The National Climate and Water Briefing

March 2012

Lake Eyre - © Pete Dobre Agenda

• Climate conditions and outlook • Questions • Hydrological conditions and outlook • Questions • Lunch

Lake Eyre - © Pete Dobre Climate conditions and outlook

Dr Andrew Watkins Manager Climate Prediction Services

Lake Eyre - © Pete Dobre Climate conditions and outlook

• Recent climate conditions and trends • Current and forecast state of key climate drivers • Climate outlook

Lake Eyre - © Pete Dobre Calculating deciles Historical record Sorted historical record Deciles 1 to 10

1 2 3 4 5 6 7 8 9 10

Group into tenths Sort and rank for deciles

Lake Eyre - © Pete Dobre Recent rainfall • February: Australia 12% below normal, New South Wales and Murray- Darling Basin double normal February rainfall • Summer: Murray-Darling Basin 6th highest, New South Wales 9th highest, Tasmania 26% below normal • Summer: Australia 2012 245mm vs 2011 367mm (2nd highest) • Summer: Victoria 2012 136mm vs February 2012 December 2011 – February 2012 2011 340mm (highest) Lake Eyre - © Pete Dobre Recent rainfall

February 2012 December 2011 – February 2012 December 2010 – February 2011

Lake Eyre - © Pete Dobre Maximum temperature

3rd hottest ‘summer’ • Australia: 8th coolest summer since at least 1910 • NSW: 2nd coolest summer on record – 1st was 1955/56 1.8°C above average • A very ‘La Niña’ summer… 1.3°C above average 8 ‘heatwaves’

February 2012 December 2011 – February 2012

Lake Eyre - © Pete Dobre A hot summer in Perth • Mean maximum temperature • Highest temperature was was 31.7 °C, fourth highest in 42.1 °C on 28 January a record dating from 1897 • Mean minimum temperature (1.3 °C above average) was the equal fifth warmest • Six heatwaves equalled the on record, and the highest summer record set in 1977–78 since 1991–92 • First time ever each summer month had two heatwaves

Lake Eyre - © Pete Dobre Minimum temperature

• Below average minima were widespread, except in the far south and west • Queensland 3rd lowest state-average minimum temperature for February

February 2012 December 2011 – February 2012

Lake Eyre - © Pete Dobre The big wet week: heaviest 7-day rainfall in southeast Australia history • Record weekly rainfall in several New South Wales and Victorian catchments (27 Feb – 5 Mar) • Double previous record in Murrumbidgee, Lachlan and Upper Murray catchments • Highest total 525 mm at Mount Buffalo (northeast Victoria) • With 294 mm, Ivanhoe (New South Wales) was only 12 mm short of annual average rainfall

Lake Eyre - © Pete Dobre So how much water are we talking about?

• Rain which fell over New South Wales (104k Gl) would fill Sydney Harbour 185 times • Victoria’s rain (23k Gl) would fill 0.9 Port Phillip Bays • Total water volume which fell on the Murray-Darling Basin (108k Gl) is equal to 8 times Australia’s mean February 14 March 5 FebruaryMarch 12 25 annual water consumption

Lake Eyre - © Pete Dobre Forecasting the big wet week (27 February–5 March)

January–March seasonal outlook Week 2–3 outlook (experimental) 7-day outlook

Lake Eyre - © Pete Dobre Forecasting the big wet week (27 February–5 March)

‘One way we can adapt to climate change (whether it brings drier or wetter conditions) is to make better use of the climate predictability we get from ENSO. By using the Bureau's seasonal climate outlooks, we will be better adapted to current climate variations, so the impact of any exacerbation by global warming will be diminished. Likewise, taking better advantage of the rapidly improving short-term weather forecasts from the bureau can help us prepare for floods better than we have been able to do in the past.’ Prof. Neville Nicholls Observed rainfall week ending 5 March (SMH/The Age, 13 March 2012) 7-day outlook Lake Eyre - © Pete Dobre La Niña – vegetation index

February 2009 February 2011 February 2012

Lake Eyre - © Pete Dobre La Niña – deep soil moisture

February 2009 February 2011 February 2012 Lake Eyre - © Pete Dobre Global conditions • US heat wave 2012: 1801 daily records set since March 9 • International Falls, Minnesota (US ‘icebox’) 25°C on 17 March - Previous record for that day: 12.8°C (records to 1895) International Falls • Chicago >80F (26.6°C) 5 successive days • Impacts on agriculture: drier and warmer • Most humid airmass on record for March means potential now for flood Snow depth (inches) 15 March 2011 vs 2012 Land surface temperature 8 – 15 March 2012

Lake Eyre - © Pete Dobre Climate conditions and outlook

• Recent climate conditions and trends • Current and forecast state of key climate drivers • Climate outlook

Lake Eyre - © Pete Dobre La Niña 2011–12

La Niña

+8 ▲

- 8 ▼

El Niño September 2011 October 2011 November 2011 December 2011 February 2012 January 2012 Sea surface temperature difference from average

Southern Oscillation Index

Lake Eyre - © Pete Dobre La Niña – the end is nigh • Significant warming of tropical Pacific – indices have returned to neutral • Latest Southern Oscillation Index around +6 • Wind and cloud patterns also show a move away from La Niña back to neutral

Sea surface temperatures difference from normal Equatorial Pacific heat content – top 400 m: • BUT… persistence of warm 1 17January March 2012 2012 difference from average water off Australia: caution still required Lake Eyre - © Pete Dobre Pacific Ocean – long range forecast

• Continued warming of the tropical El Niño Pacific is expected during autumn El Niño and winter +0.8 ▲ • Likely to see slightly warmer than - 0.8 ▼ average temperatures in April La Niña La Niña • Triple-header La Nina? Historically nine events 2 or more years, three POAMA forecast Current conditions (Feb 2012) events 3 years…

Lake Eyre - © Pete Dobre bom.gov.au/climate/enso Climate conditions and outlook

• Recent climate conditions • Current and forecast state of key climate drivers • Climate outlook

Lake Eyre - © Pete Dobre Review of summer Outlook: December to February Summer was … • Generally wetter than average, except in Tasmania and parts of the southeast • Cooler than average over New South Wales, southern Queensland and much of Western Australia • Warmer than average in far north, along west coast and in far southeast

Chance of exceeding median summer rainfall Chance of exceeding median summer maximum temperature Lake Eyre - © Pete Dobre www.bom.gov.au/climate/ahead Rainfall outlook for April to June 2012

Historical accuracy Chance of above median rainfall Simple multi-model outlook Lake Eyre - © Pete Dobre Temperature outlook for April to June 2012 Maximum temperature Minimum temperature

Lake Eyre - © Pete Dobre State of the Climate Snapshot • Dr Karl Braganza will give a full summary of the climate snapshot next briefing • Each decade warmer than previous decade • Australian mean temperatures have risen 0.9 °C since 1910 • Australian ocean surface temperatures in 2010 highest on record • Global average sea level rise 210mm Australian temperature trends 1910–present Number monthly max. temperature records set every year since 1880; recently 3mm per year • Warming around Australia cannot be explained by natural variability alone Lake Eyre - © Pete Dobre Key points

1. La Niña is approaching its inevitable end 2. Still potential for strong wet season rains 3. Record weekly rainfall over south eastern Australia in late February/early March 4. April to June rainfall outlook: likely wetter in the east, drier in the south 5. April to June temperature outlook: warmer days in south, cooler in east

Lake Eyre - © Pete Dobre Hydrologic conditions and outlook

Jeff Perkins Acting Manager Flood Forecasting and Warning

Lake Eyre - © Pete Dobre Hydrologic conditions and outlook

• Current flood situation • Storage and catchment conditions • Streamflow forecasts for March to May 2012

Lake Eyre - © Pete Dobre Hydrologic conditions and outlook

• Current flood situation • Storage and catchment conditions • Streamflow forecasts for March to May 2012

Lake Eyre - © Pete Dobre Flooding in February and March

• Queensland – Mitchell, Roma, St George (record) – Charleville, Augathella, Gympie, Blackall • New South Wales – Biggest floods in 20-40 years – Moree, Burke, Wagga Wagga, Narrendarra, Griffith, Forbes, Hay • Victoria – Nathalia and Walwa • Western Australia – Tropical Cyclone Lua (Cat 4) – Moderate to major flooding in De Gray, North Kimberley and Ord March 2012 February 2012 – Affected Nullagine, Kalumburu (record) Lake Eyre - © Pete Dobre Daily rainfall extremes

Lake Eyre - © Pete Dobre Floods in the Murray-Darling Basin

Wagga Wagga 6/3/2012 St George (February 2012) Charleville Levee holding Photo by Andrew Meares Photo by 7_Cannon (Twitter) Murray-Darling October 2011- March 2012 Lake Eyre - © Pete Dobre Flow outlook for South Australia • Currently around 20–30,000 Ml/d

21 days • May reach 60 000 Ml/d – floods some shacks (minor flooding) 14 days Darling peak – February 2011 was 93 000 Ml/d; 1956 - D/S Tilpa Lachlan peak 25 days was 350 000 Ml/d, 1974 was - D/S Condobolin 8 days 1 day 9 days 180 000ML/d 12 days 9 days Murrumbidgee peak • Peak timing based on Murrumbidgee - D/S Hay Town 1-2 days 4 days flows – mid to late April • Long travel times mean further rainfall always a possibility Lake Eyre - © Pete Dobre Murray-Darling river conditions Approximate travel times Current flood situation

Current river conditions Last 7 days rainfall Forecast for next 8 days Lake Eyre - © Pete Dobre Hydrologic conditions and outlook

• Current flood situation • Storage and catchment conditions • Streamflow forecasts for March to May 2012

Warragamba Dam spilling Burrinjuck Dam Spilling

Lake Eyre - © PetePhoto Dobre by Adam Hollingworth © Sydney Catchment Authority Photo by R.S. Williams Dartmouth and Hume dams

Dartmouth storage levels Hume Dam

Existing spillway capacity

Timelapse video Photos by ACTEW

Victoria Southern New South Wales Northern New South Monthly Streamflow Observations Monthly Streamflow Observations Wales for February 2012 for February 2012 Monthly Streamflow Observations for February 2012

High flow High flow High flow Near median flow Near median flow Near median flow Low flow Low flow Low flow Rainfall Victorian streamflow terciles Southern NSW streamflow terciles Northern NSW streamflow terciles

• Current flood situation in Murray-Darling basin • Storage and catchment conditions • Streamflow forecasts for March to May 2012

ü û ü December 2011 to February 2012 Forecast as tercile pie chart Sorted Historical Streamflow Record ü ü ü û û ü Near Most ü High ü • Mostly moderate to high skill likely median flow ü flow tercile Low flow Near ü ü ü median ü flow ü Low flow • 21 hits, 11 misses by 1, 2 misses High Streamflow flow by 2, no forecast provided at 2 û ü ü Rank/Year û ü ü sites due to very low skill ü ü ü ü A tercile hit is when the observed streamflow Observed û ü û ü for the forecast period is in the same tercile streamflow û û û as the most likely tercile from the forecast pie ü û û û chart ü What is a tercile hit ? December to February forecasts Lake Eyre - © Pete Dobre High flows more likely in Victoria

Victoria Ovens River at Bright Photo by Claire Hawksworth

Southern New South Wales Goodradigbee River at Wee Jasper Photo by NSW Office of Water

Jan 2004 Feb 2012 12476 ML 12769 ML

Northern New South Wales Halls Creek at Bingara

Murray-Darling basin: • Produces over 1/3 of Australia’s food supply • Includes 65% of Australia’s irrigated agricultural land • Generates 39% of national income derived from agriculture

• Record rainfall and widespread flooding across southeastern New South Wales and northern and eastern Victoria in March • High streamflows in February at almost all forecast locations • Record high monthly flow at Bingara in the Gwydir River • Near median or higher than median flows more likely for March–May 2012 • High storages and wet catchments leading into traditional wet season in Southern NSW and Victoria Todd River in March 2012