December 12, 2015

One Last Storm and Snow Fest In the Mountains

Even native Northwesterners are getting a bit storm weary, but there is one more storm to deal with before the weather cools and calms down.  A sea level pressure forecast (solid lines are isobars, lines of constant pressure) show a deep (975 hPa central pressure) low center off northern Vancouver Island at 4 PM.  Temperature is shown by the colored shading.  Not super warm.  That is good for snow.

This afternoon you can expect very strong winds over NW Washington and along the coast, with gusts to 40-60 mph (see the forecast of sustained winds at 1 PM from the UW WRF model).

Wind gusts at Smith Island over the eastern part of the Strait of Juan de Fuca are already (11 AM) reaching 50 knots....and they are still increasing (see below)!   These are southeasterly winds, resulting from the interaction of strong southerly winds with the Olympics.

That low center will move eastward across southern BC, weakening as it does so, but still producing a large difference in pressure (pressure gradient) over western WA and the coastal waters.   The forecast below at 4 AM illustrates this.

Winds could gust to 40-50 mph around Seattle, particularly near the water.    You might want to go to sleep with a flashlight handy.

The freezing level is relatively low right now (about 3000 ft) and with plenty of precipitation from this system, there will be substantial snow today, certainly above 3500 ft.  Then the temperatures cool behind the low (northwesterly flow follows) and we will move into a cool, showery regime with moderate snow in the mountains.    

Here is the  forecast 72-hr snow total for the next three days.   We are talking of several feet of snow in the Cascades and Olympics.   Very good for skiers.   This period will guarantee skiing over the holiday break.  And really good in increasing the snowpack for water resources next year.

The forecast models have a crazy strong storm forecast for later next week...but this is too far out to have much confidence.  Stay tuned.


  1. What a winter, we're all having.. Some folks thought this year's El Niño wouldn't dare mess with the west coast. Luckily, my name isn't one of those folks who thought that.

  2. just wondering if that "crazy strong storm" you mentioned to possibly be later next week is what shows up for Friday night?

  3. Nothing happening up here north of Bellingham. The sun is even peeking out.

  4. I'm feeling snow below 3000 - maybe 1200 - looks so unstable on the tail end and drawing much cooler air. Been 25-35 mph winds on the Sequim prairie and the blue hole is a goner.

  5. Yeah, but the blue hole lasted almost until dark. It was a good one. Standing in Sequim at mid-day, it felt like I was in the middle of a huge cyclone. All around were dark gray clouds, moving fast. Overhead, blue sky. No rain.

    But as Michael DeMarco said, it's gone now. Which is OK, since the ground at my house was getting dry again. Zero rain for the last two days.

  6. 53 mph gusts here in Eatonville this afternoon. Crazy windy afternoon! No usual.

    1. Lol! After the winds have died down they post a wind advisory! Better late than never? Why does that always happen?

  7. South Puget Sound / Case Inlet gusts of 45 mph now.

  8. Douglas firs in full sway. Fun to watch.

  9. Pretty much done occasional gust in the 30's but nothing that gets your attention like it did this afternoon before they posted the advisories.

  10. Are these storms pulling heat out of the Warm Blob?

  11. Cliff, could you comment on how this late-fall weather differs from the expected El Niño pattern if at all? Seems we have had warmer temps but more storms, precipitation, and flooding than predicted. Can you tell us where we stand?

  12. Hey Cliff, why tease with "a crazy strong storm forecast for later next week" if it's "too far out to have much confidence"? I hate getting hepped up, only to have it fizzle!


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