Thundery wintry showers

The Met Office "season so far" sunshine maps were interesting in that after June and July the negative sunshine anomalies were largely confined to south-east England, but as they publicly released updates through August, I could see those negative anomalies steadily creeping northwards. The Midlands had a particularly considerable shortage of sunshine in August which is why in the overall summer maps the region has essentially joined the south-east in having 70-90% of the average.

For England as a whole it's been the 7th dullest August in a series from 1919: https://www.metoffice.gov.uk/pub/data/weather/uk/climate/datasets/Sunshine/ranked/England.txt However, June and July were much closer to average - indeed July had slightly above average sunshine for England as a whole despite the shortage in the SE, just making it into the top 30. Maximum temperatures for June and July were warm overall, too, though for August it's been a case of cool days and warm nights - for England the mean Tmax for August was the lowest since 2011. At nearby Waddington I note that as well as having only 104 hours of sunshine (even using the Kipp-Zonen sensor, we'd normally expect around 170 hours) and no thunder-days, rainfall was less than half of the long-term average. I think "flat" is a pretty accurate description of the month just gone here, and certainly contrasted with July, when I recorded 7 days with thunder and there were quite a few contrasting episodes of weather.

Waddington came in at 103.7 hours. An approximate K-Z to C/S conversion would place it at around 120-125 hours, which would make it the dullest August in this region since 1963 (which had 109 hours). The only other duller August in a record from 1949 was that of 1954 (which also had 109 hours). Regarding January 1984, it was indeed a wet and stormy month, and also unusually snowy in the north. But in the south-east in particular, many of the fronts passed through overnight and the days were often bright and showery. December 1999 and November 1996 also spring to mind as wet months that were also exceptionally sunny at Heathrow (and I can see them on the list - 1999 ranks as the 2nd sunniest December and 1996 as the sunniest November).

I was 11 on Christmas Day 1995, and in contrast it was a white one in South Tyneside and I remember having a snowball fight in the afternoon. I also vaguely remember the rather non-descript Christmas Day of 1994, which was a dull mild day following a pre-Christmas frosty, sunny spell, and at 12:20 Tom and Jerry was being shown on the BBC, which for me at that time was something significant to look forward to. I also remember that my parents taped Daffy Duck's Quackbusters in Christmasses 1993 and 1995, and as 1993 was also a white Christmas, it led to me associating Daffy Duck's Quackbusters with white Christmasses. Also I remember that on Christmas Day 1993 I got an aneroid barometer. It started off sunny and then snow showers moved in. And that was when I was just 9 years old, and I still have vague memories of that day, too. Yes, some of us do have wacky memories like that! Incidentally Christmas Day 1987 wasn't really that mild, it would have just felt like it because of the sunshine, particularly as it was a one-off sunny day in an otherwise dull spell. It was a returning polar maritime air mass with temperatures a couple of degrees above average for the time of year. Somewhere in Scotland actually reached 18.7C in December 2019 overnight under cloudy conditions, illustrating the issue that in December, very high temperatures tend to be brought about via Tm air masses which are often cloudy. There was a very mild spell with 15-16C in the aforementioned December of 1994 (around 10th-12th I think) which was cloudy, and also around 14 December 1998. I have vague recollections of some western areas having very mild, sunny weather around 7-8 December 2001 before the continental air came in and brought frequent overnight frost.

I'm reminded of August 2008. The setup was rather different, with tropical maritime air on the northern flank of high pressure bringing lots of cloud, rather than the North Sea cloud-producing machine going into overdrive, but it was a similar story of a few weeks of generally dull wet weather being followed by dry and anticyclonic weather that was ironically even duller than what had gone before. It's rare, but this kind of thing isn't without precedent. It's possible that some parts of eastern, central and southern England could end up with a comparable shortage of sunshine to August 2008 this month, we'll have to see when the end of month stats come out, but a few days ago Waddington still hadn't reached 100 hours.

It was a sunny day in Lincoln today, for the first time since Monday. I remember being surprised at around midnight last night when the skies cleared.

When I think back, I remember cloudy anticyclonic late-August spells like this, but I was living in Tyneside at the time which is relatively prone to cloud coming in off the North Sea. Two that spring to mind are 1998 and, perhaps surprisingly, 1995 (the last four days of August 1995 were mainly cloudy in Tyneside, which was in very stark contrast to the near-unbroken sunshine of the high pressure spells earlier that month). I guess with the solar strength weakening at this time of the year, it's easier to get cloudy anticyclonic spells at this time of the year than it is earlier in the summer. To get prolonged dry but dull spells in May-July tends to require a sustained onshore wind, like in eastern and south-eastern England in Junes 1988 and 2013 and (especially) May 1991. I'm reminded a bit of late August 2008, although that was a rather different setup with tropical maritime air circulating around the northern flank of the high pressure. I remember it being rather ironic as August 2008 had been dull and wet up until that point, and a settled and warm spell was forthcoming, but it turned out to be even duller than what had gone before, with the warmth mainly coming from high minima due to the cloud cover. On the other side of the coin there have been plenty of mostly dull months that saw a sunny anticyclonic spell at the end that raised sunshine totals above the long-term normal, including some in the winter half-year. June 2018 is widely remembered as a warm sunny month, but in Exeter there were less than 100 hours of sunshine until the 20th, and then over 140 hours in the last ten days - had the anticyclone of late June 2018 settled in a different position the month might have been remembered very differently. Sunshine was also similarly "back-loaded" in the famous Junes of 1976 and 1995 in many parts of the country.

I enjoyed June and July here in Lincoln. Sunshine and rainfall were variable through the two months, but there was a high frequency of thunder in July and some fine spells in both months. I had been thinking of it as an "almost great but not quite, but still reasonable" summer in a similar vein to that of 2005. August, though, has been a letdown - "usable" but forgettable weather early in the month, and then since midmonth it's been dull and forgettable. I didn't realise quite how dull it has been though - only 95.8 hours of sunshine for the month so far at Waddington (even with the Kipp-Zonen sensor, which tends to record less than Campbell-Stokes, we'd normally expect around 150-160 hours by this point in the month). This is now placing Summer 2021 a long way behind that of 2005. Until around midmonth, negative "summer so far" sunshine anomalies were largely confined to the SE, with Lincolnshire coming out near average, but as that Met Office sunshine map indicates, in the past fortnight those negative anomalies have been spreading a fair way north.

Monday was a sunny day here. It rather lulled me into a false sense of security, I thought it would stay that way until the next batch of cloud came along on Thursday/Friday, but as it stands it looks like it could be a substantial spell of dry cloudy weather. Chances of something brighter over the weekend, but we still keep that NE wind which means there are no guarantees.

Conditions look set to continue quiet over the Arctic over the next week or so, with many parts of the region continuing to experience below-average temperatures at 850hPa. Greenland looks set to be warmer than average at times, but not warm enough to trigger substantial melting spikes like the two we saw recently. It will be interesting to see if the relatively cool conditions persist into the autumn and result in a relatively quick refreeze this year. In many recent years, even after fairly cool summers, above-average temperatures have resumed in September and October and the refreeze has been slow. Overall global sea ice extent is unlikely to be above that of 2014, which saw record high extent in the Antarctic and a relatively modest negative anomaly in the Arctic. Still, with the Antarctic now running well above average, it's probably the highest since 2014.

Looks like patches of drizzle heading inland from the North Sea judging by the radar. I don't know why it's mainly affecting Lincolnshire and not other eastern areas, but it's surprising how widespread the cloud cover is considering that high pressure is sat on top of the country. I'd been expecting this sort of weather to arrive on Thursday/Friday when eastern locations will pick up more of a northerly flow.

I think high pressure very much has established over the whole country, but the issue is that a large mass of cloud has got embedded in the high, and on the eastern/south-eastern flank we have a chilly NE wind. I haven't been on the model output discussion thread much this summer, partly because there tends to be an automatic assumption that high pressure/settled = dry and sunny and low pressure/unsettled = wet and cloudy. There is a correlation, but in the British Isles, surrounded by water, it's a long way away from being a hard and fast rule. But as noted earlier, even I assumed that it would generally be dry and sunny today and tomorrow.

I got the weather wrong for today - I didn't foresee cloud cover being quite this widespread today, especially after many of us had a sunny day yesterday and high pressure remains on top of the country. The GFS predicted extensive cloud cover today, but I subconsciously discounted it because the GFS's cloud cover predictions often aren't the most reliable - but this time round they were!

I remember pointing this out some time ago, I think the dry/settled-sunny relationship is stronger in the south-west of Britain than in the east. The Septembers of 1996 and 2014, and to a lesser extent 2002, were fairly dull in the east despite being very dry, but averaged nationally both 1996 and 2002 were somewhat sunnier than average. September 2014 was sunnier than average only in the west. Cloud off the North Sea when the high is unfavourably placed tends to be the main reason. I guess dry, settled but cloudy months are less common in the west due to the tendency for westerlies to bring rain as well as cloud. With just limited regional exceptions here and there, there was a run of sunny Septembers from 2002 to 2007 inclusive, all of which were also warmer and/or drier than average for most. I have fond memories of most of those Septembers, I think 2003 may be the pick of the bunch for me because of its contrasting episodes and warm days and cool nights. I remember the September of 2008 being a shock to the system after what I had got used to over the previous six years. The 1990s were a real mixed bag, as we had plenty of fine sunny weather in 1991 and 1997 in particular. 1999 has been mentioned in a few posts, that one had a fair amount of regional variation, as in Tyneside that month was sunny all the way through despite a rather wet, thundery second half, and felt like a continuation of the summer, but some other regions were quite dull in the second half.

Having looked at those Septembers I don't think September 1975 looks that bad in many parts of the country, overall pretty average, though it might have clashed with the preceding summer somewhat. 1974 and particularly 1976 look like they were washouts though. I remember growing up in a run of poor Septembers in Tyneside. Those of 1992 to 1994 were all dull and wet, especially so in the case of 1993. September 1995 also started off dull and very wet, contrasting very sharply with the preceding August, although there were some fine spells in the second half of September 1995 and so temperatures and sunshine for the month came out close to average. With frequent easterly winds, September 1996 was also a cool cloudy drizzly month in that region of the UK, though it was somewhat drier than average. Thus, the 1990s contain a lot of childhood memories of enjoying warm sunny weather in the summer, and then going back to school in early September with grey skies, persistent rain and a nagging north-east wind. For a large majority of the UK I'd say that 1992-94 has to go down as a run of three consecutive poor Septembers, but those of 1995 and 1996 were dry and sunny in the west, so it's only in some eastern areas that the run extends to four or five years. I don't think there's a strong link between hot dry sunny summers and cool wet cloudy Septembers. The two fine summers of the 1950s (1955 and 1959) contained marked counterexamples. September 1959 in particular was widely one of the driest and sunniest Septembers on record, and October 1959 was also one of the sunniest Octobers. September 1947, following an August that was on a par with August 1995, was generally warmer, drier and sunnier than average. September 1949 was one of the warmest on record. In recent times, September 2018 was pretty average and quite sunny.

The statistics at Waddington suggest that August 1991 was quite noteworthy around these parts: Maximum temperature: second highest (after 1990) since 1975 (narrowly beating even 1976). Only 1995, 1997 and 2003 were subsequently warmer. Rainfall: only August 1995 was significantly drier. Sunshine: only 1949, 1975, 1976, 1989, 1990 and 1995 produced sunnier Augusts in a record from 1949. If that month had been inserted into a period of generally dodgy summers it would have stood out more, but because it came straight after 1989 and 1990, it would have seemed nothing special. It also probably suffered due to being consistent rather than outstanding, with no especially hot or sunny spells that would particularly stick in the memory.

I'd be very surprised if Atlantification wasn't a significant issue in the west of the Kara Sea. Vize Island in particular has been a hotspot for increased warmth since around 2005, where the mean annual temperature has jumped by roughly 4C, and the years 2012 and 2016 were about 8C warmer than the 1961-1990 average. The sea ice has often been slow to form in this region during October-December, contributing to some particularly warm Novembers. I'm not sure about the east of the Kara Sea or the Laptev Sea but certainly my examinations of the Vize Island warming hotspot point to increased Atlantification.

I remember being surprised by Heathrow's average minimum being relatively high in August 1995 in the Royal Meteorological Society's Weather Log (+2.8 on the 1961-1990 average). Most sites were between 4 and 5C warmer than average by day and between 1 and 2C warmer than average by night. Uncomfortably warm nights were a widespread issue during the first few days of August 1995 when the heat was at its peak, but apart from that, temperatures were generally falling to around 12-15C at night even in the hotter spells, perhaps bearing out the points about low humidity. Perhaps Heathrow was affected peripherally by the London urban heat island. Sunshine totals included 295 hours at Heathrow (158%), 284 at Manchester/Ringway (174%), 250 at Durham (160%) and 254 at Glasgow/Abbotsinch (172%). I remember noting that Abbotsinch had a particularly anomalously sunny year in 1995 with every month having above average sunshine, and the year's total was 127% of the average. Manchester also fared particularly well with only February and September falling very marginally short of the average. August 1995 was generally a bit hotter than August 1947. Averaged nationally August 1947 was slightly the drier and sunnier of the two, mainly because it was more exceptional over much of Scotland and Northern Ireland, where unusually some of the normally wet areas of western Scotland saw no rain at all in August 1947. However in central and eastern England August 1995 was generally sunnier than August 1947. I remember a thunderstorm with hail on 27 August 1995 in South Tyneside - it was rather localised but thunder was reported quite widely in eastern England on that day.

I've defended this summer here in Lincoln quite a bit so far, but I agree with this assessment of the outlook for the upcoming week. Some decent days here in early August but it's indeed been becoming rather "meh" here too. Some signals for high pressure to build in about a week's time, but it does seem to be getting pushed back as we near the time. Regarding August 1996, it may have been the least impressive summer month of 1996 for many rainfall and sunshine wise, but in contrast "meh" certainly isn't a word that I'd associate with it. There was a cool changeable beginning and end, a hot spell in the middle (when, somewhat unusually, Sunderland reached 30C on the 18th) and, for some, a high frequency of thunder as well - 7 thunder days at nearby RAF Waddington. Around 23 August 1996 was particularly thundery. It was also generally the warmest month of the summer.

The weather in Lincoln has recently been "usable" - nothing too exciting, but Wednesday had a mix of cloudy spells and some sunny intervals, and yesterday was mainly sunny. Today has sunny intervals but it's windy. It's been around 22 to 24C. I'd say it's been a decent summer so far in these parts. It's been let down by a rather dull second half of June, and the first half of July was dull but redeemed to some extent by frequent thunderstorms, but the first half of June was warm and sunny and there was that hot sunny spell in mid to late July, and August so far has had some decent if unremarkable weather. To a certain extent I'm reminded of summer 2005, which I thought was almost a very good summer but it was let down by the very dull second half of July, but still at least decent overall. That summer had some big storms in Lincolnshire and NE England as well.

Yeah, I had some doubts about including 1994, and also to some extent 1990, as there was a fair amount of regional variation in those two summers. I was going mainly by the Met Office's UK areal averages for sunshine, rainfall and Tmax, which are only a broad average. Certainly I recall Lancaster's stats for 1994 being unimpressive, a dull cool June and August outweighing a warm sunny thundery July, and again in 1990 some western areas had below-average sunshine in June and August. Even in 1996 there was a regional exception in the north of Scotland. 1968 was an odd summer in that it was cool, wet and had an exceptionally dull July in most parts of England but in Ireland and western Scotland it was sunny and dry. 1977 is another summer that springs to mind as being dry and sunny in parts of the NW, also containing a hot spell in early July, making it three fine summers in a row in some regions, but June and August 1977 were wet and dull towards the SE.

I guess it depends on your standards for a "good" summer, but I reckon that by most standards 2013 would qualify as well as 2018. 2014 is also a contender, but for some the August might have let it down a bit too much. Looking further back, trying to keep standards roughly consistent, I could suggest the following from earlier decades: 1940s - 1940, 1947, 1949 1950s - 1955, 1959 1960s - 1969 (yes, just the one!) 1970s - 1975, 1976 1980s - 1983, 1984, 1989 1990s - 1990, 1994, 1995, 1996 2000s - 2003, 2006 So I don't think the 2010s having just 2013 and 2018 and arguably 2014 makes it an especially poor decade.

Some of that could well be due to the replacement of the Campbell-Stokes sunshine recorder at Hurn with a Kipp-Zonen sensor in 2004. Campbell-Stokes recorders have a tendency to overburn the card, particularly in summer. https://www.metoffice.gov.uk/pub/data/weather/uk/climate/stationdata/hurndata.txt The mean annual figure of 1,598 hours for 2011-2020, derived from a Kipp-Zonen sensor, is roughly consistent with a Campbell-Stokes figure of around 1,750 hours, which is around what was recorded during the 1990s. If we correct for the change of sensor, I see evidence of a decline in sunshine amounts in June and August (but not July), offset by increased sunshine in winter and spring. The summers of the 1990s were exceptionally sunny, and the two subsequent decades have seen a return to cloudier summers, but probably no duller than those of the 1970s.

Yes, this unsettled, showery spell since Friday has been surprisingly low in thundery activity considering how widespread the thunder often was from similar setups in May and July. There have been some exceptions though, in particular it seems that the Glasgow area has had quite a few thunderstorms recently, including some sferics across the north of Glasgow today. It makes a change as statistically Glasgow tends not to get that many on average. North Norfolk also seems to have had quite a few. From a local perspective I had a dose of reality as it seemed that in May, June and July, Lincoln got a thunderstorm almost every time thunderstorms featured in the forecast. I got a reminder that it isn't the norm for this to happen even in the more thunder-prone regions of the UK, and the run was bound to come to an end at some stage. So I can't really complain about not getting any this time round.

I imagine a repeat of the 87/88 winter would now be almost completely snowless at low levels due to the climate having warmed by just under 1C since then, because although there was some snow that winter, it was invariably very marginal. I could imagine the depression of 22 January 1988 (which for many brought the only substantial snowfall of that winter) bringing sleet rather than snow across a large swathe of England, and eastern areas being peppered with rain, hail and sleet showers from the northerlies of late February 1988. In contrast, if we go back a year, I can't imagine sleet/rain rather than snow being an issue if the synoptics of 11-14 January 1987 were to be repeated. Regarding summer 1987, even though June 2021 was dull and wet in the south-east I don't think it was remotely comparable with the very cold, wet June of 1987 which widely produced record low sunshine totals. I'm seeing more parallels with summer 2013 this year, but that of course was followed by the notoriously wet and snowless winter of 2013/14.