If you live in the Midwest, you get used to watches and warnings for T-storms and tornadoes. But those warnings usually come a couple of hours before the storms hit.
Yesterday, the National Weather Center took the almost unprecedented step of issuing warnings 24 hours in advance.
Forecasters say to expect "life-threatening" storms throughout the Midwest starting Saturday afternoon, in a path ranging from Minnesota to Texas. Kansas, Nebraska and Oklahoma are projected to receive the brunt of the damage, which could include thunderstorms, tornadoes and hail.
Here are some details on why these early warnings -- which came on Friday -- are so unusual.
WHY THIS IS UNIQUE: This marks the second time in U.S. history that the Storm Prediction Center has issued a high-risk warning more than 24 hours in advance.
WHAT HAPPENED LAST TIME: The first high-risk warning more than a day early came in April 2006, when nearly 100 tornadoes tore across the southeastern U.S. In all, a dozen people died and more than 1,000 homes were damaged in Tennessee.
WHY EARLIER WARNINGS: In the past, people often have had only minutes of warning when a siren went off. But improvements in storm modeling and technology let forecasters predict storms earlier and with greater confidence, the National Weather Service says. The Storm Prediction Center is part of the service.
NEW WARNING LANGUAGE: The weather service is now testing words such as "mass devastation," ''unsurvivable" and "catastrophic" aimed at getting more people to take heed. The warnings are being experimented with in Kansas and Missouri. The "life-threatening" warning for this round of storms, despite the dire language, was not part of that effort but just the most accurate way to describe what was expected, a weather service spokeswoman said.
The areas under the watch include parts of Illinois, Iowa, Kansas, Missouri, Nebraska, Oklahoma and Texas.