A high‐resolution version of the WRF (Weather Research and Forecasting) model has been used to study the fine structure of a cloud head and its associated cold conveyor belt jet (CJ) and sting jet (SJ) in an intense extratropical cyclone that produced damaging surface winds in northern Ireland and central Scotland on 3 January 2012. The model was run with many different initialisation times and physical parametrisations, and a run was selected that verified well against a variety of observations. New methods have been devised to visualise the 3D structure of the CJ and SJ and to attribute strong surface winds to one or other of them, and the validity of regarding the SJ as a semi‐Lagrangian feature has been assessed. The model suggests that, whereas the CJ remained mainly below the 850 hPa level as it circulated around the bent‐back front, the SJ consisted of a stream or streams of air within the bent‐back frontal zone that first ascended from close to the surface into the middle and upper‐level parts of the cloud head before descending from evaporating cloud filaments at the tip of the cloud head and reaching the top of the boundary layer slightly ahead of the CJ. The simulations did not support the idea that either the evaporation or conditional symmetric instability (CSI) played a major role in the development of these jets. The strong gusts (up to 47 m s−1) which were recorded on the north coast of Ireland appear to have been due mainly to the CJ, which by then was undercutting the SJ. The SJ was responsible for stronger surface winds than the CJ several hours earlier during the initial stage of frontal fracture, but only for a limited period.

The most damaging winds in a severe extratropical cyclone often occur just ahead of the evaporating ends of cloud filaments emanating from the so‐called cloud head. These winds are associated with low‐level jets (LLJs), sometimes occurring just above the boundary layer. The question then arises as to how the high momentum is transferred to the surface. An opportunity to address this question arose when the severe ‘St Jude's Day’ windstorm travelled across southern England on 28 October 2013. We have carried out a mesoanalysis of a network of 1 min resolution automatic weather stations and high‐resolution Doppler radar scans from the sensitive S‐band Chilbolton Advanced Meteorological Radar (CAMRa), along with satellite and radar network imagery and numerical weather prediction products. We show that, although the damaging winds occurred in a relatively dry region of the cyclone, there was evidence within the LLJ of abundant precipitation residues from shallow convective clouds that were evaporating in a localized region of descent. We find that pockets of high momentum were transported towards the surface by the few remaining actively precipitating convective clouds within the LLJ and also by precipitation‐free convection in the boundary layer that was able to entrain evaporatively cooled air from the LLJ. The boundary‐layer convection was organized in along‐wind rolls separated by 500 to about 3000 m, the spacing varying according to the vertical extent of the convection. The spacing was greatest where the strongest winds penetrated to the surface. A run with a medium‐resolution version of the Weather Research and Forecasting (WRF) model was able to reproduce the properties of the observed LLJ. It confirmed the LLJ to be a sting jet, which descended over the leading edge of a weaker cold‐conveyor‐belt jet.

A numerical simulation of an intense, narrow cold-frontal rain band (NCFR) is presented. This front was associated with localized wind damage as it moved eastwards across the United Kingdom on 24 September 2007. The model used was the operational and research Weather Research and Forecasting-Advanced Research (WRF-ARW) mesoscale model, initialized with Global Forecast System (GFS) operational model output data. The simulation produced a front strongly resembling that seen in radar imagery and conforming to previous studies and conceptual models of the anacold front. In the simulation, a strong surface horizontal wind-speed maximum is located along the southern flank of a misocyclone; this is shown to be typical of a number that form along the front. Using trajectory analysis, descending cold air parcels, which originate in the rear inflow jet and accelerate within the circulation of the misocyclone, are identified as the origin of the strongest winds. In addition to the localized strong straight-line winds, circumstantial evidence is presented for the possible occurrence of weak tornadogenesis. The results are discussed in relation to recent studies of NCFRs, squall lines and misocyclones.

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online onlyDuring the late afternoon (local time) of 15 January 2022, the Hunga‐Tonnga Hunga‐Ha'apai islands were destroyed by a cataclysmic volcanic eruption. A sequence of images from a geostationary meteorological satellite, Himawari‐8 is presented showing the early evolution of the resulting eruption column and ash cloud. The ash‐rich umbrella cloud reached to over 30km in height and up to 400km in diameter. A smaller area of over‐shooting cloud tops appears to have reached a much higher altitude, greater than 50km, well into the upper stratosphere. The explosion also produced at least one major shock wave, evidence for which can be seen by subtracting visible channel images at 10‐minute intervals.

Storm Filomena at 1200 utc on 8 January 2021, showing a sub‐section of the WRF model domain. The model’s low centre was 998hPa at this time; schematic warm and cold surface fronts are shown conventionally. Wind speeds of over 40ms−1 at 300hPa are shaded pale red and those greater than 60ms−1 at 200hPa are shaded pale blue. The flow vectors depict the ageostrophic wind and the bold contour shows divergence equal to 4 × 10−5s−1, both at 300hPa. The axis of the cross‐section shown in Figure 2 is marked by the dashed line and the approximate location of Madrid by ‘M’.

Three‐dimensional view of snow streamers producing heavy snowfall over southern England obtained from a T + 6h mesoscale model forecast valid at 1200 utc, 1 February 2019, showing a sub‐set of the computational domain 4km high and approximately 240 × 240km as viewed from the west. The 3D isosurface depicts a model reflectivity of 23dBZ, corresponding to a moderate snowfall intensity and has been shaded according to vertical air velocity according to the colour scale. Note the cellular and sloping nature of the streamers within the snow bands and the strong positive vertical velocities consistent with the presence of shallow ‘generating’ cells of upright convection at their top.

Integrated water vapour transport (IVT) from 1000 to 300hPa in the North Atlantic region 1200 utc 21 September 2021 obtained from a Weather Research and Forecasting (WRF) model run initialised with Global Forecast System (GFS) operational analysis data showing an ‘atmospheric river’ associated with an explosively deepening cyclone which produced extreme winds over Iceland.