Snow flexed its muscles Friday in the Rogue Valley, closing schools and government buildings, canceling sporting events and turning roads into ski runs.

Snow flexed its muscles Friday in the Rogue Valley, closing schools and government buildings, canceling sporting events and turning roads into ski runs.

The snow came from an Arctic front that drifted out over the Pacific and gathered up moisture before heading back inland. Combined with a stagnant cold-air mass over the region, conditions were primed for a white weekend.

Temperatures are expected to drop into record-breaking single digits tonight and Sunday, but snowfall should have died out early today, according to the National Weather Service.

"There might be some flurries, some stuff floating around in the morning, but nothing that will add up," said meteorologist Brian Nieuwenhuis.

"Sunday morning we're going to be well into the single digits," he said.

Snow amounts varied around the county Friday. Prospect and Williams reported two inches by the early afternoon, and no updated reports were available from the weather service late Friday. At 7 p.m. Friday, 6 inches of new snow was reported in Grants Pass and 6 inches in Medford and Ashland.

Four inches of new snow fell at Crater Lake by 10:30 a.m. Friday, weather officials said, expecting at least four more inches overnight.

"A lot of places are getting what we thought," Nieuwenhuis said.

At 4 p.m. Friday, there was 5 inches of new snow on the Siskiyou Summit and chains were required on all vehicles on Interstate-5 there. Mt. Ashland reported 3 inches of new snow on its website Friday evening.

As of 4:30 p.m. Friday, 100 vehicle crashes had been reported on state highways in Jackson and Josephine counties, said Gary Leaming, spokesman for the Oregon Department of Transportation.

"And that doesn't include all the spin outs that weren't reported," Leaming said.

Emergency Communications of Southern Oregon reported 24 car accidents between 8:30 a.m. and 3 p.m., according to event logs.

Snow fall kicked into high gear at about 3 p.m., and started blanketing the Rogue Valley and ODOT dispatch was swamped after the storm landed, Leaming said.

By 6 p.m. Friday, there was a dispatch report that no tow trucks were available throughout the entire Rogue Valley.

"The big issue is just the freezing ... the snow that has fallen on the ground is just going to turn into ice," Leaming said Friday evening.

Leaming said he expected the number of reported crashes to continue climbing until today.

"I think the first storm of the year does kind of bring out the worst driving behavior," he said. "With this particular storm, we're getting snow in the valley on a Friday afternoon during the commuting time. We're seeing a lot of congestions right now."

Throughout last night and early this morning, ODOT had 25 plows, sanders and de-icers, working state roads between Grants Pass and Ashland. Two of those vehicles are plows that came to support the Rogue Valley effort from the Diamond Lake and Crater Lake area, he said.

"We're running every unit that we have," he said. "Up on Siskiyou (Pass) we've been keeping up. ... We're keeping our fingers crossed."

One ODOT plow applying de-icer was involved in a rollover accident on Interstate 5 near Azalea, Leaming said. An apparently impatient U-Haul truck driver attempting to pass the plow northbound caused a multi-car pileup and caused the plow driver to lose control of the vehicle and roll into the ditch, Leaming said, adding that the driver was uninjured..

"There is a whole unit that we lost due to driver negligence," Leaming said, warning drivers to "slow down and drive to the conditions."

Early Friday, the northbound and southbound lanes of Interstate 5 were closed for over an hour 14 miles south of Cottage Grove, because of a fertilizer-hauling semi that caught fire and heavy snow, ODOT reported.

The Jackson County Roads Department also had its full plowing and sanding crew at work, the Jackson County Sheriff's Department reported.

The county dispatched nine trucks with both plows and sanders on them, as well as five trucks with just plows, which worked until 7 p.m. Friday. Two additional emergency crews worked until early this morning and all 14 trucks were back on the road at 4 a.m.

Because roads were so treacherously slippery, Brammo Inc. welcomed commercial truck drivers and others in need to park their vehicles and stay overnight at their Talent headquarters, the former Walmart building just off Interstate 5 Exit 21.

Brammo director of operations Joe Wismann said the company was happy to lend a hand to motorists looking to avoid the slick roads.

Several Rogue Valley school districts canceled classes Friday, including Medford, Phoenix/Talent, Ashland, Central Point, Rogue River and Grants Pass. Sacred Heart Catholic School, Logos Charter School, as well as Grace and Cascade Christian schools also closed.

Performances at the Craterian and Camelot theaters were cancelled, and the Rogue Valley Symphony cancelled its performance in Grants Pass.

All Jackson County Child Development Services locations were closed, and preschool, therapy, individual and evaluation programs were canceled. Rogue Community College closed all area campuses at 4 p.m. The Josephine County Courthouse and Grants Pass City Hall both closed up shop at about 2 p.m.

SAT tests hosted by St. Mary's School in Medford that were planned for today have been canceled and rescheduled for Dec. 21.

The weather also canceled several local hockey and basketball games for Rogue Valley high schools and Southern Oregon University teams.

The season-opening boys basketball games for South Medford and North Medford will have to wait until next week, as home games against Wilson scheduled for this weekend were postponed.

Wilson, a Portland school, couldn't make the trip due to weather. It was to play at South Friday night and at North today.

Check today for updated snow amounts across Southern Oregon.

Reach reporter Ryan Pfeil at 541-776-4468 or REach reporter Sam Wheeler at 541-776-4471 or Follow him on Twitter @MTwriter_swhlr.