February 12, 2021

Snowstorm Tonight

The models have converged.  Uncertainty is less.  A snowstorm will hit western Washington tomorrow.

But it will be a snowstorm with a twist: radical differences in snowfall within a matter of tens of miles. 

The theme from the movie JAWS should be playing as I show you the latest infrared satellite image (see below), with lots of moisture ready to move in tonight.

Cool air is in place.  How much snow piles up is all about moisture ..or lack of lack of moisture.  It will start snowing this evening and will continue through early afternoon tomorrow (Saturday).    

The total snowfall predicted  by the UW high-resolution model through 1 PM Saturday is shown below.

The contrasts are amazing. The southern Sound (south of Tacoma) and the Kitsap will get pummeled with 8 inches to one and half feet of snowfall.  The southern Cascades will get several feet.  Portland, cooled by the outflow from the Columbia Gorge will be whitened by 4-8 inches with some freezing rain mixed in.

Seattle and central Puget Sound will be a study in contrasts.  Near the Sound 3-6 inches of snowfall is likely, dropping to a half inch over the extreme eastern suburbs. 


The latest NOAA/National Weather Service High Resolution Rapid Refresh forecast, started 6-h later than the UW model, shows a similar, but more bountiful snow accumulation through 4 PM Saturday.
Not much snow in Bellingham and eastern WA escapes most of the snow action.


And the latest European Center model forecast of total snowfall through 4 PM Saturday is similar, but has even more snow.


Why less snow east of Puget Sound ? Downsloping easterly flow, as air moves towards an approaching low pressure area near the southwest Washington coast.  Sinking air kills precipitation

What about uncertainty?   The NWS ensemble forecasts (running the model many times) are all on the same page for  SeaTac Airport snow, but the amounts range from 4-12 inches.  The exact amount depends critically on the exact position of the low center approaching us and the amount of easterly flow.


Late Sunday and Monday there will be more snow, turning to rain on Monday.   But more on that in the next blog.

Finally, I should note that the mountains are going to get an incredible amount of snow during the next 5 days and avalanche danger will increase.   Take a look at the European Center snowfall totals through Tuesday at 4 PM.  4-6 feet in the mountains.  A lot of people have died from avalanches this year...please be careful.


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68 comments:

  1. I'm still convinced the models are not giving the wind as much credence as they should. I expect totals to be lower north of tacoma than what's currently predicted. Maybe 2 to 4 inches due to the east winds.

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  2. Wow - from 0.5' to 8" in Bellingham, depending on which model you believe.

    I guess we shall all find out soon enough!

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  3. In Tacoma, it's already beginning to snow again here. Don't know for how long but flurries here at 1:46pm.

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  4. The variation is already noticeable. A friend on Capitol Hill in downtown Seattle said they had 2" last night. Here, three miles south of downtown, not a trace of anything.

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  5. So no snow in Snoqualmie or North Bend as we are east of the Sound?

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  6. With the easterly winds, is there much of a lake (Washington) effect? Would say, the U-District get more than Kirkland?

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  7. As always Cliff, I rely on your info for the best predictions for coming weather events. However, never have I been more hopeful that predictions for the coming day will be wrong for central Olympia where we've already had nearly 10 inches of snow with 7 inches on the ground earlier today. In conclusion, thanks for your extraordinary blog!!!

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  8. Appreciative of all the excellent explanation of these snoOOow weather events particularly - thankee! As a quiet aside, why is this blog suddenly dumping a bunch of DRM warnings? "You must enable DRM in your browser to play some audio or video on this page" (..don't really want to have to do that)

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  9. By “passes” do you mean Snoqualmie/Blewett by chance? WSDOT has a different forecast with quite a bit less snow predicted.

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  10. Thank you as always Cliff. Like I wrote a few days ago - great setup for Kitsap. Curious how those east winds play out for you folks on the other side of the sound. I am specifically remembering the snow we had in Jan 2011 (you have some good blogs here on that) where east winds also played a big role. Crossing my fingers here for 8 inches or more (450 feet on a hill between Silverdale and Seabeck).

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  11. Thanks Cliff! I just arrived in Seattle from Tumwater (I escaped early). I got stranded down there for a couple days in 2019. Not this year! I'm supposed to work on Sunday, we'll see if I can even get there. Worst case scenario, I'll be stranded at home.

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  12. What area does "extreme eastern suburbs" refer to? Issaquah and Snoqualmie? I'm in Kirkland!

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  13. ah dang east bellevue is getting not much, eh?

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  14. nothing in Bothell yet and the dusting from yesterday is all but gone as well.

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  15. I agree that the models are not giving enough credence to the wind. South Hill Puyallup had very little accumulation and a lot of that has sublimated away. The roads are bare and dry even in neighborhoods with a lot of trees that normally stay wet.

    It's been snowing for a few hours and nothing is sticking, which is exactly how it was yesterday. Wind is a steady 8-15 mph out of the east and it's been that way since yesterday morning.

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  16. The east winds are starting to increase out here in Enumclaw. Very cold wind chill.

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  17. This seems to happen a lot lately, where Bellingham and Skagit get the dry, bitter, cold winds and very little snow accumulation. Kind of insulting really.

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  18. It starts snowing around 6pm, near Boeing Field, "Trace" amounts now

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  19. so far a little accumulation in Bellevue.. snow is in very small flakes and looks icy.

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  20. WRF caved spectacularly to the Euro and other models in the hours leading up to the event. It looks increasingly likely that this will be a major snowstorm for Seattle metro (well above 6" along the sound, especially in the northern neighborhoods). Any reasons for the sudden change in the forecast from the WRF?

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  21. 1200' SW Washington I have a solid 12" with 36" drifts 28F. It's an odd mixture of flakes and stuff the size of coarse salt accumulating at almost an inch an hour. Might end up with 3' by Monday. Drifts could be 6'.

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  22. Thanks Dr. Mass for keeping us informed about these recent snow storms.

    It was really nice taking a late night stroll in Kirkland at 26F with snow!

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  23. In Shoreline it's been an icy snow so far. Coming down straight like rain. And then blowing in gusts. 3-4 inches accumulation now I'd say.

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  24. It is scary out in Enumclaw. Never seen anything like it. On a side note, my power went out. PSE is pure garbage. In my 60 years of life of living around the country, I have never had so many power outages than with PSE. I moved here 3 years ago and have had more power outages with garbage PSE than I had in my entire life.

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    1. Maybe don't live in the middle of nowhere? Tens of thousands of others deal with the same thing. Get a generator.

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  25. ECMWF got it right. I'm above Lake Goodwin in NW Snohomish County. We've got 7 inches. Still snowing.

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  26. I am sitting here in Central Tacoma at 6:42AM, it's still snowing steadily here and have not checked the amounts, but it's more than a couple of inches I think. I will report a bit later. Just saw what looked lied a car drive up S 15th, right in front of my house without issue. It looked like it may have been a typical FWD sedan, street covered in the white stuff.

    Some friends were heading to Blaine yesterday in his 4x4 Nissan Frontier late yesterday. Have not heard if they made it or not, though you said that as you get near the Cascade foothills, the snow totals are less.

    Anyway, should be an interesting day!

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  27. Bellingham 7 am report - about 4 inches but coming down hard - 25 degrees.

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  28. East bellevue has 4 inches as of 7:30 am.. Honestly more than i expected, im pleasantly surprised!

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  29. 7.5 inches of light fluffy stuff and counting in Ballard at 8 am

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  30. Hi Cliff,

    I am in a debate with a colleague about what you mean by snowfall. Is snowfall the amount you expect to accumulate, or the amount you expect to fall from the sky?

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    1. Snowfall is from the sky, snow depth is accumulation

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  31. Good job forecasting, Cliff! We're on Beacon Hill and the dogs are in heaven. Perhaps 6 inches here on North Beacon. Gusty, dry snow blowing. A fairly rare event for us. I seem to recall we went ten years in Edmonds once, under the convergence zone, without a decent dry snow. It's lovely, especially the 11:00 p.m. walks when no one is out.

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  32. At 7:47AM, Central Tacoma got not quite 7 inches of the snow and it's still coming down fairly steadily.

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  33. At 8AM near Gig Harbor (Artondale) at 250’ we have around a foot on the ground give or take an inch. It’s still snowing pretty hard with plenty of moisture on it’s way from the SW. In my entire lifetime as a Wa native I have never seen such a powdery snow here in the Puget Lowlands. Because of this our big conifers are not snow loaded and breaking limbs so the chances of us experiencing a power outage has decreased quite a bit.

    I always check the data which Dr. Mass shares to get my weather information and I’m very grateful for the time and effort he spends doing so. I feel the local media has downplayed this one a bit, perhaps they’re a bit gun shy about being caught in a snow “bust”. Cliff didn’t promise our nearly epic snow, in meteorology everything is a game of chance, but presented the raw data and gave his experiences opinion. My guess based on the data was 8”-16” and it looks like we’re headed for the upper end.

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  34. Glad to say forecast was wrong about eastern King County. Saturation is beating the wind. Hard snow and 5” at 850 feet in North Bend.

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  35. Almost 10 inches above hood canal at 500' and 27 degrees, still snowing lightly with a bit of breeze.

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  36. 9:30am and at least 6" here on Orcas (~500 ft elevation)- probably more like 7 or 8, steadily coming down! Started right about 11 last night. When it comes to snow I only listen to Mr. Mass and the European Center Model, hasn't steered us wrong yet!

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  37. Solid 8" in south Bellingham at about 20'ASL and still snowing hard.

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  38. Your forecasts are so spot-on that I hang on your every word. It's difficult to know exactly how much North Lynnwood will get by the end of this, but I'm guessing 8-12". We have about 4" right now at 9:30 AM Saturday. We still have the rest of today to go, as well as Sunday and possibly Monday. It's quite lovely to look at, though, and gives me a great awe for nature in all her wonder.

    I always stay snowed-in about a week longer than others. My hubby used to take care of all that, but I cannot. So that's my reason for not 'lurving' snow.

    A more important topic for me, though, is trying to understand your maps, what lows, troughs and other terms mean, and on and on ad infinitum. Having said that, I learn a bit more each time I read your informative blogs and listen to your wonderful podcasts.

    Thank you!

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  39. Lots of snow here on Lopez Island, about 8 inches already overnight, still snowing. Models got it right! Good j

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  40. Lots of snow here on Lopez Island, about 8 inches already overnight, still snowing. Models got it right! Good j

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  41. 11 inches in Shoreline by 8am. Powdery stuff, no good for snowballs.

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  42. Spot-on, maestro! While Mt Baker and eastern Whatcom County typically get hard-hit, the current event snowfall began just at midnight, and it was very cold with tiny flakes (sectored plates). At this writing - 9:50 am - things have heated-up literally (5 degrees F), and we're getting about 1/2" per hour, and that's nothing compared to what's happening west and south of here. The light snow makes for easier digging-out. 'Actually happy to be 'on the fringe' of this front; the wood shed's getting sparse.

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  43. Feeling bitter. In black diamond, we got more of a wind storm than snowstorm. Probably less than a 1/4 inch of accumulation, more like a light dusting. How could it be that this one area was completely missed by the snow when all close by areas received at least 6 inches of accumulation or more? Strange is an understatement.

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    1. Cliff discussed this in the latest posts. Strong, easterly, downslope winds drive out the snow. Just about 8 miles east of you in Auburn on SE Lake Holm Road, I had 7" of dry snow.

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  44. 10" on North Beacon Hill. I really hope all the forecasts are wrong and it doesn't turn to rain on Sunday. I'd love a week of snow and cold like February 2019.

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  45. You nailed it Cliff!

    Great work pulling all the competing information together. The UW and HRRR models totally biffed for the Northwest interior where we already have 5+ inches and still coming down hard.

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  46. South Bellevue (Lk. Hts, just off I405 & Coal Ck Pkwy, elev. 200') We have 10" of very dry stuff. Temp is 30-degrees.

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  47. Only 3" here in Sequim/PA......snow shadow may be helping to lighten the load.

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    1. William you beat me to the comment, south of Sequim, 350' and getting close to the hills, still about 2" accumulation. Snowing lightly. I'm deep in that rain shadow and typically get less than even downtown Sequim.

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  48. Likely well over one foot of snow now near Gig Harbor (Artondale area), and no sign of slowing. Thank you, Dr. Mass, for your great weather blog. I have been following your forecasts since 2015 and have always appreciated the accurate and informative content. When you say you're going to the grocery store, I take note!

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  49. 10.5" snow accumulation on San Juan Island (about 40' elevation) as of noon Saturday. Still snowing. Weather radar predicts snow to continue throughout the day.

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  50. 11” to a foot on Capitol Hill and CD

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  51. I'd say that we have 6-7 inches here in Victoria, BC. It's hard to tell for sure though. I think that we must have had some strong N.E. winds during the night because I can see evidence of drifting. It was a pretty decent snowfall for Victoria, nonetheless.

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  52. Depending on location, I'm hearing reports of 18-24 inches in Tumwater and the surrounding Olympia area with 30 inch drifts. And the higher ups wonder why no one can get to work. Unbelievable! Until Cliff updates us, I'm not counting on getting anywhere until Tuesday.

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  53. Yup now over 10 inches of snow in the San Juans (Lopez Island)....Cliff the models you used got it right for us up north sound.

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  54. Several inches of snow in Redmond.

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  55. East Bellevue: It looked like it was gonna end at like 2PM, but then a bunch of more snow exploded in the radar, and this time it's not getting affected by the easterlies, so we got almost an inch in an hour

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  56. 12" san juan island at 300' break out the sleds!

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  57. At MLK and Union in the CD, as of 4:00pm Saturday, we have 11” as measured in the top of our car.

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  58. At least 8 inches accumulated in North Kenmore, and it is still snowing.

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  59. 8 inches in Mount Vernon at Big Rock.

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  60. Update at 5:11PM. In Central Tacoma, I think we totaled out at 10" or so by the time it stopped snowing sometime between noon and 1pm or so.

    Went for a walk and it's difficult to walk in many areas of a small route I took. Some had cleared sidewalks, but most had not. I took a friend's dog out for a walk at that time.

    Now just before 5PM, it began to snow again, but appears to have reduced or stopped completely at this time.

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  61. Got about 7ish inches @ 150' above sea level in Bellingham. 28 degrees most of the day 30 now. Snow seems to be tapering at the moment.

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