Models Coming Together = Forecast Snow Totals

11pm Saturday…

Now that we are within 18-24 hours of our snow (or no snow for some) event, the general plan is coming together nicely.  This evening it was time to put some numbers on the table and put a forecast plan together.  Let’s hope the actual weather decides to stick to that plan this time!  I’m sure there’s going to be some wrinkle at the last moment…there always is.

TRENDS I’M SEEING THIS EVENING

  • The stationary front is situated slightly farther north and the surface low pressure system that moves across the Northwest is progged by all models farther north than morning runs, and this has been the trend for at least 24 hours now.
  • This means the snow/rain line is farther north = light snow totals from the metro area south into the Willamette Valley.
  • If this is correct, Super Bowl travel plans within the metro area may be just fine with a wet snow/rain mix falling all the way through the evening.
  • The possibility exists that there will be little to no snow on the ground in the metro area by Monday AM.  I give that about a 30% chance, thus the TRACE-3″ forecast
  • Areas farther north really get dumped on…Longview to Olympia could be big winners with that elusive one foot of snow in that area.

FORECASTS I USED ON-AIR TONIGHT

markheadlines_coldwx

 

marksnow_portlandoutlookpercentages2

 

Note there is a good chance Astoria/Tillamook get far more snow than Salem?  That’s because the heavy snow falls just north of the front and specifically just north/northwest of a low pressure center as it moves onshore.  If you are south of the low pressure area, than at least part of the next 36 hours you’ll see rain.  In fact the evening run of the trusty ECMWF did exactly that, changing snow to rain in the metro area tomorrow evening even in the hills.  If that model is correct we’ll see almost nothing (snow) out of this in the lowest elevations around the metro area.

WHAT COULD GO WRONG WITH THE FORECAST?

Here’s the most obvious wrinkle.  If the front decides to sit about 70 miles farther south than expected and the low tracks inland well to our south, Portland gets a huge snowstorm from tomorrow midday through Monday AM.  But as I mentioned, the trend is the opposite direction.

FOR TOMORROW:

Be aware that between 8am and 1pm there’s a decent chance we switch to lots of snow mixed in or even all snow in the metro area.  But with temps above freezing I think a large area of sticking snow on roads is unlikely.  Of course it’ll be close and roads WILL turn snowy high up in the hills.  Factor that into your Super Bowl travel plans.

I’ll be here at work from Noon-11pm; likely doing some live Facebook videos during the afternoon while we are not on the air.  You can find those on my feed MARK NELSEN page over on the right.

Chief Meteorologist Mark Nelsen

 

43 Responses to Models Coming Together = Forecast Snow Totals

  1. Longview 400 ft says:

    Currently 35.2
    Snowing (wet)
    Slush on the deck.

  2. Update in Woodland at approx 700 feet and two miles from I-5. Temp 34 and all snow. Already starting to stick to the deck and grass.

  3. Paul D says:

    Temperature dropping in Hillsboro! Down to 38. Time for snowpocalypse February 2017!!

  4. Sapo says:

    Hope is still alive…all the 12z models trended south today, (and the 6z NAM last night too) which is a good thing. WRF has gone from saying just a trace to now 6-8″.

    And if the Euro is right, west metro gets two feet while PDX doesn’t get a trace.

    And if this ends up even further south than modeled now, major snowstorm. It’s possible, we’ll see.

  5. Mama Druid says:

    Really wet snow falling in Happy Valley at 650′ – not sticking. Temp dropped from 37 to 35 in last 30 minutes.

  6. Scooter says:

    Here near Barton Park at 300 ft. the temp. has dropped to 39 degrees with steady rain. No rain gauge but it was hard steady rain all night and the ponds here at the farm are filling from the seasonal creek and the sump pump is running for moving ground water. The long of it is for us it looks like flooding will be more of an issue.

  7. JohnD says:

    41.9′ here at 200′ in inner SWPDX. I just went out to the car and CONFIRMED a splat test! At 41.9′–are you kidding?! This means one thing, the upper atmosphere is DEFINITELT cooling dramatically. My optimism is renewed that surface temps may be cold enough to support snow eventually! Another nail biter!

    • Camas500 says:

      It’s 35 and all snow here at 500 ft. So, the cold air of 32 is just above us. Everything is turning white here in Camas just due to how much snow is falling. Now if we could just see temps drop by 3-4 degrees…

    • JohnD says:

      It bodes well that it is 33′ and snowing now in Astoria! You would “think” that it is just a matter of time for here. But we’ll see. As Mark alluded, minor changes could have major consequences,

    • Camas500 says:

      We’ve dropped to 34. Still snowing heavily. Bring that could air down from aloft!

    • Camas500 says:

      Wind seems to have picked up from ENE.

  8. umpire says:

    One last comment on the ice on Friday. At 3:30 I chipped ice off my car to travel to Milwaukie to ref a basketball game. Left NE Portland about 4:30, where it was 32 but dry. Milwaukie was 36-37, raining on my way home about 8:00. NE had another shot of zr, and the trees around Rose City golf course were covered and bent way low. So my point is, just a few miles can mean a great difference in storm outcomes, especially in Portland.

  9. Camas500 says:

    Moderate snow (all snow) in Camas at 500 ft. But, 35 degrees and not sticking. Slight wind out of the east.

  10. ron says:

    All snow now in Astoria.

  11. GTS1K' says:

    Rain/snow mix. Currently 35.7 – down from 37.5 at 7:30…

  12. Jack in Corbett says:

    Starting to snow here in the gorge at 450 foot elevation. Temp now 37 but starting to drop in last hour. Currently mix of snow and rain.

    We still have some chunks of ice from storm two days ago.

    That’s gorge weather!

  13. runrainR says:

    More snow than rain now in Happy Valley at 500′. Huge flakes! Like someone dropping snow balls. Still just 40 deg on my thermometer.

  14. Alohabb says:

    Not sure models handles this , but I’m aloha I’ve gone from 41 to 38 in the last hour and I’m not in a heavy shower.

  15. Just started snowing in Woodland, WA at about 700 feet.

  16. Longview 400 ft says:

    Currently 35.5
    Snow & rain showers

  17. boydo3 N Albany says:

    Things are moving faster than forecast. Look at the coastal temps
    already in the 30s and dropping.
    http://www.wrh.noaa.gov/mesowest/symmap.php?map=pqr&dem=&scale=6&wx=0&res=60&disp=&limit=&wfo=

  18. JohnD says:

    I guess we can’t expect two bullseyes in a row here in Portland. Looking like this time Puget Sound gets the goods. Still holding out for an unexpected miracle though. Temps–slowly–trending down along with steady rain. Still a ways to go even for a splat test.

    • Wow, ECMWF says I might get 6-8″, other models have less dramatic totals. Given how disappointing this winter has been up here snow-wise, I’ll believe the relocated Dome is broken when I see the evidence.

      Would be fun to get a good dumping tonight… it’s been five years since the last one here.

  19. runrainR says:

    Timber Jct. at 700′ snow covered and 32 deg.

  20. Alohabb says:

    Chunky rain in Aloha.

  21. Deer Is. at 750' says:

    It has changed over to snow here. Sticking to the trees and cars but not the driveway yet.

  22. Alohabb says:

    So if the front sags south, Portland will get nailed. Looking at temps and radar, is that potential occurring???

  23. Wendy-Silverlake, WA says:

    The decks and cars are turning slushy, but nothing on the ground itself. The temp was 35 with the mix, now 34 with the snow.

  24. Wendy-Silverlake, WA says:

    There’s a whole lot of snow mixed with the rain this morning.

  25. Alohabb says:

    Looks like we just missed out on the major snowfall, but 1-4″ will certainly cause issues.

  26. Paul D says:

    More excitement than the Superbowl!

  27. JJ78259 says:

    Looks like the rain maker is in process lots of heavy rain in Portland. Could be a damp Sunday!

  28. Looking forward to a major snow dump up here, 36F and falling… pdx has had their fun, here’s to Seattle area getting its turn

  29. What do you think for Woodland, WA above 500 feet?

  30. Longview 400 ft says:

    I have to admit I am looking forward to the snow than the Superbowl. But if the Seahawks were in it things would be opposite.
    I’ll keep everyone posted if things develop as forecast.

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