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An important aspect of long-range forecasts is the identification of broad scale indicators or indices that represent important aspects of the global weather patterns (e.g. El Nino Southern Oscillation (ENSO) index). 

Climagrams (a type of meteogram) give a month-by-month picture of the probability of appearance of these patterns, and of their possible amplitude.  The typical skill level of seasonal forecasts, as assessed using re-forecasts, is generally much lower than that of short range forecasts.  Skill levels are typically lower in the extra-tropics than in the tropics. Indeed in some regions, for some forecast variables, skill levels are vanishingly small. Users should familiarise themselves with verification figures from the outset to avoid over-interpretation of and over-reliance on the seasonal forecast charts.