Warm Days, Cold Days

I think most folks are familiar with the idea that temperatures turn colder after the passage of a storm. The Norwegians were the first group to figure out why this was, and they developed the well known ideas of warm fronts and cold fronts a little over 100 years ago. 

But there are other ways you can have big temperature changes from one day to the next. And these last few days were a classic example of Inland Northwest weather. Since Thanksgiving, we’ve had cloudy days with cold temperatures right around freezing. Here’s the high temperatures last Friday.

But then on Sunday, the skies cleared (in some areas) and the temperatures warmed into the lower 40s. 

But you’ll notice that there were plenty of folks who were stuck in the mid 30s. The reason? The clouds weren’t removed, just pushed into other areas by the northeast winds. 

Here’s a satellite picture from Sunday. Spokane is the red circle on the map. Note that while skies were sunny there and to the north and east, it was still cloudy in central and southern parts of eastern Washington. The northeast winds were only strong enough to push the low clouds out of Spokane, but not all of eastern Washington.

But overnight, the fog and low clouds reformed in all of the valleys of eastern Washington and north Idaho. So this is what the satellite picture showed on Monday afternoon.

This satellite picture really does a nice job of showing how the Columbia Basin that we live in is surrounded by mountains  this has a huge effect on all of our weather.  In this case, the mountains help to trap our low clouds and fog.  And the low sun angle at this time of year just can’t dissipate the fog.  And so we remain cloudy and cold all day.  No cold front.  Just thanks to fog and low clouds. Here's the high temperatures from today (Monday).

As we talked about in our last blog, a dramatic shift in the weather pattern took place.  High pressure in the West keeps us dry, while low pressure in the East is making things rather cold, and in some parts, snowy.  How long will this pattern last?  For at least another week.  There is going to be a weak weather system slipping through the high pressure by the end of this week and another slightly stronger system on the weekend.  It may start off as a little snow, but most of any precipitation will be in the form of rain.  After that, more high pressure next week, although there is a low chance of another weak weather system next week.

There is a possible pattern shift around the end of next week (Dec 13th)  that could lead to wetter weather for us.  I’ll discuss that in another blog in a day or two from now.