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Thundery wintry showers

Long range forecast team
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About Thundery wintry showers

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    Cumulonimbus Incus

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    East Exeter, Devon
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    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. It could very easily have been Jan 1984 - that was an unusually snowy "westerly" month from the north Midlands northwards. The WNW'ly type delivered widely around the 15th in particular and then there was a frontal snow event around the 21st-23rd which had similarities with that of early February 1996. https://www.wetterzentrale.de/maps/archive/1984/cfsr/CFSR_1_1984011506_1.png I remember the snow from a westerly on the evening of 11 February 2014 - I was up in North Yorkshire at the time and remember a dusting that evening, but it had largely gone by the next morning as milder air moved in. It was the only lying snow of the entire 2013/14 season, which stuck out as the most snowless season that north-east England has had in the past century. Yes, one can draw parallels between 2013/14 and 1987/88 as the winter of 1987/88 similarly marked the end of the cold winters of 1985-1987 (and the more generally snowy period of 1978-87). However the winter of 1987/88 was followed immediately by more exceptionally mild winters in 1988/89 and 1989/90, whereas 2013/14 was followed by the closer to average winter of 2014/15, which I recall had fairly widespread snowfall from westerlies around 14 and 29 January.
  2. Some interesting stationary waves at around 3:05 - is that what you meant? I have often been intrigued by those, how the clouds seem to be moving and yet staying still at the same time. They were quite common when I was living up in Tyne and Wear, but less common down here in Devon.
  3. Yes, it was. The last third of December 1987 was generally dull, drizzly and mild with a persistent tropical maritime SW'ly, but on Christmas Day we had an incursion of returning polar maritime air which was still fairly mild and brought plenty of sunshine: https://www.wetterzentrale.de/maps/archive/1987/era/ERA_1_1987122512_1.png It wasn't as mild as some of the tropical maritime air that we had either side of Christmas Day but it would probably have felt warmer in the sunshine. I don't remember the day specifically, just remember browsing some climate stats some years ago and seeing a long run of sunless days in late December 1987 interspersed with ~6 hours of bright sunshine on Christmas Day.
  4. It's hard to understand why there is a patch of ice around Spitzbergen as that region has consistently had above-average temperatures through the summer - perhaps ice has been transported down from the north? Certainly the ice patch is reflected by the fact that the capital Longyearbyen had its first lying snow of the season a few days ago, which is unusually early for recent years (in most recent years it hasn't snowed and lay there until October, although last year there was a bout of lying snow near the end of September). Over the past year it's especially been over the other side of the Arctic, especially around and northward of the Bering Sea, that we've seen exceptionally high temperatures and seen ice struggling to take hold even in winter, in a region that has historically tended to be at least partially ice covered all year round. The fact that we're unlikely to record our lowest annual minimum is a reflection of how extreme August 2012 was for its rapid melting, assisted by an intense low early in the month. It's still possible that 2019 could record the lowest annual mean sea ice extent if the refreeze is sluggish during the rest of autumn.
  5. Examining the global temperature stats from the main centres, it would appear that 1979 was when global warming got underway after the slight drop in global temperature between the 1940s and 1970s. 1980 and 1981 were both very close to being the warmest on record at the time, and from then onwards it kept warming up. I don't think Britain's climate showed any evidence of warming until around 1988-89. Winter 1979/80 was indeed fairly mild but there were several very cold and snowy winters after that, notably 1981/82, 1984/85, 1985/86, also January 1984 in the north, and the exceptional easterly in January 1987. There were also several cool summers during this period. The shift to milder winters started with the winter of 1987/88, while the shift to warmer summers started in 1989. I think we will run into cycles of cold winters again. I remember Philip Eden remarking on a 22-23 year cycle of cold winters around 1895, 1917, 1940, 1963, 1986, and 2008-2013 was a bit delayed relative to the earlier recurring cycle but not by a lot. If this cycle keeps up we might well run into some more cold winters around 2032-2035. But as the global temperatures continue to rise, each batch of cold winters will typically be less cold and less snowy than the previous one.
  6. Yes, we have a pool of anomalous warmth extending from Siberia into the Barents/Kara Sea region and towards the north of Greenland at present, which may be largely responsible for the accelerated melt: https://www.wetterzentrale.de/de/topkarten.php?map=2&model=ecm&var=34&time=0&run=0&lid=OP&h=0&mv=0&tr=24 The loss should slow down again in the next few days though as a low with cold circulation develops close to the pole, but it's looking increasingly unlikely IMHO that the minimum will be 5th or 6th lowest now - it will almost certainly be between 2nd and 4th, and if I had to place a bet it would be on 2nd lowest.
  7. I generally think of a "washout summer" as a summer with significantly above average rainfall, with emphasis on the frequency of rain rather than necessarily the quantity, combined with significantly below average sunshine. In recent years 2012 is the big standout for me, and 2004 is a contender as it was very wet, but not on a par with 2012 for lack of sunshine. In the archives, the summers of 1912 and 1954 particularly spring to mind. The stats for Durham for the summer of 1912 are shocking: all three months much cooler and wetter than the relatively cool 1961-1990 average, and with less than 50% of the normal sunshine, which would have contrasted particularly starkly with the summer of 1911.
  8. August 2000 was pretty decent in Tyneside, especially the second half, but July was distinctly dreich with maximum temperatures about 1.5C below the average and about 60-70% of the normal sunshine. June was a mainly dry cloudy month but with over a month's worth of rain on the 3rd/4th and a heatwave in the third week which raised temperatures slightly above the long-term average. And 2004 was a very, very wet summer in that part of the country, although with near or just slightly below average sunshine in all three months. Not sure what those two summers were like in the Exeter area. 2019 will go down as the strangest summer that I have experienced so far - lots of cloudy wet weather, but also a dry sunny first half of July, and apart from that, every time we've had a significant bout of warm/hot sunny weather it has broken temperature records across Europe and sometimes the UK.
  9. A sharp levelling off is evident in the NSIDC sea ice extent charts: http://nsidc.org/arcticseaicenews/ I was hopeful that the melt rate might slow down once the scattered ice patches detached from the main ice cap had melted out, but I didn't expect the slowdown to be as dramatic as this - it appears that the main organised clump of ice has melted very little over the past week. There is still potential for further reductions in sea ice extent during September as we saw in 2005 and 2010, which is most likely to happen if we get warm southerly incursions from Siberia melting the edge of the ice to the north of Eurasia and pushing it towards the pole. But it is looking extremely unlikely now that we will beat or even come close to the 2012 minimum. Indeed, there's even a slight chance that we could see little or no further melting from now, as happened in the 2006 and 2015 melt seasons, which would place 2019's minimum at only 6th lowest. I think between 2nd and 4th lowest looks most probable though, and I have a gut feeling that a melt event may happen around mid-September and push it up to 2nd lowest. Nonetheless, this isn't a major cause for celebration - for most of the spring and summer we've been tracking lowest or second lowest, we just failed to get a repeat of the exceptional August melting that occurred in 2012. 2019's annual average sea ice extent still could end up as a contender for the lowest on record.
  10. Really enjoyed watching the weather today, plenty of hefty showers in Exeter, the occasional rumble of thunder at 3-4pm and more frequent thunder at around 5-6pm.
  11. Not much shows up on the lightning detector but I got woken up in the Exeter area at 3:10am by strong winds, torrential rain and three flashes of lightning.
  12. I think it owed a lot to above-average temperatures over north Africa combined with a few days of southerly winds originating from that region. In addition the north African air mass was somewhat hotter than it has tended to be in previous heatwaves, as is particularly evident from the 850hPa charts, which show much of north Africa with 850hPa temperatures between 30 and 34C. In previous heatwaves north Africa has tended to have 850hPa temperatures mostly between 25 and 29C with some small pockets of >= 30C. This was reflected also in the 850hPa temperatures that we got across Europe with the 25C isotherm getting through a large part of France and the 20C isotherm extending up to the Scottish border - these values were even higher than anything that we saw in the August 2003 heatwave. It was a similar story with the late June 2019 heatwave also, which given the time of year was even more exceptional at the 850hPa level, but an undercut of cooler air off the North Sea prevented Britain from seeing record breaking temperatures on that occasion.
  13. In the UK it is the other way round at the official MetO observing network - maximum temperatures have generally increased faster than minimum temperatures. I get a sense that this shift occurred in the 1990s and 2000s, associated with a decrease in cloud cover, and that we may see the maxima and minima both go up by a similar amount from 1981-2010 to 1991-2020. That said, in many of the expanding populated areas of the UK the mean minimum temperature has risen more quickly due to the urban heat island effect. Edit: I see Relativistic beat me to it!
  14. The PDF doesn't say why the station over-reads in bright sunshine. It could be that the sensors are accurate but that it is in a sheltered exposure in someone's back garden. I have a Davis Vantage Vue running in my parents' back garden (and Davis are as reputable as they come for personal weather stations) and their garden frequently gets about 2C warmer than the nearest official MetO sites on sunny days in the summer half-year.
  15. 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.
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