Allow dismissing/ignoring of alerts for regions with repeating alerts

```
Users have pointed out that "Red Flag" weather alerts are quite common
across the US, especially in certain Florida areas.

We should think of a way to have these alerts automatically suppressed, or
user-acknowledged, so that a normal forecast can be displayed again.
```

Original issue reported on code.google.com by `Jeffrey.Sharkey` on 27 Apr 2009 at 10:46
