A past situation, which resembles the current situation, is called an analogue, which can then be used as a guide for what is to come. For example, by finding similar SOI patterns to the current year, we can then examine rainfall patterns from that time to use as a guide as to what will happen this year. The Bureau of Meteorology's Seasonal Climate Outlook includes a listing of several analogue years in which the SOI behaved similarly to the current year.
Analogue devices are those which communicate via a small electric current. For example, food industry flow meters send a current of between 4mA to 20mA. The lowest value would represent no flow at all; the largest would indicate maximum flow.