Wind Gusts

That's really going to depend on how well the dish is anchored to the roof, and what the roof is made of.  I assume you're worried about Hurricane Irene?

Here in TX my roof-mounted slimline has survived several storms with winds of 70mph +, without even needing to be re-aligned. . As litzdog says, it's not the dish that's the problem, it's how well it's anchored to the roof. If the bolts are correctly mounted to the studs and not just the roof cladding, it will probably survive OK

I'm 3 miles from the coast in Toms River.  My dish didn't move a millimeter during the recent blow.  I did loose signal for about 20 minutes during the heaviest rain (about 10pm I think), but that was the extent of it.