9:45pm…New Thoughts on Saturday

My forecast for later tonight and early tomorrow morning is still the same.  I think there’s a decent chance a lot of us see snowflakes tomorrow morning, but it’ll be tough to get more than a dusting due to lack of moisture.

3 thoughts on the next 10 days…

1. Colder temps, models have trended a little colder with cool air moving in from the north tomorrow night and Friday.  NAM is most aggressive with 850mb temps down around -8 to -9.  Other models not quite as cold, but we’ll have a tough time getting above 40 both Friday and Saturday even in the city under sunshine (most of the sun will be Friday).  Assuming we get some good clearing tomorrow night, it’s going to get real cold too; so I lowered both highs and lows a little again.

2. Beyond Saturday it’s going to be dry for quite a long time, back to inversion land with warmer mountains next week and cold temps in the valleys.  It still remains to be seen if we get decent east wind or not.  GFS says some decent onshore flow Monday-Wednesday as strong surface high pressure builds offshore, yet maintains a cold high over the Intermountain region at the same time.  That’s possible with the orientation of the upper ridge (just offshore instead of over or east of us).  Best guess is that we’ll see more fog next week with the inversion compared to what we saw the last week.  This pattern is going to last probably through all of next calendar week.  The 00z GFS has little no precipitation for the next 12 days!

3.  What you really want to know, are we going to get snow on Saturday?  I don’t know. 

The general idea is for an upper level disturbance to drop south out of western Canada, spinning up some sort of surface low pressure that then gives some part of Cascadia (western Oregon/Washington/California) precipitation.  The NAM and GEM are now similar showing the low coming right down through Western Oregon, sending moisture right up over a cold east wind blowing out of the Gorge = snow to sea level.   Possibly several inches Saturday afternoon and evening in the Willamette Valley if this were to pan out.  The GFS, WRF-GFS, and our RPM are all dry or mostly dry.  They have the surface low a little faster and/or farther offshore.  In the case of the GFS, the southern part of the upper level disturbance is stronger and the northern part weaker, which puts much more energy into the early Saturday low coming down the coast.  This would give a great snowstorm to SW Oregon and Siskiyou Summit but leave us dry up here.  With such variation and it still being 60 hours away, we just don’t know which solution is going to play out at this time.  I’m somewhat confident that after a cold night Friday night and a very chilly air mass still over us, if we DO get moisture it should be in the form of snow.  Forget freezing rain and probably regular rain too.

Here are 3 different maps for 4pm Saturday showing the very weak system coming in from the north on the GFS, then the much wetter NAM and GEM.  Note that on the GFS the first and stronger low has already moved down into California by that time:

gfs nam can

Chief Meteorologist Mark Nelsen

267 Responses to 9:45pm…New Thoughts on Saturday

  1. PDX Weather Nut says:

    Interesting thoughts on Portland Winter Climate: http://www.oregonphotos.com/Portland%20Cold.html

  2. Jordan (Raleigh Hills, 420') says:

    Just wondering (and hoping) to see if the 00z models switch back to snow solution for sat. or at least light snow showers… it’s really only been about a 24 hour progression, not long at all… to me it just seems right for a low pressure to form along the coast of BC and slide down around this high pressure… and WV image currently paints a lot of moisture out there. Just need it to organize and survive the trip around and down in some form…come on 00z runs!

  3. PSCZ still hangin in there with scattered snow showers on the ATX radar. Maybe a dusting this evening in the affected areas.
    D U S T I

  4. No Snow says:

    FYI it’s 36 degrees, not snowing, and wet pavement on Germantown.

  5. SnowedIn - North Plains says:

    Just out of curiosity… Was it I that started this whole “Dumb & Dumber” clip tradition?

  6. David B. says:

    I see NWS Seattle has started backing off a bit on the cold for their forecast temperatures, although they’ve been oddly silent when it comes to revising the forecast discussion (still none out for 3PM today). I imagine perhaps they’re arguing over what to say.

    Still above freezing in both Bellingham and Hope. Temperatures are falling at both stations, but that’s just because it’s evening, not from outflow cooling. Wind is still northwesterly at BLI, not northeasterly as one would expect during an outflow event. Still coming from the interior at YHE, but very weak and getting weaker.

    Really looks like the forecast Fraser outflow is a bust, to say the least.

    • David B. says:

      Moreover, it’s not as if the air coming from the BC interior is very cold. Merritt and Kamloops were just barely below freezing this afternoon. They’re typically *much* colder if there’s an arctic outflow event kicking up.

    • So do you think that kills any chance for snow saturday if by chance the low tracker closer and stronger then expected.? Today we only had a high of 35 with snow rain mixed should we expect the same saturday.

  7. SNOW! says:

    what is the chance of getting snow on Saturday now mark? :(

  8. WEATHERDAN says:

    Contrary to what some of you believe it really hasn’t been all that long when we had warm weather before July. In 2009 we had a lot of warm weather in May and June. In May of 2008 Salem hit 99 degrees. In 2006 Salem had 95 degrees in May, and 101 in June. In 2005 We had a week of + 70 degree day the first half of March. It has just been the last 3 years we have have had cruddy springs and early summers. But we had a warm summer in 2012. The first since 2009. So maybe we are out of that pattern. As far as getting less snow here, that has been along term trend. With the apparent global warming trends observer around the globe I doubt that it will reverse itself anytime soon. As for me I would rather a the sun and hot weather of the summer than the snow and cold of the winter anyway. Next week I expect with the cold northerly flow to max out at 36-42 degrees. With minimums between 18-24 degrees. Some fog down here in the valley otherwise a lot of sunny weather. And I still think we will have some snow Saturday night. Remember, baseball spring training is just 5 weeks away. And daylight savings time is a mere 9 weeks away.

    • PDX Weather Nut says:

      I hate really hot weather. Anything above 80 is too hot. Frankly I much prefer the snow we used to get over the cold rain. Last real snow in PDX was in December of 2008.

  9. W7ENK says:

    Currently raining in Milwaukie, 0% mixing, splat test = Negative. 39 degrees.

  10. Some additional thoughts(Weather related) Anyhow…. Models have trended to really weaken if not eliminate Saturday’s system. I see no reason to suggest otherwise, BUT I did want to say with northerly flow coming down off the British Columbia Coast over Vancouver Island it doesn’t take much to spin up a disturbance or low pressure area. We’ve seen it happen before in the past, so why couldn’t it this time? I am optimistic for this possibility, but again, not expecting it. Let’s just see how things develop on IR Loop tonight up in the Gulf of Alaska and especially Friday – Friday night before we completely rule everything out.

    • We’re about to the point where we can watch things evolve(or not evolve) in real time on IR/WV Loops.

    • Jordan (Raleigh Hills, 420') says:

      I agree. Sure seems weird for everything to just go to crap all of a sudden. I don’t know that I totally buy it. Maybe it’s a trend towards a drier system, but I don’t know that nothing is going to form at all… but with this luck, there probably will be nothing. At least there is still some upper level energy and flurries showing up on some of the models… just going to have to wait another 24 or 36 hours before we really have a confident forecast.

    • pappoose in scappoose says:

      And it’s fun to watch the bands form and move around. Not nearly as boring as watching grass grow. I would even rate it above watching clouds go by! Hahaah!

    • runrain says:

      Hey, it happened in Happy Valley this morning. It snowed here about as hard as I’ve seen it in some time. It was just localized.

    • marcus says:

      looks like a little disturbance to our north in the Puget sound area anything coming from that?

    • Josh in Sherwood says:

      Marcus, that’s a Puget Sound Convergence Zone. It won’t get any farther than Tacoma. Even so, it’s moving NW to SE. It’s going to stay there until there is nothing left to wring out.

    • Cooler air mass streaming out over the relatively warmer ocean waters = potential Cyclogenesis too.

  11. alohabb says:

    The natives are getting restless

  12. germantownsummit1000' says:

    Snow… again??? 33.8

    Geez, this is getting so boring.

  13. josh "the snowman" from Everett, WA says:

    To everyone, I’m not a troll. I just don’t jump to conclusions when there is too much uncertainty present. Saturday could just as well jump back on board with tonight’s runs. I’ve seen it a million times, it can happen.

    Mark even admits that anything outside of 36 hours is a 50/50 at best, sometimes even worse than that. How about that super snowstorm we were supposed to have 2 years ago that fizzled out within 12 hours?

    Let’s all stay within ourselves and not do the “sky is falling” routine. Some of us who are doing it know better.

    Fyi, Erik. I received an inch from this event.

  14. JTBeaverton says:

    Ive been reading this blog for weeks and weeks since the first brush with snow in december..It is frustrating at times but all of you have good info and it is definetly entertaining at times….

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