Turning Colder and Snowier

December was a rather mild month, and that's putting it mildly.  The temperature remained below freezing for only one day in the month, and that was on the 1st.  All the rest saw the mercury rise above the 32F mark each day.  We had several days in the 40s, and we nearly reached 50F on the 5th.  It was the warmest December at Deer Park going back to 1998.  At Spokane Airport it was the third warmest December since 1947. All of this is likely a product of a strong El Nino.  

But we're looking at a significant pattern change in the weather.  You've probably already heard about it or seen it on your phone app or TV  broadcast.  

Here's what the upper level weather map currently looks like.  You've all seen the storms heading into California recently in the news.  As these storms make landfall south of our area, we only get a weak dying weather front.  But the deep cold area of low pressure over the Aleutian Islands will play a role in our pattern change.

By this weekend, part of that Aleutian Island low will drop into the Pacific Northwest.  Meanwhile the California storm will be over the southern Plains.  This combination brings colder than normal temperatures to just about all of the lower 48 states, something we haven't seen much of this winter.  The new low in the Aleutian Islands will send another storm our way during the early part of next week.

Here's a timeline of the temperatures we'll see for the next 10 days.  For the next few days we'll remain rather mild.  Temperatures will start to drop a bit by late Friday and get rather cold for the weekend.  They'll stay around freezing for the second weather system.  We'll get the coldest temperatures so far this winter by next week, with highs in the 20s and lows in the teens or single digits.  There's a LOT of uncertainty in the forecast for the end of next week.  Some computers are forecasting a return to the 40s, while others keep our high temperature below 0F.  No way to know at this point what is going to happen that far out.

The precipitation-type graph helps shows what we're expecting for the next 10 days.  Rain with some mixed snow will be the dominant weather type for Thursday through Friday.  Snow will start in earnest late Friday night and continue through Saturday evening.  After a short break on Sunday, the second weather system will bring more snow to our area on Monday and Tuesday.  There's a decent chance of snow even for the rest of next week.

As always, the snowfall amounts are the toughest part of the forecast.  For the first storm, the consensus is 3-4".  Locations west of Spokane will see less, while some folks in northeast Washington will get more than 4".  Here's what one computer model thinks will happen.

The second weather system currently has more uncertainty.  It's similar to the first storm, but there's much less agreement in the computer models on the exact storm track and where the snow will fall.  So we'll have to stay tuned for updates on that second system, as well as to find out how much snow we may receive after that.