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xmetman

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  1. I have always been fascinated by weather maps and atmospheric patterns or more strictly atmospheric circulation. So I decided to download the freely available NCEP re-analysis data to investigate it and used it initially to produce weekly mean pressure charts for the British Isles and the eastern Atlantic for the first 15 weeks of 2014. I now have data to display pressure charts for anywhere in the world in six hourly time-steps, and although the data is fairly coarse (2.5° x 2.5° grid), I can now produce weekly, monthly and seasonal charts of mean pressure and anomalies which I think provides me with a way to better understand atmospheric circulation, and how for instance last winters cyclonic weather evolved. On examining the results I did notice just how one mean weekly pressure pattern could dramatically change from week to another. See how the Icelandic low for example appears in week 12, drifts SSE the following week, before moving back and dissipating by week 15! Of course this could be my coding that’s at fault, or it could be that a 7 day mean is just too fine an interval to look at circulation patterns, and that monthly means should be the norm. I plan to delve a bit more into this whole area and perhaps look at generating a daily ‘rolling’ chart to get a better feel for how circulation patterns suddenly transition from cyclonic to anticyclonic or vice versa. I plan to keep an archive of mean monthly pressure and anomaly charts for the British Isles, along with the daily objective Lamb Weather type, and graphs of progression and cyclonicity using this NCEP data. Hopefully I’ll be able to update this monthly, the annual data files are large and grow to 30 MB by the end of the year, so roll on a fibre optic broadband connection. If you are interested in the software development behind the images have a look at the development page. Charts at xmetman
  2. I was just looking at the rainfall totals that I compile from UK SYNOP observations for the last month and was struck by how dry parts of Eastern England and Scotland have been. East Anglia has been particularly dry with Wattisham and Marham receiving just 15.5 and 16.1 mm of rain respectively up to 0600 this morning. As far as I see I have had received close to 100% of reports from the vast majority of sites, but of course I don’t see any corrections that may have been reported. I am sure the Met Office do, or have had problems with the Hawarden SAMOS (#1 driest site), as the 4.3 mm total looks far too low. Also the total from Exeter of 24.8 mm looks on the low side as well, I say this because we live less than 10 miles from there and I’ve collected 50.4 mm so far this month. I can’t say how dry any particular station has been because I don’t have any long-term averages for April, or come to that for any month for any of these UK sites. I know that spring months can be dry especially as April has been quite anticyclonic but I would have thought that 15 or 16 mm is probably less than 40% of average at a guess. Skye tops the wettest places with 122 mm, and unusually Dunkeswell in East Devon is at number two with 118 mm which surprised me. On closer inspection Dunkeswell did have over 30 mm of rain on the 21st, and have caught a lot of rain from the late afternoon showers we have been experiencing during the last week in East Devon.
  3. As you all know I keep a very close eye on Central England Temperatures and so far 2014 is certainly pushing the upper boundary for the warmest year since 1772, with a mean to date (1 January to 27th April) of 7.34°C, which is +2.13°C above the long-term average, and the third warmest in the daily series back to 1772. Interestingly four of the other top seven warmest starts to a year also occurred in this century, and 2014 is paralleling 2007 very closely. Table and graph at xmetman
  4. I finally got round to processing the latest UK Precipitation datasets that I download from the Met Office to have a closer look at the figures for last winter and see just exactly how wet it was region by region across the United Kingdom. Of course it goes without saying that the winter of 2013/14 was wet across all regions of the United Kingdom and particularly so in the south. Interestingly though, the North East and Central regions of England escaped the worst of the rain and the flooding that other parts experienced. Most regional records were smashed, but probably the most telling is the national England Wales monthly dataset that started in 1766 with an anomaly of 180% of the 1961-1990 average. I previously looked at the individual station values of precipitation in a previous blog if you are interested. As usual let me know what you think and of course let me know if you think I’ve got any of my maths wrong. The blog contains maps of regional winter anomalies as well as charts of rainfall since 1931 in SE England and 1766 across England and Wales. xmetman
  5. I was delving into the Objective Lamb Weather dataset maintained by the Climate Research Unit [CRU] at the University of East Anglia [uEA] as you do, and decided to rank some of the parameters in the dataset and place them in a tabulated grid, and at the same time display the matching surface chart from the Wetterzentrale archive. The UEA produce four datasets for the hours of 00, 06, 12 & 18, but I decided to use the midnight one so I could display the corresponding file from the Wetterzentrale archive. The only drawback with this is the Lamb Weather Type is not calculated as it is with 1200 UTC data. So before you write in complaining about why the great storm of 1987 doesn't appear, its due to the fact that it was at its height at around 0600 UTC (or maybe an hour or so later) and would have slipped through the net. More details and the following images in my xmetman blog: (1) Highest daily 0000 UTC Gale Index (1871–2014)(2) Highest daily 0000 UTC MSLP (1871-2014)(3) Lowest daily 0000 UTC MSLP (1871-2014)
  6. I've just run an analysis on rainfall totals for the last 30 days (18 February to 20 March) that I collate from SYNOP observations from the UK and across the world. After such a wet winter, things have dried out very well across a lot of the UK, and for some places Its been a very dry 30 days, which although not exceptional for the months of February and March because they can be very anticyclonic, its such a great contrast from the preceding months. Hawarden in Flintshire is the top dry spot and has received just 4.8 mm of rain, and many other sites in Eastern England recording less than 20 mm of rain. Capel Curig has finally lost top spot as the wettest place in the UK coming in at number seven. The top four wettest sites are now in Scotland, with Lusa on the Isle of Skye receiving 378 mm (14.9") of rain in those 30 days. Even here in mid-Devon my gauge total for the last 30 days is only 32.8 mm. Theses figures are of course unofficial and my best guess, but I do think that they are pretty accurate. If anyone in the Met Office would like to confirm or deny this I would be delighted to hear from them. At the same time maybe they could send me the detailed rainfall statistics for theses sites, so that I could calculate a percentage anomaly! I did ask for detailed information records for just three sites in the SW of England from them, but I'm afraid that even I, with my insatiable thirst for climate data, can't afford the £4749.65+VAT that it would cost me. I reckon that I would be looking at a total bill of £243,284+VAT for the 148 sites that I presently collate, and that's why I keep doing the lottery! See blog for images: Images (1): Total Rainfall Map of Western EuropeImages (2): Total Rainfall Map of UK with tabulated list of rainfall totals. xmetman
  7. Hi The latest HURDAT2 data has just been released by NOAA for last year 2013. Although the season officially ends on the 30th November there was a late unnamed storm that appeared on the 3rd December for 3 days or so which brought the count up to 12 tropical storms and 2 hurricanes. Full report in blog with the following images: (1) N Atlantic plotted chart of 2013 tropical cyclones (2) Gantt time line. (3) Tabulated list of 2013 tropical cyclones (4) Annual ACE & hurricane count totals 1986-2013 (5) Table of Predictions of tropical activity in the 2013 season (courtesy of Wikipedia) (6) North Atlantic ACE 1851-2013 - scatter graph and anomalies in bar chart (7) Map of North Atlantic Track Frequency 1851-2013 xmetman
  8. Hi I've just done some work on what was the wettest place in Europe during winter 2013/14 and I found it to be Eik Hove in southern Norway. I did notice that it was the wettest place despite a good three weeks of January were it was more or less dry! The reason it was so dry is that a ridge of high pressure over Finland effectively blocked any lows in the North sea from crossing in to the Baltic as they had done in December (when we were on holiday there). xmetman
  9. Hi I have expanded on the work I did in analysing climate data reported in SYNOP reports for the UK to look at the whole of Europe. On the whole the results that I got from over 1300 sites look very good, and I only had to intervene at some sites because of minor corruption either in encoding or in transmission. Most countries in Europe did report 12 hourly rainfall totals at 0600 and 1800 UTC so all I had to do was add the two values up to get a daily total. Only one country let me down and surprisingly it was Iceland who couldn't or wouldn't use the good old 6 group which every one else does. To cut to the chase the wettest place in Europe I found to be was a place called Eik Hove (01425) in southern Norway with 1448 mm (57.0″) of precipitation since December 1st. Full report with map and table of ~60 wettest places in my blog. xmetman
  10. Hi Looks like this winter could break the record for lowest number of air frosts [DJF]. I make the count 4 so far for 2013/14, and although the current lowest is 6 in 1924/25, there doesn't seem to be a cold snap coming this side of March. A 'CET frost' is always more difficult to achieve than a local air frost because it's a composite calculated from a number of sites. My total air frosts this winter for mid-Devon is in fact 11, but then again we are outwith the Central England area. I've attached some other charts in my blog as well: (1) Annual daily number of frost days(2) Daily Frequency of Frost & Ice Days 1878-2014(3) Annual daily mean minimum(4) Annual total of Frost & Ice Days 1878-2014 xmetman
  11. Hi The lows maybe not as intense, and the gradients not as tight, but that means the features that wrap around the lows are slower and take longer to clear, so if you have a look at the estimated accumulations for today since 0000 UTC they are still as high in my opinion. at least for the SW of England & Wales as they have been for any of the events in recent weeks. xmetman
  12. Hi I read an article in the Guardian today and it has me puzzled. Lord Stern states in the third paragraph of that article that climate change has arrived and is now happening. This may be correct , but what he says next to support his claim is not: “Four of the five wettest years recorded in the UK have occurred from the year 2000 onwardâ€â€œOver that same period, we have also had the seven warmest years†With regard to the rainfall in the UK I use as my evidence the UKP dataset maintained by the UKMO and which dates back to 1766, and is in fact the oldest instrumental record of its kind in the world. <Image:England Wales Annual Rainfall (1766-2013)> You will see from the graph of the England Wales Precipitation series that only two and not five of the years since 2000 are in the top five wettest years (2000 & 2012), the next 21st century year 2002 appears at number 11. So instead of four out of five its 2 out of 5, or to be fair its 2 out of 10! What a whopper. The second one is worded ambiguously in my opinion – what I think he’s trying to say is that 7 of the warmest years have occurred since 2000. As far as I can tell Lord Stern is still talking about the ‘UK’, as he was in the sentence before with regard to rainfall. So he is talking about UK temperatures and not global temperatures, and therefore I use as my evidence here the Central England Temperature series, which is also maintained by the UKMO and dates back in its monthly form to 1659. <Image:Monthly CET Annual Anomalies for 1908 – 2013> As you can see in the rank tabulated list above, of the top ‘seven warmest years’, only three of the top seven occurred in this century 2006 (#1), 2011 (#2) and 2002 (#5), so why did Lord Stern say that ‘we had the seven warmest years’ when we only had three? I’m obviously missing something or other here, and I’m sure someone will explain what Lord Stern did mean in his article and point out what evidence he is using to support his claims about the five wettest and seven warmest years in the UK. Believe it or not, I’m a climate change agnostic, but I do have a passion for weather statistics, and hate it when someone is being more than a little misleading in using them! xmetman
  13. Hi I've spent the last couple of days wracked in pain from my first (and hopefully last) attack of shingles whilst writing an application to total rainfall up for this winter for the UK from the SYNOP observations that I download from FSU. As well as a tabulated/ranked list of the accumulations, which Capel Curig is currently top of, there are a couple of plotted UK maps which I didn't contour, although its easy to see the wet spots. Hopefully I've got my logic right, and these totals that I've grabbed from the 0600 & 1800 UTC SYNOP observations are correct! As far as I can see, it maybe that after today's rainfall, Haytor will beat Shap to 1000 mm, and be the wettest place at least in England, so far this winter. xmetman
  14. Hi Here's a link to a map of estimated rainfall accumulation for the period 0000-1030 UTC for today over southern England on my blog: xmetman In Mid-Devon we had 6 mm which is slightly over what the 15 minute radar produced. Obviously the more frequent the image the better the estimate and for this part of Devon it should be close. Highest totals are in SW Wales and the Brecon Beacons with total in excess of 40 mm. I notice that the upper catchment area of the Thames around Cirencester have received an estimated ~8-10 mm. The map shows a noticeable rain shadow to the lee of Dartmoor with the area around Okehampton having less than 2 mm. It would be interesting to know just how accurate my estimate is? Now if only the UKMO (and why not the EA) made their hourly SREW rainfall data that they gather from their automatic rain gauges public! Which in the current climate (excuse the pun) would be a very sensible idea. Of course that'll never happen, with both organisations jealously guarding whats left of their monopoly on rain. I notice that there is already a request (by MeteoGroup) for SREW data which they made last year languishing on the data.gov site: Bruce.
  15. Hi After such a wet month as January 2014, I decided to look at what evidence there was for an increase in incidence of extreme rainfall events across the United Kingdom. The best way to do this as far as I can see is to use the daily records that make up the UKP datasets and which are maintained and made freely available by the Met Office. They split the country up into nine sub-regions and provide daily values back to 1931 for each. On top of this they have 3 sets of composite regional values for Scotland, Northern Ireland and England Wales as well. The report contains graphs with an annual count of days with more than 12.7 mm of rain, and days with more than 25.4 mm of rain from 1931-2014, with the obligatory moving average and trend for all the UKP sub-regions. (1) Central England(2) E Scotland(3) SW England & S Wales(4) NE England(5) N Scotland(6) NW England & N Wales(7) SE England( S Scotland(9) England & Wales(10)N Ireland I'll let you decide if global warming is the cause of the increase over England and Wales, and if it is, why has there been a decrease over the north of Scotland since 1931? xmetman
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