Looks like you can turn off the voice notification by pressing Home / Setup (gear button in bottom right) / Voice / Severe weather warning (last one in list) on the Nav screen.
Thanks, I'll give it a try. Just found and turned on traffic today, red and yellow all the way up the I15 from Pala, got off at Pala and took the back roads, adds an extra 5 miles, but at least I was moving.