Moisture Manager Update 2 June, 2014

• Favourable atmospheric indicators at odds with developing El Niño sea surface temperature measurements in the Tropical Pacific.
• Uncertainty exists on the severity of El Niño impacts; with the “decoupling” of atmospheric indicators with sea surface temperatures
• The Bureau of Meteorology models predicting a reduced longer term Niño 3.4 SST warming offering hopes for spring rainfall
• Southern Oscillation Index on a steady rising trend with 30 day average currently +3 and daily value of +17
• Warm local Australian sea surface temperatures provide a potential convective moisture source through the winter months
• Seasonal Global Circulation Models surveyed show uncertainty on winter rainfall and generally warmer than average winter temperatures

1. Summary of Climatic Indicators

   Measure	Indicator	Current Status		Forecast Trend
   Sea Surface Temperature Indices	Pacific Ocean – Niño 3.4	+0.5		Dry
   	Pacific Ocean – Composite Index	+0.1		Neutral
   	Indian Ocean	0.0		Neutral
   Mean Sea Level Air Pressure	Southern Oscillation Index	+3.0		Wet
   	Southern Annular Mode	0.0		Neutral
   Tasman Sea Upper Atmospheric Air Pressure	Blocking	+20		Wet
   So, does this mean rain? Click here for more information on the indicators and an explanation of what they show.

2. Rainfall and Temperature Guidance Summary

   
   

   Source	Model Released	Temperature Forecast (monthly)	Precipitation Monthly Outlook
   JMA (JPN)	28 May	Average June	Rain Qld Week 3&4 June Rain NSW Week 1 June
   UK Met Office (UK)	25 May	Average/Above average winter	Average winter
   BOM (Aust) and POAMA2	15 May	Above average June	Below Average June
   JAMSTEC (JPN)	27 May	Above average	Average Winter

    

   • Models not aligned on precipitation forecasts and caution needs to be taken on surveyed results
   • Temperature predictions showing a more consistent trend for an above average winter period

3. Murray-Darling Basin June Rainfall Summary

   

   Figure 1. Observed weekly rainfall totals for the Murray Darling Basin.

4. An important indicator to Watch in the 2014 El Niño

   The El Niño Modoki Index or “Composite” sea surface temperature (SST) Index

   The 1997 El Niño was a landmark El Niño year due to the separation of the Niño 3.4 Index with the El Niño Composite Index. In this particular year, the Niño 3.4 Index reached record levels above +2.0, whilst at the same time the “Composite” Index plummeted into negative territory to below -1.0. The distribution of sea surface temperatures in Pacific is proven to influence moisture supply to Australia in El Niño events. In 1997 Australia received average spring rains which led to researchers re-writing many of the widely held principles about the easterly SST warming in the Pacific.

   Figure 2 shows a strong traditional El Niño with warming of SST’s in the eastern Pacific;

   

   Figure 2. A typical El Niño event with warming in the eastern Pacific Ocean (SOURCE: JAMSTEC, 2013)

   Figure 3 shows sea surface temperatures and measuring zones of El Niño Composite Index, with added sea measurements in the far eastern and western Pacific as well as traditional zones in the Niño regions. This SST distribution is typical of a severe 1994 or 2002 El Niño event.

    

   

   Figure 3. Sea Surface Temperature distribution in an El Niño “Modoki” event, with extra measuring zones north of Australia and West of South America (Source: JAMSTEC, 2014)

    

Next Update: 16 June, 2014

Before relying on the material in any important matter, users should carefully evaluate its accuracy, currency, completeness and relevance for their purposes, and should obtain any appropriate professional advice relevant to their particular circumstances.