Inland Northwest White Christmas Outlook

 Are we going to see a White Christmas this year?  Now that Christmas is less than a week away, there is increasing confidence with the upcoming forecast but a few details are still unknown.  Let's dive into it!

Historical chances

Let's begin with a map of the climatological chances for a White Christmas.  

Source: NCEI.  Based off 1991-2020 Normals

As you can see, the chances depend quite a bit on location.  It's no surprise that for the Inland NW, the further north you go, the better the chances.  Historically chances are only around 10-20% for the Tri-Cities area into the Lewiston-Clarkston Valley, increasing to near 60% for the Spokane area, while chances are 90% or higher for Republic and the Methow Valley.

This year

So far we have only talked about historic chances and you may be asking, "What about this year?"

Great question; let's take a look

We will begin with our current snow depth as of this morning courtesy of our CoCoRAHS and COOP observers.  

Snow depth reports (inches) on December 19th, 2023

Areas along the East Slopes of the Cascades have snow on the ground, as does the Republic area and the areas around Deer Park, Elk, and Athol.  Some other areas have light amounts of 0.5-1.0" of snow on the ground.  The Wenatchee area, Columbia Basin, Spokane area, and down through the Palouse and Lewiston area have little to no snow on the ground.  

So for many areas, chances of a White Christmas will come down to the weather leading up to Christmas.

For the next several days, mild temperatures are forecast before a cool down to normal temperatures from Dec 23rd-25th, so we expect there will be more melting of our current snow through Friday.  Here is a look at the forecast high temperatures from Dec 20th-25th.

NWS Forecast of High Temperatures, issued 3 PM December 19th, 2023

What is going to cause this cool down?  A weather system will usher in a cold front by Friday night.  Snow levels will also lower, with the best chances for lower elevation snow into Saturday across the Idaho Panhandle.  Here is a map showing the chances for 1" or more of snow:

NBM (National Blend of Models) probability of 1" or more of snow from 4 AM PST Dec 22 - 4 AM PST Dec 24th, 2023

The map shows little to no chances for 1" of snow for the Okanogan Valley down through the Columbia Basin and Lewiston area, a 10-20% chance for the Spokane area down through the Washington Palouse, increasing to 30% or higher for the Idaho Palouse and much of the Idaho Panhandle.

What about after that? Another weak weather system may arrive Christmas Eve night into Christmas Day.  Given the colder air that will be in place most of the precipitation is expected to fall as snow if any develops.  As of this writing (Dec 19th), there is a 20-30% chance of light snow for most of the region with a 40-50% chance along the East Slopes of the Cascades.  It's possible high pressure will be strong deflecting all precipitation north of the region. Stay tuned to the forecast for updates.  For the latest forecast for your area, head to weather.gov/spokane   

So for this year a White Christmas is forecast for the East Slopes of the Cascades, Republic area, and in the mountains.  Elsewhere, not all hope is lost yet.  Merry Christmas!