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 Widespread rain in southern SA and western VIC welcomed by croppers
Moderate to heavy, soaking rain moved from southern SA into much of VIC east to Melbourne and the Goulburn Valley overnight giving widespread falls of 20 to over 50mm.
The rain that has occurred in the past two days, and is continuing across central VIC with a little into the NSW Riverina, is well timed to start the winter cropping season across much of SA, western and central VIC and the southwest of NSW. It prepares the way for crops such as wheat, barley and canola and will also provide good subsoil moisture for grazing country on the fringes of crop areas.
It resulted from a moist infeed of tropical air from the Indian Ocean in a northwest rainband meeting an upper trough and cold pool that moved up from the southern ocean. The instability as these elements aligned overnight caused many thunderstorms and heavy falls in the Wimmera, Mallee and far SW NSW during the 24 hours to 09.00 this morning. Locations in all three states have reported twice or more their monthly average rain for April. There were about 20 record one-day falls for April across the three states including three rainfall stations, all in the Wimmera, with histories of over a century. The standout was Woomelang, 75km SSE of Ouyen, which registered 103.2mm, its highest for April since it opened in 1900.
The Wimmera Mail-Times* has a good article on the event from the farmers' standpoint, while the photos, videos and tweets in the Bendigo Advertiser* give a feel for the day and its impact on activities.
  IRI longer-term forecasts for rain and temperature in line with BoM
The latest forecasts from the International Research Institute for Climate and Society at Columbia University are in broad agreement with the BoM seasonal forecasts for coming months. In addition its predictions for El Niño, La Niña, and the Southern Oscillation (ENSO) development are in agreement. A background to IRI's climate work is given here.
IRI rainfall and temperature probability forecasts are based on multiple models and given for four three-month periods in advance, so the April issue is for May-June-July (MJJ), June-July-August (JJA), JAS and ASO. Looking broadly at Australia's precipitation, they see a 40 to 50% probability of below normal rainfall in the May to July quarter across most of eastern Australia and the SW half of WA, gradually intensifying to 45 to 60% chance of below normal rain by the August to October quarter across the whole northeastern half of the continent. In WA, only the far SW corner has such a high chance of below normal rain. The remainder of Australia is close to or a little above normal.
Temperatures are compared against those for the period 1982 to 2010, so given that global warming has gradually increased figures since then it is not surprising that most areas in the world show "above normal" temperatures as we adjust to the new normal. For Australia, IRI's mean temperature expectations are not as dramatic for the MJJ quarter as those of the Bureau, but do gradually expand in area and increase slightly in intensity through to the ASO quarter.
IRI's 4x3-month forecasts are issued soon after the 20th of each month and simple full-globe versions are here. A greater variety of more detailed maps can be accessed here, where you can also select just a map of Australia and play with how you want the probabilities displayed in many different and useful ways.
IRI uses an impressive set of global climate models to show its estimates of likely ENSO chances, including the POAMA model used by the BoM. Graphs and tables show each model individually so you can see the degree of agreement and the general trend, and you click on any of the graphs for larger versions accompanied by more specific information. The trend of almost all models is for ENSO to continue neutral at first, then move towards En Niño in our Winter and Spring.
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