Climate Outlook and Review September 2018 Author: Prof Roger C Stone
Overview The European, UK, and US long-term climate models that focus on forecasting central Pacific sea surface temperatures are continuing to predict further development of an El Niño. Most El Niño events persist until the southern hemisphere autumn (eg April/May). Due to the fluctuating nature of the current El Nino development, most rainfall forecasts for northern Australia, especially north east Australia, currently indicate varying and patchy rainfall probability forecast values for the next three months and which also suggests some relief rainfall during the September - November period for some regions. For Queensland (and northern Australia generally), using the statistical system (SOI phases) and based on a rapidly falling SOI Phase at the end of August, for the September to November 2018 period, the SOI phase system shows generally around a widely varying 20%-60% probability values of exceeding seasonal long-term median rainfall for many regions (see map Figure 1). The improved BoM POAMA 2.4 model indicates patchy rainfall probability values for most northern regions for the September to November total period (Figure 6). For the longer term (e.g. summer November 2018 to January 2019) the European ECMWF GCM forecast system suggests 40-60% (ie close to long-term climatology) for the long-term rainfall values (Figure 8). The MJO: The MJO would most likely be due again in about fourth week in September. Temperatures: for regions, the BoM POAMA 2.4 system indicates above median maximum temperature probability values for much of Northern Australia. The SOI phase system is suggesting above normal maximum temperature values for the September to November period, 2018. 2
Figure 1: Forecast rainfall probability values for Queensland - probability of exceeding the respective long-term seasonal median values overall for the total September to November 2018 period. Regions shaded darker grey have a 50%-60% probability of exceeding median rainfall values relative to this period of exceeding median values. Regions shaded orange have a 20%-30% probability of above median rainfall while those shaded yellow have 30%-40% probability of above median rainfall values. 3
4 Figure 2: Probability of maximum temperatures averaged over the three-month period September to November 2018 being above the long-term median for this time of the year. Regions shaded blue have a 60%-70% probability of above median maximum temperatures. Regions shaded dark grey have about 50%-60% chance of exceeding median maximum temperature values.
5 Figure 3: Probability of minimum temperatures averaged over the three-month period September to November 2018 being above the long-term median for this time of the year. Regions shades blue have 60%-70% probability of above median minimum temperature values. Regions shaded darker grey have a 50% - 60% probability of exceeding median minimum temperature values.
Figure 4: Northern Australia probability rainfall values, averaged over the three-month period September to November 2018 of being above the long-term median for this time of the year. Regions shaded grey have a 40%-50% probability of above median rainfall. Regions shaded yellow have 30%-40% probability of above median rainfall values, while those shaded orange have a 20%-30% probability of above median rainfall. Figure 5: Forecast rainfall probability values for Australia for the overall period September to November 2018 (after Stone, Hammer and Marcussen, 1996). Regions shaded darker grey have a 50%-60% probability of above median rainfall for this particular overall period. Regions shaded yellow have 30%-40% probability of above median rainfall values, while those shaded orange have a 20%-30% probability of above median rainfall. 6
Figure 6: Bureau of Meteorology Forecast rainfall probability values for Australia for the overall period September to November 2018. Dark brown-shaded regions have 20%-25% probability of exceeding median rainfall, and so on. 7
Figure 7 (a): Monthly SOI values since January 2010 the most recent phase is rapidly rising phase with the SOI very much on an oscillating roller coaster ride. The most recent 30-day average value to 31 August was minus 6.7 (-6.7). Figure 7 (b): recent trend in SOI values (30-day averages) as at 01/09/2018 8
Longer-term forecasts: The ECMWF and POAMA models provide useful assessments of longer-term rainfall probability values for agricultural regions. The ECMWF example below suggests about a 40-50% probability of above median rainfall for November 2018 to January 2019 for Queensland and Northern Territory. This output is updated for public use on the 16 th of the month. Figure 8: ECMWF forecast rainfall probability values for Australia and the region generally for November 2018 to January 2019 (Courtesy ECMWF). The forecast for most regions is about a 40-50% probability of above median rainfall for this seasonal period. 9
Figure 9: CPC General Circulation Model forecast of sea surface temperature anomalies through to June 2019 this model is strongly suggesting further El Niño development over the coming months. 10
Recent forecast maps As these forecasts are issued for a three-month validity on a rolling monthly basis, it has been decided to provide a continuous reference to these forecasts, as below: Seasonal climate forecast valid 1 September to 30 November 2018 Seasonal climate forecast valid 1 August to 31 October 2018 Seasonal climate forecast valid 1 July to 30 September 2018 Seasonal climate forecast valid June to August 2018 11
Seasonal climate forecast valid 1 May to 31 July 2018 Seasonal climate forecast valid 1 April to 30 June 2018 12
Madden Julian Oscillation (MJO) According to BoM s, USQ s and NOAA s forecasting systems and analyses, the MJO may next be due again around fourth week in September. Please also refer to the interesting BoM website (below) for updated information on the MJO. The information below also presents a one-stop shop as requested from industry for such information to be available. For updated climate information Click on the following links: For the MJO For weekly SSTs For easterly (and westerly) wind anomalies across the Pacific For sub-surface temperatures across the Pacific For ECMWF forecast products (note the web site for this output has changed) For plume forecasts of SSTs in the central Pacific For a complete history of the SOI The Long Paddock Additional information on ENSO 13
USQ Research Centre for Applied Climate Sciences Please email Prof Roger Stone at Roger.stone@usq.edu.au This program is jointly supported by the Department of Agriculture and Fisheries, the University of Southern Queensland and Meat and Livestock Australia, MLA Donor Company 14