Saturday, January 6, 2018

Snowpack Update: Slightly Low Today But More Snow is Expected

It is just past the new year and folks are wondering about our snowpack.  What is the current status?  Will La Nina give us abundant snow in the future?    This blog will take these questions on.

First, the current status.  Here is the percentage of normal of snowpack (from the wonderful SNOTEL web site).  Snow water equivalent (SWE) is shown, the amount of liquid water that would result from melting the snow/ice.   

Low values (less than 50% of normal) in Oregon, California, and Nevada.   But much better over WA state, at 75% to 100% of normal.  Low, but not significantly down.
A better view is found in an expanded image over WA State.  The Olympics and north Cascades are in good shape, but the central and southern Cascades are closer to 75% of normal.  Enough to open our ski areas and not to worry about water next summer.

The snow levels (elevation of hitting snow) on the western side of the Cascades are certainly higher than during  the past few years. 

I can demonstrate this with the NOAA snow analyses for the region for this and the past two years (below), showing you the snow depths on January 6 for 2016, 2017, and 2018. 

Much less this year. Less snow over the high plateau of eastern Oregon, and MUCH less over the middle to lower slopes of the Olympics and Cascades.

 Interestingly, the average conditions (temperature and precipitation) over the past 90 days have not been that unusual over WA state (see below), with temperature being near normal and precipitation above normal.  But averages can be deceiving, we just haven't gotten the right weather set-ups for snow:  much of the time we had high pressure (cold and dry), with occasional warm/wet periods.  Neither are great for snow accumulation in the mountains.

But there is great reason for hope.

This is a La Nina winter, and the effects of La Nina (more snow in our mountains) usually don't snap in until after the New Year.  The latest sea surface temperature anomalies (difference from normal) over the central tropical Pacific show we are firmly in a La Nina, with colder than normal ocean temperatures (see below).  La Nina's tend to produce cool/wet conditions over the Northwest: which means SNOW.

To put it another way, the atmospheric dice are weighted for Northwest snow!  What about the new model forecasts from the UW WRF forecast system?  (see below).  Encouraging.

For the next 72 hr, substantial snow (.5 to 3 feet) in the north Cascades and southern BC.

And even more for the next 3-day period (ending 4 AM Friday).

So if you enjoy skiing and winter sports, I would be optimistic.  Things are ok now, but may get very good during the next month.  But no guarantees.😊 


AnneScott said...

Yesterday's heavy rain and high snow levels melted some of the existing snowpack too. The rivers shot up very fast yesterday around Vancouver BC.

Nicholas Michael Cummins said...

Thanks for the interesting post. One thing that does seem a bit off to me is the first snow depth image for 2016-01-06 showing widespread, albeit light, snow cover over the Puget Sound lowlands and the Willamette Valley. I don't recall a major lowland snow event in Jan. 2016, certainly not one that resulted in low-elevation snow cover spanning from the Fraser River Valley through the southern end of the Willamette Valley.

Rod said...

Thanks, Cliff, for giving the link to the snotel site.

Raveneye View said...

A bit optimistic.

Eric Blair said...

Nicholas - the area around Portland and most of the Willamette Valley was hit with more than three major snow events in last year's winter season, and early January was one of the more significant ones on record. Moreover, the temps became much colder than normal, and the streets around Portland were iced over and nearly impassable for over two weeks last January after that major snow event.

Ansel said...

Yes it's true- the Cascades are marginal for snow and if the climate warms by just 3-4 degrees, Snoqualmie and Alpental will be history as far as skiing. Mount Pilchuck used to host a ski area but it died for this reason. Our ski areas are not that high, and they average very close to the freezing mark even in midwinter. Contrast the Rockies where, although there are dry years, it is NEVER too warm for snow in midwinter. I went to school 4 years in Gunnison Colorado. In four winters, it never once rained, even in town, during the period December through February. If there was precipitation it was ALWAYS snow.

This is why our glaciers have shrunk so much. It is not about precipitation. It is about temperature. (It is also the reason the quality of our skiing often sucks.)