Characterising the variability of sting jet windstorms

Sting jet windstorms present a mesoscale phenomenon which has been documented to occur in at least some Shapiro-Keyser type extratropical cyclones. A number of studies have shown that sting jets are associated with the release of conditional symmetric instability in the cloud head of such cyclones, near the region of frontal fracture that typifies these cyclones. The general evolution of a sting jet is now well described, however questions remain regarding the variability in key characteristics of the phenomenon and indeed whether they are common in the Shapiro-Keyser class of cyclones.

Recently, other authors have documented sting jets in two cyclones that tracked across Scotland in the winter of 2011-2012; Friedhelm and Ulli. We create sting jet resolving 24 member ensemble simulations of these cyclones using the Met Office Unified Model. Initial condition perturbations are obtained from the operational global ensemble prediction system. The simulations are analysed to provide an estimation of the range of variability in sting jet characteristics including descent rate, windspeed, and possibility of multiple jets.