Wednesday, 5 January 2011 - Monthly Climate Summary for Tasmania - Product code IDCKGC17R0
Tasmania in December 2010: Cool with severe thunderstorms and heavy rain in the north
Severe thunderstorms were a prominent feature in December, affecting the state on several days during the first half of the month. Overall, rainfall was above average in the north and Midlands but below average in the southeast around Hobart and the Derwent Valley. Both maximum and minimum temperatures were cooler than usual in most areas, making it one of the few cooler than usual months of 2010.
- Several severe thunderstorms with flash flooding
- 86 mm in a day at Erriba
- Many cool days with some mountain snow on the 26-27th
Severe thunderstorms, mainly in the north
Several severe thunderstorms affected Tasmania during December, causing localised flash flooding. Affected areas included the southeast on the 3rd, the northeast on the 4th, the northwest around Wynyard, Preolenna and Wilmot on the 8th, the north including Launceston on the 11-12th, Scamander on the 15th and Devonport on the 17th. The worst reported damage occurred in Devonport on the 17th, with several businesses and roads affected.
Wet in the north, dry in the southeast
Troughs, low pressure systems, thunderstorms and fronts all contributed to a very wet December in the north. Most northern sites had over 100 mm, and inland areas between Sheffield and Scottsdale had at least double their normal December rainfall. Barrington, with 177 mm, had its wettest December on record and a few other sites, including Launceston, had their wettest December for at least 20 years. The Midlands and parts of the east were also wetter than usual, having been affected by thunderstorms on the 3rd and 20th, but only a fraction of this rain managed to reach the south. Consequently, December was drier than usual in most of the south and especially in the southeast around Hobart and the Derwent Valley. The driest site for the month was Hermitage with 21.6 mm.
The heaviest rainfall occurred on the 7-8th as a trough crossed the state. Erriba had 86 mm in one day, followed by Mole Creek with 58 mm. This rain caused flooding of the Meander, Mersey, Forth and Macquarie river basins. Despite the heavy rain in the north, Mount Read was still the wettest site with 294 mm. Erriba and Mount Barrow were not far behind, with totals of 239 mm and 227 mm respectively.
A cool start to summer
Summer had a slow start with many December days recording much cooler than usual temperatures. Averaged over the month, maximum temperatures were around a degree cooler than usual, and near two degrees cooler than usual at some sites in the Midlands. There were many cool to cold days between the 5th and 27th. Of note were the 5th, 10th, 21st and 26-27th, when temperatures struggled to reach 20 °C. There was even some mountain snow in the south just after Christmas. The coldest day was 2.9 °C at Mount Wellington on the 21st.
There were a few exceptions to the cool conditions: temperatures reached the high 20s in the north on the 4th and in the southeast on the 8th and 31st. It was also warm in the west for the first 9 days of the month as easterly winds blew over the state. The hottest day was 29.4 °C at St Helens on the 4th. On the same day Wynyard reached 28.8 °C, its highest December temperature since 1998.
Nights: warm at the start, then cool
From the 1st to the 10th nights were warmer than usual as moist air from the Tasman Sea was directed over Tasmania much of the time, restricting overnight cooling. The 3rd, 4th and 8th were especially warm, with extensive fog that persisted into the afternoon in some areas. Strahan had the warmest night, not falling below 20.7 °C on the 8th, the warmest night there since 1983. Launceston had 2 nights over 17 °C and Hobart had 4 nights over 15 °C.
the easterly pattern was replaced by westerlies with several cold
fronts crossing the state. Northerly winds on the 15th kept overnight
temperatures warm, but otherwise nights were generally cool,
particularly on the 13th, 16th, 22nd, 24th and 27-28th. Mount
Wellington fell to -3.3 °C on the 27th as snow fell on the
mountain. On the same morning Cape Grim had its lowest December temperature on record, falling to 6.9 °C.
Averaged over the month, minimum temperatures were generally slightly warmer than usual in the west and slightly cooler than usual elsewhere.
|Extremes in December 2010|
29.4 °C at St Helens Aerodrome on the 4th|
|Warmest days on average||
21.4 °C at Ouse Fire Station|
|Coolest days on average||10.2 °C at Mount Wellington|
2.9 °C at Mount Wellington on the 21st|
-3.3 °C at Mount Wellington on the 27th|
|Coolest nights on average||
2.1 °C at Mount Wellington|
|Warmest nights on average||
12.9 °C at Hogan Island|
20.7 °C at Strahan Aerodrome on the 8th|
|Warmest on average overall||16.4 °C at Flinders Island Airport|
|Coolest on average overall||6.1 °C at Mount Wellington|
|Wettest overall||294.2 mm at Mount Read|
21.6 mm at Hermitage (Shannon River)|
86.2 mm at Erriba (Jubb Road) on the 8th|
|Highest wind gust||
157 km/h at Maatsuyker Island Lighthouse on the 10th|
Click on a map to show it full size in a pop-up window
|Record highest total December rainfall|
for December 2010 (mm)
|Macquarie Island||142.2||123.1||in 1951||63||78.3|
|Barrington Post Office||177.2||169.4||in 1993||44||72.3|
|Highest total December rainfall for at least 20 years|
for December 2010 (mm)
Most recent December
at least this wet
|Mole Creek||173.0||173.9||in 1973||37||68.5|
|Launceston (Ti Tree Bend)||91.4||145.1||in 1985||25||47.0|
|Record lowest December temperature|
in December 2010 (°C)
|Cape Grim BAPS (Comparison)||6.9||on the 27th||7.0||on the 6th in 2002||20||11.8|
|Summary statistics for December 2010|
|Northern (district 91)|
|Bridport (Sea View Villas)||19.3||-0.8||24.2||4th||10.7||-0.4||4.5||28th||62.5||44.4||average||141%|
|Burnie (Round Hill)||18.7||-0.7||22.6||30th||10.9||-0.2||6.0||27th||125.2||63.8||v high||196%|
|Cape Grim BAPS (Comparison)||17.0||-0.2||21.2||3rd||11.5||-0.3||6.9||27th||60.2||46.3||high||130%|
|Cressy Research Station||20.4||-2.4||29.2||4th||8.2||-0.2||-0.5||28th||91.4||46.8||high||195%|
|Launceston (Ti Tree Bend)||21.2||-1.2||27.3||4th||10.7||+0.1||3.7||28th||91.4||47.0||v high||194%|
|Luncheon Hill (Forestry)||17.3||-1.2||26.2||4th||8.7||+0.2||2.8||27th||126.4||95.6||high||132%|
|Scottsdale (West Minstone Road)||19.5||-1.3||27.0||4th||8.7||-0.5||2.8||28th||82.6||67.6||high||122%|
|Sheffield School Farm||18.2||-1.3||26.0||4th||8.0||-0.9||2.8||27th||193.0||69.9||v high||276%|
|Wynyard Airport||19.1||-0.4||28.8||4th||9.3||-0.2||3.9||28th||138.4||65.2||v high||212%|
|East Coast (district 92)|
|Bicheno (Council Depot)||19.1||-0.9||25.1||29th||11.6||+0.1||5.5||28th||60.1||68.5||average||88%|
|Fingal (Legge Street)||19.3||-2.2||27.0||4th||8.2||-0.4||0.3||28th||92.6||50.0||high||185%|
|Lake Leake (Elizabeth River)||16.3||-1.3||23.2||31st||6.7||-0.2||0.3||28th||89.0||73.1||high||122%|
|Maria Island (Point Lesueur)||18.5||24.3||4th||11.6||7.2||27th||59.4|
|Orford (Aubin Court)||19.3||-1.1||26.2||4th||10.6||+0.1||5.3||27th||58.8||64.0||average||92%|
|St Helens Aerodrome||20.2||29.4||4th||11.3||5.3||28th||64.0||49.8||high||129%|
|Swansea Post Office||19.8||-0.9||26.0||29th||10.1||-0.4||2.0||28th||59.4||59.9||average||99%|
|Midlands (district 93)|
|Ross (The Boulevards)||20.8||-1.8||27.2||4th||8.4||-0.1||0.0||28th||77.4||40.4||high||192%|
|Southeast (district 94)|
|Cape Bruny (Cape Bruny)||18.2||0.0||25.2||8th||10.4||-0.2||5.0||27th||64.4||59.7||average||108%|
|Cape Bruny Lighthouse||17.4||+0.4||24.5||8th||10.6||+0.3||5.0||22nd||83.4||76.7||average||109%|
|Geeveston (Cemetery Road)||19.3||-0.6||27.4||8th||8.9||+0.3||3.4||27th||60.2||71.4||average||84%|
|Grove (Research Station)||19.5||26.3||8th||8.3||2.9||28th||62.2|
|Hobart (Ellerslie Road)||20.3||0.0||26.2||8th||11.2||+0.4||6.4||27th||31.0||56.7||low||55%|
|Maatsuyker Island Lighthouse||15.9||+0.2||26.6||8th||9.8||+0.2||5.5||27th||112.2||90.5||high||124%|
|Melton Mowbray (North Stockman)||19.9||-1.9||28.7||31st||8.7||-0.2||3.6||27th||27.8||37.2||average||75%|
|Tunnack Fire Station||17.6||-2.0||23.4||8th||7.1||-0.3||1.6||27th||90.8||53.8||v high||169%|
|Derwent Valley (district 95)|
|Bushy Park (Bushy Park Estates)||21.2||-0.8||27.5||31st||8.9||-0.2||3.0||16th||40.2||50.6||average||79%|
|Maydena Post Office||18.3||-1.4||25.6||31st||8.1||+0.7||2.5||27th||106.9||89.6||high||119%|
|Ouse Fire Station||21.4||-1.6||28.4||31st||8.6||0.0||2.5||27th||29.0||35.1||average||83%|
|Central Plateau (district 96)|
|Lake St Clair National Park||16.2||-1.0||26.0||31st||5.5||+0.5||-0.2||31st||143.6||134.1||average||107%|
|West Coast (district 97)|
|Hartz Mountain (Keoghs Pimple)||13.4||-1.4||20.8||31st||4.3||-0.8||-1.1||27th||68.0||80.1||low||85%|
|Scotts Peak Dam||18.1||-0.2||28.0||2nd||7.5||-0.4||1.5||27th||171.8||155.5||high||110%|
|King Island (district 98)|
|King Island Airport||18.8||+0.2||27.6||31st||11.3||+0.4||5.8||30th||57.0||50.9||average||112%|
|Flinders Island (district 99)|
|Flinders Island Airport||20.3||+0.2||28.6||31st||12.6||+0.8||4.5||31st||68.4||58.3||high||117%|
|Antarctica and Macquarie Island (district 300)|
A Monthly Climate Summary is prepared to list the main features of the weather in Tasmania using the most timely and accurate information available on the date of publication; it will generally not be updated. Later information, including data that has had greater opportunity for quality control, will be presented in the Monthly Weather Review, usually published in the fourth week of the month.
This statement has been prepared based on information available at 9 am on Wednesday 5 January 2011. Some checks have been made on the data, but it is possible that results will change as new information becomes available.
Averages are long-term means based on observations from
all available years of record, which vary widely from site to site.
They are not shown for sites with less than 10 years of record, as they cannot then be calculated reliably.
The median is sometimes more representative than the mean of long-term average rain.
The Rank indicates how rainfall this time compares with the climate record for the site,
based on the
(very low rainfall is in decile 1, low in decile 2 or 3,
average in decile 4 to 7, high in decile 8 or 9
and very high is in decile 10).
The Fraction of average shows how much rain has fallen this time as a percentage of the long-term mean.