Trends in synoptic circulation and precipitation in the Snowy Mountains region, Australia, in the period 1958-2012

The hydroclimate of the Snowy Mountains, south-east Australia (SEA), is influenced by tropical and extra-tropical synoptic scale weather systems. Accordingly, it is sensitive to any changes in the mid-latitude westerly wind belt, the dominant driver of precipitation in winter, and the entrainment of moisture from tropical latitudes, particularly during the warmer months of the austral summer. The region has historically observed a cool-season (April-October) dominated precipitation regime, However, evidence is presented of a decline in precipitation during the autumn and spring transition months. Autumn precipitation is particularly important for crop sowing and agricultural production in the Murray-Darling Basin downstream of the Snowy Mountains, whilst spring precipitation influences snowmelt and water storage replenishment in the Snowy Mountains. Instead, we show a change in the annual precipitation distribution is evident with an increase in precipitation during warmer months. Trend analyses for the period 1958-2012 show a decrease in annual frequency of precipitation days capable of generating inflows to the catchments of the Snowy Mountains of -1.4 days per decade on average, whilst the precipitation they generate has increased by +5.7 mm per decade. These results align with climate change projections that precipitation events are becoming less frequent but more intense. (C) 2015 Elsevier B.V. All rights reserved.