The first thing to come to mind is that when things get rough outside it is time to stay inside. Or at least restrict travel and stay off the roads as much as possible. The best emergency situation is the one you avoid entirely.
Develop friends along your travel routes. Invite people into you house overnight and foster a spirit that encourages people to trade nights on the couch. Keep it casual and light.
If you have to go out:
Whistle. Great idea. Cheap, light, compact, easy to use. Why would anyone go out without one?
Perhaps a spare battery for your cell phone. It would have been a shame if his phone died before he could get a signal out. If your in a vehicle a charger that draws off the vehicle's power system. Perhaps one of the hand-cranked chargers would be a good idea.
Letting someone know where your going, expected arrival time with some mention of when to consider the person lost and, of course, the route. Don't depend on verbal instructions. Write it down and have them pin it near the phone where it won't get lost. You don't need to write a novel. A simple 3 by 5 card is often a good format. Be sure to include all the relevant phone numbers. Including your cell number so they can call you if your running late. This gives them an easy step before calling out the Coast Guard. Also a quirk in some systems is that sometimes you may be able to receive a call but not call out.
When things get really rough outside it is time to do the three-step: Present a itinerary to a responsible person shortly before you leave. Call a responsible person at your destination shortly before you leave to let them know your on your way. When you get where your going you call the person and tell them you arrived.
During a hurricane or in blizzard conditions it may make sense to do this for something as minor as crossing the street. If phones don't work use alternate means of communications.
During extreme weather events it can also be useful to coordinate with authorities and let them maintain a running account of what conditions are like along the travel routes. Often the police and highway patrol are no more aware of which routes are open, closed or iffy than anyone else. If they are informed they can often advise people who simply have to travel, or emergency crews, which routes are best and what to look out for.