I have been using the el-cheapo Radio Shack 12-260 model that looks for the WX channels as soon as you power it up. This one picks up only the WX Infomation transmitted from the picked up channels where you are located. You get all of the alerts and sort of have to know what county you are in to know where the alerts are for.
The newer WX RADIOs all have the SAME feature where you can only listen to selected counties and other type of National Alerts...
This feature doesn't work well when you are on-road always changing where you are located at. You have to be able to switch this type of mode OFF.
I have my Radio wired into my OFF-ROAD POPUP trailer and had to adapted down the 12VDC power cord to 6V using a radio shack multi-tap power plug... Being in a POPUP trailer high winds are the things you would worry about... I turn my WX RADIO off when we pack to leave and then when we setup the power gets turned back on and the WX RADIO comes up on the right channel for that area automatically.
Its nice and loud and goes off with all the local weather alerts for me...