ST. LOUIS — States across the nation’s midsection are bracing for another round of winter storms expected to add to thick ice that already has glazed roads, grounded flights and prompted class cancellations.

Winter storms are typically associated with heavy snowfall, but the one that began hammering the southern Plains and Midwest on Friday dumped freezing rain — a condition even harder for road crews to treat. A slick road was suspected in a fatal wreck Friday in Missouri, where long stretches of Interstate 44 and Interstate 55 were ice-covered. More freezing precipitation was expected in parts of the nation’s central corridor throughout most of the weekend.

Hundreds of schools were closed Friday, including several college campuses. St. Louis closed all city operations as it braced for what could be its worst ice storm in at least a decade.