In another example, past observations are use to adjust the hydrologic model. The current time is when model states are saved. The future will use forecast or historic data as input to the model to produce possible hydrographs. Here, a series of hydrograph traces are generated, each based on a particular set of input values. The resulting traces give an idea of the range of possible flows.
For this case, because all of the traces are above this point, the probability that this flow will occur is very high. For the this second case, there is a medium chance flows at this level will occur since some of the traces were above and below this point. For the third case, chances of this flow are low, since all of the trances are lower than this particular value.