Wednesday December 22
— ARCTIC OUTBREAK EVENT —
For all residents of the PNW, wx through the entire Christmas & New Year’s holiday period will be SNOWY, COLD and memorable, if model projections verify. Therefore, this Special Statement is warranted.
Washington: broadly speaking, the Arctic Air will arrive during the Christmas weekend - the coldest may be delayed by 24-36 hrs. NW WA & Vancouver BC areas will get hit first with snow and WIND, as the Fraser Gap Outflow picks up during the weekend. Fraser Gap WIND will be powerful and likely to cause some power outages. WIND chills will be dangerous for exposed skin. Most of the moisture will push farther south into OR, but enough will be around for a few inches of snow to accumulate by Monday. Western WA in general will receive snow, with temps dropping into the low teens (or lower in wind sheltered areas) by the middle of next week. Sub-zero temps east of the Cascades are probable.
Oregon: colder air will be a bit slower to arrive (per usual in these type of patterns), so don’t expect much SNOW until Sunday Dec 26. A few inches of SNOW will be on the ground by the Monday morning commute. Snow on Monday could be rather heavy south of Salem. The coldest period next week will arrive by Wed or Thu, as more moisture streams in, as well. SNOW will likely be heavier in the southern Willamette Valley through next week (similar to 2008). Columbia Gorge Outflow increases significantly next week. Temps, with snow on the ground, are likely to drop below 10 degrees, esp on the 29th & 30th, and again New Year’s morning. Sub-zero temps east of the Cascades.
Prepare for extended sub-freezing temperatures. Models are trending toward high & low temps remaining below freezing for several days. Whatever snow that falls will remain in place. Patrons with hoops/tunnel growing systems need to prepare for snow-weight issues, per past experiences. When we begin to get out of the winter grip, freezing rain and/or rain will add considerable weight to greenhouse covers.
Currently, the key snow periods are charting for Sunday/Monday Dec 26,27; Tuesday night Dec 28. Thu night & Fri Dec 30,31; Tue Jan 4 - WA only. Cumulative snow during the entire holiday period could be over 10” for most west side locations. We have seen several model runs keep the cold air in place through at least Jan 6, with more snow, as well. However, the trend is for warmer, wet weather to bring the PNW back to normal that week. We’ll review this later.
In Summary: a White Christmas is possible for Patrons north of Portland. Snow is highly likely across all western WA & OR the day after Christmas & next week. Sub-freezing temperatures for several days, with single digit lows possible west side. Exiting the Arctic event could mean freezing rain, at times.
Update again on Christmas Eve.
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