Because it's a forecast, look up the definition of the word for yourself, it's a best guess prediction of what somebody beleives will happen, somewhat different than a report which is a statement of what happened. Beware, words can be funny, there could be a report of a forecast or a forecast of an upcoming report. Some call it semantics, I see it as using different words that mean different things.
For example, I'd say the words “expects a rain shower tomorrow”. What does that mean, does your forecast say that you expect a shower to happen? Maybe some of us just find using the word “expected” more funny, I find it's an improvement over the previous version. For example, do your forecasts say that you expect rain, cold, hot, calm, hot or a mix of all of those things? Some forecasting software that I've seen does have this limitation, but I don't recall the name or what it's called, maybe it's called “forecasting software”. There are other ways to do forecasts with multiple levels of uncertainty, and you can go with a forecast of uncertainty. A forecast of one level is pretty simple, I'm just going to use that word again. And another one, forecast of uncertainty is to say we have no idea what the forecasts might be. Another type of.