A Chilly End To February Ahead; Snow For Some

9pm Sunday…

Have you noticed the snowflakes in the 7 Day Forecast here at FOX12 or on your weather app?  I’ve got the scoop…

First, We will not be having a snowstorm this week in the lowest elevations of western Oregon or most of SW Washington.  But we should ALL see snowflakes in the air or even and SOME of us will get some snow on the ground.  I don’t think you’ll see me snowblowing a foot of snow in Salmon Creek again:

snow

That said…later this week we’ll be in a weather situation where many of us will see snowflakes.  But this time we won’t have a cold east wind blowing out of the Gorge or a cold air mass to give us a widespread snowstorm.  
Instead we get light showers and clearing periods Wednesday through Friday; it happens to be a colder version of the “showers and sunbreaks” pattern we often see in the winter and spring.  We’ve seen this pattern only two other times this winter…back in early December (it kicked off the fun stuff on the 5th) and on February 6th.  In both of those situations little or nothing fell in the very lowest elevations along I-5.  That includes much of the metro area.  That’s because often in this setup we get a breezy southerly wind coming in off the 50 degree Pacific Ocean, keeping the lowest elevations just a few notches above freezing.  Not always, but maybe 90% of the time.

We can’t predict the sticking snow elevation (the “SNOW LEVEL”) well in these “snow shower” patterns like we have later this week either.  No matter how often someone tells you it’s going to snow down to 750′, or 500′, or 250’…forget that nonsense…I generally stick to 1,000′ increments in these situations nowadays.  That’s because (for example) heavy showers in one location could drag the snow level down to 300′, yet just light showers 10 miles away don’t drop snow at 1,000′!  I’ve seen that happen many times.

In general, the higher up you live the better chance you have for sticking snow later this week.  Cooler nighttime air, by just a couple of degrees, for Wednesday night and Thursday night means a better chance for sticking snow down below 1,000′.  That’s assuming showers keep going all night as well.  That’s why I think the best window for a dusting down in the lowest elevations is the late night and early morning hours Wednesday night through Friday AM.  Of course as we get closer we’ll refine the forecast and give you more detail…as always.

You can see the general idea just by checking out the ECMWF snow forecast through Saturday:

ecmwf_snowthrusat

See the big empty hole here in the valleys?  And as we saw back on February 6th, models often overdo the lowest elevation snowfall in these marginal setups.  Check out the Cascade snowfall!  It looks like some of the best this season with very low snow levels from Wednesday until further notice

marksnow_mthoodfcst

Here’s the ECMWF ensemble chart from this morning’s run.

tseries_850t_000-360_portland

That’s the next two weeks, time goes from left (right now) to right.  Green line is average 850mb temperature for the date (temperature at 4,000′ in celsius), the blue is the operational run and red is average of all the ensemble runs.  This screams a very chilly last week of February and first week of March.  To get sticking snow with onshore flow this time of year we need -7 to -9 at 850mb.  Notice we’re very close to that several times in the next two weeks.  Of course if we lose that onshore flow and get decently heavy showers at some point, it could snow/stick all the way to sea level even as warm as -3 or -4.  So the main message here is that we’ll be flirting with snow in the lowlands several times in the next 2 weeks.  Anything is possible so let’s get the wishcast express loaded up folks!

WishcastingExpress

Chief Meteorologist Mark Nelsen

31 Responses to A Chilly End To February Ahead; Snow For Some

  1. WEATHERDAN says:

    As of noon Salem now has 13.43 inches of rain on the month. Between 15-16 inches likely. Normal is 4.25 inches. Just incredible. Peace.

    • Roland Derksen says:

      Amazing to see how much rain you have there in Salem. I haven’t counted the last few day’s amounts here, but they’ve all been small, so I estimate about 5.50 inches for me. Not an unusual total for February.

  2. Jake-(Gresham near Nadaka Nature Park) says:

    Welp,

    Looking at the latest runs (RAM, NAM, GFS, and Euro) it’s painfully apparent that the cold is just not coming South enough to cause any risk of snow for the valley. Euro takes most of the arctic air into Chicago, Illinois and Eastward. If this was late December early January we’d probably be looking at an ice storm maybeish over snow?

    So I’m fine if this just turns out to be a very early Spring snow thing for the hills and Cascades and nothing else. Long range, GFS show some snow event for mid valley a week from now but that’s still along ways away.

  3. I could be wrong of course, but I just don’t see any widespread significant snow from the coming setup. Flakes in the air, maybe a fleeting dusting on the bark dust AT MOST for most of us. Those in the hills above 500 to 1000 feet might see accumulations of a few inches. Even those will be slushy and tend to melt within 24 hours.

  4. JohnD says:

    Nice to see the protracted nature of this pattern. Just a little kink here and there and we’re in the money. Hopefully we’ll end the winter with a bang at some point(s) over the next couple of weeks!

  5. Jason Hougak says:

    The GFS is only trending colder and colder. Great news as the mountains have not built up any new snowpack in the last month.

  6. Mark, not to jump too far ahead but I guess I will…is next year shaping up to be another LA Nina year or has the general consensus about next winter not in yet. Definitely looking forward to the warming months ahead but just curious because it seems sometimes that consecutive weather years seem to repeat themselves. Thanks Mark!

    • JJ78259 says:

      This years La Niña is already over we are in a Nuetral Phase. Some are mild El Niño next year buy many are saying to early to tell.

    • JJ78259 says:

      This years La Niña is already over we are in a Nuetral Phase. Some are saying a mild El Niño next year but many are saying to early to make a decision.

    • I thought I heard last week that the Pacific Ocean off the coast of Oregon is still cooling or at its coldest point. Wouldn’t that indicate that we are still in the La Nina pattern? I sure hope that next winter won’t be La Nino. That means most likely drier than average and not much snow. I hope for at least a neutral winter. Does anyone recall what the winter of 08-09 was? Nina or neutral?

    • W7ENK says:

      ENSO 3.4 Index never technically reached La Niña status. Remember, the threshold is +/– 0.5C for five consecutive months. It was there for a cumulative 3 weeks, spread across 5 weeks back in October and early November. Before and since then it stayed in a Negative Neutral pattern, until last week when it sharply crossed above the 0C line into Positive Neutral territory. Most recent reading was +0.13C where it’s been for only a week, so definitely not something to base any sort of prediction upon.

      And again, please remember: FIVE CONSECUTIVE MONTHS

  7. Jake-(Gresham near Nadaka Nature Park) says:

    All I can say is I’m glad I went to Home Depot, took care of fixing up stuff for my folks, and we probably won’t see ice out of this (fingers crossed!). I’m happy, let Mark go on vacation and the snowstorm commence. 😛

  8. I really hope this is a sign of a colder and wetter than normal spring/summer package this year!! Sure feels like that could easily happen.

  9. Bring it on!! I so appreciate your detailed forecasts, Mark. No sensationalism, just the fact. Thank you. Because of you, I left my studded tires on!

  10. Mark Bergal says:

    I think the big story here is how chilly it will be and for a prolonged period. Last year this time we had numerous highs above 60 and things were blooming. Certainly not the case this year. If I remember correctly Mark hinted a while ago we could likely see a pattern like this as we move into Spring. Good call Mark

  11. pappoose in scappoose says:

    Wait! Don’t leave without me!

  12. Lee Wilson says:

    Well.. if it happens it happens..ill zet up the let it snow blow up i have and post it lol.

  13. joel294 says:

    Good post Mark…March 2012 in the south valley will always remind me of what can happen especially when we go by the 3rd week of February cut off point as a general rule.

  14. Jason Hougak says:

    Tired of hearing the lowlander whine about the snow. It’s time to let the foothills express snow machine blow!!!

  15. Paul D says:

    Toot toot! All aboard! Let’s ride!

  16. W7ENK says:

    lol 😆

    Not going to see anything stick below 500 feet.

%d bloggers like this: