End of Winter Snow Rumors

Have you heard rumors of possible snow this weekend?  Even without being at work today, I know regular folks must be hearing things because hits to this blog just about doubled since yesterday, to the highest level since the end of January’s snow & flooding almost a month ago.  That’s with no interesting weather occurring right now!  Here’s the scoop…

1. Over the past 5 days, computer model simulations of the weather patterns (moisture, temps, weather systems etc…) have been showing some variation or another of a cool or cold spell coming somewhere this Friday or beyond.  We get several runs from each different model each day, and each goes out to at least 15 days.  You can imagine the amount of information we have available nowadays!  Our job in the past 15 years has morphed from one of forecasting to one of forecast model babysitting!  Which one is correct or which two are most likely seeing something the others aren’t?  You get the idea.
2.  Some models at varying times have shown a historic late season cold spell and decent chance for snow to sea level, while at times others have not.
3.  They ALL agree on AT LEAST cooler than average weather with snow down into the higher hills again Saturday through sometime next week.
4. They do NOT agree that snow will be showing up in the lowlands.
5.  As of right now (10:45pm Monday), the best guess is marginal hilltop snow showers Saturday night and/or Sunday and no snow in the lowest elevations, and no blast of arctic air either.
6.  The main issue right now is models are all over the place on details except for #3 above.


Main issue this evening is models appearing to have no clue what is going to occur beyond Friday (other than the general trend of colder).  I have a feeling this is why local meteorologists are playing it quite safe with snow talk tonight.  One could hardly reconcile the excitement and wishcasting going on in weather forums/blogs and Facebook sites around the region right now with what is seen on TV and official forecasts.

The 12z/18z GFS and 12z ECMWF were all pretty reasonable with a decent chance for lowland snow beginning Saturday evening once 850mb temps dropped to -7 or so.  But they were also very dry, or at least just flurry-ish.  I’m not working (just today), but if I was doing the 7 Day forecast, I would have gone maybe 40 both Sunday and Monday and lows 25-28.  Just a few flurries on Sunday’s forecast too based on these runs.  If one of those earlier and colder models was correct, maybe only mid-upper 30s for a high Monday?

But now the 00z GFS comes in and produces far more of a splitting system Saturday, and then a return to more westerly flow Sunday and beyond.  The 00z GFS barely gives the hills a chance for snow…game over on that one.  However, the GFS has been really bad lately, so let’s throw that one out.  Note the huge variability in the 00z GFS ensemble chart after Sunday morning (just before the “27th”):

The new 00z ECMWF is in now in…slightly different, but quite a bit warmer.  It has a first wave coming through Saturday as all the model do, but warmer with thicknesses barely supporting hilltop snow too in strong onshore flow.  Then a 2nd wave comes down from the north late Sunday with a better chance for snow to lower elevations; although still marginal.  The ECMWF now has only -7 or -8 at 850mb as it bottoms out Monday morning as it too shows colder air digging farther south offshore with a very slight “splitty” look to that trough:

If you take both 00z runs at face value:
1. We don’t have any arctic air on the way  (although only a few runs/models have shown that the last few days anyway)
2. Snow to the lowest elevations could be very spotty Sunday if at all.

I don’t think one can read too much into any one model run or any one time period of runs, but it’s fair to say there is a lot of uncertainty to this weekend’s forecast.  It is possible we get out of this with very little interesting weather, or this evening’s run are just having issues with shortwaves.  Brian MacMillan’s 7 Day forecast sure looks good now…

Chief Meteorologist Mark Nelsen

23 Responses to End of Winter Snow Rumors

  1. Mark Nelsen says:

    12Z ECMWF & GFS are almost identical on 850mb temps Saturday through Tuesday, bottoming out around -8 or -9 Monday morning. Mainly or all dry Sunday-Tuesday morning.
    The ECMWF has a little wave coming down from the north during the day Sunday or snow showers, but then dry after that.
    More cold troughs beyond Tuesday on both models.
    I like how Brian in Battleground sums it up “not cold enough for snow, but not warm enough to enjoy the outdoors”. I think he means widespread valley snow, but you get the idea.
    I’m feeling better after the 0z & 12z runs.

  2. Joshua in Lake Oswego says:

    The 12z GFS does not appear cold enough for snow down to the floor to my eyes. There also isn’t too much mositure once the colder air gets here.

  3. W7ENK says:

    Okay, so the 00z GFS and Euro last night both killed our snow… Although, the 06z GFS brought it back this morning, so we’ll see what the 12z runs bring. If the 12z Euro says no, then our snow chances are pretty much dead. My daffodils would appreciate that, I’m sure!

  4. Barberton says:

    Farmer’s Almanac predicting snow Feb. 21-27th….hmmmm. We’ll see if it’s right.

  5. Andrew (Portland....Sylvan Highlands ~800 feet) says:

    06z back on track with cold and snow once again this morning.

    • Joshua in Lake Oswego says:

      Yea it is! Impatiently awaiting the 12z…

      I am torn about the upcoming possible snow/cold- I just got my first motorcycle and my Team Oregon class is this weekend at PCC Sylvania. The elevation there is at least 500′ I believe. Both saturday and Sunday, my class starts at 8 am.

      I am really excited to learn my beginner riding skills, get my license, and start riding next week. I am also very excited about the possibility of snow/cold. They definitely do not go well together. I guess in the worst-case scenrio, I will either get to ride my motorcycle for the first time or have weather cold or harsh enough that I cannot ride it.

  6. Kyle says:

    Okay. I give credit to the heavy rains last January. I admit it was exciting watching the rain be measured in inches at the Salem airport as that doesn’t happen too often either despite wishing it were all snow.

  7. Kyle says:

    Since we did NOT get the snow/ice that Seattle got I hope this depressing winter is one for the record books. If not at least the top 3 depresing/gloomy winters in the history of the PNW with low mountain snow.

    If it were not for Seattle getting creamed in January I’d put this up in par with 2002 except 02 had a sharp Artic blast around Halloween and a long sunny spell sometime during Feb……………………..

    • W7ENK says:

      I seriously hope no one is keeping an official “gloominess” record, but I’d have to agree that this winter would certainly be amongst the top 5, at least since I’ve been alive. I can’t speak for anything before 1979, however.

  8. Kyle says:

    50F today. WINTER CANCEL!!

  9. PNWweather says:

    Hi Mark

    Great analysis again as usual.

    Ted Buehner at NWS Seattle long ago back in 2003 told me “if you don’t learn to look at all levels of the models as well as several models themselves, the most of the time you will have egg on your face”. Yes I tried to predict snow at Seatac once back then and I failed awfully.

    Thankfully I have learned a lot more since then and know to interact terrain into the picture when these models come out. I also try my best not to lean way to much on the GFS and tend to believe the EURO much more most of the time than the GFS.

    It helps that I have observed the weather around here for 42 years now because boy has it ever taught me a lot of what is not only normal here but normal in many places around the Northwest as well.

    I think we see more of the believeable picture always in the immediate observations and as we follow the trends of those over time we often find that not only do we need even better forecast models but we also learn to read the ones we have better and at times find that the models come out over done more often than not.

  10. Karl Bonner says:

    That 00z GFS run is a COMPLETE mess after the first 5 1/2 days! I don’t blame the TV stations for being confused and cautious in their forecastig, because it’s so hard to figure out just what’s exactly going to happen. Well it makes for good suspense at least!!!

  11. bgb41 says:

    2/20/2012 Oregon (All) Temperature Summary

    High:58 at PROVOLT SEED ORC(1180 ft)
    Low: 47 at DW6842 Gold Beac(449 ft)

    High:23 at HARL BUTTE(6071 ft) & ALAKES Haines(7979 ft)
    Low: 4 at CRANE PRAIRIE (5500 ft )

    Largest Diurnal Change: 31 degrees
    CRANE PRAIRIE (35/4 ) (5500 ft )

    Heaviest Rainfall:
    2.26″ at LOG CREEK(2800ft)
    1.90″ at SOUTH FORK BULL(2630ft)
    1.89″ at YELLOWSTONE MTN.(3080ft)

  12. Mark, I knew this would happen when you told us to put away our shovels and take off our studded tires on the Ten O’Clock News! Just teasing you Nelsen!! 🙂

  13. “The party’s over”…..

    48°……0.40” rain today.

  14. W7ENK says:

    Yup… I’ll believe it when I see it, and that applies to all ends of the spectrum!

  15. BEn T. says:

    Interesting week to come.

  16. Longview - 400 ft says:

    Here is hoping once again!!!!!!!!!!!!

  17. g says:

    Too good to be true

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