By Kevin Murphy
(Reuters) - A rare fierce October snow storm rolled out over the central Rocky Mountains on Friday, downing trees and forcing closures of state offices and more than 200 miles of Interstate 90 across parts of Wyoming and South Dakota, state highway officials said.
Up to 30 inches of snow was forecast to drop in parts of the Black Hills region of western South Dakota from the storm, the National Weather Service said.
"It's not normal this time of year, but it is not unheard of," said Cory Martin, meteorologist for the National Weather Service in North Platte, Nebraska. "But this amount of snow for an October storm is on the higher end."
Heavy rain, golf-ball sized hail and winds of 60 to 70 miles per hour were forecast later Friday in Oklahoma along with severe storms in Kansas, the National Weather Service said.
The National Weather Service, which is running on a reduced staff because of the federal government shutdown, issued blizzard and severe winter storm warnings across the Upper Plains through Saturday morning.
The Black Hills of South Dakota had seen up to 19.5 inches of snow on Friday morning and up to 10 inches had fallen in Wyoming, the National Weather Service said. The heavy snow had caused some power outages in the Casper, Wyoming area.
South Dakota Governor Dennis Daugaard ordered state offices closed in the Black Hills and six counties in the southwestern part of the state and said further closures are possible.
Interstate 90 was closed for about a 220 mile stretch from Sturgis, South Dakota, to Sheridan in northeastern Wyoming, according to transportation departments in both states.
The National Weather Service was forecasting from 8 to 18 inches of snow in northeast Wyoming and the western South Dakota plains, and 18-30 inches in the highest regions of the Black Hills and up to a foot of snow in Nebraska.
(Additional reporting by Heide Brandes; Editing by David Bailey and Diane Craft)