— 46 IREC Farmers' Newsletter No. 200 — Spring 2018 Winter Equatorial Pacific to depth Spring Equatorial Pacific to depth 1982 Weak warming at depth (dry) Very warm and an El Nino Sept-Dec (dry) 1986 Weak warming at depth (wetter) Weak warming and weak short lived El Nino Oct-Dec (wetter) 1987 Moderate warming at depth and El Nino from May-Aug (wetter) Warming decreased but weak El Nino till Nov (drier) 1991 Moderate/weak warming at depth (wetter) Strong warming and El Nino in Oct-Dec (drier) 1994 Weak warming at depth (drier) Moderate warming for El Nino in Oct-Dec (drier) 1997 Strong warming at depth and El Nino June-Aug (drier) Strong warming at depth and El Nino Sep-Dec (average) 2001 Moderate warming in Jul (average) Warming decayed to neutral Aug-Dec (average) 2002 Strong warming at depth (drier) Strong warming at depth and El Nino Aug-Dec (drier) 2004 Moderate warming in Jul (average) Weak to no El Nino (average) 2006 Moderate/weak warming at depth (drier) Strong warming and El Nino in Oct-Dec (drier) 2009 Strong warming to depth El Nino in Jun-Jul then decayed (average) Strong warming to depth El Nino in Oct-Dec (average) 2012 Moderate/weak warming at depth (drier) Warming decayed to neutral Aug-Dec (drier) 2014 Moderate/weak warming at depth (drier) Warming decayed to neutral Aug-Dec (drier) 2015 Strong warming at depth and El Nino June-Aug (drier) Strong warming at depth and El Nino Sep-Dec (drier Vic, wetter NSW) Many weather models predicted an El Nino for spring and the odd model forecast one for late winter. During the winter, only one climate indicator seemed to be within a ‘bull’s roar’ of an El Nino. DESPITE models and predictions, rainfall in many areas was less than average in autumn and winter—what we might expect with an El Nino event. So, what has got the models fired up this year? It’s all to do with the undersea heat that developed in the eastern equatorial Pacific Ocean as a result of a strong burst of reversed trade winds in February. This strong west wind near Papua New Guinea sent warm water under the Pacific and on its way to the South American coast. Such a beginning is essential for the start of an El Nino, but fortunately it doesn’t guarantee one. Looking at some recent undersea cross section data from 1982 to the current date, the years where undersea temperatures were warm in winter have been extracted and followed onto spring to see what eventuated (Table 1). Strong warming that developed early and lasted through the season, such as 1997, 2009 and 2015, is fortunately not Table 1. Years during which undersea temperatures were warm during July and the resulting spring Despite no indications of El Nino in climate models through winter, the season remains dry. — 46 IREC Farmers' Newsletter No. 200 — Spring 2018 Catchment inflows for 2018