That is the theory, but imagine living and working in a place such as I do, roughly halfway between the Fort Worth, TX and Shreveport, LA NWS offices. The weather service relies on their own respective radars to get a visual of any hail or hook echos that may appear. The problem is, of course, that Tyler itself is on the edges of each radar site, thus making it hard for them to see the smaller storms that inevitably produce the spin up tornado or the pocket change hail over here. When this occurs, there is no warning, there are no sirens blaring, there's no alert at all sent to us. We're just kind of on our own, with local meteorologists sounding the alarm via the airwaves, breaking into regular programming for weather coverage (and God help any of us if a significant storm is approaching during a Cowboys game).
I can't tell you how many times there has been a small rope tornado or quarter sized hail falling in east Texas, yet we'll be officially only under a Severe Thunderstorm Watch, with nothing going out over our phones, and Cody Gottschalk, Brett Anthony, Katie Vossler or Mark Scirto already on the air stating "we're just waiting on the Shreveport NWS to issue the *insert weather disaster here* warning", as the monitor behind them shows a full fledged tornado spinning up and reaching for the ground.