Winchester High Street – 1 August 2024 (courtesy 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.)
Below are some of the images that I posted on Twitter concerning the heavy rain and flooding from thunderstorms across parts of southern England on Thursday. Although 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 scored nul points with a yellow warning for thunderstorms on the previous day, the warning they issued for Thursday was fully justified 👍.
The Grimness Index in July 2024 (50.7) was not quite as high as i#that in July 2023 (69.7) 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., but it still made for a mediocre month.
Much lower than average pressure to the north (-8 hPahPaA Hectopascal is the SI unit of pressure and identical to the Millibar), and higher than average pressure in the central Atlantic (+5 hPa), produced a W’NW flow and lower than average temperatures across 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..
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 are going overboard at the moment about high UVUVUltraviolet (UV) light is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. levels and the dangers of getting sunburnt. It’s a bit ironic, because so far (June 14th) 2024 has seen the coolest and cloudiest start to a meteorological summer in at least 23 years. What’s puzzling is that they never mention in their forecast that UV levels can be considerably higher on a mountain than on lower ground. I used AIAIArtificial intelligence is intelligence - perceiving, synthesizing, and inferring information - demonstrated by machines, as opposed to intelligence displayed by animals and humans. in the form of ChatGPT to confirm what I already suspected. I well remember two colleagues at RAF Kinloss coming to work for a night shift, both as red as a beetroots, after a days hillwalking on Ben Wyvis on a sunny day. Back in the 1980’s people weren’t so concerned about the risk of skin cancer from getting sunburnt, but today skin cancer are much more common.😮
Spring 2024 saw a very warm spell from approximately the 8th to the 20th of May with anomalies across northern Scotland of +7°C, followed quickly by a cold spell, from the 4th to 12th of June with anomalies of -5°C. 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 thought little of both spells, despite May ending up the warmest since records began in 1883. They argued that the cold spell wasn’t that unusual, or as cold as the temperatures in many recent years, despite the fact that snow fell on ground above 800 M in Scotland for at least five consecutive days. They didn’t seem to want to factor in that the cold spell had occurred at a time when global temperatures were 1.54°C above the pre-industrial age or that North Atlantic SSTSSTSea Surface Temperatures are at record levels. What a strange attitude to take. 😮
Of all months, June in Central England is the slowest to catch on to the fact that global temperatures have increased by close to, if not more than 1.5°C since the start of pre-industrial times. This is certainly true for the seven day period between the 5th and 11th of June in 2024, which was 17th coldest in the daily series that started in 1772. The mean temperature of 11.34°C was 2.31°C below the 1961-1990 LTALTALong Term Average. This is usually defined as a 30 year period by the WMO. which made it the coldest period since 2001.
Anyone who is fortunate to have a Davis Vantage Pro2 AWSAWSAutomatic Weather Station as I do, know only too well, that the software it comes with doesn’t present the climate data it collects at all well. I’ve made a new unit in my VP DelphiDelphiDelphi is a general-purpose programming language and a software product that uses the Delphi dialect of the Object Pascal programming language and provides an integrated development environment for rapid application development of desktop, mobile, web, and console software. application, to graph temperature data a little more clearly. I recently came across some LTALTALong Term Average. This is usually defined as a 30 year period by the WMO. data for StrathpefferStrathpefferStrathpeffer (Scottish Gaelic: Srath Pheofhair) is a village and spa town in Easter Ross, Highland, Scotland, with a population of 1,469., I don’t think it’s been calculated from real weather data but probably derived from gridded monthly climate data 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 make available. I mention this LTA data because it enables me to calculate anomalies, something dear to my heart. Anomalies let you gauge how the climates been performing, whether a day has been hot or cold, or a month or season wet or dry, in your own back garden.
The lower chart shows mean anomalies for the last 90 days for Strathpeffer, and clearly shows why May 2024 was a record warm month in northern Scotland. The top chart shows temperatures for the last year, and by dragging the yellow coloured box you can replot the lower graph to show the anomalies for the period you are interested. The width of the yellow box can also be adjusted with the mouse as well.
Mean pressure across 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. in May was around 3 hPahPaA Hectopascal is the SI unit of pressure and identical to the Millibar below the LTALTALong Term Average. This is usually defined as a 30 year period by the WMO.. In fact lower than average pressure was strung out westward across the central Atlantic all the way to the United States. Mean higher than average pressure persisted across Scandinavia (+6 hPa) resulting in a very slack pressure pattern across the country.
I’m guessing, but it looks like the snow that stopped play at Buxton was from heavy snow showers over high ground, enhanced by that trough close to Liverpool at 12 UTCUTCCoordinated Universal Time or UTC is the primary time standard by which the world regulates clocks and time. It is within about 1 second of mean solar time (such as UT1) at 0° longitude (at the IERS Reference Meridian as the currently used prime meridian) and is not adjusted for daylight saving time. It is effectively a successor to Greenwich Mean Time (GMT).. I remember the day quite clearly because I was a window cleaner back then in Sheffield. Needless to say, I didn’t get many houses done that Monday. 😉
This PDFPDFPortable Document Format (PDF), standardized as ISO 32000, is a file format developed by Adobe in 1992. of the day in question is courtesy of 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
The first 20°C maximum in central England occurred on the 10th of May this year (2024), which is just about the average date for it to occur. In this ever warming world it’s gotten progressively earlier over the years. The linear trend (1878-2024) reveals that it occurred as late as the 20th of May back in 1878, but it’s now closer to happening three weeks earlier on the 28th of April. This is another new addition to my Daily CETCETCentral England Temperature application.
The resident Icelandic low for April was displaced southeastward again this month by higher than average pressure across Greenland, and lower than average pressure in the northern North Sea, leaving the British Isles in a slack cyclonic westerly flow on the mean pressure chart.
Flannan Isles Lighthouse is a lighthouse near the highest point on Eilean Mòr, one of the Flannan Isles in the Outer Hebrides off the west coast of Scotland. It is best known for the mysterious disappearance of its keepers in December 1900. From what I read in the Wikipedia article the disappearance of the three lighthouse keepers occurred on the 15th of December or shortly thereafter.
The weather from the 15th to the 17th from what I can see in the reanalysis charts was quite rough to the west of the Hebrides, with a westerly gale on the 15th,that backed southwesterly by the 16th. The switch to a tropical maritime air mass would explain the poor weather conditions reported by the steamer “Achtor” later on the 15th. As for the men being swept off the island by a freak wave who knows, the gradients are tight so there must have been gale force winds at that time, but possibly not storm force.
I download the site specific NWPNWPNumerical weather prediction uses mathematical models of the atmosphere and oceans to predict the weather based on current weather conditions. data that resides in the HTML 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 weather application requests whenever anyone looks for a forecast for a location for a number of my applications I’ve written to visualise the forecast data in a table, graph or on a map. Parsing the data was a tricky business, but I persevered, and can now grab a week of one and the three hourly data for any number of elements including temperature. As well as visualising the data, I thought it might be interesting to do a spot of forecast verification by comparing the three hourly forecast data with the actual values from 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. observation for any location in the world. I know that the forecast values although quite accurate, are far from being spot on. The question I was intrigued to find out was just how accurate they are. Here are some recent preliminary results I have produced from the add-on to my 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 NWP application I wrote a number of years ago.
Notice the very warm day on the 6th of April associated with storm Kathleen, and how underestimated temperatures at Kinloss were because of a slight foehnFoehnA foehn, is a type of dry, relatively warm, downslope wind that occurs in the lee (downwind side) of a mountain range. It is a rain shadow wind that results from the subsequent adiabatic warming of air that has dropped most of its moisture on windward slopes (see orographic lift). As a consequence of the different adiabatic lapse rates of moist and dry air, the air on the leeward slopes becomes warmer than equivalent elevations on the windward slopes. effect.
Generally a pretty good result with temperatures +/- 2°C at Heathrow.
Again at Exeter temperatures within +/- 2°C of the forecast, although it didn’t do well with some of the minima, and the 8th of April was a bit of a disaster because heavy rain suppressed temperatures.
I’ve noticed that recently the Met Office are in the process of updating the NWP data their app uses, so they must have some concerns themselves about its accuracy, although the changes in the NWP might have more to do with forecast weather, rather than forecast temperatures. At the moment I am still using the old data and haven’t switched to the new trial data. In the meantime, let me know about what you think about the accuracy of the forecasts the Weather App produces in your area. I’ve still got a bit more testing, tweaking and bug fixes to do to my verification application, but I’ll keep you posted.😉
Is it possible to get a heatwave in Spring? I beleive it is, and it seems to have already happened at least once since the start of astronomical spring in central Europe. I reckon that maximum temperatures anomalies of 10°C above the LTALTALong Term Average. This is usually defined as a 30 year period by the WMO. constitute a heatwave day. The definition of a heatwave of course is that these high temperatures should occur for at least three consecutive days or more. So the charts I’ve constructed are just a simple count of days with anomalies higher than 10°C. I’ve not any deep research into this, but have just added a chart for 2023 for a comparison. I think, like a lot of others do, that with global surface temperatures and North Atlantic SSTSSTSea Surface Temperatures being at unprecedented high levels as they are at present this is portentous, and summer across mainland Europe could see a record number of severe heatwave events and the risks that this brings. Hopefully I’m proved wrong, and surges of warm air flooding up from the tropics won’t occur too frequently.
Not surprisingly, in this ever warming world of ours, the dates of the earliest and latest air frosts in Central England getting respectively later and earlier. The code behind that produced the scatter graphs below was a lot harder than I imagined. Along with the scatter graph and data grid, I also decided to add a smaller horizontal bar chart just to plot the annual distribution. The application is a lot more versatile than just finding the earliest and latest frosts and will come in useful in spotting other events in the daily CETCETCentral England Temperature series. As you can see from the linear trend in the graph below of minimum temperatures, the date of the latest air frostair frostAn air frost occurs when the temperature of the air falls below 0.0°C in Central England is now closer to the 5th of April, much earlier than the 16th it was back in 1878.
The date of the first air frost is now 11 days later on the 13th of November, rather than the 2nd of November, as it was closer to back in 1878.
I never noticed this rare ‘Heat Burst’ that occurred at Donna Nook in NENENorth East Lincolnshire on the 25th of July 2019. I still have the hourly SYNOPs from the AWSAWSAutomatic Weather Station at Donna Nook so I can construct a crude thermograph for that evening. As you can see the temperature surged to 32.2°C a rise of 10.2°C between 1950 UTCUTCCoordinated Universal Time or UTC is the primary time standard by which the world regulates clocks and time. It is within about 1 second of mean solar time (such as UT1) at 0° longitude (at the IERS Reference Meridian as the currently used prime meridian) and is not adjusted for daylight saving time. It is effectively a successor to Greenwich Mean Time (GMT). and 2050 UTC, at the same time dewpoints fell from 18.3°C to 12.6°C, with the relative humidity falling to just 30%. This was called by a heat burst, the theory behind heat bursts are that they’re the result of a downdraught of very warm and dry air associated with a decaying thunderstorm. Worldwide they are very elusive, and 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. extremely very rare mesoscale event indeed. You can read more about them on Wikipedia. I came across the event after reading about it the book “Very British Weather” 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, who says I never give them credit?
I did a search on Twitter and found that the Met Office did tweet about the heat burst the next day and included their own more detailed thermograph.
Now here’s a mystery, after downloading the archived SFERICs from BlitzortungBlitzortungBlitzortung.org is a lightning detection network for locating electromagnetic discharges in the atmosphere (lightning discharges) with very low frequency receivers based on the time of arrival (TOA) and time of group arrival (TOGA) method. for that day, I found there weren’t any! So what’s going on? Did a visiting holiday maker wild camping on the beach start a barbecue under the Stevenson screen just after 9pm? No, on running another query on Blitzortung I find there wasn’t a single SFERIC detected on the whole planet for that particular day! “Vorsprung Durch Technik” as they say in Germany.
No investigation would be complete without a plotted 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. chart for the hour in question. As you can see despite what Blitzortung believes there were some heat thunderstorms around, and look to have been medium level affairs, after all this was the day that Cambridge set a new UK record for the warmest July day of 38.1°C.
One final curiosity about this heat burst concerns an AMOUK ship that turn up very regularly in the UK SYNOP reports. I say ship, but because occasionally they do report on land 😲. I still don’t know what they are or who they belong to, I guess they are some sort of mobile AWS which usually turn out very accurate observation for extended periods. I could write software to track them, but that’s another story. The reason I mention them here is that AMOUKo5 reported an even higher temperature at sea of 33.1°C with a dewpoint of 9.6°C, just offshore (53.5N 0.2E) of Donna Nook at 21 UTC. Notice too that the old Humber light vessel (03380) reported a temperature of 29.0°C at that time as well.
I saw someone mention this on Twitter/X yesterday, so I thought that I’d take a closer look. A comparison between the maximum temperatures on [A] Easter Day 2024 and [B] Christmas Day 2023. As you can see it was colder on Easter Day in the southeast compared to Christmas Day, but much warmer in Scotland on Easter Day that it was on Christmas day. Not a lot of people know that. 😉
The exceptional heatwave across Belarus, Ukraine & E Russia continued this lunchtime, with anomalies as high as +19°C, the highest I’ve seen. Juxtaposed with the very cold air across Finland, Sweden and northern Norway.
Look no further for a reason for all the depressing cloudy, mild & wet weather in March 2024. The anomalous Icelandic low that’s a resident feature of anomaly charts in any month of the year, decided to take a holiday.
I was researching Ben Wyvis in Wikipedia for an article that I was writing and came across this incredible picture looking east from Loch Glascarnoch towards Ben Wyvis, with what looks like a shallow layer of fog covering both the loch, the A835 to its south, and the glen beyond. I would guess the picture was possibly taken on high ground to the south of the loch, and judging by the direction of the shadows on the fog layer at around lunchtime.
The credits show that the picture was taken by D.J.MacPherson with a creation date of 2009-01-02. At first I thought that there had been some kind of trickery involved with its production, but when I checked the weather chart for midday on the second of January 2009 and found it had been a frosty, clear anticyclonic day in the northwest Highlands with fog reported at Aviemore and Kinloss which seemed to fit. The only odd thing is that there’s no proper snow cover on Ben Wyvis.
What clinched it was when I checked the NASANASAThe National Aeronautics and Space Administration is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research.EOSDISEOSDISThe Earth Observing System Data and Information System is a key core capability in NASA’s Earth Science Data Systems Program. Designed and maintained by Raytheon Intelligence & Space, it is a comprehensive data and information system designed to perform a wide variety of functions in support of a heterogeneous national and international user community. Worldview visible satellite image for that day.
So my bit of amateur “meteorological sleuthing” paid off 😉
February 2024 was a cyclonic month across the 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., with a strong broad W’SW gradient that stretched from central Atlantic into northeast Russia. The Icelandic low was elongated further east into the northern Norwegian sea (-9 hPahPaA Hectopascal is the SI unit of pressure and identical to the Millibar), and the Azores high displaced to the southeast towards the Canaries (+4 hPa). Mean 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. was below normal across the whole of IONA by as much as -9 hPA in northern Scotland.
There’s been a steady decline in the number of air frosts occuring in Winter [DJFDJFMeteorological Winter comprising the months of December, January & February] 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. since 1960. In the southeast of England the decline in the last 64 years has been at the rate of 1.8 days per decade or 11.3 days. In the north of Scotland the decline has been somewhat slower at the rate of 1.4 days per decade or 8.6 days overall.
The climate record for air frosts only extends back to 1960 in the gridded form. I’m quite sure it could easily be extended back to at least 1884 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, but they obviously don’t seem to find the time or enthusiasm to get around to it. You would think that the work would be trivial, since they must already have gridded daily night time minimum data, perhaps they’re hoping for a crowd sourced group of volunteers to step in and do it for them.
Above is a map of accumulated rainfall on the 21 February from 0000 to 0900 UTCUTCCoordinated Universal Time or UTC is the primary time standard by which the world regulates clocks and time. It is within about 1 second of mean solar time (such as UT1) at 0° longitude (at the IERS Reference Meridian as the currently used prime meridian) and is not adjusted for daylight saving time. It is effectively a successor to Greenwich Mean Time (GMT). and estimated from weather radar. Is it evidence of rainfall bunching as mentioned in the recent Deep Dive given by Alex Deakin? Maybe. Here’s the link to the paper “Rainfall enhancement downwind of hills due to standing waves on the melting-level and the extreme rainfall of December 2015 in the Lake District of northwest England” (link).
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.
