The Ridge Will Shift and the Northwest Will Warm

The last few days there has been substantial sun, but there has been a chill in the air because we have been on the eastern side of a big ridge of high pressure.  As I have described several times in this blog, there is northerly flow on the eastern side, with cooler air moving out of the north.   Today's (4 PM) upper-level chart at 500 hPa (roughly 18,000 ft) illustrates this situation.

As illustrated by the temperatures at Seattle-Tacoma Airport, today's temperatures were near normal, even with a lot of sun (red line, average high; blue line average low). Fairly strong northerly winds were blowing and they had a decidedly cool edge to them.

But everything is going to like the change and most of you (except skiers) will like the change.

The ridge will not be going away, but will shift eastward so that by early next week we will be on the western side of the ridge, a region with southerly flow and warm air.  

Here is the upper-level flow (500hPa) that I showed you above.

By Saturday morning (8 AM) , the ridge has moved eastward and tilted.

And by Tuesday morning it has strengthened and moved to the Rockies, with the Northwest under warm southwesterly flow.  A small shift further eastward and we could be in heavy rain.

Now lets watch the surface air temperatures evolve (purple is cold, red/orange is warm).

Tomorrow's highs are in the lower 50s.

Major warm up by Friday (4 PM), with upper 50s getting into western Washington, 60s in western Washington, and 70s in CA.

By Monday afternoon, 60s are into western Washington and Tuesday will be even warmer.

Precipitation?  According to the Weather Services forecast of the accumulated precipitation from the GFS model, we will be essentially dry (white).  But those poor devils in the eastern U.S. will be wet...and much of that will be snow in the Northeast.

The persistence of the ridging/high pressure over the west this year is extraordinary.  Based on the latest forecasts,  It appears that there is little chance we will build much snowpack during the next week or so.