Colder Weather On Tap This Week & Snow???
Sunday evening update —
Here is the latest GFS (Global Forecasting System) model output map valid for this coming Wednesday morning. It shows a very chilly trough right over the Pacific Northwest.
See the Image here.
It looks like computer models are coming into better agreement on the idea of a colder weather pattern taking hold across much of the Pacific Northwest later this week. If the current pattern sets up as modeled, snowfall levels will fall to the valley floor by later this week and into the New Years holiday weekend. First, a strong system will slide into the Pacific Northwest Monday night and Tuesday. The air mass behind this system will be cold, with temperatures falling across the Pacific Northwest on Wednesday. At the same time, an even colder air mass will spill into Eastern Washington and Oregon. By Thursday, the pressure gradient through the Columbia River Gorge will increase, which will help to deliver even colder air into NW Oregon and SW Washington. Temperatures will likely fall to just above freezing for daytime highs in Portland by late in the week. Overnight lows will dip into the 20’s across the lower elevations of NW Oregon and SW Washington. The amount of available precipitation after the coldest air arrives is still uncertain, but anything that falls will likely be snow down to the valley floor Wednesday and beyond.
If the upcoming pattern verifies, we could be looking at our coldest New Year’s holiday in a number of years. One of our areas colder and snowier New Years holiday’s occurred when several inches of snow fell on December 30th and 31st 1992 along with high temperatures in the lower 30’s and lows in the 20’s. A similar pattern occurred on New Years Day 2004 when the area received as much as 6″ of snow, however temperatures were not as cold as they were in 1992. With the continuance of the strongest La Nina (cooler than normal sea surface temperatures in the tropical Pacific) since 1955, I would not be surprised at all to see more low elevation snows in and around the local area this winter.
I will post updates as needed this week. But I would prepare for some chilly weather with very low snow levels anytime Wednesday and beyond!