Create seasonal outlook for TOC

[steeleb]

Using historical TOC during runoff at intake, see if we can get at TOC outlook

[steeleb]

Need to work through some ideas for indexes to use in the linear model for magnitude of TOC - right now it's tied to SWE and there are outliers (late season snow, early melt) that are throwing a wrench in the model. ideally the index takes into account SWE and melt statistics of some form.

@KECognac see PR #87 for more context.