Severe thunderstorms occurred over eastern Scotland on 14 August 2025, leading to impacts from flash flooding, lightning strikes and notable damage from hail up to 5cm in diameter. Hail of this size is rare in Scotland, especially north of the Central Belt. Given the marginally favourable pre-convective environment, it is hypothesised that a cell merger event, combined with locally enhanced ascent around complex terrain, contributed towards the very large hail observed. This article examines the environment and evolution on the day, summarises the reported impacts, and provides some historical context.

WeatherVolume 79, Issue 8 p. 260-260 Weather images Weather images Dan Holley, Dan Holley orcid.org/0009-0008-6110-2162 Search for more papers by this authorGemma Plumb, Gemma PlumbSearch for more papers by this author Dan Holley, Dan Holley orcid.org/0009-0008-6110-2162 Search for more papers by this authorGemma Plumb, Gemma PlumbSearch for more papers by this author First published: 02 August 2024 https://doi.org/10.1002/wea.7601Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume79, Issue8August 2024Pages 260-260 RelatedInformation

On Saturday 2 December 2023, a persistent stream of snow showers affected south Cumbria through much of the day and into the following night, originating from the Irish Sea. As much as 30-40cm of snow accumulated in parts of the South Lakes, unprecedented in modern records according to local long-standing weather observers, and resulted in significant transport and power disruption. This short article examines the meteorological setup responsible and briefly highlights some of the challenges in forecasting snow accumulations from maritime convection.image

Around midnight on 1/2 November 2023, Jersey (Channel Islands) was impacted by a supercell storm which produced both a tornado, rated T6/IF3, and very large hail. This article presents details of that remarkable hailstorm and places it into context by investigating severe hail events during the October-March cool season in the UK and Crown Dependencies of Jersey, Guernsey, and the Isle of Man. The storm is compared to previous 'dual-hazard' events during the cool season, where both a tornado and severe hail were produced.

During a lengthy cold spell that affected the United Kingdom in December 2022, two significant snowfall events occurred over the Cotswolds and Home Counties, leading to some disruption. This short article provides a summary of the events and analyses the meteorological setup responsible using a variety of observations.

Long, narrow filaments of intense water vapour transport, known as atmospheric rivers, dominate the poleward transport of water vapour in the mid-latitudes (Nash et al., 2018). Although perhaps more well-known for their role in extreme precipitation along the west coast of North America, atmospheric rivers are also a key driver of high precipitation events in western Europe (Lavers and Villarini, 2015). They are typically associated with the warm conveyor belts of mid-latitude cyclones and the advection of moisture northeastwards from the North Atlantic Ocean (Lavers and Villarini, 2015; Dacre et al., 2019). Following heavy rainfall at the start of the month, during 6–8 October 2023 a prolonged quasi-stationary frontal rainfall event led to widespread flooding across the Central Belt and Highlands of Scotland. The event was associated with an atmospheric river that had originated over the subtropical North Atlantic Ocean a few days earlier (Figure 1), confirmed by air mass back-trajectories (not shown). Initial data from the Scottish Environmental Protection Agency reveal that a wide area received at least 75mm of rainfall over 48h (Figure 2), with upwards of 170mm measured in the wettest areas. Impacts included widespread fluvial flooding with one fatality, major landslides on principal routes (e.g. all main roads into Argyll and Bute were cut off for some time) and the complete curtailment of rail services into Scotland. Scottish farmers stated that they suffered some of the biggest losses in food crops that the industry has ever seen.1 The synoptic meteorological situation of the event was unusual and unlike those of previous widespread flood events over recent decades in Scotland. Typically, such events are associated with extreme orographic enhancement of precipitation in warm sectors of extratropical cyclones, such as occurred in December 1994 (Eden, 1995) and in Storms Desmond and Frank during the winter of 2015–2016 (Barker et al., 2016; Otto et al., 2018), or in conjunction with the additional effect of rapid snowmelt which led to the Tay flood of January 1993 (e.g. McCallum and Grahame, 1993; McEwen, 2006). On this occasion, however, the polar front lay quasi-stationary through a slack trough positioned across southern Scotland (see Weather log charts for 6–8 October 2023, this issue). With the continuous advection of an extremely humid air mass on its equatorward flank from west to east, total column integrated water vapour exceeded 40mm (Figure 3), exceptional for the location and time of year.2 In addition, surface air pressure values were unnoteworthy during the event, rising from 1012 to 1016hPa on 6–7 October to 1020–1024hPa by midday on 8 October across the affected area (Figure 1). The relatively weak pressure gradient on 7–8 October and resulting slack surface winds meant orographic enhancement of the precipitation was especially limited, amounting to less than a factor of two in the worst affected areas, unusual for the Highlands. What was noteworthy, however, was the temperature and humidity contrast across the front. The mean 24-h dewpoint on 7 October exceeded 15°C at both Carlisle and Keswick (Cumbria), whereas on Shetland that evening the dewpoint fell below freezing in a northeasterly airflow with cyclonic curvature (with an overnight minimum of −1.9°C at Baltasound). Additionally, at mid-levels on the equatorward (warm) side of the front, a moderate west-southwesterly jet with anticyclonic curvature persisted, with a maximum speed of 40ms−1 at 600hPa located just above the zone of greatest horizontal water vapour flux, near 700hPa (~3km) (Figure 4). We therefore postulate that isentropic ascent of this very warm and moist airflow at the frontal boundary, combined with mid-level jet and enhanced by a cold northeasterly undercut due to the building high pressure, led to strong warm frontogenesis producing steady precipitation, which remained anchored over the same area. This configuration differs from the schematic and conceptual picture of atmospheric rivers presented by Ralph et al. (2018), where the low-level jet is located at 900hPa (~1km) on the warm side of the front (compare their schematic figure with Figure 4) and of most low-level pre-frontal jets and conveyor belts in the UK (Browning, 1980). Finally, Figure 5 shows a height-time radar reflectivity (dBZ) plot from the morning of 7 October 2023 from LERADAR (Kidd et al., 2021; Graham et al., 2022), a vertically oriented 24GHz microwave radiometer based in Stornoway in northern Scotland. It lay within the cold northeasterly undercut of the polar front, but was intercepting precipitation from the warm, moist air riding up the frontal surface from the southwest. The marked shear between the upper west-southwesterlies and the lower northeasterlies can be seen in the trajectories of the falling hydrometeors. A prominent change in the angle of shear of the hydrometeors occurs at the bright band or melting level (initially 1400m, decreasing to 1100m, seen from right to left in Figure 4), as the gently falling ice crystals or snowflakes (terminal velocity ~2ms−1) melt into much faster falling large raindrops (terminal velocity ~6ms−1). Extreme precipitation events such as highlighted case can be expected to increase in severity in a warmer climate (Myhre et al., 2019). It is worth noting that antecedent sea-surface temperatures, over both a large extent of the North Atlantic Ocean and in the immediate vicinity of western Scotland, were at record-high levels during summer and early autumn of 2023 (see McCarthy et al., 2023). This flooding event also followed the most anomalously warm month on record for the global-mean temperature (Rohde, 2023). In addition, Kahraman et al. (2021) found that a reduction in translatory velocity of storm systems, leading to them becoming quasi-stationary, could enhance event accumulations and flood risk beyond expectations from studies focusing on precipitation rate alone. None. We would like to thank both Matt Priestley and Richard Dixon for helpful comments which improved this manuscript. We also thank Chris Kidd (NASA GSFC/University of Maryland) for the template used in Figure 5.

A quasi-stationary multicell thunderstorm affected parts of mid-Suffolk on Sunday 25 July 2021. The epicentre was the village of Brettenham, where extreme rainfall resulted in over 180mm falling in under 2 h. Local flooding occurred, including significant crop damage. The amount of rain observed in such a short duration challenges UK rainfall records. A detailed mesoanalysis is constructed to analyse the meteorological conditions present, using surface observations from a combination of conventional and privately owned automatic weather stations.

On 25 July 2021, a violent storm took place over parts of East Anglia, UK. The highest measured rainfall was 181mm in about 1.75h. Rapid rises in river flow took place and homes were flooded. This storm exceeded the generally accepted probable maximum precipitation (PMP) for this area of 164mm. The highest official rainfall was 80mm showing the value of unofficial rain gauges. These results have significant implications for PMP in East Anglia and elsewhere in the UK.

WeatherEarly View Short Article Crowd sourcing snow depth measurements – a case study during the easterly outbreak of February 2021 Dan Holley, Corresponding Author dan.holley@weatherquest.co.uk Weatherquest Ltd, The Enterprise Centre, University of East Anglia, Norwich Research Park, Norwich, UK *Correspondence to: D. Holley dan.holley@weatherquest.co.ukSearch for more papers by this authorIan Gooch, Weatherquest Ltd, The Enterprise Centre, University of East Anglia, Norwich Research Park, Norwich, UKSearch for more papers by this authorChris Bell, Weatherquest Ltd, The Enterprise Centre, University of East Anglia, Norwich Research Park, Norwich, UKSearch for more papers by this author Dan Holley, Corresponding Author dan.holley@weatherquest.co.uk Weatherquest Ltd, The Enterprise Centre, University of East Anglia, Norwich Research Park, Norwich, UK *Correspondence to: D. Holley dan.holley@weatherquest.co.ukSearch for more papers by this authorIan Gooch, Weatherquest Ltd, The Enterprise Centre, University of East Anglia, Norwich Research Park, Norwich, UKSearch for more papers by this authorChris Bell, Weatherquest Ltd, The Enterprise Centre, University of East Anglia, Norwich Research Park, Norwich, UKSearch for more papers by this author First published: 12 April 2021 https://doi.org/10.1002/wea.3974Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat Abstract Weatherquest have developed an online tool (www.weatherquest.co.uk/snowdepth) allowing members of the public to submit snow depth measurements at their location, at any time. This paper explores the potential benefits of combining user-submitted snow depth measurements with existing official reports to create a denser network of observations, including a case study focussed on East Anglia during a cold and snowy easterly outbreak in early February 2021. Early ViewOnline Version of Record before inclusion in an issue RelatedInformation

During the morning of Sunday 31 October 2021, damaging winds affected a corridor from Dorset through the south and east Midlands to Lincolnshire, associated with a mesolow that developed along a cold front. Hundreds of trees were damaged or blown over, bus and train services were significantly disrupted and numerous buildings were also impacted. Provisional analysis by TORRO suggests at least eight confirmed tornadoes, and an additional six probable tornadoes, occurred within the much larger field of wind damage. During the morning of Sunday 31 October 2021, damaging winds affected a corridor from Dorset through the south and east Midlands to Lincolnshire. Hundreds of trees were damaged or blown over, with numerous reports of impacts to property, especially roofs, fences and walls. Significant disruption occurred to bus and train services, particularly due to trees blocking roads and railways (BBC News, 2021a). Northamptonshire Fire and Rescue Service received more than 130 calls of incidents (BBC News, 2021b), while police in Lincolnshire received around 110 calls in 90min. In the immediate aftermath, and the days and weeks following the event, TORRO members worked closely to collate as many damage reports as possible, and carried out detailed in-person site investigations where necessary. The reports to date suggest the damage path was at least 20km wide, in some places as much as 30km, and approximately 400km in length stretching from the Dorset to Lincolnshire coasts (Figure 1). Wind observations from both Met Office sites and privately owned weather stations highlight the occurrence of widespread gusts to 50–60kn within this corridor, and in several cases in excess of 60kn. Particularly strong gusts were recorded along the south coast, with 76kn (87mph) at the Isle of Portland, but even well-inland unofficial gusts of 67kn (77mph) were reported at Netheravon Airfield and Harnham (both in Wiltshire) and 64kn (73mph) at Turweston Aerodrome (north Buckinghamshire). The most damaging winds occurred in the vicinity of a distinct 'hook' feature evident in radar imagery (Figure 2), located around the western and southern flanks of a mesolow that developed along a cold front. The centre of the mesolow appeared to make landfall on the Dorset coast around 0750 utc near Weymouth, and tracked north-eastwards while deepening with an average forward speed of approximately 26ms−1, before exiting to the North Sea around 1205 utc near Easington on the East Riding of Yorkshire coast. The mesolow was fairly compact, with 3-hour pressure falls in excess of 10hPa noted at some observation stations along its path. The overall damage swath is far wider than is typical for tornadoes in the UK, the widths of which are often less than 200m across. It is evident from the site investigations that many areas experienced straight-line winds, near and to the immediate east of the radar-observed outer hook feature (labelled 'O' in Figure 2), along the southern and south-eastern flank of the mesolow. Nonetheless, provisional analysis suggests at least eight confirmed tornadoes, with an additional six probable tornadoes, were responsible for narrow swathes of much more substantial damage, primarily located along the immediate south-western flank of the mesolow, close to the southern tip of a narrow, intense radar echo on the immediate western flank of the mesolow (labelled 'I' in Figure 2). Several of these tornadoes occurred in Oxfordshire, impacting the communities of Cassington, Church Hanborough, Eynsham, Tackley and Water Eaton. The strongest tornado, rated T4 on the International Tornado Intensity Scale with estimated wind speeds between 100–118kn (Kirk, 2014), caused substantial damage in Burleigh Wood (Figure 3). TORRO issues non-routine forecasts concerning severe convective weather 1. An outlook, including the risk of brief/weak tornadoes associated with small-scale circulations along the frontal zone, was issued in the late evening on 30 October for a large portion of the UK and Ireland covering the period of this event. More detailed analysis is still being undertaken, but so far the general evolution and damage pattern observed is similar to several past events in the United Kingdom, including two cases documented by Clark (2011) and Young and Clark (2017). In the meantime, TORRO welcome any further reports of damage for either this or other events, which can be submitted via the severe weather report page on the TORRO website 2. TORRO are very grateful to the many members of public and local residents for damage reports and aiding site investigators, including Rachel Leach and Nick Baimbridge (Blenheim Estate), Jonny Stewart (London Oxford Airport), Gary Chisholm (North Northamptonshire Council) and Maria Herlihy (Environment Agency).

The heatwave that impacted the UK in mid-July 2022 was not only remarkable for the extent and intensity of the heat, but also for how well it was forecast several weeks in advance. In this short article, we analyse the performance of the GEFS, a global numerical weather prediction model run by the US National Centers for Environmental Prediction, highlighting its ability to forecast 40°C temperatures in the UK several weeks in advance.

A multicell thunderstorm cluster affected parts of the Breckland region in south Norfolk on the afternoon of 16 August 2020, producing as much as 240mm of rain. A detailed mesoanalysis is constructed to analyse the meteorological conditions present using conventional observations, reanalysis and privately owned automatic weather station observations. While the instantaneous rain rates observed are not unprecedented, when maintained over several hours result in this event ranking as the highest August daily rainfall on record in the United Kingdom.

On Sunday 16 August 2020 a major thunderstorm occurred in south Norfolk. Over 150mm rainfall in 4h was measured over a large area, which ranks it amongst the highest historic extreme rainfalls in the United Kingdom since the start of the twentieth century. The hydrometeorology is now described. Since little damage was caused by the storm, and the official rain gauge network not dense enough for a detailed description, over 100 unofficial gauges are used to give a much better description. The importance of the event in terms of its rarity and new data for the design of hydraulic structures is described.

An area of low pressure over the southern North Sea, named Storm Odette by the Royal Meteorological Institute of Belgium, produced an extended period of disruptive winds, exceptional rainfall and notably low temperatures to parts of the United Kingdom between 24–26 September 2020. Several sites recorded their coldest September daily maximum temperature on record, while parts of Norfolk experienced one of the longest duration of gales to affect the area during the past 30 years. This short report explores the storm’s formation, significance and impacts, with a particular focus on eastern England.

ABSTRACTDeep moist convection (DMC) requires three ingredients: instability, moisture and lift. One measure that incorporates two of these, instability and moisture, is convective available potential energy (CAPE). A 10‐year climatology of CAPE over Great Britain is presented covering the period 1 June 2002–31 May 2012, based on a 9‐km grid spacing implementation of the Weather Research and Forecasting (WRF) model, with two‐way interactive nesting. Appropriate tests are carried out to verify model reliability by comparing simulated and observed CAPE. CAPE is found to be highly variable both spatially and temporally, the highest values being produced during Spanish plume events. A strong relationship is confirmed between surface temperature and CAPE magnitude, the highest CAPE across Great Britain during this period locally exceeding 3000 J kg−1. In an average year, 15 days produce CAPE in excess of 500 J kg−1 somewhere in Great Britain, 4 days > 1000 J kg−1 and 1 day > 1500 J kg−1. Three main CAPE seasons are identified: ‘land dominated CAPE’ between April and September, ‘sea dominated CAPE’ between September and January and ‘low CAPE’ from January to April. The southern North Sea witnesses significant CAPE all year round because of a combination of favourable synoptic situations, including warm air plumes in spring/summer and cold air incursions over warmer seas in winter. CAPE is not a direct predictor of thunderstorm incidence, due in part to the confounding effect of convective inhibition (CIN). However, at the annual scale, when comparing against an existing days of thunder climatology, we observe a close correspondence with >500 J kg−1 CAPE frequency.