With a Superdish, it should be a pretty strong storm to knock out the signal, and it should not last that long. It sounds like you might need to have your dish realigned. E* has put a new signal strength on most recievers. They now read around 40-70 for a good signal strength. With the older meter it is around 90-110. I think only the legacy recievers still have the old meter, but I have seen a few 301's still have it.
usually due to an installer that slaps a dish on the roof and points it where they think it is. directv and dish both do this. my neighbor has had dish since 96 and it went out once during a tornado warning. then my friend's goes out when someone sneezes. i have heard people argue about who has the best signal strenght, they are the same, it just depends on how good its pointed. if your dish is easy to get to, order a meter off ebay for $10 and point it yourself, thus saving $50 for a S/C, and every time it becomes misalighned.