Seasonal with a Chill

 

We tip our Mugs in honor of our Nation’s Veterans.  Their service will always be treasured.  Weather for the next couple of weeks will be quite seasonal, with another COLD outbreak possible in several days.  Here ya go —

 

For this weekend and into next week - expect a little precip in the Willamette Valley today, but not much, as the system is stretched out off the coast, weakening any impact.  The associated Low will slowly ‘fill in’ as it tracks across northern CA, keeping the PNW on the dry side.  An east wind out of the Columbia Gorge will begin to increase by the start of next week because a weak High pressure ridge will build over the Continental Divide.  Winds will not be as strong as the last shot, but enough to move piled leaves around.  Cool temps, with plenty of sunshine likely Mon through Wed.  

 

A Modified Arctic Air mass may arrive in the PNW as next week ends.  This 'Yukon Dome’ (our term), could be COLDER than last week, if models verify.  High pressure will build during the week over the Yukon & interior Canada before dropping into the lower 48.  When we see barometric pressures over 1040 mb in Yukon, we subsequently have the potential for a cold outbreak in the PNW.  This doesn’t always happen because that cold dome may weaken or drop too far east to impact the PNW; however, we simply don’t get an Arctic Blast without a 1040+mb Yukon/Interior Canada Dome forming first.  Anyway, for now, we forecast the potential for colder weather to begin arriving late Thu night into Fri.  Fraser Outflow will develop first, then, as the cold air mass descents over eastern WA & ID, cold air will rush west out of the Columbia River Gorge.  A familiar pattern.  There will not be mid-level moisture associated with the leading edge of the cold front, so snow is not a real issue at this time.  It will be chilly, but dry, next weekend, Nov 19,20.  Temps in the 20s at night; 30s to 40s for daytime highs.  Sunny.  Strong winds over southern OR & northern CA on Saturday.

 

For the week of Thanksgiving:  a short-shot of surface snow or snow/rain mix before all rain is possible on Tue Nov 22 for NW WA only, as a warmer, WET pattern transitions into the PNW.  Depending on which model scenario plays out, for a day or two, most of the precip could be limited to western WA, maybe clipping NW OR from Salem north, before the whole region gets dripping wet as the holiday period progresses. Or, it may simply be wet everywhere.  The storms charting for the holiday period are likely to be quite wet and windy.  Normal for late November.  

 

Post-Thanksgiving week: temperatures are likely to cool down a bit, as storms moving in from the west-to-northwest will have lots of cold air support.  Great mountain snow period.