Synoptic‐Scale Precursors of Extreme U.K. Summer 3‐Hourly Rainfall

Champion, Adrian J.; Blenkinsop, Stephen; Li, Xiaofeng; Fowler, Hayley J.

doi:10.1029/2018jd029664

Cited by 15 publications

(34 citation statements)

References 40 publications

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“…Consistent with Champion et al . (), we consider 3‐hourly aggregates of rainfall observations which are thought to relate to flash flooding to a greater extent than hourly intensities.…”

Section: Methodsmentioning

confidence: 99%

“…These events were included in the composites of Champion et al . () (their Table ). Preliminary analysis had also marked these events as suspect based on a lack of corroborating evidence from the Met Office daily weather reports and the Mogden observations during the 17:25 and 17:49 event were marked as unchecked in the raw data.…”

Section: Methodsmentioning

confidence: 99%

“…Complimenting Champion et al . (). Here we focus on synoptic precursors in the west Europe region as well as the large‐scale North Atlantic, considering additional thermodynamic variables, including evaporation and dew point temperature, which display stronger links with extreme precipitation changes than surface air temperature (Lenderink and van Meijgaard, ).…”

Section: Introductionmentioning

confidence: 97%

“…Champion et al . () characterized atmospheric conditions prior to intense sub‐daily rainfall in summer over two UK regions estimated from a compilation of quality controlled, hourly rain gauge data (Blenkinsop et al ., ). Here we investigate in more detail the regional‐scale atmospheric precursors to intense sub‐daily rainfall, extending to all UK regions and exploiting the latest, updated quality controlled rain gauge data (Blenkinsop et al ., ; Lewis et al ., ).…”

Section: Introductionmentioning

confidence: 99%

“…While Champion et al . () also considered atmospheric stability metrics (e.g., wet bulb potential temperature), which are physically linked with intense thunderstorms and mesoscale convective systems (Lewis and Gray, ), in the present study we are interested primarily in the larger scale precursors relating to atmospheric circulation patterns and moisture amount and transport.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Atmospheric precursors for intense summer rainfall over the United Kingdom

Allan

Blenkinsop

Fowler

et al. 2020

Intl Journal of Climatology

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Intense sub‐daily summer rainfall is linked to flooding impacts in the United Kingdom. Characterizing the atmospheric conditions prior to the rainfall event can improve understanding of the large‐scale mechanisms involved. The most intense sub‐daily rainfall intensity data generated from rain gauge records across the United Kingdom over the period 1979–2014 are combined with fields from the ERA Interim reanalysis to characterize atmospheric conditions prior to heavy rainfall events. The 200 most intense 3‐hourly events for six UK regions are associated with negative anomalies in sea level pressure (<−2 hPa) and 200 hPa geopotential height (<−60 m) to the west or south west of the United Kingdom 1 day earlier, with above average moisture, evaporation and dew point temperature over North West Europe. Atmospheric precursors are more intense but less coherent between regions for composites formed of the 25 heaviest rainfall events but all display substantial moisture transport from the south or south east prior to their occurrence. Composites for the heaviest events are characterized by a tripole geopotential anomaly pattern across the North Atlantic. Above average geopotential height and dew point temperature over Newfoundland and below average geopotential height but elevated evaporation in the North Atlantic are found to be weakly associated with an increased chance of the most intense sub‐daily rainfall events 5–9 days later.

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“…Consistent with Champion et al . (), we consider 3‐hourly aggregates of rainfall observations which are thought to relate to flash flooding to a greater extent than hourly intensities.…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Atmospheric precursors for intense summer rainfall over the United Kingdom

Allan

Blenkinsop

Fowler

et al. 2020

Intl Journal of Climatology

Self Cite

View full text Add to dashboard Cite

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North Atlantic air pressure and temperature conditions associated with heavy rainfall in Great Britain

Barnes

Svensson

Kjeldsen

2021

Intl Journal of Climatology

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Severe flooding in the United Kingdom is often linked to the occurrence of heavy rainfall events, which can be characterized by the synoptic scale meteorological conditions over the North Atlantic region. Seasonal heavy rainfall events (summer and winter 1-day maxima) were extracted from 125 locations across Great Britain over the period 1950-2017. For each event, anomaly sealevel pressure and 2 m air temperature conditions across the North Atlantic sector were extracted. In contrast to earlier studies, these two datasets were combined and clustered to identify how the pressure and temperature conditions co-vary within each half-year to produce heavy rainfall events. Distinctly different spatial patterns were found for four classes in summer and for three classes in winter. For all classes there is a negative sea-level pressure anomaly centred over or near the British Isles. However, whereas in summer the low pressures are associated with either predominantly cold or warm anomalies over most of the North Atlantic, in winter two phases of a smaller-scale fourpole temperature pattern emerges. Nevertheless, for one of the winter classes the cold anomaly over the northwest Atlantic is so deep, persistent and widespread that, unusually for the winter season, a significant relationship between the class's frequency of occurrence and the Atlantic Multidecadal Oscillation (AMO) index is found (r = −.39). Further, for both seasons heavy rainfall occurs when the AMO and the North Atlantic Oscillation (NAO) are in opposing phases. Particularly, positive NAO and negative AMO result in heavy rainfall in western Britain. Two classes in each season are consistent with positive and negative phases of the NAO, and the two non-NAO summer classes are associated with a northward extension of the subtropical high pressure and heavy rainfall in the southeast. The association between heavy rainfall and large-scale circulation and temperature drivers can find application in, for example, weather generators.

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Heavy versus extreme rainfall events in southeast Australia

Warren

Jakob

Hitchcock

et al. 2021

Quart J Royal Meteoro Soc

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Focussing on the major cities of Brisbane, Sydney, and Melbourne in southeast Australia, this study seeks to determine the environmental factors that distinguish between heavy rainfall events (HREs) and extreme rainfall events (EREs). Using daily rain gauge observations, HREs and EREs are defined for each domain based, respectively, on the 95th and 99th percentiles of wet‐day rainfall for the period 1979–2018. K‐means clustering is applied to mean sea‐level pressure, data from ERA5 to obtain a set of representative large‐scale circulation patterns associated with these events. Composite synoptic maps, mean vertical profiles, and a series of column‐integrated diagnostics are then examined for each cluster and used to compare the environmental characteristics of HREs and EREs. For all three cities, HREs are associated with an upper‐level trough to the west, with large‐scale ascent, positive column water vapour (CWV) anomalies, and strong moisture transport over the analysis domain. For Brisbane and Sydney, the clusters are characterised by a coastal trough/low with moist onshore flow from the Tasman and Coral Seas. For Melbourne, circulation patterns are more distinct, with clusters characterised by a front, a cut‐off low, and an inland trough. Compared with HREs, EREs show a more amplified upper‐level trough, with stronger vertical motion and larger CWV anomalies over the analysis domain. In Brisbane and Sydney, EREs also feature stronger and deeper onshore flow, promoting enhanced moisture transport. A diagnostic termed upward vapour transport, which combines the key ingredients of high CWV and large‐scale ascent, is shown to discriminate well between HREs and EREs in all three domains. In contrast, surface temperature, which is frequently linked to rainfall extremes via Clausius–Clapeyron scaling, shows significant overlap between the different event categories, particularly for Brisbane and Sydney.

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Synoptic‐Scale Precursors of Extreme U.K. Summer 3‐Hourly Rainfall

Cited by 15 publications

References 40 publications

Atmospheric precursors for intense summer rainfall over the United Kingdom

Atmospheric precursors for intense summer rainfall over the United Kingdom

North Atlantic air pressure and temperature conditions associated with heavy rainfall in Great Britain

Heavy versus extreme rainfall events in southeast Australia

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