Just a quick note to make a note about how late an Autumn it’s been in 2023. Its now past mid October, and many trees here in StrathpefferStrathpefferStrathpeffer (Scottish Gaelic: Srath Pheofhair) is a village and spa town in Easter Ross, Highland, Scotland, with a population of 1,469. are still have more green leaves than they do brown, and although the Service and Birch tree have lost most of their leaves, others have not. I witnessed late, even very late Autumns in Devon over the years, but not here in Scotland since we returned five years ago. Why is Autumn late? Simple enough, summer was pushed into September and early October by a rather cold mid-summer as these anomaly charts show. The numbers in the pink boxes by the way are the mean anomalies for the gridded temperatures for the whole map, the graph is for temperatures at the grid point 57.5N 5W, the closest to home. It does make you wonder if meteorological summer should now be a four month period rather than a three which also includes September, whilst Autumn should now include December. By the way the title of that graph should read Mean Temperatures and not anomalies and another thing to put right.
One country in Europe that’s bucked the trend of a warm summer in 2023 was Iceland. I’ve noticed this in the monthly anomaly charts for mean temperature that I produce, so I decided to spruce up my chart grid viewer to see if I was right in my assumption, and as you can see in this chart of weekly mean anomalies I was. What caused it is may have been persistent high pressure across the Greenland ice cap to the northwest of Iceland, and a shift southward of the Icelandic low, which in turn allowed more days of northerly or north-westerly flows and hence the lower than average temperatures.
It’s not easy to verify these findings because even the Icelandic Met OfficeUKMOThe Meteorological Office is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy site offers no real clues to how they categorised this summer’s temperatures. If you’re by any chance reading this in Iceland, please let me know how you found it😉
I was watching the Deep Dive video produced by the UKMOUKMOThe Meteorological Office is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy, and presented so well by Alex Deakin about the weather in September 2023 on Youtube as you do. He showed two anomaly charts for MSLPMSLPMean sea level pressure is the pressure at sea level, or, when measured at a given elevation on land, the station pressure reduced to sea level assuming an isothermal layer at the station temperature., one for the first half of September and the other for the second half that showed how anomaly charts for the whole month can sometimes be misleading. In this case it was how the remarkable warm spell in the first half of the month contrasted with the more mobile second half. The resulting anomaly chart for the whole of the September cancelled out the anticyclonic SE’ly in the first half that brought all the high temperatures.
The mean temperature for the UKUKThe United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and Northern Ireland. for September 2023 in the gridded series was 15.2°C which equalled that of 2006.
I have added a new viewer to my SYNOPSYNOPSYNOP (surface synoptic observations) is a numerical code (called FM-12 by WMO) used for reporting weather observations made by manned and automated weather stations. SYNOP reports are typically mad hourly and consist of groups of numbers (and slashes where data is not available) describing general weather information, such as the temperature, barometric pressure and visibility at a weather station. climate application to display estimated daily temperatures for the whole of the UKUKThe United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and Northern Ireland.. I use as many daily reported maximum and minimum temperatures from WMOWMOThe World Meteorological Organisation is a specialized agency of the United Nations responsible for promoting international cooperation on atmospheric science, climatology, hydrology and geophysics. stations 03001 to 03950 as I can to calculate a UK mean for all stations below 250 M amslAMSLThe height Above Mean Sea Level.. That equates to around 120 observations each day. Nowhere near as accurate as the 1 km x 1 km gridded estimates from the UKMOUKMOThe Meteorological Office is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy, but good enough for me. As you can see it picks out the two heatwaves that have occurred this year. It does look like my estimates maybe just two high though, because mean temperatures in both July and August were much close to average than this. That’s not really that surprising because its totally dependent on an even spread of site location, but they tend to be further south and coastal sites. I suppose that I could use all available sites, even those on mountains, and adjust their temperatures down to sea level.
To say that the estimated global temperature for July made it the warmest on record of any month since 1850, it seems that no one bothered to let August know, and August had no intention of following suit, at least in our corner of the world.
Iceland was noticeably colder than average again.
The record high SSTSSTSea Surface Temperatures kept the North Atlantic ~ 1°C above the LTALTALong Term Average. This is usually defined as a 30 year period by the WMO..
The intense heatwave in southern France seems to have been cancelled out by an equally cold start to August that no one seemed to notice.
According to the 42 day forecast for 2M temperatures from the ECMWFECMWFThe European Centre for Medium-Range Weather Forecasts is an independent intergovernmental organisation supported by most of the nations of Europe. It is based at three sites: Shinfield Park, Reading, United Kingdom; Bologna, Italy; and Bonn, Germany. It operates one of the largest supercomputer complexes in Europe and the world's largest archive of numerical weather prediction data., it looks likely to be a mild, if not warm start to meteorological autumn 2023 across much of Europe. Let’s hope they’re forecast is wrong, it has been before.
What surprised me about temperatures in July 2023 was how the media went on a frenzy and adopted what was a North African heatwave and described it as an whole encompassing European affair, when mean temperatures across a large part of the continent for much of the month were below average.🤔
As you can see the colour scale I use for temperature is dynamic rather than using a fixed set of colours as preferred by the BBCBBCThe British Broadcasting Corporation (BBC) is the national broadcaster of the United Kingdom, based at Broadcasting House in London. It is the world's oldest national broadcaster, and the largest broadcaster in the world by number of employees, employing over 22,000 staff in total, of whom approximately 19,000 are in public-sector broadcasting. and UKMOUKMOThe Meteorological Office is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy. It may not be transferable and directly comparable to any other month, but I find it much easier to find the hot and cold spots, and I can easily switch back to a fixed scale in software if necessary.
As far as I can see in the SYNOPSYNOPSYNOP (surface synoptic observations) is a numerical code (called FM-12 by WMO) used for reporting weather observations made by manned and automated weather stations. SYNOP reports are typically mad hourly and consist of groups of numbers (and slashes where data is not available) describing general weather information, such as the temperature, barometric pressure and visibility at a weather station. observations that I’ve downloaded for July 2023, and in complete contrast to July 2022 when temperatures exceeded 40°C, there wasn’t one single day when the maximum temperature [06-18] exceeded or equalled 30°C. Not many people know that😉
Courtesy Copernicus- the picture that caused all the fuss
Just a quick look back at the heatwave of July 2023 across the Mediterranean. There was a great deal of interest in this taken by the media in the UKUKThe United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and Northern Ireland., particularly the BBCBBCThe British Broadcasting Corporation (BBC) is the national broadcaster of the United Kingdom, based at Broadcasting House in London. It is the world's oldest national broadcaster, and the largest broadcaster in the world by number of employees, employing over 22,000 staff in total, of whom approximately 19,000 are in public-sector broadcasting.. As far as I can see it was in my opinion, and that’s what this blog is all about, was sparked off initially by some overzealous reporting by the new (to me) Rome correspondent who was interviewing a selection of British tourists in the centre of Rome in the middle of a hot sunny day. I think this was in reaction to a warning from METEOAMMeteoAMThe Italian Meteorological Service is an organizational unit of the Italian Air Force (Servizio Meteorologico dell'Aeronautica Militare) and the national meteorological service in Italy. The weather forecasts and other services serve both the armed forces and the general public. of a severe heatwave dubbed Cerberus on the 13th. If you’ve ever been to Italy or abroad you’ll realise it’s usually a good idea to hide from the sun at this time of the day😉 As far as I can ascertain from observational data there was a short 3 day heatwave (see thermograph below) at Rome’s airport. The trouble with observational data from Italy, as is the case in the UK, you can only access a subset of it, and unfortunately Rome has only one SYNOPSYNOPSYNOP (surface synoptic observations) is a numerical code (called FM-12 by WMO) used for reporting weather observations made by manned and automated weather stations. SYNOP reports are typically mad hourly and consist of groups of numbers (and slashes where data is not available) describing general weather information, such as the temperature, barometric pressure and visibility at a weather station. station situated at the airport on the coast. Because of the HIEUHIUrban Heat Island (UHI) is an urban area that is significantly warmer than its surrounding rural areas due to human activities. The temperature difference is usually larger at night than during the day, and is most apparent when winds are weak. UHI is most noticeable during the summer and winter. The main cause of the UHI effect is from the modification of land surfaces I’m sure it was much warmer in the centre of Rome. Not only is there a shortage of observational data for many countries, I challenge you to find any up to date LTALTALong Term Average. This is usually defined as a 30 year period by the WMO. climate data for any of them either. What I mean here by up to date is the LTA for 1991-2020 and not that for 1971-2000 that I have for many stations. You would have thought in these days of “global boiling” the latest climate station for all member countries would be available on the WMOWMOThe World Meteorological Organisation is a specialized agency of the United Nations responsible for promoting international cooperation on atmospheric science, climatology, hydrology and geophysics. website – no it isn’t – and if it wasn’t for Wikipedia, and some nifty parsing, I wouldn’t have collected over 800 LTA records across the world as I have. I’ve been watching and examining heatwaves closely across the UK and Europe since I retired from the Met OfficeUKMOThe Meteorological Office is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy in 2011. There are no rules as to what constitutes a heatwave, and therein lies the problem. The UK have one set of rules and every other country has another, and that’s why I argued, mainly to myself because few people read what my views are or give a damn about them either, that instead of a rigid threshold for summer months of X°C for a region, as the UKMOUKMOThe Meteorological Office is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy do, a “heatwave day” should be defined on the anomaly of the maximum temperature for each individual station. Over the years I’ve developed software and I usually default to an anomaly of 6°C above the LTA. Personally I think this is much too low for a severe heatwave, and probably should be ~+10°C. The thermograph for Seville shows the extent of the heatwave there using this 6°C rule. Three distinct heatwave days up to the 28th. These anomalies are calculated using the 1981-2010 LTA and not the much colder LTA of 1971-2000.
Seville 1981-2010 LTA
These thermographs for Rome, Decimomannu and Palermo use the 1971-2000 LTA. and because they anomalies calculated using this slightly colder LTA, the anomalies are much warmer than if I had the ones for 1991-2020. I’ve emailed METEOAM to see if I can obtain them, but am not hopeful I will be able to source the latest climate data. I shouldn’t need to do this, or rely on Wikipedia to supply them, this basic climatological data should be available from the WMO. That aside the three thermographs do highlight a series of heatwave days, with many as 15 at Decimomannu in Sardinia with an extreme maximum of 46.8°C.
I hope I’ve explained the importance of using the latest LTA for all stations to get an unbiased picture of July’s heatwave. The map below of total heatwave days shows the number of days with a maximum temperature anomaly of 6°C or higher. There’s no doubt that it was hot across a large of southeastern Europe using the +6°C threshold, particularly across parts of northern Algeria and Tunisia. There are what looks like spuriously high anomalies scattered around these are probably caused by out-of-date LTA.
Number of days with a maximum temperature [06-18] >=+6°C
If you look at the next chart this shows the total number of days with anomalies of +10°C or more, and what I maintain are severe heatwave days. Heatwaves in the UK must last at least three consecutive days or more before they can be officially labelled a heatwave, many of the sites in the chart below away from North Africa have one or two, and even if they have more they may not be consecutive.
Number of days with a maximum temperature [06-18] >=+10°C
Looking at reanalysis gridded temperatures and anomalies up to the 26th reveal what I think was really going on. The core of the heat was across the north of Algeria and Tunisia, occasionally some of that very hot air escaped transferring northwards from Africa to affect parts of Sardinia, Sicily, southern Italy, western Greece and the Balkans, and because SSTSSTSea Surface Temperatures temperatures in the Mediterranean were at record levels during July, the sea didn’t cool the air at the surface as much as it could. The other thing is the media got a hold of this story and ran with it, this was easy to do, because they already had stories about heatwaves in the southern states of America and China, and as the month went on wildfires broke out, and it was also announced that July was very likely to be the record hottest month – a perfect combination for catastrophising the whole thing🥵. For the record heatwaves don’t cause wildfires people do.
These two charts underline how warm June and sunny the June of 2023 was across the UKUKThe United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and Northern Ireland.. It set new extremes in most regions, but not everywhere.
It’s been the warmest June since at least 1884 in the north of Scotland by a massive 1.2°C😲 It’s hard to believe just how warm June 2023 was in the north of Scotland, particularly so because we now call it home. The warmest in at least 140 years by a big, big, margin.
It’s official, June 2023 was the warmest June since temperatures recorded started in 1884. Rather surprisingly it only came in as the fourth sunniest. Anomalies show that the north of Scotland was both the sunniest and warmest region in the UKUKThe United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and Northern Ireland. during June.
I’ve developed a single purpose application to analyse hourly temperatures for any station during a month. There’s more work to be done on it as it could be extended to look at other climate variables.
Notice the cold thread with the easterlies at the start of the month and the much warmer second half thread. Average temperatures sometimes hide the true story.
Compare those results with those from maritime climate of southern Ireland.
The warmest June since at least 1846. A very sunny month, particularly in the north, and generally drier than average in most places, with the exception of more localised flash flooding from thunderstorms.
Temperature anomalies show the effect of the early heatwave across Iberia from the pulse of hot air from northwest Africa in the last week. The central Atlantic remained colder than average again, but it was much warmer than average across the Ukraine and southwest of Russia.
The north-south temperature gradient in anomalies continued into March across the UKUKThe United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and Northern Ireland.. It’s slightly ominous that +4°C anomalies are evident again across Morocco and a number of times the SSWSSWA sudden stratospheric warming (SSW) is an event in which polar stratospheric temperatures rise by as much as 50 °C in the course of a few days. The warming is preceded by a slowing then reversal of the westerly winds in the stratospheric polar vortex. SSWs occur about six times per decade in the northern hemisphere, and about once every 20-30 years in the southern hemisphere.’ly flow during the month pumped warm air across Iberia and into the south of France. This seems to have been a recurring theme in recent years and could provide the method of delivery for hot air in what could be another record breaking hot summer across central Europe.
The ECMWFECMWFThe European Centre for Medium-Range Weather Forecasts is an independent intergovernmental organisation supported by most of the nations of Europe. It is based at three sites: Shinfield Park, Reading, United Kingdom; Bologna, Italy; and Bonn, Germany. It operates one of the largest supercomputer complexes in Europe and the world's largest archive of numerical weather prediction data. are brave enough to let you turn the clock back on their 42 day forecasts and see how they performed. Not very well in the case of last week as it happens.
6-13 Mar 2023 Mean temperature anomalies
When this kind of thing happens, it always knocks your confidence as regards their promise of a milder than average April.
13 Mar – 24 Apr 2023 2m Mean temperature anomalies
I have been collecting hourly SYNOPSYNOPSYNOP (surface synoptic observations) is a numerical code (called FM-12 by WMO) used for reporting weather observations made by manned and automated weather stations. SYNOP reports are typically mad hourly and consist of groups of numbers (and slashes where data is not available) describing general weather information, such as the temperature, barometric pressure and visibility at a weather station. observations for many years now from across the world. I must have many tens of millions of observations dating right back to 1973. So I thought it might be interesting to look at some of these hourly observations in more detail. I have always thought a 24 hour moving average of temperature for somewhere, gives a much better view of the temperature data than just the daily extremes. So the comparison graph between summer 24 hour average temperatures at Heathrow airport and Coningsby for 2022, shows that although Coningsby is now infamous as being the warmest place in the UKUKThe United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and Northern Ireland., with a maximum temperature of 40.3°C, it’s not when you calculate a 24 hour average. Furthermore. analysis of the number of hours above the UKMOUKMOThe Meteorological Office is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy heatwave threshold at Heathrow of 133 hours, far surpasses that at Coningsby of 97 hours, even though the threshold at Heathrow is 28°C and only 27°C at Coningsby. So, not unsurprisingly, I can safely conclude that Heathrow was still the hottest spot in the UK despite what happened on the 19th of July.
