Tonight is the GPS Apocalypse It rolls over to zero at midnight

That’s right, GPS tells “time” and “date” with Week Number and second-and-a-half increments into the week. The first GPS epoch began the Sunday before the start of a new decade, and midnight on Sunday, January 6, 1980 was the first time the Week Number incremented. If you tell your GPS (or car dashboard or clock or whatever) that it’s more than 10 years off, the Epoch will be interpreted incorrectly and the date and time will be shifted by 19 years, 8 months, and some odd number of days, hours, minutes, and seconds.

Source: blog.fosketts.net