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Thundery wintry showers

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Thundery wintry showers last won the day on November 12 2012

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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
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    Sunshine, convective precipitation, snow, thunderstorms, "episodic" months.

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  1. Arctic Sea Ice Discussion 2017 - The Melt Season

    I thought calling the minimum was premature back then, but it seems unlikely to be beaten now, as the Arctic sea ice extent has continued to slowly increase despite the storm. It may have helped that the storm has a fair amount of cold air in its circulation.
  2. I recall that when we've had northerlies and little troughs running down the western flank of the northerly flow with embedded pools of warmer air, the GFS has tended to outperform the UKMO and ECMWF, as the latter two models tended to underestimate the extent of the warmer air and so forecast snow instead of rain or sleet. The other main advantage of the GFS model is of course much of the data being freely available. But the ECMWF has been the best-performing model overall since at least 2006. There was a time when the UKMO model didn't do significantly better than the GFS, particularly at day 6, but I recall that it gained ground several years ago and these days tends to be a little behind the ECM overall at days 4-6 but a fair way ahead of the GFS.
  3. August 1998 and August 2007

    I remember Augusts 1998 and 2007 mainly for their lack of notable weather events. August 1998 was a north-south split month, and from the Midlands southwards it was generally dry and sunny with fairly warm days and chilly nights, but further north it was breezy and sunshine was mostly near or slightly below normal with below-average daytime temperatures, although even in the north most places were drier than average. I was in South Tyneside that month and there were numerous sunny and fairly warm days in the first two-thirds, when the winds were mainly westerly, but in the last third the wind veered northerly and it turned cool and cloudy with a few days having maxima of 13 or 14C. In August 2007 there was a rather different regional distribution, with east Wales, the Midlands and north-east England coming out driest and sunniest relative to normal, whereas northern Scotland and to a lesser extent East Anglia had a cloudy month. Correspondingly in South Tyneside the month was predominantly dry and sunny with average temperatures. August 2000 was a pretty significant turnaround from earlier in the summer in South Tyneside, the second half was quite memorable, often sunny with sporadic heavy downpours, although we had sea fog on the 21st while most other regions had thunderstorms. The month must have been pretty memorable in Northern Ireland (again especially the second half), where Aldergrove reported well above average rainfall and sunshine, and 7 days with thunder. It was also a very sunny month in parts of East Anglia. However, some areas such as Manchester only had close to average sunshine. July 2000 was a west-east split month, dry and sunny in western Scotland (the Glasgow area fared particularly well if I remember rightly) but very dull and rather cold in the east. Lowestoft had only 50% of average sunshine, and parts of Norfolk had mean temperatures 1.5 to 2C below the 1961-1990 normal according to RMetS Weather Log.
  4. Strangely the lightning detector on the radar suggests that the lightning fizzled as it approached Exeter, but in fact there's been a lot of lightning around here, especially just to the south, during the past two hours, not so much to the north. Probably the most spectacular thunderstorm that I've seen since the 18 July 2012 one in Norwich.
  5. Summer 2017 Discussion

    Here in Exeter this has been a month of very marked contrasts- we had that exceptional hot and sunny spell from the 17th to 21st, with maxima between 27 and 30C for five consecutive days which is somewhat unusual for Devon, but the early part of the month was dull and wet, and since the 22nd it's been mainly dull with the odd spot of drizzle. Funnily enough June 1976 had below average sunshine over much of western and northern Scotland despite the near-nationwide hot sunny spell at the end, but I think we'd be hard pushed to find a summer month for London that had a similarly large temperature deviation but below average sunshine. It's an oddity that we'll probably see more of as our climate warms. Looking further back, the Junes of 1966 and 1982 were warm (but not as warm as this June) but dull and wet for most, although in the case of 1966, Heathrow was one of the few locations in the UK that had slightly above average sunshine. Those two Junes were also rather different in character to this one, with frequent cyclonic/southerly regimes and a high frequency of thunder.
  6. Summer 2017 Discussion

    When I was little I believed that I hated hot weather, and everybody seemed to be going on about how 30C was bliss, and nowadays I welcome heat in brief doses and lots of people say this is selfish because of the misery and inconvenience that it causes. You just can't win sometimes! I generally find low 20s most comfortable (high teens are also fine if it's sunny and not too windy) but welcome short spells of high 20s and even low 30s mainly for variety and novelty value. I must admit that this recent heatwave got a bit too much for me after the first few days, the main problem being the duration, which was the longest in June since the very famous one in 1976. As for the upcoming spell of weather, I don't think it will be a washout, with fronts moving across the country relatively infrequently, but it may well turn out persistently cloudy for many. Probably a bit dreich in the north at times but with comfortable temperatures in the south.
  7. June 2017 C.E.T. Forecasts

    1966 has often intrigued me, as June was the warmest month of that year, but it was also the dullest June on record in Scotland by a fair margin. It was also an unusually thundery month in many places. Frequent cyclonic/southerly regimes appear to have been the culprit, and given the surprising lack of sunshine, there were probably a lot of slow-moving fronts over Scotland. As for the current month, it seems very difficult to get a run of significantly below-average temperatures at the moment with plenty of anomalous warmth around the extratropical Northern Hemisphere, propagating up to the 850hPa level. The GFS ensembles are consistently going 1-2C above the long-term normal out into Fantasy Island range.
  8. Arctic Sea Ice Discussion 2017 - The Melt Season

    Interesting, albeit scary, to see that the sea ice volume anomaly increased during May despite a relatively slow reduction in the sea ice extent. NSIDC shows the melt rate accelerating somewhat over the last couple of days, fuelled by relatively warm air masses over the Barents/Kara region as well as notably warm air over the Chukchi, Beaufort and East Siberian seas. http://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/ Forecasts from the GFS and ECMWF look rather concerning with high pressure remaining persistent over the region with the thickest sea ice, and also maintaining relatively warm air masses over the Barents/Kara and Chukchi/Beaufort/East Siberian seas. Even the cold air close to the North Pole looks like being mixed out in about a week's time, so we could well see 2017 catch up with 2016 in two or three weeks' time.
  9. Arctic Sea Ice Discussion 2017 - The Melt Season

    It's surprising that, according to NSIDC, the rate of sea ice melt hasn't sped up during the past week despite the emergence of a dipole anomaly, although the strength of the dipole and the input of warm air masses into the Arctic Ocean have both been rather weaker than previously projected by the GFS and ECMWF models. Some relativvely warm air from central Eurasia may introduce some melting around the Barents/Kara area in the next week, where the sea ice extent is currently high for recent years, but at the same time we may see a let-up in the warm anomalies around the Chukchi and Beaufort seas. I agree, we're currently in an interesting position given the low health of the ice but rather larger extent than this time last year.
  10. Both Exeter and my parents' in North Yorkshire got proper big thunderstorms today.  Staying up at my parents' this weekend, but due to an ill-timed trip to South Shields, I contrived to miss the whole lot!

    1. Daniel*


      That's most unfortunate zilch here in SE London

  11. Model Moans, Ramps and Banter

    1975 and 1984 spring to mind, and 1994 was another decent example in some areas of the country. That said, I have a feeling that this year's June could well end up as another dull wet one with southerly tracking lows.
  12. Arctic Sea Ice Discussion 2017 - The Melt Season

    Interestingly this year's sea ice anomaly distribution is much the opposite of where it was at this time in 2012, this time we have near average sea extent on the North Atlantic side, including the Barents and Kara seas, and below average extent around the Bering, Chukchi and Beaufort seas. In 2012 the Barents/Kara area was the main area with abnormally low amounts of sea ice. The impending dipole anomaly pattern is likely to displace more sea ice over towards the North Atlantic side and enhance the negative anomalies in the Chukchi and Beaufort seas. In the short term this may not necessarily result in big net losses because it may also help slow the rate of melt in the Atlantic sector, but in the long run it may well contribute to massive losses later in the season when the sea ice bordering North Atlantic regions breaks up and melts out, leaving, well, not much beyond the immediate vicinity of the North Pole.
  13. Arctic Sea Ice Discussion 2017 - The Melt Season

    The GFS operational runs and ECMWF ensemble means continue to suggest a dipole anomaly pattern setting up in about 7-9 days' time with high pressure over the Arctic Ocean, which would accelerate the (recently fairly slow) rate of melt: That said, tonight's ECMWF operational run didn't go along with this, so it's not a certainty yet.
  14. Summer 1912 in Durham was pretty vile by the looks of it: http://www.metoffice.gov.uk/pub/data/weather/uk/climate/stationdata/durhamdata.txt Relative to the relatively conservative 1961-1990 period, sunshine was 46% of normal, rainfall 179% of normal and the mean max temperature was 2.4C below normal. The temperature and sunshine stats would look even bleaker compared with more recent reference periods.
  15. Arctic Sea Ice Discussion 2017 - The Melt Season

    Arctic sea ice extent currently looking less exceptionally low according to NSIDC, creeping within 2 standard deviations of the mean: http://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/ Despite this, though, I think the 2012 record is still potentially under serious threat, due to the continued record sea ice volume anomaly, and the emergence of large areas of low sea ice concentration around the edges of the ice sheet. I'm expecting May 2017 to have a similarly high rate of melt to May 2016, which would leave us comfortably at second lowest by the end of the month, and ahead of 2012.