2005. The 30-year sunshine averages (whether you're using 1961-1990 or 1981-2010) are based on Campbell-Stokes sunshine sensors, which in the UK tend to record 10-15% more sunshine in the summer months than Kipp-Zonen sensors. So to make it a fair comparison you'd have to shave ~12% off the 30-year averages for June/July/August and then compare the resulting figures against the sunshine data for 2006 onwards. If you do that you'll find that at Heathrow, since August 2011 the only significantly duller than average August was in 2015, with the others all close to or a little above the long-term average. It's true, though, that even if you allow for the ~12% difference, no recent August has been as sunny as those of 2003 and 2005 at Heathrow, or for that matter 1989, 1990, 1995 and 1998.
  2. I often find the Exeter climate quite boring, but in the current spell I seem to be doing rather well, having a succession of convective sunshine-and-showers days (which included some thunder on Friday, albeit quite distantly) while most other areas of the country have had a lot of dull damp weather, which looks like continuing during this coming week. I certainly wouldn't fancy being in Tyneside with that nithering north-easterly off the North Sea that is forecast for Tuesday and Wednesday. This isn't intended as a gloat, but more for sake of balance, giving the South West credit where it's due and making up for the occasions when I complain about my area not getting the weather I want (which is not unusual in this area of the country if it's thunderstorms or especially snow you're after).
  3. Augusts 1993 and 2007 were both in the "dry and quite sunny but cool" category at Heathrow. I expect that if we get similar synoptics in August 2019 it will not be as cool as those two Augusts were (especially as they were rather extreme cases of their type), though cool compared with most recent years.
  4. By my estimations Heathrow's sunshine total for August 1991 was 129% of its 1961-1990 average, so not as high as the England SE/Central S region as a whole, but still pretty high. An odd quirk is that the Augusts of 1989 and 1990 were both sunnier, but there were no comparably sunny Augusts from 1977 to 1988 inclusive. One problem with comparing recent sunshine data for Heathrow against any long-term average is that the long term normals are based on Campbell-Stokes sunshine recorders (or estimated equivalents) but since 2005 Heathrow has used a Kipp-Zonen sunshine sensor which tends to record about 10-15% less sunshine in the summer months.
  5. Very heavy showers in the vicinity of Exeter at 5-7pm this evening, but surprisingly no thunder, despite localised rainfall intensities of over 100mm/h according to the Netweather radar.
  6. Another intriguing facet of this is the way two near-identical charts can produce different results due to the history of the air masses. On 14/15 May 1995, although the weather under the weak trailing front was similar it was reasonably sunny to both the north and south of it. This time around it has generally been much cloudier.
  7. I posted in the other thread about how today's synoptics are remarkably similar to those for 14/15 May 1995: I remember 14 May 1995 fairly well, when in Tyneside I was under a similar belt of rain to what much of the north-east is having today, it started off as sunshine and showers but with a lot of cloud generally, and then turned into persistent rain during the afternoon and evening. The synoptic progression from here looks set to continue to be strikingly similar to May 1995 for a while, and in May '95 things switched around on the 20th and we had a week of southerlies after that. This time around it may well be that we get high pressure building over the UK, rather than to the east, which means it could end up dry and sunny for most in a week's time.
  8. As far as I'm aware 1982 and 1983 were both thundery years across much of England, primarily due to an exceptionally high frequency of thunder in June 1982 and May 1983. Averaged over the UK those months may well have been beaten by June 1980, which wasn't quite as thundery over most of England but was more so over Scotland and the north-east of England, as thunderstorms from Spanish plume events penetrated a long way north early in that month and there were several days of thundery showers and sunny intervals starting on the 22nd. Note that unlike say July 1994, these thundery months in the 1980s were generally dull and wet. Also a correction: May 2016 was pretty warm overall, though not as warm as those of 2017 and 2018. June 2016 was also warm away from the east coast, albeit cloudy and wet for most. We had cool Mays by recent standards in 2010, 2012, 2013 and 2015 though, and the last three were followed by cool Junes as well, though only 2012 sticks out for me as a washout. Today's synoptics remind me a lot of 14 May 1995, a day that stuck a bit in my memory because in Tyneside we had a cold front draped across the region and it started off with sunshine and showers and some potent convective cells and then turned into persistent rain in the afternoon, and it's been a similar story across the north-east today, but with the front a bit further south, with the majority of the rain instead over north and east Yorkshire. In the case of May 1995 we had a southerly tracking low bringing dull cold wet weather and localised snow on the 16th/17th followed by a return to sunshine and showers, but a sudden switch happened on the 20th/21st and then from the 21st to 28th we had warm southerlies. It looks like things could similarly switch around this month in about a week's time, with high pressure possibly building further west than on 21-28 May 1995, which means we could be faced with a spell of dry, sunny and fairly warm weather towards the middle of May 2019.
  9. Yeah, that probably is indeed the case with many instances of the restrictions on children's play and various other examples. I think a closely related mechanism is also often behind the apparently heavy-handed reactions to one-off instances of people saying things that in hindsight were dubious - I get an impression that it's often motivated primarily by the desire to minimise risk of succumbing to a media storm, reputation damage and possibly even litigation from offended third parties by being seen to fall short of the zero tolerance/maximum punishment approach. But as few groups like to admit that, it's usually easy enough to frame it as showing that we have zero tolerance for anything that could be seen as offensive and especially discriminatory. A bit like how it's easy to frame litigation risk aversion as being motivated primarily by child protection when in reality it often is not. It's also worth noting that, despite the popular notion that the younger generations are "snowflakes", when I was growing up it was often people in my grandparents' generation, raised on comparatively authoritarian 1950s values, who were the most defensive of the idea that we must "hang 'em and flog 'em" and that "the minority have to spoil it for everybody else" etc, not recognising the link between these measures and the trend towards adults being overprotective of children.
  10. I think the "snowflake" problem is more down to rising social risk aversion, where we increasingly take heavy-handed approaches against anything that might be misinterpreted in a way that one or more people, especially if it's groups that traditionally face discrimination, might find offensive. It's an effective way of being seen to "do something" about discrimination but not necessarily particularly effective at actually addressing it. It gives a disproportionate voice to the minority who feel that anything that causes the slightest offence to anybody should be clamped down against (who have probably existed throughout human history). A common upshot is that we all end up having to tread very carefully because of some incident where a few bigots acted in ways that were well out of order. This is not limited to political correctness and for example it is also the main mechanism that has resulted in children losing scope for indulging in unstructured play under minimal adult supervision over the past few decades (trying to minimise risk of them getting hurt). The idea is that it gets people to think about the impacts of their words and actions on marginalised groups, but quite often our society just finds ways of continuing with the same discriminatory norms but framing it in different terms/language to make it sound progressive. For example, when I was little I was told that any sort of "girly" behaviour was "gay" and that I had to "man up" and "be a man". Today, it isn't considered PC to say those things, so I get told that the same behaviours are "creepy" and "inappropriate" and that "things are changing, it's becoming more acceptable for men to show their emotions openly, but there's a time and a place for it, and in many cases it's only acceptable when interacting with a female partner". Many of the "rules" governing acceptable male behaviour have not actually changed much since the 1950s, but they are more insidious, and as very few people actually say "be a man" these days, it makes it easy for others to deny that these attitudes still exist. I get a strong impression that this kind of thing goes on a lot re. discrimination against various traditionally marginalised groups too. But of course instead of tackling these weighty issues it's much easier just to blame it all on the younger generations becoming "snowflakes" and "loony lefties".
  11. Indeed, 1975/76, 1983/84 and 1989/90 were very good examples of pairs of fine summers. I think of the mid-90s as having had a "trio" (1994/95/96) rather than a pair, and the 2000s examples (2003 and 2006 being the main anchor points) are not so convincing. But I recall 2005 being pretty good apart from the very grey and cool last third of July. Looking further back in the archives we had a "trio" of such summers in 1933/34/35, but in general there was less of a tendency for them to be grouped together in the early to mid 20th century. There were also some pairs of very contrasting summers (1911 and 1912, 1958 and 1959 for instance). There was also a very contrasting "trio" with a very fine mid to late summer in 1955 flanked by washouts in 1954 and 1956.
  12. In South Tyneside (where I spent most of my life, but I've moved around a bit) it was 2003/04, which had 10 days of lying snow, including 4cm on 22 December, about 7cm on 28-29 January and about 11cm on 28 February, which may have been the deepest snow in the area at that time since February 1991 (although of course exceeded by a large margin in 2010). 1998/99 was the second snowiest mild winter with 8 days, but on that occasion only 9 February (5cm) had a depth greater than 2cm. As in 2003/04, northerly outbreaks during an otherwise westerly-dominated winter were the culprit. I don't think 2018/19 would have challenged those two in the Tyneside area as to my knowledge snow was only lying there during the first three days of February. I imagine it's probably unusual for Exeter to get any lying snow in a winter this mild (yes, there was some here on 31 January, giving about 80% cover at 0900 on 1 February) but I recall reading posts from someone at Exeter University who reported lying snow there in late February 2004.
  13. I think a lot of modern pop music plays it too safe, with the same predictable chord sequences, harmonies and lyrics, but I also felt the same way when I was growing up in the 1990s. But you don't need to delve too far outside of the traditional pop arena to find musicians and bands who are experimenting and trying different things, and again I could have said that in the '90s. What probably happens to a lot of people is that as they are growing up the traditional pop music sounds relatively novel, but when it doesn't really develop much over the subsequent decades, and you've heard hundreds of songs that sound similar, the novelty wears off, giving the impression of a general decline.
  14. The easterly of late February 2006 was indeed somewhat tame. I was at university in Leeds that year, where there had been several accumulations of snow in the February 2005 easterly, albeit with daytime thaws. The February 2006 easterly gave a few snow showers at times and a frontal rain/sleet event, but nothing accumulated on the ground. However, as quite often happens in that type of setup, the Atlantic side of the Arctic cooled down to near-normal and the Scandinavian blocking high retrogressed to Greenland opening the back door for a potent northerly, which set in on 27 February and persisted until 6 March, and it was this northerly that brought fairly widespread snow cover at times plus a big dumping for north-east Scotland. Late February 2006 was more of a letdown for snow lovers because the airmass source was easterly but eastern Europe wasn't cold enough. In early February 1986 we were pulling up relatively mild air masses from the south-east, before an easterly source developed towards the end of the first week and gave mostly sub-zero temperatures for the rest of that month. As for this spell, I don't think the duration of warmth is all that unusual, as it was similarly exceptionally warm in February 1998. I think what's primarily unusual about this spell is how it has widely been sunny as well as mild, with markedly high diurnal ranges as a result (February '98 was also notably sunny in some areas, but it was very much a NW-SE split month). But it does seem that it doesn't take as much as it used to to get exceptionally high temperatures, which is most likely a result of the elevated global temperatures making the dice more strongly loaded in favour of warmth.
  15. As 4wd suggested it depends significantly on the temperature of the higher layers of the atmosphere: if the precipitation has to fall through a large layer with temperatures >0C then it is more likely to turn to sleet or rain than if there is only a shallow layer of >0C temperatures near the surface, as it takes time for snowflakes to turn to rain. Another factor is the relative humidity - the lower the relative humidity, the greater the tendency for snow at above freezing temperatures to evaporate rather than turning to rain, and the process of evaporation cools the air around the snowflakes cold. A general rule of thumb is that if the average of the dry bulb temperature and the dew point, or alternatively the wet bulb temperature, is around or below zero then it will probably snow, but it doesn't always work as a lot also depends on how shallow the >0C layer is. Being near the coast with an onshore wind often means greater relative humidity than further inland, and also the temperature tends to be raised due to the warming effects of the sea. I've seen snow showers in the spring months with a temperature as high as 8C, and occasionally even in February. This is typically due to a combination of low relative humidity and a shallow layer of solar-heated >0C air near the surface, typically if we get a sunshine-and-showers setup from a northerly, or (more rarely) cold zonality as happened repeatedly in March 1995. In heavier showers the colder air further up tends to be dragged down to the surface through the aforementioned evaporative cooling process, which can lead to some pretty sharp temperature drops. On Christmas Day 1999 I saw wet snow fall with a temperature of 5C in a chilly westerly regime, but that seems to be the upper limit for December. As 4wd pointed out if you get a temperature inversion you can get freezing rain, with rain falling at temperatures of around or below 0C, which freezes on impact with the ground. More rarely you can get ice pellets, where snow turns to rain and then starts to refreeze again as it approaches the surface, and these tend to broadly resemble hailstones.
  16. Yes, I've been reminded of mid February 1998 recently, which interestingly was in a year with a very strong El Nino, contrasting with the weakly positive ENSO state of this year. I had a feeling that this mild spell was also likely to be accompanied by plenty of sunshine in many parts of the country, which is relatively unusual at this time of year, and so far it has proved that way. Mild weather accompanied by bright sunshine may also be widespread in about a week's time, but it does depend on the positioning of the high to the east. The current setup has the high pressure further north/east which means we're not getting quite as warm an air mass as on 13/14 February 1998 but on the other hand the clear sunny weather has pushed further north today thanks to the more southerly component to the airflow (on the 13th February 1998 it got into much, but not all, of northern England, resulting in maxes of around 17C in the Tyne and Wear region, while in the south it exceeded 19C in some places, but Scotland and Northern Ireland stayed cloudy). The February 2008 spell had the high pressure further west than this which led to the widespread high sunshine totals and colder nights. I have fond memories of that latter spell, which I spent in Norwich, where there were some stunning sunsets. It's hard to see a route to anything significantly colder before the back end of February now, but indeed, it could change pretty quickly as we head into March.
  17. ENSO has behaved much as forecast prior to the winter as far as I can see, with indices between +0.5 and +1.0. When I looked at the ENSO analogues back in November 2018 it seemed that a transition from neutral to weakly positive (+0.5-1.0) heading into the winter months was more strongly correlated with reduced westerlies and northern blocking in February than a strong El Nino (strong El Nino winters have included the exceptionally warm February of 1998 and the fairly warm one in 2016, as well as the cold north-easterly February of 1983). But indeed, for whatever reasons the atmospheric circulation has not followed suit this year, despite that plus the favourable SSW and MJO signals that Nick F referred to. I still see a bit of potential for something colder from the east arriving during the latter part of February but the odds against something that could bring widespread snowfall is increasing - a moderately cold south-easterly at this time of year would be more likely to bring predominantly dry cloudy weather to the east and sunshine to sheltered western areas.
  18. Looks like my 2.6C is a bust as well - until a few days ago I had been hopeful that the recent westerlies would be a blip and that the high would eventually head N/NE drawing in colder easterlies as many of the longer-term signals had suggested for February, but this now looks increasingly unlikely, in spite of the weak El Nino combined with the Madden-Julian Oscillation heading into phase 8. A head-scratcher!
  19. CET 2.6C, EWP 47mm. Probably lots of easterlies mid to late month, hence the low guess, but no prolonged spells of extreme cold.
  20. I doubt 2018 will be behind 1998 because 2018 was by far the warmer year of the two in the Arctic, and even HadCRUT4 (which does not interpolate over the Arctic) has 2018 running about 0.05C warmer than 1998. The Met Office article's figures includes values from several sources and has 2018 averaging 0.13C warmer than 1998, putting it 4th warmest. ERA-INTERIM even has 2018 as provisionally the third warmest year, probably mainly because 2015 was a cold year in Antarctica and it was less warm in the Arctic than several recent years, and in NASA's GISTEMP 2018 and 2015 are currently just 0.01C apart for January-November. My feeling is that 2019 will end up a little below their central estimate but warmer than 2018, and a lot depends on the strength of the El Nino.
  21. Having had some more thoughts I'd like to bump my CET prediction up to 4.2C please. Still going with 48mm for the EWP.
  22. CET 3.9C, EWP 47.6mm. Overall quite mild in the north and cold in the south. Probably some wintry weather around midmonth from the N or NE aided by the sudden stratospheric warming event but my suspicion is that the main wintry spells of the winter will fall in February instead.
  23. A scary rate of decline recently, which has just edged ahead of 2016 and 1979 as the lowest Antarctic sea ice extent for the time of year on record. Anomalously high melting on both sides of West Antarctica appears to be to blame, with large areas of open water where we would normally have ice. Around the Antarctic Peninsual and off East Antarctica the sea ice extent is near average.
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