If you feel some pressure in your forehead today, there could be a reason.
Currently, the Northwest is experiencing unusually high barometric pressure.
In fact, the third highest pressure in the last 25 years, reaching around 1042 hPa, is shown in the pressure graph at SeaTac below (red dashed line shows the highest pressure observed yesterday) .
This extreme pressure lowered the water level, resulting in much less high tides in Seattle than would occur under normal pressure (see below, red observed, blue predicted )
Late tonight and tomorrow morning, an air wave will move over, bringing light rain in the lowlands and snowfall in the mountains. Nothing special.
And then the chilling fun begins on Saturday. This morning, cold air (purple, blue) begins to move in from the Northeast.
And by Sunday morning it will spread to the entire region.
Cold air will lead to high sea level pressure and a large pressure difference will create strong winds blowing into and downstream of gaps in our country’s terrain.
As shown in the wind gust forecast Sunday morning, strong northeasterly winds blowing out of the Fraser River Valley into northwest Washington, and a downward sloping easterly wind will descend on the Cascades from North Bend to Enumclaw, moving towards west and south Sea-Tac. Some bumpy landings can be expected.
And now I’m going to let some of you down. Almost no lowland snow accompanies cold air. The setup is just wrong.
Here’s the cumulative snowfall through Sunday at 4am.
There may be a few snowflakes between Portland and Chehalis, but beyond that, all of the snow will be at higher elevations. Good amount in the Rockies.
Sunday and Monday mornings will be quite cold (in the mid-20s in the western lowlands), so disconnect hoses and keep your pets indoors.
