I am using the Echo Speaks SmartApp and the Ambient Weather SmartApp together with a single webCoRE piston to provide severe weather alerts on my Echo devices.
The piston subscribes to the alertdescription attribute of the PWS and looks for changes every 60 seconds. If it sees a change it plays the alerts as an announcement on whichever Echo devices you’d like. The piston currently plays alerts on all devices but it could very easily be re-written to only play them on selected devices
Hope this helps someone. If you have any questions or suggestions please let me know.