Weekend Snow Possibilities & Cold Weather Next Week

5pm Thursday

The coldest airmass we’ve seen in late February since at least 2011 will be arriving Sunday night.  Now that we’re within 3 days of possible snow at the lowest elevations, it’s time to get into a bit more detail.

HIGHLIGHTS FOR WESTERN VALLEYS

  • There is no chance for lowland snow through Saturday night...we’ll have typical rain showers through this time.  In fact quite windy & mild Saturday (50-52 high)
  • During the daytime Sunday, the sticking snow level will hover in the metro area hills (close to 1,000′).  But we’re talking off/on snow showers.  Sunbreaks in-between combined with typical daytime heating keeps the “stickage” in the hills.  Showers will be light as well which helps.
  • Roads below 1,000′ should remain snow-free during the daytime Sunday
  • Sunday evening colder air rushes in, but it’s very dry air too.  Most likely snow showers change to light flurries and then end.  Temperatures drop below freezing all areas
  • Any water left on roads Sunday evening will freeze, plus some spots in the western valleys may see light snow accumulation on those roads.  There will be icy/snowy areas on some roads for the Monday AM commute but it may not be widespread
  • Total snow at the lowest elevations?  Could be NOTHING for many of us through this period…not a real wet pattern.  I’d be surprised to see much above 1/2″ in the city.  1-3″ more likely up above 1,000′ of course.

 

TO SUMMARIZE:  AT THIS TIME, I THINK “SLEDDABLE” SNOW IS UNLIKELY FOR MOST OF US IN THE LOWEST ELEVATIONS.  LESS THAN 1″ IS LIKELY FOR MOST

This graphic summarizes my snow thoughts:

Beyond Monday morning, the vast majority of our models keep us dry through Wednesday.  The airmass will be the coldest so far this season.  Very dry air combined with clear skies could drop most of us into the teens Monday night and/or Tuesday night.  But under bright and strengthening late February sunshine, afternoon highs should still make it close to 40 each day.  Think typical Central Oregon winter weather.

WHAT ABOUT COAST & GORGE?

COAST: Too warm during the daytime Sunday for sticking snow out there, but ZERO to 1/2″ would be my best guess for coastal towns Sunday evening and night.

GORGE:  We don’t have a cold easterly wind blowing in the Gorge, so not much different from westside.  A TRACE to 2″ is most likely Sunday evening through Monday AM.

 

TECHNICAL DETAILS

For a snow/cold event, models are in surprisingly good agreement through at least Monday.  All show the upper-level trough digging down right over us Sunday and Monday from the north.  The sequence of events sure looks like the November 2010 freeze.  The cold air just drops in from the north instead of coming at us through the Gorge.  850mb temps are in -6 to -8 range during the daytime Sunday, which this time of year should be (just barely!) enough to keep sticking snow off the valley floor.  If we had more vigorous showers forecast by models I would go for sticking in spots during the day.   Then they are all in good agreement drying things out quickly after 00z Sunday PM.  Folks this is a classic case of moisture disappearing right when the cold air arrives (like Nov 2010).  Note the 4pm Sunday to 4pm Monday precipitation forecasts from both WRF-GFS and ECMWF…almost nothing

And you see the snowfall forecast through Sunday 4pm…which seems a bit high even though it’s showing all of 1/2″ at most in the metro area.  Check out the Cascades!  Yep, this should be the best weekend of the entire winter up there!

How about the cold?  I’ve checked out the February 2006 and February 2011 late season cold snaps.  A few interesting points…one is that the cold airmass modifies quickly compared to midwinter events.  The other is that with full sunshine and weak Gorge wind, it’ll be easy to get highs up into the upper 30s.  Thus my forecast highs of 38 both Monday and Tuesday.  Both ECMWF and GFS bottom out 850mb temps around -11 to -12 over Portland on Monday.  That’s real cold for this time of year, although not record low.   It’s interesting that we’ve never made it down to -14 over Salem after the first few days of the month.  This is also not going to be a big east wind event for us, even Monday and Tuesday.

Later next week?  Since we have more cool troughs dropping in on us later in the week, the most likely scenario is a switch to onshore flow and rapid modification of the airmass.  That would lift snow levels above the valley floor in the 2nd half of the week.  That happened in 2006 and 2011…not much snow going out of the cold airmass since there is no Gorge wind to hold in the cold air.

I will be off for my weekend the next two days, but back in Sunday.  If there’s anything dramatically different from what I’ve posted above, I’ll update this blog on Saturday.  Otherwise you can assume nothing has changed.

Chief Meteorologist Mark Nelsen

 

 

104 Responses to Weekend Snow Possibilities & Cold Weather Next Week

  1. Light sleet showers for the past hour or so. No accumulation.

  2. Dang wind, blew the snow off the trees!

  3. I think us having a light wind is helping the snow to stick a bit.. How about the rest of you got any pics or Vids?

  4. GTS1Kft says:

    Spittin’ rain – 38.3…..

    • Elisa in Kalama says:

      42° in Ocean Park still windy but nothing like earlier. And of course there is rain. Heading home to Kalama in the morning. Hopefully I’ll get stuck at the beach!

  5. Clear skys and low temps. I sould be able to run my heater at 853 watts for about 3.5 hours before trees shadow hits them. Or use our bread machine to make some home made bread.

    Icould also use our smaller 800 wat grill to make ham and cheese sandwhiches. When done with cooking, use the Oasis machine we have and make some hot coco.

    Then fire up mr buddy heater at night to stay nice and warm.
    That is or plan to beat the cold weather .

  6. I appologise for the 2 accounts, apparently I was using another account on another device that was set differentyly, I have a total of 8 devices.

  7. W7ENK says:

    Is it just me, or does this seem a bit weird for middle February?

    Kinda early, I would think… 🤔

  8. W7ENK says:

    Winter Weather Advisory just issued for Portland metro.

    https://inws.ncep.noaa.gov/a/a.php?i=19253750

  9. Wendy - Silverlake, WA says:

    There seems to be a severe lack of wind today. It was windy for awhile this morning, but it has been sunny and nice for the last couple of hours and somewhere between 45-48 degrees depending on which thermometer you look at. Is this going to change anything? I was under the impression the front would pull the cold air down south so just curious what is going on.

    • Sprayandpay says:

      I am hoping it’s just WAA ahead of the system. Warm Air Advection where warm air is pulled up ahead of the cold system before temps drop when the system fills in due to the SW flow.

      There are many things it could be actually but I’m hoping that’s the most dominant role.

    • Lee Wilson says:

      Oh we had winds, I had posted video evidence but it seems that some one doesn’t like the truth lol.

    • muxpux (Longview) says:

      We had quite a bit of wind here just south of castle rock. Several large limbs came down, and while taking a walk, heard lots of popping and creaking coming from the trees over the roar.

      • thankfully our nieghbor wasn’t under his tree, a 3 inch branch came crashing down, I think his tree is dying…its becoming a giant stick…It should be core sampled to check for core rot.

  10. cgavic says:

    I wish I lived in welches. we live in sandy at 885 feet, but in a little valley in sandy which gets cold and snow when the higher end of sandy doesn’t get anything at all…

  11. Garrison - Aumsville says:

    I’m a bit of a newb here, but is there a forecast model that comes out at noon everyday? Can someone tell us the results of it???

  12. Sprayandpay says:

    Get ready to bring your stinkiest dirtiest generator out!

  13. Another thing to keep in mind is the chance of snow later next week as we transition out of this cold air. Based on my experience, significant lowland snow tends to happen more often as cold episodes end than it does as they begin.

  14. Roland Derksen says:

    Slushy snow falling here this morning after a night of cold rain. Tomorrow will be more intresting however. We’ll probably see some “real” snow.

  15. Model runs have been pretty consistent that I will get rain-shadowed (actually snow-shadowed) due to westerly flow, so I don’t think I’ll see more than a dusting.

    The question for my area is the wind; the Fraser outflow is forecast to be on the strong side. That’s caused localized outflow windstorm conditions on the island before. In fact, we’re something overdue for such a windstorm, given that the most recent Fraser outflow episodes have not caused one to manifest.

    Makes me glad I heat and cook with propane; gale force winds, temperatures in the 20s, and no heat is not the best of combinations!

  16. JohnD says:

    Overall during the next few days it will be a lot of fun being a weather fanatic–even without a significant snow accumulation expected in the city. A pretty good chance that there will be a snow shower or two at certain points–especially in elevation. And it will be fun finally getting a batch of bonafide cold air. Definitely looking forward to driving here and there to do some “snow spotting” on Sunday! And who knows: Maybe we’ll luck out and have an intense shower come right over us?!

  17. WEATHERDAN says:

    Let it snow let it snow. Peace.

  18. Tanis Leach says:

    I’m just hoping this is half an inch and Wednesday Night to Thursday morning is a larger event if the 12z European model turns out.

  19. ocpaul says:

    But, then again….

  20. Hey if you going in the mountains, take care, Avalanche warnings are in effect as well in sme areas.
    http://www.intellicast.com/Storm/Severe/Bulletins.aspx?location=USWA0064

  21. Nahtalkin says:

    Brian has a low of 19 degrees Monday night for Portland and a high temp. for Tuesday of just 37, this is almost exactly what I saw in my dream last week……I guess the “Great Spirit Chief” wasn’t fooling me at all…. You never can tell sometimes he’s playful just like the “Trickster Coyote”…….Enjoy the snow Sunday afternoon and be careful driving Monday morning. Peace to all.

  22. Jason Hougak says:

    The ECMWF and GFS are both inline for cold weather through the extended period. Night skiing tonight for pre birthday celebration!!!

  23. Jake in Gresham says:

    Pretty clear this first wave of arctic air is really just cold air for us in PDX. Sunday through Wednesday are going to be chilly. About it.

    So a flop for those that wanted to at least see snow in the air. Not confident we’ll even see that.

    The second wave of arctic air according to the GFS appears to be backing off. Washington Seattle area may get a surprise but I’m not seeing it down here for PDX with a gorge influence. Get ready for Spring folks. My 2 cents.

  24. Ken in Wood Village says:

    Hmmm, a little impressed with the 12Z GFS. It want’s to keep us cool to cold for a longer period of time. I’m posting a GFS model but not sure if it will show up correctly. Last time I posted this it looked so different from the actual website. Let’s hope it does it right.

  25. Just looked on the radar, some wares are getting snow mixed with rain, while passes are getting slammed.Ths snow mixed with rain is about 20 miles N.W of us and its jsut a a small sliver. Were also getting some good gusts of winds.but nothing srious.

  26. Models are flopping around as to the amount of snow I’ll get. They did that before Christmas, too. I think it’s pretty safe to say that it will be cold and I’ll see at least some flakes in the air. Beyond that, it really doesn’t seem possible to tell quite yet.

    If memory serves, last time it wasn’t until about 6 hours before the event that the models all settled down and converged (which happened to be on the snowier end of what they had been forecasting).

    Also, no models are forecasting an epic dump of snow in the lowlands, so it’s pretty safe to assume that won’t happen.

  27. Jason Hougak says:

    Some of the guys in NWS office are really getting excited about this on the PDX weather discussion. Not sure how many of you visit that part of our NWS site but really a weather geeks paradise when it comes to weather like this. http://www.wrh.noaa.gov/total_forecast/getprod.php?wfo=pqr&pil=ZFP&sid=PQR

    • Ken in Wood Village says:

      When the weather starts getting interesting I always look at the NWS discussion to see what they are saying…hehe!!! Looks like it’s a very complex weather ahead. 🙂

    • Diana F. says:

      Those NWS discussions are a veritable goldmine, and a daily, a.m. and p.m. read!

  28. hmm, we will have to see 🙂 Everytime we say snow though we seem to scare it away. I am looking forward to seeing it, but as for the icey conditions, I think I will keep our car parked.

    so rats, no chances of a power outage.

  29. alohabb says:

    In preparation I’ve gone to the store and stocked up on all the essentials in case I am unable to get around for a period of time. A couple 12 packs of my favorite beer and crap food.

  30. Paul D says:

    Schools have already been canceled for Monday!

  31. W7ENK says:

    NWS is jumping on board… kinda.

    SPECIAL WEATHER STATEMENT
    LOWLAND SNOW POSSIBILITY
    NATIONAL WEATHER SERVICE PORTLAND OR
    914 PM PST THU FEB 15 2018

    LOWLAND SNOW POSSIBLE LATE SUNDAY NIGHT, MONDAY MORNING.

    COLDEST TEMPERATURES OF THE WINTER LIKELY EARLY NEXT WEEK.

    https://inws.ncep.noaa.gov/a/a.php?i=19190018

  32. W7ENK says:

    😂😂😂😂😂

    Lol

    No.

  33. F40 Fan says:

    LOL !!! Always love it when the TV Mets say it will be a minimal event maybe a flake here and there… As we wake up to a snowstorm….

    • Ken in Wood Village says:

      Been there done that!!! I think it was 1995 or 1996 (not sure what month) were they said it was going to be just about an inch of snow but the snow kept coming (but the thing about that storm was we had a lot of East wind). In the end, I think downtown Portland had between 5-10″ of snow. I lived off 134th and East Burnside in a duplex. The way the building was orientated, we had a snow drift in front of the front door that was about 6′ tall. I’m 6’2″ so I’m thinking it was about 6′. We had to enter the apartment through the back door…lol. It was an amazing snowstorm. I can’t remember, but I think they actually issued a Blizzard Warning for that storm. 🙂

      • JohnD says:

        ‘Really need the East Wind for major winter weather in our climate. We all know it.

      • It was in 95 but then back in the 80’s we wound up with 3 feet of snow one time…that was quite the site to see, lost power due to high demand, but we had a pot belly stove tht kept us kids nice and warm. we would heat water on the stoves top and make hot cocoa, then we’d plave out meets in the snow to keep them frozen..we were with out power for 3 days 🙂

    • JohnD says:

      It is just that Mark is a really really skilled craftsman and normally spot on. There have been exceptions though–as he would be the first to admit. In the end Mother Nature decides!

  34. oregonalex (Rock Creek, 240 ft) says:

    Down to TWELVE!??!??!??
    Did Mark just casually put 12F west of Cascades on his slide for next week?

    The lowest HIO (being the coldest spot around) has been in recorded history after Feb 18 is 17F, and that in the early sixties. Even high teens would be a big deal. 12F would be historic, not to mention a horticultural bloodbath in my yard.

  35. Anonymous says:

    thank you! have a great weekend!

  36. ocpaul says:

    Wow, thanks for all the ‘positive’ news. Glad to hear the chance of lowland snow is minimal. Said no one, ever.

  37. JohnD says:

    🙂😒 It will be fun having a bit of cold air for a day or two–and maybe with luck observe a flake or two. But overall not the overview that most of us were hoping for.

  38. Ken in Wood Village says:

    First 😉

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