SOI rises sharply to +16.5, lifting spring rain hopes GREGOR HEARD 25/09/2008 3:47:00 PM The 30-day Southern Oscillation Index (SOI) has lifted sharply, back up to +16.5 – a pattern that generally suggests better than average rainfall and a move to a La Nina pattern. Bureau of Meteorology meteorologist (BOM) Lyn Bettio, however, says that while the move is a positive for farmers hoping for spring rain, it has not yet gone on long enough to be significant. She also warns that there are other factors required to usher in a La Nina. Ms Bettio said that along with having an SOI above a reading of eight for a couple of months, other factors, such as sea surface temperature and trade winds, need to fall in line with a La Nina pattern, and this is not happening yet. In parts of the northern Western Australian wheat belt and most of Queensland, chances are rising for above average rainfall, with the chance of higher than usual rainfall for October through December rising to between 65 and 70pc...