ENSO and Seasonal Outlook - QueenslandJim Davidson, Bruce Gunn: Queensland Regional Office

Compiled with the assistance of William Wang, Elise Chandler, Andrew Watkins & Grant Beard, National Climate Centre, Melbourne

Climate conditions and outlook

• Recent climate conditions

• Current state and forecasts for key climate drivers

• Outlook for rainfall temperature, fires, storms, floods

La Niña – a very strong event

One of the strongest La Niñas on

record: 1917, 1955, 1975

July 2010 – March 2011 Rainfall

highest on record: 752mm

(707mm in 1973-74)

July 2010 – March 2011 day

temperatures 2nd lowest

July 2010 – March 2011 rainfall deciles

July 2010 – March 2011 maximum temperature deciles

A return to drier conditions

• Rapid breakdown of the La Niña in autumn changed rainfall patterns over Australia

• January to March: 77% above normal rainfall for Australia (2nd highest on record)

• May to July: 24% below normal rainfall for Australia

January to March rainfall deciles

May to July 2011 rainfall deciles

bom.gov.au/jsp/awap

• Recent climate conditions

• Current state and forecasts for key climate drivers

• Outlook for rainfall temperature, fires, storms, floods

Climate conditions and outlook

September La Niña indicators

• Southern Oscillation Index • Septemb

er 2010: +25

• September 2011: +5

2010 2

011

bom.gov.au/climate/ensoSouthern Oscillation Index (SOI)

La Niña

El Niño

Current state of ENSO

7

Subsurface temperatures indicate collapse of western Pacific warm anomaly & re-intensification of central Pacific cool anomaly.

2011

Another La Niña developing?

•US NOAA already calling this a La Nina

•But the majority of dynamical models of the ocean indicate that the cooling of the central Pacific ocean may have peaked.

•Not yet coupled into atmospheric circulation and SOI

Pacific Ocean – forecast

• Neutral Pacific Ocean

conditions consensus

forecast for spring and

early summer

• Number of models show

some further cooling

• El Niño(warm) highly

unlikely

• Weak La Niña(cool)

remains possible for

(late?) summer

Australia’s POAMA model forecast for NINO3.4 (August 2011)International climate

model forecasts

MODEL / 

GROUP

Forecast Start Date 1-3 MONTHS

(Sep 2011 to Nov 2011)

4-6 MONTHS

(Dec 2011 to Feb 2012)

POAMA

Australian Bureau of Meteorology

29 August Neutral Neutral

POAMA-2 (Experimental) 

Australian Bureau of Meteorology

1 August Neutral Neutral^

GloSea UK Met Office 12 August Neutral/Cool Neutral/Cool#

CFS NCEP (US) 28 August Neutral/Cool Cool

CGCMv1 * NASA GoddardGMAO(US) 1 August Neutral Neutral/Cool

System 3 ECMWF (EU) 1 August Neutral Neutral/Cool

JMA-CGCM02 Japan Met. Agency 11 August Neutral Neutral

KMA-SNU Korean Met. Administration Unavailable Unavailable Unavailable

BCC_CMA BCC/CMA (China) Unavailable Unavailable Unavailable bom.gov.au/climate/enso

Climate conditions and outlook

• Recent climate conditions

• Current state and forecasts for key climate drivers

• Outlook for rainfall temperature, fires, storms, floods

Vegetation – abundant grass growth across much of the country

Rainfall Deciles for the past 3 months

• Rainfall in July, and early August has been well below average

• Upper soil moisture is drier than normal

• However, deeper soil moisture remains average to above average

• Hence, slight potential for above average run off if significant rain occurs

BUSHFIRE OUTLOOK 2011-12

Number of SEQ severe storm days per season (1956-2000)

Number of severe thunderstorms in SEQ usually peaks in November

Lightning activity in SEQ usually peaks in December

Number of severe storms in SEQIf ENSO:

• Neutral ~ 35% above average• El Nino ~ 5 % below average• La Nina ~20% below average

Yeo, C. 2005. Severe Thunderstorms in the Brisbane region and a relationship to the El Nino Southern Oscillation, Aust. Met Mag. 54 (2005) 197-202.

PRELIMINARY:Rainfall Outlook for October to December

This time last year

Spring 2011

PRELIMINARY: Not for public release

Global model forecast

Soil moisture from AWAP

Top layers are average to dry, although lower layers are generally average to wet.

Full storages & wet subsoil imply potential for above average runoff after onset of significant rainfall

16

Current upper layer soil moisture

Current lower layer soil moisture

SOI and Queensland Floods ~1920 to 2009

Jun 2010-Mar 2011

SOI = 19.1

1973/74

1955/56

1975/76

1950/51

Tropical Cyclones

Preliminary outlook:

Slightly above average numbers of tropical cyclones are expected in the Eastern (Coral Sea) region during the 2011-12 season.

Average of 3-4 tropical cyclones each year in Coral Sea-all or none could be severe, and possibly make landfall

This outlook is based on statistical relationships between annual tropical cyclone numbers, and the El Niño – Southern Oscillation (ENSO).

This outlook is based on neutral ENSO conditions that currently persist in the Pacific Ocean, however some allowance has been made for a potential return of weak La Niña conditions by the end of the year.

The outlook will be reviewed and updated over the coming months as more data becomes available

Key points - ENSO

• La Niña has ended, the Pacific has returned to neutral ENSO conditions (neither La Niña or El Niño), but precursors for another La Niña are clearly there.

• Neutral conditions are forecast to continue through spring, but a reforming (weak) La Niña remains possible.

• If the ocean cools a little further + the SOI rises, and these conditions remain at these elevated levels for several weeks, only then will we consider we have a resurgence of the La Nina.

Key points – ENSO ctd

• Far cry from where we were at this stage last year• La Niña indicators much weaker than at this point in

2010 (2010-11 was possibly second strongest after 1917-18, and stronger than 1973-76)

• A borderline neutral/La Niña summer is less favourable for widespread above median rain than the very strong event we had last year.

• Change in forecast is possible. BoM will be closely monitoring.

Key points – Season Outlook (Queensland)

At this early stage…..

• Above average 2011-12 fire season over much of Queensland• Average to above average number of spring/early summer severe

storms in SE Queensland• Above average rainfall likely across Queensland in Oct – Dec period,

particularly in the north of the state• Tropical Cyclones: preliminary indications are for slightly above

average number of tropical Cyclones in the eastern (Coral Sea) region in 2011-12

• However the chance of widespread flooding and above average However the chance of widespread flooding and above average cyclones is cyclones is not as high as last yearnot as high as last year

• Nevertheless, there will almost certainly be Nevertheless, there will almost certainly be major floods somewhere major floods somewhere in Qld during 2011-12 though unlikely to be as widespread as in Qld during 2011-12 though unlikely to be as widespread as 2010-112010-11

Key points – Season Outlook (Queensland)

• BoM will be closely monitoring for any changes.

• ENSO Wrap-Up and Climate Models summary will be updated fortnightly

• The The seasonal outlook will be updated on seasonal outlook will be updated on 2828thth September September

Thankyou

Bureau of Meteorology Queensland