Cold and Lowland Snow Potential

Models have pulled back significantly since my last post. Initially, it looked like it would be a perfect setup for cold and snow with the trough digging south and a bit over the ocean which helped with snow chances. Now models are starting to show most of the cold eject out into the Pacific which would not be favorable for lowland snow.




The change is clear in the 18z GFS, the trough doesn't dig into the Northwest and instead goes out over the ocean.


Similar with the EURO.
Although SOME over the ocean trajectory can be good for lowland snow, this is way too much over the water and it doesn't really get the cold air there. This is well illustrated on the 850 MB temp maps which were showing temps get down to -10 but now only down to -7. This is because the trough doesn't really dig south and most of the cold air never makes it to Washington or Oregon. -7 is still cold enough for snow and I will get into snow chances next. But this is certainly a major step back from what the previous runs were showing.

Lowland Snow Potential

We are now at the time-frame where I can say there is SOME potential for lowland snow this weekend. A frontal system enters the area on Friday and behind it, the colder air fills in. By Saturday evening, snow levels will lower significantly and a convergence zone looks to form in Western Washington. In the PSCZ, snow levels could drop down to sea level, and a quick inch of snow will be possible through Sunday morning. Going forward into Sunday and Monday, things look to cool down a lot and the snow level should stay at sea level throughout Sunday evening and Monday in Western Washington. This is the period of time that is worth watching for some impact lowland snow in Seattle. Moisture chances look to be on the lower side at this time, but models do not handle mesoscale features well at this point. But if some sort of low pressure were to spin up and provide moisture, could be a snowy Monday for the Puget Sound. 

The Portland metro will likely be too warm for snow in this period but could be some snow at 500 feet and above.

After Tuesday, models have no clue what will happen but I do expect things to remain cold and snow chances should continue.

At this point, I do not think there will be any major snow in Seattle or Portland but there is still a lot of uncertainty surrounding temperatures and the amount of moisture present. 

Will keep updating.

Have a good night!!

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