Two hundred years of thunderstorms in Oxford

Abstract

The long instrumental meteorological records from the Radcliffe Observatory site in Oxford (where records commenced in 1772) are well known, and have recently been documented to 2018 by Burt and Burt (2019). Less well-known, and still largely in manuscript or paper format, are the noninstrumental records also maintained by the Observatory which documented the occurrence of fog, snowfall, thunderstorms and the like. Records of thunderstorm occurrence at the Radcliffe Observatory, by date, are complete between 1828 and 1986, excluding the years 1936 to 1970 for which only monthly totals are available. Since 1986, a reliable private record of thunder frequency from Oxford, very close to the Radcliffe Observatory site, has been used to extend the record to 2019, forming a record of almost 200 years of thunderstorm frequency for the city -a record probably unique anywhere in the world. This newly digitised record, made available for the first time, is examined for long-term (decadal) trends in thunderstorm frequency, and by Lamb Weather Type. Comparisons are made with other long-period records from west London, around 75km southeast of Oxford. Reasons to account for the marked reduction in thunderstorm frequency in the last decade are suggested. Figure 2. An example of the monthly 'Characteristics' data published in the Radcliffe Results volumes. This is for August 1878, the most thundery month on the long Oxford record, when 10 days with thunder were noted. Note the differences between 'thunderstorms' and 'thunder heard' and 'lightning' (only) -only the first two are counted as a 'day with thunder heard' .

Thunderstorm tracking in Northwest Europe for enhanced hazard preparedness

“…An increase in lightning and thunderstorms activity in the British Isles and northern Europe as well as around areas of increased elevation have been modelled (Kahraman et al, 2022). Despite this predicted increase in thunderstorms and lightning, there has been an observed decline in thunderstorm days in Oxford, England (Burt, 2021) which has been successfully linked to the decline in occurrence of thunderstorm producing synoptic set ups (Lamb weather types). Understanding the distributions of thunderstorm variables by weather pattern or type may therefore provide insight into future thunderstorm behaviour where the variability of weather pattern occurrence, as a result of climate change, can be modelled.…”

Exploring relationships between weather patterns and observed lightning activity for Britain and Ireland

“…Similarly, Burt (2021) compared thunderstorm occurrence over Oxford, southern England with the Lamb (1972) circulation types and found that 53% of all thunder days were associated with cyclonic flow but without any specific wind direction. Surprisingly, the second‐highest category (9% of thunderstorm days) is associated with anticyclonic conditions, which Burt (2021) suggests could be due to local outbreaks on the edges of anticyclones. In summer, he found that unbiased south‐easterly flow and cyclonic south‐easterly flow were also strongly linked to increased thundery activity over Oxford.…”

“…They show that the weather patterns prevalent on severe hailstorm days tend to be cyclonic, with flow from the south and south-east. Similarly, Burt (2021) compared thunderstorm occurrence over Oxford, southern England with the Lamb (1972) circulation types and found that 53% of all thunder days were associated with cyclonic flow but without any specific wind direction. Surprisingly, the second-highest category (9% of thunderstorm days) is associated with anticyclonic conditions, which Burt (2021) suggests could be due to local outbreaks on the edges of anticyclones.…”