Friday, 1 June 2012 - Monthly Climate Summary for Tasmania - Product code IDCKGC17R0

Tasmania in May 2012: Wet with two bursts of heavy rain

May was wetter than usual across almost all of Tasmania after two bursts of heavy rain and several cold fronts. Some areas, mainly in the east and on King Island, had their wettest May on record or their wettest May in more than 20 years. Days were cool while nights were mostly mild. 

• 67 mm in an hour at St Helens
• Wettest May day on record for a number of sites
• No extremely cold nights
• Hobart's wettest May since 1986

Extremes Maps Records Summaries Important notes the top

Low pressure systems bring heavy rain

Two complex areas of low pressure moved near Tasmania during May bringing locally heavy rainfalls. The first persisted near the state from late on the 1st until the 5th with the heaviest rain falling on King Island during the afternoon of the 3rd and overnight. Daily totals reached nearly 100 mm in eastern parts of King Island, giving City of Melbourne Bay (97.6 mm), Naracoopa (88.8 mm) and Surprise Bay (52.0 mm) their wettest May day on record. Heavy rain also affected eastern Tasmania with most areas recording 30 to 50 mm and locally heavier falls near the coast. The highest totals were around Bicheno and Swansea with 108 mm falling at Friendly Beaches during the whole event. Woodbridge's 57.6 mm on the 4th was its highest May daily rainfall on record.

Further heavy rain affected Tasmania on the 25th and 26th with widespread totals of 50 to 100 mm in the east. Again, some sites had their highest May daily rainfall total on record with daily totals reaching up to 103 mm at Nugent. Thunderstorms in the northeast during the afternoon of the 25th brought some very intense rainfall; St Helens Aerodrome received 67 mm in just one hour, an intensity expected less than once in 100 years. The rain caused flash flooding along with moderate flooding in the Macquarie River and minor flooding in the South Esk River.

Wet overall

Heavy rainfall around the 3rd and 25th combined with rain from a number of cold fronts during the month to ensure May was wetter than usual across almost all of Tasmania. Several sites, mostly in the east, had their wettest May on record or their wettest May for many years. The highest rainfall total was 426 mm at Mount Read, although the true total was probably higher as it is likely some snow was lost. 

Only a few areas had less than 100 mm, mainly in the Central North, Fingal Valley and Derwent Valley. Flinders Island Airport was by far the driest site, with a total of 33.6 mm. Fingal was the second driest site with 55.0 mm.

Cool days and mild nights

Average daytime temperatures in May were generally near average in coastal areas and below average inland. The 1st and 9th were the only days that reached over 20 °C, peaking at 22.3 °C at Scamander on the 1st. In contrast, temperatures struggled to reach the low teens between the 11th and 13th in a cold southerly airflow with widespread showers and snow to 600 metres behind a cold front. The 12th was especially cold: Mount Wellington only reached -1.8 °C, the coldest day of the month, and a number of sites had their coldest May day in 12 years.

Overall, minimum temperatures for May were near average in the north and one to two degrees warmer than usual in the south. The 2nd, 9th and 22nd were particularly warm for this time of the year with many areas not dropping below 10 °C. Nights were cool between the 12th and 14th, coinciding with the chilly days behind a cold front that crossed the state on the 11th, but many sites in the north and east were colder on the 20th or 29th when winds were light and skies were clear. There were no extremely cold nights; the coldest temperature was -4.0 °C at Fingal on the 29th. May temperatures in Tasmania often drop much lower than this.

Hobart: wettest May since 1986

Hobart was much wetter than usual during May with a total of 92.2 mm, double the long-term average. This made it Hobart's wettest May since 1986, and the tenth wettest May on record. Most of the rain fell in two periods: firstly between the 2nd and 4th and then again from the 23rd to the 26th. Daily totals reached 23.6 mm on the 3rd and 34.6 mm on the 26th; the latter was Hobart's wettest day in over a year.

Though Hobart's average minimum temperature of 8.1 °C was only about a degree warmer than usual, the lack of cold nights was remarkable. A typical May in Hobart has seven nights below 5 °C; this month the lowest temperature was 5.2 °C on the 12th. Since records began 130 years ago, 1988 was the only year there wasn't a May temperature below 5.2 °C. The warmest night was 12.4 °C on the 22nd.

Maximum temperatures in Hobart ranged from 10.7 °C on the 12th to 20.4 °C on the 1st. There were several days below 13 °C, but the average maximum of 15.4 °C was still a degree warmer than usual. 

* The true total at Mount Read is probably higher, as it is likely some snow was lost.

Extremes Maps Records Summaries Important notes the top

Maps
	Observed	Anomaly	Decile rank
Total rainfall
Mean daily maximum temperatures
Mean daily minimum temperatures

Click on a map to show it full size in a pop-up window

* note: there are gaps in the historical record at this site, so it is possible a higher value has gone unreported.

Extremes Maps Records Summaries Important notes the top

Extremes Maps Records Summaries Important notes the top