A Mild Winter So Far, But That Could Change

As we've discussed in this blog, the winter of 2024/25 got off to a decidedly mild start.  So how does this winter compare to historical data?  The map below shows the temperature ranking for the U.S. for December.  Pink colors indicate that December was in the top 3rd of warmest Decembers ever, going back to 1895.  Orange color shows areas that were in the top 10% of warmest Decembers ever.  As you can see, much of the western U.S. was in the top 10%, including parts of eastern Washington and north Idaho.  



After a very wet November, we had a pause in the action after Thanksgiving.  But the mostly-rain storms reappeared by the middle of December.  So for the 2 months combined, nearly all of eastern Washington has had above-normal precipitation, with the Columbia Basin receiving twice as much precipitation as normal.


To put this in historical perspective, the precipitation we've had so far puts us in the top 10% of wettest November-Decembers.  



It's worth noting that this anomaly includes the Columbia Basin.  That doesn't mean that Moses Lake has had as much precipitation as Newport.  Just that the Basin has also been getting more precipitation than normal.  The Cascade rain shadow hasn't been as much of a factor, since most of these storms have been coming at us from the southwest.

So how does this translate to snow cover?  You can see in the map below that the Cascade valleys as well as north-central Washington has a good snowpack on the ground.  The rest of eastern Washington as well as north Idaho doesn't have much snow to write home about.


The current state of the mountain snowpack depends a lot on where you're looking.  Orange and yellow dots indicate below-normal snowpack, green dots are near-normal snowpack, and blue dots are above-normal snowpack.  


In general, the mountains of eastern Washington and the Panhandle are in decent shape.  The Cascades are lacking in snowfall so far this winter.  It's worth noting that the snowpack in southern British Columbia is also running behind normal.  This could have implications for the flows on the Columbia River this spring and summer.  But we still have 3 more months to accumulate mountain snow.

In the short term, after our weak storm system today, we'll be dry for the next week through Thursday, aside from an occasional snow flurry.  Temperatures will continue to be mild for the first half of next week as strong high pressure will spread over the northwest US and southwest Canada.


Then we could see a bit of a change.  High pressure is expected to move farther out to our west.  This pattern leaves us open to the potential for cold air to come down from Alaska and Canada.  First time we've seen this pattern this winter.  Too much uncertainty at this point to make any specific predictions.  But expect temperatures to at least be colder next weekend, probably the coldest of the winter so far (which isn't saying much).  A light snow on Friday might accompany the cold front.










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