I read wx radio mentioned, preferably portable/handheld. And I think they should be standard equipment for all chasers but make sure you have one that auto-scans to keep tuning to the closest station every 30 seconds or so as you're roaming the region in and out of several different signals. Not all do.
http://www.radioshack.com/product/index.jsp?productId=3506942 put this in "Travel Mode" and forget about it. No need to bother with putting in SAME codes.
I also read "axe" ... For the truly ambitious and those with the storage means, a small/medium chainsaw might be prudent, as well as a tow strap or chain to pull downed trees out of the way if you have an appropriate vehicle.
A backup cell phone in the event yours somehow "becomes inoperable" (due to dropping in a puddle of water for instance). Get a trac-phone or similar from Walmart and pre-load it with 30 minutes or so. Make sure to put in all of your important numbers you don't know by heart, and always leave it in the glovebox along with it's charger if it's different than you already have.
If you wear rx glasses and need them to drive (or read), perhaps a cheap spare pair might be wise to keep in your chase vehicle, as well.