By Rod Hill on 2012-01-14
Here is what I have learned, from west wind snow events, since my Portland arrival in 1999.
The following should be expected Saturday overnight - Early Tuesday. After that, the snow levels will sharply rise.
1. Areas below 500 feet: A mix of rain and snow with temperatures near and above freezing. 1" snow spots will be possible. The city center of Portland will remain mostly wet. The best chance for icy roads & snow cover at the lowest elevations will be early Monday.
2. Near & above 500 feet: Better chance of all snow. Daily snow accumulations of 1-3" will be possible.
3. 1,000 feet: Freezing temperatures and snow will be likely through the period. This is the real "WILD CARD" of the forecast. Sometimes with a westerly flow, the hills warm at times and the snow melts. Other times, the air stays cold and heavy snow stacks up! My best guess this time if for daily accumulations of 2-5" of snow.
4. Coast Range: 4-8" of snow Sunday & again Monday. Chains should be carried. All passes will see snow cover.
5. Cascades: 6-12" of snow Sunday & again Monday. Snow accumulation should be expected outside of Gresham, the whole way up the mountain.
Valley Snow Mix, Sunday - Early Tuesday