SPOKANE, Wash. (AP) - Yet another winter storm pounded Spokane on Monday, extending the holiday break for tens of thousands of children after Spokane County's sheriff recommended that all county schools remain closed because of hazardous roads.

The National Weather Service also warned that the number of roof collapses in the area could rise as heavy rains are forecast to arrive Tuesday and add crushing weight to the tons of snow already on many rooftops. Rising temperatures could also quickly melt snow and cause flooding later this week, the agency said.

Rising tempers also were a problem.

One motorist was questioned by Spokane police after gunshots were fired Monday morning at a private snow plow operator who was clearing a parking lot. Police said the motorist apparently got upset when the plow operator honked his horn.

"It's safe to say that fuses are short, people are frustrated and we are having an increase in neighborhood disputes regarding snow related issues," said Jennifer DeRuwe, a police spokeswoman.

Spokane, a city of 200,000, was largely shut down Monday, as up to 8 inches of snow fell. More than 5 feet of snow has fallen on the city since Dec. 17.

The eastbound lanes of Interstate 90 across Snoqualmie Pass in the Cascade Range were reopened Monday afternoon after being closed overnight by heavy snow. The westbound lanes remained closed. Also closed were most highways in the Palouse, in the state's southeast corner.

About an inch of snow fell on Seattle late Sunday, but disappeared after overnight rain and daytime temperatures in the mid-40s.

The weather service said Ritzville in Eastern Washington broke its 24-hour record for snowfall when 5 inches fell in the period that ended at 6 a.m. Monday. The previous record of 3.5 inches was set in 1980, and records have been kept since 1899.

The service posted a winter storm warning for the west slopes of the Cascades through Tuesday morning, with another foot of snow expected beyond the 12 to 18 inches that has fallen since the latest storm began Sunday. Avalanche danger was listed as extreme in the Cascades.

For Eastern Washington, the forecast calls for snow to change to rain because of rising temperatures Tuesday, with a deluge of up to 2 inches expected in some places.

"The combination of rain and rapid snow melt could create significant urban and small stream flood issues," the service said.

The agency also warned that rain can be absorbed by snow and develop into a crushing weight, especially on flat or low-sloped roofs. There have already been 28 roof collapses in Spokane.

"The problem of snow loading is going to get worse during the next two days," the agency said, in an area running from Davenport, Wash., to Sandpoint, Idaho.

A major problem is that ice covers many storm drains, preventing water from entering, the agency said.

In the Spokane area and the Palouse, winds and snow made driving hazardous, and most of the roads from Spokane to beyond Pullman were closed Monday morning.

Washington State University's Spokane campus, along with Eastern Washington University, were closed for the day.

Spokane children, whose Christmas break began two days early because of snow, got another day off as school had been scheduled to resume Monday.

That changed after Spokane County Sheriff Ozzie Knezovich took the unprecedented step Sunday of "strongly" recommending that all schools remain closed. Knezovich, who acts as director of emergency management for the county, said officials would decide later Monday if schools will open Tuesday.

Knezovich and mayors Rich Munson of Spokane Valley and Mary Verner of Spokane were worried that children would have to walk on streets to get to schools because snow covered most sidewalks. School buses would also have trouble in snow-covered streets.

"We don't want to have a loss of life," said Munson, who added that some snow piles on the streets of his city were already 8 feet high.

Verner said Spokane is spending an estimated $150,000 a day on plowing, with bills since mid-December probably exceeding $2 million.