Iceland has been rather cold for much of this year. The reason I’ve put it down to was persistent NW’ly winds flowing down from off Greenland ice cap. This month however, a tongue of colder water SSTSSTSea Surface Temperatures has extended E’NENENorth East from the coast of SE Greenland and wrapped itself around Iceland’s north and east coast. You can see the effects of this if you look at temperature anomalies so far this October for Iceland. The cold month we’ve seen across much 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., and which the media love to describe as ‘rather chilly’, may also be a symptom of the colder air across Iceland and those same NW’ly winds.
How long these low SST will continue around Iceland is anyone’s guess, and what if any effect this will have on the coming winter. One thing I have noticed for some time in the long-range 16 to 30 day text forecast 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, is the mention of higher pressure to the northwest of the UK which might be in somehow linked.
Towards mid-November, high pressure may become more focussed towards the northwest of the UK, allowing a gradual trend towards colder and perhaps more unsettled conditions, especially in more southern and eastern areas.
A cold pool has developed in the last six weeks off the coast off the coast of northwest Ireland and western Scotland. It’s incongruous, because at the moment the SSTSSTSea Surface Temperatures of the North Atlantic are at the second highest level since 1981, and possibly many hundreds of years before this. It’s expanded & consolidated a little more during the last week, but what’s behind it? Answers on a postcard to the usual address.😉
The curious thing in March was that although Atlantic SSTSSTSea Surface Temperatures were at record high levels, the air above it (in the central Atlantic at least) was 2 degrees colder than average.
Climate Pulse is a new interactive website that’s just been released by the ECMWF. It’s a wonderful way to visualise global air and sea temperature data in graphs and in a 3D Globe. I may be wrong but the graphs look like they use the plugin from Highcharts, the globe has limited functionality compared to the graphs but is still pretty good. Web applications as good as this are gradually putting me out of a job, and although they do allow you to download the daily data as a CSVCSVA data file using Comma Separated Variable format. file, I can only match the visualisation you get in a Windows application on a PC which is already out there on the web and available to all, and that can only be a good thing.
I wonder if the current high SSTSSTSea Surface Temperatures off the west coast of Africa will spark off more Cape Verde tropical cyclones than occurred last year? For the record 2023, was a little above average using the accumulated ACEACEAccumulated cyclone energy (ACE) is a metric used by various agencies to express the energy released by a tropical cyclone during its lifetime. It is calculated by summing the square of a tropical cyclone's maximum sustained winds, measured every six hours. The resulting total can be divided by 10,000 to make it more manageable, or added to other totals in order to work out a total for a particular group of storms. index for the year in the North Atlantic. There were a handful of storms that originated from the around the Cape Verde Islands although I am unaware of any correlation between the number of cyclones and SST. As you can see that at the moment the SST is around +3°C and two degree warmer that at the same time last year. SST are fickle, and can change quite quickly, especially close to the coast, so these higher than average SST may well not persist into June.
Atlantic sea surface temperatures [SSTSSTSea Surface Temperatures] have been increasing exceptionally quickly over the last 12 months. Even allowing for the fact that the increases coincide with an El NinoEl NiñoEl Niño 'The Boy' is the warm phase of the El Niño–Southern Oscillation and is associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific event, what lies behind them in both the North Atlantic and globally remains a mystery. As you can see from the first chart, a 365 day moving average, the linear trend since 1981 has been at the astonishing rate of +0.249°C per decade. To investigate the rise in SST I’ve developed a program to download and visualise the daily SST data from the Climate Reanalyzer site and to plot these three charts that I’ve included. I am thankful to Professor Eliot Jacobson (@eliotjacobson) for the link to the data, and the inspiration for the first two of these three charts. ToDo: It might be very useful if I were to overlay the ENSOENSOEl Niño–Southern Oscillation is an irregular periodic variation in winds and sea surface temperatures over the tropical eastern Pacific Ocean, affecting the climate of much of the tropics and subtropics. The warming phase of the sea temperature is known as El Niño and the cooling phase as La Niña. events on the first of these two graphs.
As you can see 2024 has picked up where 2023 left off and is considerably higher than 2023 was at this date.
The waters around IONAIONAIslands Of North Atlantic.
Yes I know there's an island called Iona, but this is so I don't have to use the term 'British Isles' when referring to the whole of Ireland and the UK. are all still well above average for early January. In fact the southern North Sea is +1.7°C above the LTALTALong Term Average. This is usually defined as a 30 year period by the WMO., and has been for some considerable time. It’s no wonder when we do get a cold Arctic northerly or a continental easterly, why temperatures are even more attenuated by the SSTSSTSea Surface Temperatures than they usually are.
The latest SSTSSTSea Surface Temperatures were a bit of a surprise. I realise that globally SST are currently at record levels, so I was surprised to see how much blue there was on the chart. Obviously the belt of high anomalies in the central Pacific, Atlantic and Indian ocean must be at very high levels indeed. The northern Baltic has managed to ice up this year, but SST in the Black Sea and Mediterranean are still well above average.
The southeast of the North Sea and Baltic remain remarkably warm still with anomalies widely of +3°C above the LTALTALong Term Average. This is usually defined as a 30 year period by the WMO.. Is the warm summer of 2023 across Europe a product of these high SSTSSTSea Surface Temperatures, or as seems likely, these high SST are just a by product of the very warm summer? The central north Atlantic, although still much warmer than average, is much cooler generally that at the same point last year, how this bodes for the weather in this autumn and coming winter is anyone’s guess, but mine would be for a very mild, wet autumn and winter, but don’t quote me on that because I’m no expert😉
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.
The surge in SSTSSTSea Surface Temperatures that began in June has gradually been subsiding since the start of July, and now we’re starting to see some blue negative anomalies appear around the British Isles at last. What triggered this surge in SST’s is anyone’s guess. Perhaps a giant hydrothermal vent briefly opened on the mid-Atlantic ridge in the North Atlantic and spewed out an enormous amount of super-critically heated water for a couple of days? It may sound totally wacky, which it probably is, but there have been a number of hotspots that suddenly appear and disappear just as quickly in the last 10 years that I’ve been watching SST across the globe.
SST anomalies may have been falling across the Atlantic but they are still at record high level in the Mediterranean sea, particularly at the western end along the coast of north Africa.
Five out of the seven Met Services around the world have finally published their estimated global temperature anomalies for February 2023. I swear they get slower at updating their estimates each year. The Europeans are always first off the mark to report these days, but the slowest by far are 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, who have only just published their estimate for January. The comparison graph (above) shows that the weak third dip in anomalies that started in 2016 has now all but fizzled out. Now that the double dip La NinaLa NiñaLa Niña is an oceanic and atmospheric phenomenon that is the colder counterpart of El Niño, as part of the broader El Niño–Southern Oscillation climate pattern. The name La Niña originates from Spanish for "the girl", by analogy to El Niño, meaning "the boy". In the past, it was also called an anti-El Niño[1] and El Viejo, meaning "the old man." event has come to an abrupt end, and world ocean SSTSSTSea Surface Temperatures at record highs, you can only expect global anomalies start to rocket through the rest of 2023.
Dear Diary It’s a slow job cooling the oceans with a two-week cold spell. SSTSSTSea Surface Temperatures are still between 1°C and 3°C above the LTALTALong Term Average. This is usually defined as a 30 year period by the WMO. in waters that surround IONAIONAIslands Of North Atlantic.
Yes I know there's an island called Iona, but this is so I don't have to use the term 'British Isles' when referring to the whole of Ireland and the UK., and the cold snap has only done a little to lower them from where they were at the start of November.
Dear Diary, There’s no getting away from it that no matter which direction cold air will affect the country, be it from the east, northeast or north in the coming days, it will have to come across seas with temperatures that are several degrees above their LTALTALong Term Average. This is usually defined as a 30 year period by the WMO. for this time of year. Things are starting to cooling down though and it’s good to see the reappearance of the cold blob in mid-Atlantic (see graph of SSTSSTSea Surface Temperatures below) where SST have been falling since the end of September, and the cooler waters in the Norwegian Sea to the north of the Faroes and Shetlands are also managing to hang in there as well.
Two distinct areas of lower than average temperatures split by the above average warmth of the Baltic Sea this lunchtime. Notice how the fog that’s reluctant to clear over Ireland is depressing the temperature.
