Watch weather if planning on west-side Christmas

Holiday traffic on Interstate 90 over Snoqualmie Pass is expected to be 40 percent heavier than a typical December weekend, according to the state Department of Transportation.

DOT is predicting the heaviest traffic will be on Sunday following the holiday from 3 to 6 p.m.

Weather will play heavily into how heavy traffic is, DOT said. For the snow-filled Thanksgiving holiday weekend this year, 33 percent fewer drivers traveled over Snoqualmie Pass and 45 percent fewer crossed Stevens Pass compared with a milder Thanksgiving 2009.

With AAA expecting close to 3 percent more drivers for Christmas this year, a calm-weather weekend could bring out even more, DOT said.

Before leaving, DOT recommends drivers check the WSDOT website www.wsdot.wa.gov and pack winter weather supplies, including tire chains.

Potentially challenging conditions are possible in the Columbia River Gorge, DOT said. Forecasted heavy snow combined with windy conditions Saturday could create slick conditions and reduced visibility.

But so far, DOT said radar hasn't picked up any storms similar to Thanksgiving weekend. For winter driving tips, go to www.wsdot.wa.gov/winter.

Based on historical data, WSDOT expects the following travel conditions Thursday through Sunday:

w I-90 Snoqualmie Pass. When Christmas falls on a weekend, travel over Snoqualmie Pass is close to 40 percent greater than a typical December weekend. Traffic could get congested on westbound I-90 from 3 to 6 p.m. Sunday.

w Highway 2 Stevens Pass. Travel over Stevens Pass will remain near average for a December weekend with increased traffic all day Sunday.

w I-5 Olympia to Tacoma. Drivers can expect congestion southbound I-5 Thursday from 10 a.m. to 6 p.m. Similar congestion is expected northbound Sunday from 10 a.m. to 6 p.m.

w I-5 north to Canadian border. Possible congestion from 3 to 6 p.m. Thursday.

Drivers can expect to pay $3.18 a gallon for gas during their travels in the Tri-Cities, according to AAA's Daily Fuel Gauge Report. That cost is up over last year's $2.80 per gallon.