The Twitter alert would be received as a text message, where it would also make an appearance over in one’s Twitter timeline accompanied by an orange bell. This particular service was mooted and worked upon right after the devastating Japanese tsunami a couple of years ago, where Twitter proved to be the communications tool of choice in locating information at time of the disaster. According to the Environment Agency, “We will only use Twitter Alerts to share urgent information about a significant risk to life or the environment as a result of flooding or an environmental incident.” I guess this alleviates any kind of concern that you might have about privacy issues and unwanted spam.