Morning Update: Rain Arrival A Bit Later

9:30am Thursday…

It’s cold out there!  At 9am temps in the mid-upper 20s across all of the metro area except those spots exposed to the “milder” east wind coming out of the Gorge.  The east wind will gradually die back this evening, but I don’t see any mixing south wind (if any) until after the rain begins.  So no one below 1,000′ (most of us) will see a dramatic warming today.  As mentioned last night, if rain was arriving right now, or earlier, we would have a widespread freezing rain event west of the Cascades…it’s all about timing.  So where is the rain?  Save this link to radar to watch it during the day.  You generally want a “green” area to get rain all the way to the ground.  Those are echoes above 20dbz.  It’s trying to move onto the central Oregon coast at this hour.  All coastal sites have jumped well above freezing, so no freezing rain out there today.

A change this morning in timing though…all our mesoscale models have slowed down rain arrival in the valley yet again; this is very good news.  Here is the 1:30pm RPM rain/snow outlook


and 1pm WRF-GFS


Both show no (other than a sprinkle) rain arrival in the valleys until after the noon hour.  They DO still hint that some of those isolated valley locations in the Coast Range could see freezing rain (Vernonia, Manning, etc…) to start.  But with the forecast later arrival of rain, that decreases further the chance that we see anything frozen on roads here in Portland.

I did notice one more thing on morning models/maps.    This system is so weak, there is a possibility we don’t get ANY mild mixing wind today either in the Valley or the Columbia River Gorge.  I think it’ll just be in isolated spots.  So high temps may only be around 35 and we just sit there tonight (assuming solid cloud cover).  And in the Gorge there is plenty of dry air left to allow some evaporational cooling as the precip starts.  Could still be icy out there late this afternoon or evening when the rain moves in.

The layer of cold air over us west of the Cascades is incredibly thin.  32 degree and warmer temps are only around 700-800′ up!  By the time you get up to 2,000′ it was 46 degrees over Salem!  Now that is a good inversion.

More later….

Chief Meteorologist Mark Nelsen




55 Responses to Morning Update: Rain Arrival A Bit Later

  1. I say to hell with this E PAC ridge. Yay, we had our cold wave. But come on folks, look at the collective damage done by this sustained anomaly which dates back to early fall. Little snow in the mountains, skiiers (including myself) bummed, ski areas closed, possible water issues next summer if this continues, etc etc. What I wish for Christmas is good old fashioned cold Gulf Alaska trough, boatloads snow in mountains, some active frontal passages, ie cool moist PNW weather.
    I take a long cool wet winter/spring over this crap.

    • slim1357 says:

      I’m with you PeterB. This has certainly been interesting weather but that ridge can’t go away soon enough.

  2. Marcustheweathernut says:

    Believe it or not but it’s actually snowing lightly in woodland…..??? Upper layers must have cooled enough with evaporatinal cooling from the virga!!!!

  3. Ron says:

    steady light rain in Astoria, but we’ll above 40 degrees–feels downright balmy!

  4. Ryan says:

    Radar showing some precip right over I-5 between woodburn and Salem. Below freezing. Any Fz rain reports?

  5. alohabb says:

    29 in Aloha. Not warming up real fast.

    • Ryan says:

      Was the bulk of the moisture supposed to be this far north? If it had come in more south, it would be a mess right now, at least south of Tigard and west of PDX. It’s well below freezing there while PDX is up around 34/35. C’mon precip, get here already!

  6. Like a Kid in Snow says:

    I am in Dallas and we are getting this very light snow…I do not know all the differences in precipitation but it is definitely not ice pellets. It is tiny flakes or kind of like flying frost I guess. At first I thought it was just the trees losing their frost but it is everywhere. The radar is showing precip over us right now.

  7. vernonia1 says:

    37 @ Timberline??? whoa…..

  8. Taylor says:

    32 degrees here at Clackamas, OR we will just get plain rain here when it comes in. No worries here! 🙂

  9. vernonia1 says:

    no comparison between the link from Mark & the one of WA They are getting WET

  10. Garron near Washington Square says:

    I have friends coming in from Banks area for lunch and Christmas shopping this afternoon. I called it off just now as a precaution. I don’t think that where I live in Beaverton there will be a prolonged freezing rain event, but them getting back home, they might be at a higher risk. Temp here still hovering 26-27 wind calm at 10:30. Still about 24 out just past Banks, only they have a very light east wind as well. I’d hate to have them get stuck on the side of 26 on their way home.

  11. Hal in Aims says:

    hopefully school districts in certain areas are monitoring closely

  12. boydo3 N Albany says:

    Last Thursday when it looked like it was actually going to snow, it was fun! Friday was a snow day! Then Sat and Sun….Mon, Tues, Wed…..Thursday. Kids are all sledded out. No school for a week.
    Moms and Dads are tired of it. Snow is so dry you can’t make a snow ball or a snow man.
    Only the main streets are snow free. Garbage collection ceased in my neighborhood a week ago. Thus lots of garbage cans still at the curbside since last Thursday night. But at least it’s frozen so it doesn’t stink.
    Broken pipes in schools, businesses, homes….
    Fender benders daily…
    Plumbers and body shops are booming!
    I’m pretty much ready for some plain ol’ rain! And since I’ve been unable to work (I’m in construction don’t ya know), the paycheck is gonna be a bit skinny at the end of this month.
    It’s pretty outside. And walks in the snow are nice, but.. yeah, I’m ready to be done with it. I think the kids in the area are ready too..I KNOW the parents are! 🙂

  13. dharmabum says:

    Rob, where are you? We need a long range prognostication.

  14. dothgrin says:

    Query: 10:13 and 25 degrees in Aloha/Hillsboro with moisture rolling in very soon. Any thoughts on afternoon ice?

    • Ryan says:

      Mark says no, but I find it very hard to believe we warm up 6-7 degrees in the next couple hours with no south wind. Just watch the temps closely!

    • dothgrin says:

      Unless temps shoot up in the next hour (clouds are already filling in over the area), I see a flaw in the forecast for the western side of the metro area. The first radar signatures are just kicking in near Forest Grove.

    • …been warming up quickly here outside vernonia, 30.8, and it looks like i’ll be above freezing by the time moisture hits the ground…

    • Garron near Washington Square says:

      I believe the farther west ie towards Forest Grove, Banks, the better the chance for freezing rain you’ll get. That being said, I believe Mark covered the fact their will be no moderation NO SOUTH wind componet is huge in these events. We may stay just around freezing all day today W/O a south wind. While if you were just a couple hundred feet higher, the temps are well above freezing.

    • vernonia1 says:

      up to 33 @ 10:45 in Vernonia.

  15. Aloha Rainshadow says:

    Just outside checking temp with handheld Kestrel therm…25.2 just near Intel.

  16. Kenny says:

    The new 12z GEM is brings a snowstorm to the region starting sometime next Friday through the weekend. It is COLD.

    • Ryan says:

      Good news! Thanks Kenny.

    • Kenny says:

      The new 12z GEM spins up a surface low and makes the perfect track as it makes landfall at the Central Oregon coast and goes straight east. This pulls cold gorge east winds. Huge snowstorm if this verifies, tons of moisture.

      • Ryan says:

        That sure does look juicy! Cold enough though? It’s only 8 days out, so that’s better than 10+ days out. Any thoughts, Mark? Or are you still tracking today’s temps closely?

    • Chuck on Mt Scott says:

      Only 10 days away 🙂

    • Aloha Rainshadow says:

      This setup would probably be marginal, because the storm is coming in from the NW, it looks like a 2008 setup with the triple point needing to stay W and E of Portland…problem is, even if there is an east wind blowing…there may not be cold enough in the basin…this is 192 hours out and will not verify. Either way it still looks transitory in nature with cold air coming in behind then heights building rapidly as the HPressure moves in over the PNW.

    • Kenny says:

      It will be cold enough for snow because it would be offshore flow pulling in the cold gorge winds. Then after it snows the snow will remain on the ground and not melt because even colder air arrives.

    • Aloha Rainshadow says:

      Kenny, just because there’s gorge winds, doesn’t mean it will be cold enough. You have to have some cold built up in the basin and that may not be the case that point. Initially it is not an offshore flow because the low is coming in from the NW, on top of that, if a triple points shows up and is N of Ptown then you are out of luck as well. At first glance, a low coming in south of Portland is great but there has to be other ingredients as well to get a snowstorm.

      If you follow the progression, there is a low that comes in ahead of that one, north of portland, that would scour out a lot of cold basin air…2mT on that model shows no snow for portland with the initial arrival of that low, maybe after it passes through and showers arrive, then you would be looking at some snow showers but at face value, that does not show a snowstorm for PDX. If you were thinking wetbulb…that wouldn’t be the case here either with a saturated column of air.

    • Model Rider says:

      Not to mention its only one model and the GEM.

  17. maryinsellwood says:

    26 degrees in Sellwood. Think icy frost on windshields, trees and grass. Very beautiful morning.

  18. Ryan says:

    Hillsboro will be interesting. They’ll get the precip first and its still 24 there with no win. Sun will be gone there first too. I’m calling ice in Hillsboro around 1pm.

  19. runrain says:

    Up to 28.2 now in Happy Valley. Radar shows precip near Lincoln City yet cam shows dry roads. Highway 18 in the coast range could be an issue with temps there still around 24 deg.

  20. Ryan says:

    Onto next week.

  21. poolsidemike says:

    wait! Winter hasn’t even STARTED yet!!!!!

  22. poolsidemike says:

    it “looks” cold there still and the clouds are thickening, keeping the sun from doing it’s magic! Not that I’m a fan of ice, but I think the idea of no or very minimal mixing and getting the cold air out of here could lead to some surprises a little later….definitely will be dependent on where you are. Even if there’s just some sprinkles, that could be enough to make a mess for a bit….we will see……

  23. gratefulduck says:


  24. slim1357 says:

    Mountain snow? Hoping for at least a few inches at Timberline for tomorrow.

  25. Sifton says:

    Only 100 days roughly till spring! Let the countdown begin…….

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