Mountain snowpack has fallen behind; could impact water supply

December was a cold month with plenty of precipitation, wet, frozen, and even freezing. Our region’s mountain snowpack is averaging 110% above normal.

But after a milder and drier than average January, our mountain snowpack has fallen behind. In the Puget Sound region, Olympia, Seattle, and Bellingham were all warmer than average during the month and only had around half of the average precipitation.

Snow flurries dust western WA but unlikely to continue

Last winter, we also had a milder and drier period from mid-January to mid-February resulting in the mountain snowpack ranging from 65% to 95% of the standard average for the middle of February. As of Feb. 1 this year, the latest snow depth statistics from the Northwest Avalanche Center showed that the Cascade and Olympic Mountain snowpack ranged from 58% to 93% of normal.

The amount of water in the snowpack is important since our mountain snows are ‘water in the bank’ for the coming summer and fall seasons.

The Natural Resources Conservation Service mountain snowpack water equivalent map shows the Olympic and Cascade Mountain basins that drain into the Puget Sound area ranging from 79% to 90% of average.

Last winter, the cool, wet spring allowed the mountain snowpack to catch up by mid-May, resulting in a mountain snowpack that was close to average. The mountain snowpack usually reaches its peak around April 1st, but last year was an exception.

There is still time for the mountain snow to catch up, and a change from this drier weather pattern looks like it will unfold starting late this week. A series of Pacific weather systems are slated to move onshore, with rain at times and mountain snow heading into the middle of next week.

The outlook for the rest of February shows around seasonal temperatures and increased odds of greater-than-average precipitation. And looking ahead through spring, the outlook offers greater odds on cooler than average temperatures and around normal precipitation.

These outlooks offer the promise of building up our mountain snowpack, providing water supplies for agricultural irrigation, fish, recreation, and consumption this fall.

Water resource authorities will be keeping an eye on our mountain snowpack during the rest of this winter and heading into spring, and so will all of us.

Follow Ted Buehner, the KIRO FM news meteorologist on Twitter