A complex low-pressure system crossed Tasmania on Thursday 10 May, then deepened to the north-east the following day, bringing strong, gusty and moist southerly winds over the state.
Rain and thunderstorms brought exceptionally high rainfall to the south-east of Tasmania, in particular to Hobart and the nearby Wellington Range, where almost all recording sites reported their highest May daily rainfall on record (and in some cases their wettest day for any time of year) in the 24 hours to 9.00am on 11 May. The daily totals of 236.2 millimetres at kunanyi/Mount Wellington and 226.4 millimetres at Leslie Vale were second and third highest on the list of the top three highest May daily rainfalls ever recorded in Tasmania (behind 258 millimetres at Gray on 18 May 1986).
Much of the rain fell in about six hours on the Thursday evening, leading to flash flooding in many streams in southeast Tasmania. The very heavy rain was caused by a highly active line of thunderstorms that traversed Hobart over a number of hours, with each thunderstorm following a similar path as it moved in from the east.
Hobart recorded 128 millimetres, with a third of that falling in one hour between 10.00pm and 11.00pm on the Thursday evening. Flash flooding affected parts of Hobart’s central business district, Salamanca, South Hobart, Sandy Bay, New Town, Blackmans Bay and Kingston. The Hobart Rivulet broke its banks, and several cars in adjacent streets in South Hobart and near the Hobart waterfront were swept away.
The event had an annual exceedance probability of less than one per cent and caused extensive damage to bridges, roads, buildings and other infrastructure.
More than 13,000 homes lost electricity, more than 30 schools were closed and a few homes in Sandy Bay lost their roofs as winds lashed the city. Emergency services received hundreds of calls for assistance, with State Emergency Service crews responding to more than 280 calls. Electricity supplies were re-established to most affected suburbs by late the following day.
Evacuation centres were established at Mathers House in the city and at Kingston for people requiring shelter, information and support.
Several roads were closed in the greater Hobart region overnight due to landslips, with council crews clearing rocks and dirt from roadways. While flights continued to operate out of Hobart Airport, there were some delays as ground staff were unable to get to work.
On 14 May, the Australian Government declared the floods a disaster, enabling relief funds to be available for those affected.
The Insurance Council of Australia (ICA) declared the floods a catastrophe, ensuring that claims by those affected were given priority. By late August, ICA reported that almost 8,800 claims had been lodged, with private property claims exceeding $99.7 million and public infrastructure claims exceeding $37 million – bringing the total damage bill to more than $137 million.
Hobart City’s damage bill remained at $20 million, and Kingborough Council expected losses to exceed $2 million. The University of Tasmania’s Sandy Bay campus suffered extensive flood damage, with the damage bill estimated at $15 million.
No fatalities occurred as a result of the floods.