How the Grinch Stole Northwest's Christmas Snow

We are now getting close enough to the holiday season to make an unfortunate forecast:  there probably will not be enough snow for Cascade mountain skiing during this holiday season in WA and OR.   As we will see, a major grinch will be a strong atmospheric river that will develop next week.

We start with a very poor snowpack in place.  Here is the % of normal snow water equivalent (SWE) in the western U.S. mountains. The western Cascade slopes are now 15-20% of normal.  The Olympics are 23%.  A bit better in the north Cascades and the eastern slopes, but still considerably below normal. With the recent precipitation, the California Sierra are doing much better....a nice turn of luck for them!

The NW Avalanche Center summarized the snow situation (snow depths) at some major ski areas (see below).  Mount Baker is 9% of normal, White Pass has NO SNOW,  Crystal has 6%, and Stevens has 25%.  We are way worse off than last year, which was not a good year.  6 out of the 11 sites have ALL TIME RECORD minimum snow for Dec. 15th.

So we start off with a sparse snowpack.  Next week a major ridge of high pressure builds over the West Coast.   Here is temperature anomaly (difference from normal) for the NCEP ensemble mean at 850 mb (around 5000 ft) for Monday December 21st at 4 PM.   Warmer than normal (orange colors).

The Climate Prediction Center (CPC)'s 6-10 day forecast for December 22-26th continues the trend with warmer than normal in the west.

A major issue is that a major atmospheric river will form over the weekend.  Warm, moist, air with heavy rain over Northwest mountains.  Here is the vertically integrated water vapor content prediction for Saturday at 10 PM.  Very juicy (red and white indicates the highest values).  There will be more flooding...guaranteed...bad for snowpack.

What about snow this week?  Let me snow you the UW WRF model totals for the next two 72 hour blocks.   First, 72h hours, perhaps 3-6 inches in the WA Cascades.

Next 72 hour, up to a foot in the north Cascades, but not much south of Snoqualmie.  Much more in the mountains of SW BC.   Whistler will be in better shape,

The trouble is that we won't get that much snow this week and then that snow will be hit hard by the heavy rain and warm temperatures.  Sorry.