Snow/Ice Thursday? Noon Update

Is there going to be a snow/ice storm in Portland tomorrow?  I’m not sold on that for now, but you should make (worst case) plans for tomorrow morning’s commute.  We’re only talking a few degrees between wet roads and icy roads!

A few minor changes in models/maps have made the forecast even more challenging now for the Portland Metro Area.  It would be a poor choice to forecast all rain tomorrow in our area.  Last night I pointed out that was a possibility we’d see spots of freezing rain and/or spots of snow (far westside) and now the chance of SOMETHING frozen has increased in both cases.  That said, I’ve never seen a major snow/ice event in an airmass that sees high temperatures around 40 degrees (today).  Salem in the mid-upper 40s this afternoon?  That doesn’t inspire a lot of confidence in a snowy/icy day tomorrow either.  But here we go…

The National Weather Service is going all-out for a MAJOR event tomorrow.  A winter storm watch for much of northwest Oregon, a blizzard watch for the Gorge, and a winter storm watch there as well.  You can see the area in the blue/green, they have it all the way down to Salem.  They are thinking 4-6″ snow for us, that IS the official forecast!  And 1-3″ snow plus possible freezing rain in Salem.

wsw

This is my forecast as of early this afternoon.  We get another run of models in between 7-9pm tonight, so that will be the “final call” and my forecast may change!

METRO AREA

  • A SNOW STORM IS DEFINITELY NOT ANY SORT OF A “LOCK” AT THIS POINT. Don’t get mad at me if at noon tomorrow it’s raining with some icicles hanging off a few trees and a wet dusting of snow on the ground.
  • Light snow/freezing rain/rain (a wintry mix) arrives around daybreak tomorrow and continues throughout the day.
  • Temperatures dip to right around freezing or even a notch below around sunrise, then rise into mid 30s by noon
  • 1-2″ snow is possible, but more likely a sleet/snow/freezing rain mix.
  • 3-5″ snow is possible in western Washington/Yamhill counties (Carlton, Forest Grove, Banks, 2-4″ Scappoose)

IF temperatures only dip to 32 (most likely scenario), many roads may stay wet, especially if we get freezing rain only.   You need temperatures around 30 or lower to freeze icy onto roadways during the day. Snow will more easily stick to roads, so if I’m a couple of degrees off and it’s all snow?  It’ll be a real mess! 

Iciest roads are likely to be in West Hills and near the Gorge if it ends up being a minor marginal event.

WILLAMETTE VALLEY

  • Probably too warm for either snow or freezing rain (except for a pocket or two)
  • Up against the Coast Range (western side of valley) a better chance for a couple inches of snow…maybe Sheridan area?

COLUMBIA RIVER GORGE

  • Looks like a winter storm!
  • Mainly snow all day tomorrow
  • 5-8″ totals
  • Mainly freezing rain or ice pellets around Corbett, Cape Horn…could be thick glazing by late in day
  • Snow ends Friday morning and it stays cold through the weekend, much of the snow is going to stick around
  • I-84 will be a real mess, might want to put off travel for 1-2 days

CASCADES

  • It’s going to snow on Mt. Hood
  • 8-12″ by Friday morning

So why did I change my forecast towards colder/icier?

1. Soundings on WRF-GFS and NAM-MM5 are SLIGHTLY colder

2. Once WINTER STORM WATCH and BLIZZARD WATCH show up on people’s phones/email I can’t ignore it in a situation like this that is a close call.

3.  ECMWF (my favored model) still shoves a ton of moisture in over us, hard to ignore that

What points toward no big snow event?

1.  Surface temps are marginal (as mentioned above) ..even with evaporational cooling it’s going to be tough to get us below 32 tomorrow morning.  If model soundings are correct and it’s only ice pellets or freezing rain, most streets will remain wet  Our big snow/ice storms happen in an airmass where the high temp is 35 or lower (under sun) the day before.  There isn’t any colder air coming…this is it.

2.  Worried about all models (except ECMWF) shoving moisture farther south now.  12z NAM says we are on the northern edge of the precipitation…Hmmm

3. Still don’t like those soundings.  The WRF-GFS has done quite well in the past with soundings predicting precipitation type.

4.  This isn’t a biggie, but our RPM is saying all rain with just freezing rain spots.  We’ll see, not always a stellar performer in the past.rpm

I’ll try to blog again after the 00z models come out.

Chief Meteorologist Mark Nelsen

126 Responses to Snow/Ice Thursday? Noon Update

  1. Linda Osmon says:

    Well snow I can handle my deck is frozen and slick and I can hear the freezing rain in the trees. Heard that sound more times then I care to remember. Everyone be careful because I am in Gresham.

  2. Jason Hougak says:

    Is that precip reaching the ground in Lane county?

  3. Jason Hougak says:

    1300′ cascade foothills
    33.0F up from 32.1F little over an hour ago, seems a bit more breezy though. Starry skies with some high overcast. No power since about 2-2:30 according to wife. Lost power last night too. Fire stocked and generator running.
    Nail biter… so early in the year that I’ve got that feeling… but who know records are meant to be established and broken. Praying for snow and staying home with kids to enjoy it.

  4. BigBank Hank says:

    Where is Rob’s “expert” analysis???

  5. Hal in Aims says:

    has been 33 and breeze/gusty here for the last 3 hours….

  6. B1900 Pilot says:

    Forget the snowstorm. Can Al Roker talk about the weather for 34 hours straight? #Rokerthon

    Live streaming at the nbc today show website.

  7. bonine4336 says:

    I know everyone is focused on snow/sleet mess, But I have to say that around town this is the most wind damage to trees that I’ve seen at least since the windstorm of Jan. 9, 2000. Many uprooted trees in N. Portland. My garden is a pile of douglas fir boughs from my neighbors 100′ tree. So interesting to get this much damage in my neighborhood. Its been fun to watch. BTW the peak gust on my anometer so far is 58 mph.

  8. JohnD says:

    35.8′ here in inner SWPDX. Breezy- gusty. Lowering barometric. Seems like we’re ripe but it is “only” Nov. 12, after all, and really early for a heavy hitter. (Yeah, I know…1977, etc.). Really pulling for it though, as always. Just hope the “wet bulb” does its thing well and the “warm nose” goes elsewhere. Really would be cool to get a decent event this early–and hopefully a harbinger for the rest of the season!

  9. Joshua says:

    Temp hasn’t budged in over 3 hours. That can’t be good.

  10. W7ENK says:

    In case anyone was wondering…

    Up to the minute updates here:
    http://isitsnowinginpdx.com/

  11. alohabb says:

    Kptv just said not likely.

  12. Tyler Mode says:

    Pictures from last night and today. Quite a bit of damage out in eastern Clark County. In fact, it’s the most damage from wind I’ve seen (outside of the tornadoes) since the 1995 storm.

    Also, I was quite surprised to see ice on the waterfalls in the gorge so early, and despite the temps in the mid to upper 30s. I think the dry air helped aid in developing that ice.

    Peak wind that we measured at Crown Point was just under 90 mph.

  13. Dramatic weather fan:) says:

    How much of this precip is actually going to survive too the surface with these low DP and east winds!? I’ve seen it a hundred times. Big winter storm coming, only to never see it reach the ground!!! Hope I’m wrong:)

  14. paulbeugene says:

    Nothing coming down yet here in Eugene. no snow, no rain

  15. Wendy-Silverlake says:

    Can someone post a link that shows where the rain/snow is expected to go and when. I used to have one a long time ago, but didn’t transfer it to my new computer. Sorry, can’t remember what it’s called at all. All I remember is you can run your mouse over the different times and it shows what is projected. Thanks. Hope my description makes sense. 🙂

  16. Dringus says:

    Looking at 00zgfs looks a lot like 18z and more north with precip than garbage NAM. Which is good.

%d bloggers like this: