We’re about a month away from meteorological winter, and mother nature won’t allow us to move into spring without another cold and snowy feeling.
The cold is certain, including a hard freeze across the region.
Snow forecasts are less certain – but it looks like the lowlands west of Washington or Oregon will see flakes of snow – the question is which.
The movement of cold air into the Northwest has another meaning: rainfall adds significantly to wet California.
Cold
On Wednesday and Thursday, a high-pressure trough will dominate the area, creating cool, cloudy but generally dry conditions (see upper–500 hPa pressure level–map for Wednesday morning below).
One benefit of high pressure would be to prevent astronomical King Tides, minimizing flooding and tidal overflow.
But on Friday and Saturday, a lower trough will move south down the eastern slopes of the great ridge, pulling cold air from northern Canada into inland British Columbia and into the Pacific Northwest.
This is the upper level map for 7pm Saturday. You can see the high pressure offshore ridge, but a considerable amount of roughness is moving through our region.
I have studied these snow situations for decades. This is not a structure/location perfectly suited for heavy snow on the lowlands of Washington, but close enough to worry about.
Now, take a look at the surface pressure chart at 7 p.m. Saturday, with color showing the temperature right on the surface. Wow….I’m going to go get my gloves and beanie ready! Purple and blue indicate cold air….cold enough for snow.
You will note a low center off the northern coast of Oregon. Weak type, but has enough “juice” to bring snow to most locations. Too far south and weak to whitewash Seattle…. but one small mistake can change everything.
By 4 p.m. Sunday, cold air will spread throughout the Northwest region. It is important to get homeless people off the streets on Monday and Thursday mornings. The temperature will drop to about 20 degrees. A hard freeze.
OK, you want to know about snow. Here is the cumulative amount of snowfall through Sunday night.
A small error in the forecast can dramatically change the snow prediction….so stay tuned.
