WEST SEATTLE SNOW? Newest forecast suggests two possibilities


Thanks to Alan for the photo – an SDOT snowplow-equipped vehicle by Riverview Playfield today. Rehearsing, perhaps? The afternoon “forecast discussion” is out and the National Weather Service is talking a little more about possible snow:

There has been very good agreement in the models that it will be about as cold as it gets aloft Sunday and Monday in an upper trough. That means at 500mb, where nobody lives, it will be -38c. But at the surface, that means that as showers move through the area, the snow level will fall to near sea level. Looking at 850mb — at first wet snow showers would probably only stick to the grass, but as you get out into Monday and Tuesday as colder air comes down the Fraser — then colder weather and a hard freeze become likely. Of course it often happens that the moisture is gone by the time the coldest air arrives. For now the forecast is light on details and light on snowfall. By the time you get out to Wednesday, the GFS suggests an overrunning snowfall that turns to rain later in the day, but the Euro is slower–holding that off til Thursday.

Bottom line, too soon to say, but snow is a distinct possibility. So this is the perfect time for getting familiarized with SDOT wintry-weather resources – all collected in this recent post. Metro‘s snow/ice info is here. (If and when wintry weather arrives, of course, we’ll deploy those resources in our 24/7 coverage too.)

5 Replies to "WEST SEATTLE SNOW? Newest forecast suggests two possibilities"

  • Erithan December 2, 2016 (11:45 am)

    Saw last night some very, verrrrrry brief snow/rain mix. =)

    • MetPatrick December 2, 2016 (1:48 pm)

      Not possible, soundings showed FL at 3800 ASL so there was no way you saw a rain snow mix, add into the fact that warm layer extended well beyond 850mb makes this statement VERY suspect.

      • Erithan December 2, 2016 (2:54 pm)

        When I said brief I meant literally seconds, was just a wisp beneath the street light, called my dad who walked out and confirmed it was a bit of a mix during that brief moment.

        sorry if I offended, was just meant as a little comment since I noticed it, some spots do tend to get a bit cooler because of lack of light etc.  not trying to argue. I may have been wrong, I know, my Seattle snow panic brain perhaps kicked in! Hehehe

        • MetPatrick December 2, 2016 (3:49 pm)

          It’s ok and I apologize if my quip was a bit snarky but after reading your comment, my brain shouted NOPE, NOPE, NOPE…I will reiterate that is is very unlikely ( on the order of 99.9% ) that what you saw was likely “Mizzle” ( unofficial meteorological term ) which the layperson often confuses with rain/snow mix esp. when precipitation is super light and fine by definition. 

          This mistake is widely made and by no fault of the observer but educating those unfamiliar with the myriad of Atmospheric conditions usually leads to incorrectly identify a precipitation type or cloud formation etc.

          I will again confirm after looking at the mid and upper level obs during the time period you stated in your comment and the temps from the surface to 4000 ft were too warm for snow outside of the freezing level which at the time was near 3800 ft so it’s extremely unlikely that frozen precip forming above 4000 ft made it through that warm column below 3800 ft down to the surface.

          • Erithan December 2, 2016 (5:23 pm)

            No worries, can be hard to get things across on the net sometimes. ;) Thanks for the information! Learned something new! =) I also feel old! Lol

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