What I'd do to rate the systems is have a catagory system set up, from 0 through 5, each for wind speed, storm surge, and rain fall, (you can include tornado threat as well, but that would be a bit harder to judge)

Each catagory would have it's own rating system:
wind:
0 - Under 74MPH (Tropical Storm)
1 - 5 standard Catagories, I suppose you could
include Extreme for anything above 175MPH

Storm Surge:
0 - Minimal storm surge under 3 feet
1 - Minor storm surge 3 - 5 feet
2 - Moderate 6 - 9 feet
3 - Significant 10 - 15 feet
4 - Strong 16 - 20 feet
5 - Major 21 - 30 feet
Extreme - 30+ feet

Rainfall:
0 - under 1" expected
1 - 1 - 2"
2 - 2 - 4"
3 - 5 - 8"
4 - 9 - 12"
5 - 12 - 18"
Extreme - Over 18"

you can then modify slightly for coastal effects and other variables to come to an expected storm effect. Perhaps making a general numbering system for the public.

a slow moving tropical storm can have devastating consequences with rainfall...

a former cat 5 storm can have incredible storm surge even after it weakens wind wise.

a winding up storm can bring incredible wind destruction even on the otherside of the coast, and not have that storm surge effect.

give the public information, just don't overwhelm them with it.

I'll post more when I get to a computer that doesn't make me feel like i'm on a 300 baud modem LOL

-Mark