Huge Improvement in Mountain Snow Situation and Much More is in the Forecast

Ski areas are opening and expanding operations throughout the region for a good reason:  the past week has brought large additions to the mountain snowpack....and models are suggesting much more is coming during the next ten days.

The mountain snow situation this fall has been a roller coaster ride, with huge snow dumps followed by warm atmospheric rivers that took most of it away.  Fortunately, the snow roller coaster ride is over, with substantial gains during the next month.


To see how much better things have gotten, compare the USDA SNOTEL percent of normal snow water (SWE) on December 1st and this morning (see below).

On December 1, after multiple warm atmospheric river events, the entire Northwest was below normal with ALL of Oregon and half of Washington possessing less than 50% of the normal snowpack. Forget Thanksgiving skiing this year!

But what a difference two weeks made.  This morning the red (below 50%) areas are almost gone, with several areas near normal (green) in northern Washington, northern Idaho, and importantly in the central Sierra Nevada range.  HUGE improvement.



What Happens Now?

During the next 48h, most of the snow action will be south of Seattle, as a Pacific low-pressure system moves southeastward off the Pacific coast, making landfall over central Oregon (see surface weather map at 10 PM Wednesday).  This forecast map below shows sea level pressure (solid lines) and low-level temperatures, with blue and purple colors indicating cold air.   Very cold east of the Rockies.


The snow accumulation through 4 PM Thursday reflects this low-pressure track, with the Oregon Cascades and northern California enjoying 1 to 2 feet of additional snowfall.   This is excellent for water resources to our south.

On Saturday, a weak front will move through our region(see surface map of sea level pressure and temperature at 4 AM Saturday), which will move the precipitation north again.


The 48h snowfall total ending 4 PM Saturday shows the shift northward, with substantial amounts in the North Cascades and southwestern BC.   Our snowpack will be solidly near normal for the entire region by this time.


The Seattle Times had a headline about lowland snow in Seattle...but that is not going to happen this week.  I guess they are trying to sell more newspapers with that headline.

The subsequent five-day period brings even more snow in the mountains (see the forecast by the European Center Model below), with up to approximately two more feet above 4000 ft.


What about the European Center one-month forecasts?   You better take a deep breath before you view this.

For the next month (through January 14th), the EC extended model is going for much colder than normal conditions over the entire West Coast (see below)


And snow will be bountiful over the entire region (6-10 feet)


And don't forget we are in a moderate La Nina, with the rest of the winter weighted towards cold/wet conditions.



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