Attribution of Exceptional Mean Sea Level Pressure Anomalies South of Australia in August 2014

August 2014 saw very strong monthlypositive mean sea level pressure (MSLP) anomaliesand intense daily to multiday MSLP events south ofAustralia and in the Tasman Sea (Fig. 32.1a). To thewest of Tasmania there were monthly anomalies ofover 10 hPa (2.4 standard deviations from the mean),the highest on record since 1979 using ERA-Interimreanalysis (ERAint; Dee et al. 2011), or from 1850using the Hadley Centre Sea Level Pressure analysis(HadSLP2r; Allan and Ansell 2006). Atmosphericblocking west of Tasmania on 1015 August (Figs.32.1b,c) featured the highest daily August MSLPanomaly in either record in that location. Blockingwas seen in the south Tasman Sea later in themonth, including the highest daily MSLP anomalyon record at that location. The spatial distributionof the monthly MSLP anomalies resembles a wave-3pattern (Fig. 32.1a).