UK Weather - Summer 2015

[Simon Culling]

The weather has cooled down over the last few days with a few showers but is set to warm up again briefly on Friday and Saturday (10/11th July) especially in the south. Looking further ahead there is greater confidence in a return to the more unsettled west-north westerly flow that dominated in the late spring/early summer time period and this will mean cooler and wetter weather for the UK. It has been rather dry overall in the south for a couple of months and a bit of rain would be useful for the gardens - my lawn has a few brown patches developing.

The CET foe July was 17.8*C (+2.1*C) up to the 8th and the EWR was 21mm up to the 7th which is 34% of the monthly average - this is skewed towards more northern parts at present.

[Simon Culling]

It has been quite warm and muggy over the last few days with a reasonable amount of sunshine but also a few showers and thunderstorms. Maximum temperatures nationwide have been 27.1*C at RAF Northolt on Friday (9th July) and 26.6*C at Writtle on Saturday (10th July). There were some very elevated storms in the SW of England and along parts of the south coast on Friday evening with some beautiful displays of altocumulus Castallatus and Mammatus. Estimates of the cloud base range between 12,000-15,000ft which is particularly high and the c-g discharges must have been a spectacular sight. The storms did not produce a great deal of rain as much would have evaporated on the way down.

The CET for July was 17.4*C (+1.6*C) up to the 11th and the EWR was 23mm up to the 10th which is 37% of the monthly average.

The weather is expected to be a little more unsettled for the week ahead but looks like remaining warm and rather humid in more southern parts of the UK. We could do with a bit of rain as the grass in turning brown around here.

[Simon Culling]

We have seen some more unsettled weather this week with patchy rain and drizzle, but it has remained rather warm and humid. Today (Thurs 16th July) has been warm (up to 24*C) and somewhat humid as a warm plume spreads up from the south - it was 33*C this afternoon in Paris. This air is being drawn north by a deepening low (will be 990mb by midday Friday) which is moving north just to the west of Eire and Scotland and it is expected to partially destabilise later this evening to give elevated thunderstorms over central and eastern England. Some of the fine mesh models are suggesting the formation of an MCS over SE England later in the evening which will then move north into east Anglia but these systems are not easy to forecast. Much will depend upon how much extra lift is supplied by an approaching (from the west) upper trough.

Ahead of this plume we have seen a couple of quite chilly nights in more northern parts with a slight frost (-0.6*C) recorded at Katesbridge (N Ireland) on Wednesday morning.

The low mentioned above will bring two wet and breezy days for the golfers at the Open Championship at St Andrews, which will make scoring a bit more difficult than today.

[Simon Culling]

A quite thin line of thunderstorms developed during the evening of Thursday 16th July extending NNE from the Isle of Wight past the west side of London and on into East Anglia. The storms became particularly severe around midnight from north London through Cambridgeshire and into Norfolk with frequent lightning and torrential rain. There are reports of quite a few private stations receiving between 60-85mm in a couple of hours and hailstones up to 30mm have been photographed. These were elevated storms yet again, forming on the NW edge of a plume of hot air moving north-east from France but they only affected a narrow band. I could see lightning in the clouds for upwards of 3 hours to my east and north but not a drop of rain here.

It has remained on the warm side here in the south, but as you may have seen on the TV, the Open Golf Championship at St Andrews was delayed by heavy rain on Friday and strong winds today. It looks a little better tomorrow (Sunday) with sunshine and showers and much less wind - max temp only around 15*C.

[Richard]

Yes it didn't look nice for golf

[Simon Culling]

It was somewhat inclement to put it mildly. On the Sunday morning the play was suspended because the balls were being blown across the greens when the players went to putt them! The highest gusts reported at nearby stations were 50mph at RAF Leuchars, 48mph at Dundee Airport and 43mph at Strathallan (which is a bit further inland). The final round on Monday was played in bright sunny weather with a max of about 17*C and some good scores were posted as the wind was much lighter.

It has remained rather warm and muggy in the south with daytime highs between 23-25*C but quite a lot of cloud at times. Fresher and cooler further north and they have had any rain that has fallen. The models are giving mixed signals for the weekend with a couple suggesting quite a soaking for us here in the south - the gardens could certainly do with it.

The CET for July was 17.0*C (+1.1*C) up to the 20th and the EWR was 40mm up to the 19th which is 64% of the monthly average. The rainfall figure is skewed to the north as the south has only received a few spits and spots and localised thundery downpours. This shows how countrywide statistics can be misleading at times.

[tgsnoopy]

Interesting the speeds are in miles not kilometres. I thought the UK had gone metric already. For some reason I had the impression it was just the US dragging the chain so to speak. At least they got the temps right

[Richard]

Mind you we are not fully metric here either,if anything our retail industry seems more and more to be reverting back to advertizing goods in imperial measurements.

[Simon Culling]

We converted to the SI systems about 10 years ago for commercial purposes, but many older people still prefer some of the old imperial measures. The only imperial measure in common use is for a 'pint' of beer which you can still buy at the pub. However, the weather forecasts still give wind speed in mph and still provide a conversion to Fahrenheit or 'old money' for temperature.

It has been a wet day today in Milton Keynes (and most of southern Britain) with a mid-afternoon temperature of just 13*C. Many places have had 10-20mm already with more to come for more south eastern parts. A developing low, which was over the Channel Islands (at 1003mb) at 1200GMT is forecasted to move ENE to be in the southern North Sea by 0600GMT tomorrow with quite strong winds developing on its back edge.

The rain will be welcomed by many as we have been quite dry here in the south for a couple of months, and with another weather system following hot on this ones heels there will be more rain on Sunday.

[Simon Culling]

Friday into Saturday provided a good rainfall for most of England and Wales with 20-40mm hitting many gauges with the top total being 70mm in the 24hts to 0900 on Saturday at Beccles, which is in the county of Suffolk. There was a convective element to some of the rainfall with a clump of elevated thunderstorms moving along the south coast on Friday evening. Further rainfall occurred on Sunday with another 10-20mm to most places, so we have all had a good watering. It has also turned much cooler, with afternoon temperatures of 12-15*C on both Friday and Sunday afternoons.

The CET for July was 16.5*C (+0.5*C) up to the 26th and the EWR was 68mm up to the 25th which is 109% of the monthly average - and it is much more evenly distributed after the recent rains.

We currently (Monday evening) have quite a big low (995mb) slap bang over the north of the UK feeding blustery winds off a cooler than average North Atlantic bringing sunshine and showers. It should dry out a bit towards the end of the working week but this will give us some chilly mornings - I would not be surprised to see some local ground frost in rural areas.

[Richard]

Early to have frosts, mind you it normal to have summer frosts here too, there has only been the one year in the 14 living here that there has been no frost during the three month summer period.

[Simon Culling]

You raise an interesting point Richard. Here in the UK the vast majority of the official Met Office stations are on low ground and either in habited areas or on flat ground which makes an air frost unlikely in the two summer months of July and August. The frost hollow sites and those in the Scottish mountains will record an air frost in a few summers but will record a ground frost in most years. However, many more sites will record an occasional ground frost in these months which will be of more interest to farmers and gardeners, and this is the more likely scenario this week on Wednesday and Thursday nights.

The UK record low for July is -2.5*C at both St Harmon (Powys, Wales) and at Lagganlia (Inverness-shire) and that for August is -4.5*C, also at Lagganlia. I do not think these stations are still operating.

I would suggest that our July and August would correspond to January and February in New Zealand.

[Tim S]

You raise an interesting point Richard. Here in the UK the vast majority of the official Met Office stations are on low ground and either in habited areas or on flat ground which makes an air frost unlikely in the two summer months of July and August. The frost hollow sites and those in the Scottish mountains will record an air frost in a few summers but will record a ground frost in most years. However, many more sites will record an occasional ground frost in these months which will be of more interest to farmers and gardeners, and this is the more likely scenario this week on Wednesday and Thursday nights.

The UK record low for July is -2.5*C at both St Harmon (Powys, Wales) and at Lagganlia (Inverness-shire) and that for August is -4.5*C, also at Lagganlia. I do not think these stations are still operating.

I would suggest that our July and August would correspond to January and February in New Zealand.

The technical term for this is the urbam heat island effect. I would imagine this would be quite significant in UK cities and even towns due to the fact your buildings are close together and green spaces are decreasing. This would trap a lot more warm air than a suburban layout like we have in NZ. Ie. Single dwelling properties with quite large sections. European cities like Paris and Berlin are some examples of a large heat island effect. It can be up to 5C warmer in the centre of Paris than on the outskirts on a clear calm night.

[Simon Culling]

Thursday morning was a bit on the cool side, but Friday morning was positively chilly for mid-summer with a ground frost recorded in quite a few places. The lowest temperatures were over central and southern England + Wales with the following minimums recorded:

0.9*C at Sennybridge (Brecon, mid Wales)
1.1*C at South Newington (Oxfordshire)
2.0*C at Exeter Airport
2.5*C at RAF Benson (grass min -1*C)
2.6*C at Shobdon (England/Wales border)
2.7*C at Pershore (grass min -1*C)
3.3*C at RAF Shawbury (also England/Wales border, grass min -1*C)

[islandwatcher]

The first 6-months of 2015 have been an almost constant wind or breeze where I live in north London. This seems to have manifested as my vegetable plants growing more slowly but the daily temperatures had not been favourable to plant life in any event.

[Simon Culling]

It has been somewhat warmer in the last few days following the shock of a ground frost at the end of July and also mostly dry. The final CET for July was 15.9*C (-0.1*C) making it the third month in a row below the 1961-90 average (which is still used by the WMO). The final EWR was 87mm which is 140% of the average, so on the wet side, but much of this fell in 5 days near the end of the month.

A number of people have raised the point about 2015 being rather windy (re the last post) and the Met Office published a short piece on their Blog which suggests this is the case. See this link:

http://blog.metoffice.gov.uk/2015/07/24 ... hat-windy/

An ex employee of the Met Office operates his own Blog and he has produced some very interesting pieces in the last six months. He also concludes that 2015 has been windier than the average but for different reasons. Please see the link below to this story on his blog.

https://xmetman.wordpress.com/2015/07/30/windy-2015/

[islandwatcher]

The Earth tilts on it's axis toward the Poles so we all endure weather changes irrespective of where we live. However, I have never been satisfied that the degree of tilt is the same each year. Our respective seasons seem to have become unbalanced and unreliable.

[RWood]

The Earth tilts on it's axis toward the Poles so we all endure weather changes irrespective of where we live. However, I have never been satisfied that the degree of tilt is the same each year. Our respective seasons seem to have become unbalanced and unreliable.

The degree of tilt alters very slowly over long time-scales. In short time spans the changes are tiny, and to suggest otherwise is arrant nonsense. This excerpt from a Wikipedia article says most of what one needs to know...

Using numerical methods to simulate Solar System behavior, long-term changes in Earth's orbit, and hence its obliquity, have been investigated over a period of several million years. For the past 5 million years, Earth's obliquity has varied between 22° 02' 33" and 24° 30' 16", with a mean period of 41,040 years. This cycle is a combination of precession and the largest term in the motion of the ecliptic. For the next 1 million years, the cycle will carry the obliquity between 22° 13' 44" and 24° 20' 50".[16]

[Simon Culling]

The weather has remained rather quiet here in the UK with generally warm and pleasant days and mild nights. The CET for August was 16.2*C (+0.2*C) up to the 7th and the EWR was just 4mm up to the 6th, which is only 5% of the monthly average of 77mm. There is the possibility of a few showers early in the new week, but it is looking generally dry and warm for the next couple of weeks.

The Met Office have produced a page on the July record high of 36.7*C recorded on the first of the month at the following link which gives some historical comparisons for the UK:

http://www.metoffice.gov.uk/climate/uk/ ... g/july2015

Another summary (for the month of June) by the Met Office provides an interesting aside. The daytime high temperature for the 30th June (as detailed in a post above) was 30.5*C at RAF Northolt and this would have been recorded late in the afternoon. However, the temperature reached 32.5*C shortly before the 09:00GMT standard observing time on the 1st July at the London Heathrow site and this value is now the actual maximum for the 30th June. I would imagine a number of sites in and around London would have beaten the Northolt figure (including Northolt itself) by the time of the 0900GMT recording hour - which is actually 10:00 British Summer Time. It must be a fairly rare occurrence in the summer months in the UK when the actual monthly maximum occurred in the following month!

[Nev]

Thanks for the link Simon… some really good info there!

[Simon Culling]

No problem Nev. We have had a wet couple of days to end this week with some very heavy thundery rain on Thursday especially over south eastern costal counties with some flooding and lightning strikes to houses. However, the last of the rain should clear tonight and the weekend looks cooler and fresher but mostly dry with sunny periods - and we look like having another ground frost on Saturday night.

The CET for August was 16.5*C (+0.4*C) up to the 13th and the EWR was just 11mm up to the 12th which is only 14% of the monthly average. However this will increase significantly when the rainfall of the last two days is added on.

[Simon Culling]

We have the interesting situation of our weather being somewhat in retrograde motion at the moment with some rain approaching from the east rather than the more normal south west or west. A trough extending NW from a low over the Balkans is forecast to spawn a small low in the North Sea which will be just off the NE coast of England (1008mb) by 1200GMT tomorrow (Tues 18th August). It will then continue moving NW across Scotland before being absorbed into an Atlantic low on Wednesday. This will bring mainly light rain to eastern counties of England + Scotland but might give reasonable amounts to the east facing slopes in the more north eastern parts.

It will not have any real effect on us here in the south and we will continue with the dry and settled weather but with quite a lot of cloud around and occasional sunshine. It might warm up a bit towards the weekend.

There was patchy ground frost on Saturday/Sunday night in more western parts with the lowest air temperatures recorded on the 16th being 2.4*C at Shobdon (Herefordshire, near the England/Wales border) and 3.2*C at Exeter Airport. Also, 1.1*C was recorded at Altnaharra in NW Scotland.

[Simon Culling]

The westward moving low produced more rain than originally anticipated especially in more north eastern parts, but it did only affect eastern counties of both England + Scotland. The rain was split between two rainfall days on the synops, so selected 48 hour totals to 00600GMT on Wednesday 19th August were:

48.8mm at Fair isle (halfway between Orkney + Shetland in N Scotland)
45.2mm at Kirkwall (on Orkney, N Scotland)
33.4mm at Loftus (Northumberland)
28.8mm at Aberdeen Dyce Airport
27.8mm at Leconfield (E Yorkshire)
20.2mm at Wainfleet (Lincolnshire)

The rain did not quite make it as far inland as Milton Keynes but it was cloudy for most of Tuesday (Ac + As sheet) with some virga visible, but a shower passed by on my east and south giving a few spits of rain, but also a fabulous display of mammatus in the Altostratus cloud which had a base around 10,000ft. This picture does not really do it justice and I wish that I could have reached a wider horizon. The display was from the SE to the SW and right up to the zenith and became very pink as it moved away to the south west and a bit of low sun under the As caught it. Unfortunately my photo of this did not come out well.

[Orion]

Plenty of bubbly texture there

[Simon Culling]

We have picked up a warm southerly today (Fri 21st Aug) and now the sun has broken through the Cu+Sc in the late afternoon the temperature has shot up to 25*C. We will continue to draw in this southerly wind into the weekend courtesy of a big high over Scandinavia with the mercury passing 30*C tomorrow in the south east, but a low is forecast to develop over France and move north west to be in the Irish Sea (at 992mb) by midday on Sunday. A trailing front down the west side of the UK will give a lot of rain to Ireland, Wales and western parts of England, but the warm plume over the east should spark off a few storms. Timing and location is difficult to pin down at the moment, but I would favour central England on Saturday evening. Let's hope we get another decent lightning show.

The CET for August was 16.1*C (+0.1*C) up to the 20th and the EWR was 44mm up to the 19th which is 57% of the monthly average - reflecting the heavy rain at the end of last week.