mPing for iOS (free) is a unique weather app from the University of Oklahoma. The 'Ping' stands for Precipitation Identification Near the Ground. mPing is designed so that volunteers like you can make observations to crowdsource data to improve the next generation of weather radar.
Radar doesn't work very close to the ground, and most weather sensors near the ground are at airports. That leaves a lot of geography without radar coverage. The idea is that reports from observers streaming in will improve the algorithms used in weather predictions and reports.
The researchers are especially interested in things like hail, and the size of the hailstones -- but don't get hit by one!. To submit a report, select the type of precipitation, and your observations are transmitted and compared to radar plots.
mPing lets you see what others are reporting, and you can view a US map that shows live reported weather events. Those events can be zoomed in on for more details. You'll benefit, because you get a clear idea where hazardous weather is happening. If you make reports, forecast models will get better and better. I didn't see any nasty weather around me, but could see live reports from Texas and the East Coast. If you'd like to see what the data looks like without using the app, visit this link.
mPing is simple enough to operate, and the GUI is clean and inviting. It is a universal app that requires iOS 7, and it's optimized for the iPhone 5. If you're really into weather and want to help with meteorological research, mPing is just the app for you.