1. The Australian Summer of 2009-2010 Nicholas Klingaman Tropical Cyclone Ului (tracking west) Tropical Cyclone Tomas (tracking east) MODIS Image on 16 March 2010

2. Temperature and Rainfall Anomaly in DJF-mean maximum temperature (1961-1990 climatology) Decile of DJF-mean maximum temperature (based on 1950-2009) Warmest summer on record in Western Australia (since 1950) Second- warmest summer in Tasmania

3. Temperature and Rainfall Total rainfall in DJF Percentage anomaly in DJF rainfall (based on 1900-2009 climatology) Summer is the dry season in SW Australia, so discount dry anomalies here. Exceptionally wet across most of eastern Australia, including drought-stricken Murray-Darling Basin.

4. An uncharacteristic response to El Nino? Niño 4 and rainfall for December Niño 4 and rainfall for January Niño 4 and rainfall for February Instantaneous correlation between monthly means of Niño 4 and SILO (gauge-based) rainfall for 1900-2008. Red (blue) indices dry (wet) during El Niño.

5. Tropical Cyclone Olga Tropical Cyclone Olga wound its way across northern Queensland in late January, bringing 200-300 mm of rain to nearly all of the state. Note that the DJF total anomaly across Queensland is approximately 200 mm. There are typically 0-3 tropical cyclones in Queensland each summer, but landfalling cyclones are approximately 3x more frequent during La Niña than during El Niño.

6. Climatological DJF 850 hPa wind (NCEP/NCAR) Anomalous DJF 850 hPa wind (NCEP/NCAR) Note the stronger westerlies south of Australia and stronger sub-tropical easterlies, associated with Tasman Sea blocking. 850 hPa wind

7. Note higher pressures in Tasman Sea between Australia and New Zealand, as well as southward shift of Southern Ocean storm track. This is consistent with blocking in the Tasman Sea, leading to dry and warm conditions over Tasmania and more cyclones penetrating into the interior of New South Wales and Queensland. Mean sea-level pressure

8. High pressure over southwest Australia, combined with stronger easterlies bringing warm air from interior, has led to heatwaves in Western Australia. 500 hPa Geopotential Height

9. Tropical Cyclone Ului 9-21 March Dots every six hours Intensified from Tropical Storm to Category 5 hurricane in ~24 hours: 980 hPa to 918 hPa (central pressure) 65 mph to 160 mph (sustained wind) Category 1 at landfall in Queensland. Tropical Cyclone Ului

10. Accumulated rainfall (mm) from TRMM over 15- 22 March.