The National Weather Service (NWS), the weather service used by Zap Weather, was severely impacted last week due to what appears to be a badly written Android app.  Details on the name of the app and the exact cause have not been disclosed.  Unlike this app, however, Zap Weather behaves nicely with the NWS by caching its weather data it receives from the NWS to minimize data loads between your Joomla site and the NWS.  Our guess is that this app did not cache its data, causing a network load on the NWS servers as more people downloaded and used the app.  You can read more about it in an article from mashable.com.