Changes in the weather

We have had a very unusual fall and winter - a high pressure ridge parked itself off our coast and has been giving us a mild dry winter and sending paralyzing cold and snow to the North East. But nothing lasts forever

From Cliff Mass:

The Ridge Begins to Shift
This has been the winter of the ridge, an area of high pressure in the in the lower to mid atmosphere that has brought us consistently warm temperatures.   Downstream of our persistent ridge there has been a trough over the eastern U.S. that given them unending cold and snow.

But the ridge is shifting, with substantial implications for our weather in the Northwest.

Let me remind you of Ridge 101.  The plot below shows a situation with a ridge over the western U.S.  The color shades are the heights of a pressure surface (in this case 500 hPa).  Where the higher heights push northward, there is a ridge, pushed southward--a trough.   When the ridge is over us (like in this figure) we are generally dry.  During most of the year, we are also warmer than normal when the ridge is overhead (but during the middle of winter sometimes we can be engulfed by fog at low levels).  East of the ridge there is northwesterly flow, bringing cold air from the north.   If a disturbance is embedded in this NW flow, we can have precipitation--yes, even snow.  On the western side of the ridge, there is southwesterly flow:  warmer than normal temps and usually wet.  This is when we get the atmospheric rivers, with heavy precipitation.

Much more at the site. We can use the snowpack. That and some late-season skiing - the lack of snow has been killing local businesses...