Very cold night across much of Europe with an anticyclone of over 1050 hPa across Norway. I notice that overnight temperatures fell to a minimum of -32.5°C (-26.5°F) at Drevsjo in central Norway (WMO 01393) (fig 2). Unsurprisingly, it was also where the highest MSLP pressure was to be found (fig 3). It would be interesting to see the adjustment tables they use to calculate a QNH pressure from the station QFE for a station that’s already 674 M above sea level. Meanwhile back in good old blighty, Dunkeswell in Devon did rather well to get down to -5.0°C overnight (fig 3), to make it the fourth coldest low-level station in […]
I’ve just downloaded the latest NCEP reanalysis data and run the stats for MSLP across the world, and you can see why the first half of October 2017 has been so mobile, and relatively mild over the British Isles, by studying the latest mean pressure and anomaly chart for the North Atlantic (fig 1). The MSLP anomalies across the North of Scotland are around 6 hPa below the 1948-2014 long-term average, whilst across southern England they are 1 hPa above. In contrast a belt of higher than average pressure extends right from the western Atlantic, across America and into the central Pacific, and highlights the reasons behind the recent devastating forest […]
I don’t know if the 937.6 hpa read at Stornoway at 0020 UTC on the 20th of December 1982, was indeed the lowest minimum pressure of the 20th century recorded in the UK, but it was certainly extremely low. This is the midnight chart that I have reassembled from the old SYNOP reports (fig 1). References Burt S.D, (1982) New UK 20th Century Low Pressure extreme; Weather 38(7) pp. 209-213
The pressure has fallen surreptitiously and steadily over the last few days here in the southwest, from around 1028 to 992 hPa without most of the population probably even noticing, unless of course they still have a hall barometer that they tap before going out to work, but that’s my very old-fashioned 1950’s suburban view of the world, that’s all but gone in these days of smartphones and tablets. That fall of pressure and the recent dry spell, got me thinking about the obvious close correlation that exists between air pressure and precipitation, so I thought that I would overly the pressure and precipitation in a single graph, and […]
You may wonder why I can produce a fairly accurate barograph for the last seven months for some obscure farm in the heart of rural Shropshire. The reason why I can is that the six-hour reanalysis MSLP data that I download from the NOAA 20th century reanalysis project is based on a 2.5° x 2.5° grid, and Stockings farm is little more than a few hundred yards from latitude 52.5° north and longitude 2.5° west (fig 1). The barograph (fig 2) shows the anticyclonic nature of last Autumn and Winter, the pink vertical bars are the five named storms that occurred during that period. I thought that I’d made a […]
I’ve just been looking at the mean pressure chart for April 2017, and it was certainly an anticyclonic month with a large +12 hPa anomaly to the west of Ireland which produced a sizeable 1025 hPa anticyclone at 50°N 12°W, and a northwesterly flow across the British Isles. This made April 2017 a very dry and rather mild month across the British Isles, which although cloudy in the far west, was rather sunnier than average elsewhere. April 2017 does look to have a fairly strong resemblance to the April’s of 1967, 1980, 1982, 1995, 2015 and 1997.
There’s no doubt about it April 1938 was quite an extraordinary month across the British Isles. Not only was it the most anticyclonic April on record, it was also the most anticyclonic* of any month in the objective LWT series that started in 1871 (fig 4). Mean anomalies for the month were in excess of +16 hPa above the 1918-1947 long-term average across northwest Ireland (fig 2 & 3), and according to the MWR for the month : Mean pressure markedly exceeded the average throughout the British Isles, the excess at 7h. ranging from 10.6 mb. at Lerwick to 16.7 mb. at Malin Head. The mean pressure over Scotland […]
Just a quick look at the latest pressure anomalies across our part of the northern hemisphere so far this month. The intense Scandinavian anticyclone that persisted for much of the month until recent days, has left a massive positive anomaly (+19) over Norway, this combined with a belt of lower anomalies (-8) stretching from the eastern central Atlantic to southeast Greenland (fig 1), have resulted in a mean south or southeasterly flow across western Europe (fig 2) for the first 16 days of February 2017. This has given us a rather mild and relatively dry February so far.
I got a little fed up with hearing every BBC weather presenter churn out the phrase “this are of low pressure is very unusual for the time of year” and decided to investigate the truth of the matter. Of course, it all depends on what you term “unusual”, I know personally that as I get older how easy it is to forget past events, and that the low now tracking into Ireland might not be that unusual at all, and that’s when gridded MSLP data and weather statistics drawn from that data come into their own. I’ve used the NCEP reanalysis six hourly MSLP data back to 1948 to […]