PORTLAND -- A cold front that was expected to reach the Portland Metro area early Monday afternoon is sagging south which will delay its arrival into the evening.
KGWMeteorologistMattZaffino said rain would turn to snow starting around 7 p.m. Commuters were expected to largely miss out on running into snowy roads.
Into the early evening, the front edge of the cold air will start to work its way in, around 5 p.m. north of Portland. Then, around 7 p.m., it will transition to all snow, KGWMeteorologist Nick Allard said.
Overnight, the snow will stop but it will be followed by very chilly and dry air. These cold temperatures will likely create very icy conditions Tuesday morning, Allard added.
On Monday morning, many commuters were surprised by patches of black ice in Clark County, causing a large number of accidents on I-5 and SR 500, as well as other major roadways.
The biggest problem was people getting caught due to a feeling of security. Even through the temperature was a degree lower, once they hit the ram, they were spun sideways and caught completely off guard, said Captain Chris Moen with the Vancouver Fire Department.
Moen encouraged drivers to leave work early if they can, for Tuesday's commute. He said it's also a good idea to fill up your tank before you hit the road in case the trip home ends up being much longer than usual.
In Portland, freezing fog was the biggest problem for morning commuters, creating sheets of ice on some overpasses and bridges.
The bottom line is that this is an evening system which could produce as much as three inches of snow around 500 feet in the Metro area Monday night, especially in the higher hills. The Gorge could get about five inches and the foothills up to six inches, Allard said.
Snow began falling Sunday
Snow started falling Sunday afternoon in the higher elevations of the foothills, from Longview south to the Willamette Valley.
On the valley floor, including in Portland, there was a mix of conditions - but mostly rain.
TriMet put chains on all its buses Sunday night as a precaution, but then took some of the chains off Monday morning for routes that were totally dry during the morning commute.
Bend residents may wake up Wednesday morning to minus five degrees, he said, and The Dalles might drop down to single digits.
Special weather statements were issued for the Portland Metro Area, Vancouver, Central Willamette Valley, Central and Northwest Oregon Coast Ranges, Northern Oregon Cascades and foothills, Upper Hood River Valley and Western Columbia River Gorge.
KGW Meteorologists have forecast that this winter is shaping up as a strong La Nina weather pattern. La Nina patterns have traditionally been associated with above average precipitation and heavier snow accumulations. More: La Nina winter expected