It is not a pretty picture.
Lights go out.
Flights are delayed, baggage is lost. ATMs run out of cash, cellular calls won't go through and cable TV is showing static. The information is being released as a precaution, to avert public panic at the first sign of a disruption in electricity or another essential service that may coincide with the date rollover but was not caused by the computer glitch. Some failures may take weeks of study before Y2K can be blamed or dismissed as the cause. But any of those things that happen on January 1st will immediately be presumed to be the indication of a Y2K problem.