SnapshotIt’s been a chilly April, and apparently it’s going to get chillier yet!  The maps right now for the next few days don’t really look any different than last night at this time.  Brief warming the next two days is followed by a historically cold airmass for this time of year (April 18-21st) this weekend.  I found the maps from April 23, 1961.  That was the morning that up to 3" fell in the West Hills and dustings even in the lower elevations.  The pattern was very similar to what’s coming this weekend.  A quick drop of cold air down through Western Canada dug out a trough along the West Coast.  The day after, the low was centered a bit more to the east of us.  It may have been a "deformation zone" as steady/heavy precip. sat over us before the trough moved off to the east.  The 850mb temps and upper level heights are forecast to be a bit LOWER this weekend compared to that event.  I’m increasingly convinced that several inches are likely in the hills by Saturday morning and MAYBE some to the lowest elevations too.  It’ll all be about precipitation intensity and timing.  If we don’t get good showers at the right time (overnight and early A.M.), then no snow.  But imagine if heavy/steady precip. were to arrive over the metro area at daybreak Saturday???  Mark Nelsen

45 Responses to

  1. Justin says:

    Mark, that was me with the info on the 1961 snow event. PDX had a high of 43 that day, yet Spokane made it into the 60’s! Was definitely an evaporational cooling event. Probably was a deformation band that set up over us in a perfect position, like you said.
    The old METARS are awesome as well. My personal favorites are the October 12, 1962 storm (sustained winds of 63mph at PDX!) and June 12, 1980 (heavy ash fallout from Mt. St. Helens).

  2. Rob…no drooling on the makes the electrons run…….

  3. Roy,
    Actually to my recollection I cannot seem to remember seeing snow fall ever in April. Maybe a mix during an afternoon hail shower? I am unsure.

  4. Ah yes Mark you know me too well. A PDX-DLS surface gradient of -16.8mb is indeed a fantasy of mine. I imagine at times TTD-DLS cracked -17mb! Wow. I would like to see it exceed -14mb next Winter.

  5. that was at 42nd and king road in Milwaukie…

  6. … i remember making snow angels in that april ’61 snowfall…i was 7 going on 8 and have always remembered it as seeming particularly late in the year…

  7. TheTriforce Silverton 360ft says:

    It’s 51F and cloudy. Don’t forget about the humid spell in mid July last year. Yuck!

  8. Mark Nelsen says:

    Not sure who you are with no name…but great info! I was going off the Oregonian article in Raymond Hatton’s Portland Weather Book.
    I missed the Troutdale and Battleground snow totals. I was scanning only SNOW columns, not SNOW DEPTH. Why would an observer give a snow depth, but no actual snow…very frustrating. I’ll correct the graphic for the future.
    More important; I wasn’t aware that weather underground had the hourly data back in time! The first thing I did was check December 24th, 1983 for PDX-DLS pressure gradient. I had heard from Jim Little that it was just incredible through the Gorge at the end of that cold spell. Well, it’s a Dr. Rob fantasy…16.8 millibars! I’ve never seen anything above the 14 millibars just before the flood of 1996 during that cold spell. That produced gusts 90-100 mph in Corbett.

  9. Richard says:

    On about the 12th of June, 1981, while attending school at The University Of Utah, I experienced the temperature go from a high of about 86 degrees in the late afternoon, to roughly 34 degrees, with a short burst of two to three inches of heavy, wet snow, in the late evening.

  10. Anonymous says:

    Mark, FWIW the date you’ve been talking about is actually April 22, 1961. You can see the observations from PDX that day here
    PDX had several hours of heavy snow at 33.1F, so it probably stuck to the grass even there.
    The Vancouver-Battle Ground area had 1-3″ that day, and 2″ was measured at the Troutdale airport.

  11. Runrain says:

    I remember low level snow in April growing up in Portland in the 60’s. I always thought it was funny how mid-March would come along and people around here lately say “snow season is over”. I was even starting to believe it myself, figuring that my memory was foggy. Glad to see a chance coming, confirming that my memory is firmly intact!

  12. wendy-silverlake,wa says:

    April 17th, 1976 it snowed several inches in Longview. That was the day my sister was born, and my parents had a lot of trouble getting off the hill into town to have her. They had 6 or 7 inches and town had 2 or 3 inches. Don’t know if Portland area got any snow that day or not though. This is a story my parents like to tell.

  13. JohnD says:

    Mark’s stats of April 23, 1961 as being at least one recording of late, season snow is interesting. I do believe that there have been other similar historical events although I have not taken the research of that to task.
    I will say this with certainty: When I was a young boy growing up down in Albany (Mid-Valley)in the ’60’s I recall vividly a strong snow shower during the month of May 1963. While at school one morning a torrential cold shower came over, which presently turned to all snow and began to cover car tops and grassy areas before ending a little while later. I remember the Albany Democrat Herald newspaper noting that a May snow “event” had not happened before since 1948. I have told this story to my wife several times over the years. She is from Massachusetts where May snow, while not common for even there, does happen in an occasional year.

  14. Mat ne portland says:

    Hey Mark, I didnt know it was Twinsday at the office. I didn’t know you were taking style tips from Wayne Garcia either. How cute. lol

  15. gloriousnumber1 says:

    Well I would prefer one extreme or the other. It would be awesome to see a few inches over the entire valley floor. Except for a few exceptions, only the hills have seen significant snow this year. I wish I could have traded all those “traces” and “flurries” for one big storm. But I will echo what someone else said, to be 80 degrees one weekend and snow on the next would be cool. I have heard some places like montana and colorado are like that.
    Also, a few questions: What are the records for the latest time in the spring that snow has fallen at or below 1000ft? Or how about in the valley even if it was not measurable?
    I’ll take a snowy memorial day weekend yaaay!!! I know I’m talking crazy, but oh well. If it happens now in mid-april, why not late april? Late april is almost early may, which is almost late may, which is almost June, heck why not then? I mean it makes sense.
    I took my snow tires off early march figuring all snow threats would be over. But I underestimated Oregon weather and Mark said “we have no cold air in the forecast, so we’re done” (speaking about snow) so I thought it made sense. Not his fault though.
    Sorry for rambling, just had to say this to people who understand it.

  16. JOHND says:

    Yeah I can’t stand the word “normal”. The word should always be “average”. I guess we can get caught up in semantics but it really bugs me when weather people refer to temperatures as above, below, near, etc. “normal”. If you look closely on any given day you rarely achieve the “normal” low or high temperatures. The term “normal” is derived from averages and–to me–that should always be the correct term.

  17. jacobc BPA says:

    Good to see Ashley out of the pen

  18. Roy ~ maybe there's a few snodaze heading our way? says:

    You’ve seen snow fall in April… I think you’re referring to the realization (or not) of it actually “sticking”… (which is what you’re cautiously optimistic over) >> As am I… But it should be fun to see for us lowlanders (as it was a couple weeks ago..)

  19. Roy says:

    The first thing you need to know here, is that this weather is not “WACKED OUT”…
    It is “TYPICAL” in terms that at any point, AND ON “A-N-Y” GIVEN YEAR… this can happen (and will)… “THAT” in my mind is ‘typical’…
    I’ve been around here, and have had family here in oregon for almost 110 years +… YES, this is typical weather…
    (notice I didn’t say “normal”…)
    Ahhh Haaaa… Think about it.

  20. A downer? who me? neverrrrr. I’d love to see it. As always I am remaining cautiously optimistic. I think it’s just too hard to grasp the concept of snow actually falling in mid April.

  21. Mat ne portland says:

    Rob, don’t be a downer. Its going to snow. hehe

  22. ashkley watson says:

    thanks for your explination on our climate, however I don’t feel that it really answered my question. More than just our average climate factors are involved in our screwed up weather as of late.. please chime in mark nelson!!!!!

  23. And of course as I am sure everyone is well aware of any easterly Gorge wind is going to have no impact on this weekends situation. Simply put there just is no cold air east side to speak of. I did however contemplate one thing that could help a tad and that is if there is/was any decent snow cover over central-southern British Columbia (This has a more significant impact during late Fall/Winter). Even then I am sure any effects would be minimal as the air mass heads south from Canada. We really want either heavy convective showers, or a convergence band of solid yet steady moisture developing to progressively pull the snow level lower and lower preferably during the overnight hours. As far as any wind element we’d be better off with light or calm winds. Personally I am not on any snow band wagon nor can I get excited about what IMO is a slight chance from 8-9:00 PM until 7:00-8:00 AM for snow showers or a mix. I’m more eager to see if we get some good sun breaks to destabilize things with a very cold air mass overhead coupled with steep lapse rates, LIs near zero, and likely some CAPE developing I think the chances for widespread convective activity is greater than our snow chances.
    – Dr. Rob

  24. JOHND says:

    As much as we low elevation snow lovers don’t always like to admit it, we live in a “marine climate” and that really pretty much tells it all. The Pacific Ocean and its influences simply generally (of course with some exceptions) keep the lowest elevations just a little bit too warm for snow. That is why the concept of “freezing level” is so dramatic around here. (Temperatures fall on average 3.5′ per 1000 feet.) Of course we can–and do–have a certain uniqueness with the Columbia River Gorge influence. When we finally do get some cold/arctic air to seep west of the Rockies and fan through the Gorge via winds driven by a high pressure system, that is when we are all getting pumped because nature’s dance is literally on our doorstep and all bets are off. But even then Pacific storms have to track just right to produce Portland snow–at least of much duration. And yeah, it just wasn’t one of those years for that. Above 1000′–historical in some places. Just not near or at sea level.
    A little while ago today the NWS issued a very compelling bulletin about the potential for this weekend–comparing possible conditions to those of our “best” periods of the true winter period! How cool would it be if we DO have an historical event. 80′ one weekend. Snow the next! How awesome!! We’ll see.

  25. Ashley Watson says:

    very important question to ask, Why is it that these very cold arctic systems can’t hit us right in dec-jan time frame. That makes no sense to me. The bottom line is the mountains have had so much snow and on the valley floor only a skiff a few times. What is going on in the atmosphere that is just wacking everything out. I feel as if we are in the sacramento valley climate now. There mountains and foothills could have lots of snow but right on the valley floor mabey a trace. What is going on???? Can someone who has posting powers please post this on western usa weather fourm so maybe I can get some answers.

  26. Ashley Watson says:

    very important question to ask, Why is it that these very cold arctic systems can’t hit us right in dec-jan time frame. That makes no sense to me. The bottom line is the mountains have had so much snow and on the valley floor only a skiff a few times. What is going on in the atmosphere that is just wacking everything out. I feel as if we are in the sacramento valley climate now. There mountains and foothills could have lots of snow but right on the valley floor mabey a trace. What is going on???? Can someone who has posting powers please post this on western usa weather fourm so maybe I can get some answers.

  27. Sean In Tigard says:

    I was thinking the same thing….maybe its a “wait until it gets closer” thing

  28. JOHND says:

    If we have the potential for a historical late season low level winter (spring) weather event, I can’t believe that no one is sounding off about that.

  29. jacob BPA says:

    I know all of you really wanted a pic of the FAB 5 so here you go this is the Research vessel Yamal thats Rissian for “I cant beleive its not butter ”
    Thats steve to the Left Walking towards me and tv

  30. Luvry says:

    Sean, how ya doin? Just wanted to point out that our summer of 07 was pretty cool, I actually don’t even really remember any oppressive heat that lasted more than a day or two and that only happened a couple times itself.

  31. Ryan (Walnut Grove) says:

    So where the heck have these cold moist systems been hiding all winter long?! It seems timing is always off a bit here in the PacNW for the valleys.

  32. (To the tune of Mary Jane’s Last Dance)
    Portland’s Last Chance
    A month ago it was really really brown,
    Had a lot of bare trees and snow comin’ down,
    But it warmed up fast, and the sun came out,
    With the flowers on the trees and the colours real bright.
    Well the cold moved down, down from Canada,
    Blew the charts away was more than we’ve seen,
    Started lookin’ brown and the temp was really fallin’,
    They said it’s like Winter but I’ve gotta keep lookin’.
    Last chance in Oregon…one more time before the rain.
    I feel summer creepin’ in and I’m…tired of this game…

  33. llabrulf says:

    Don’t know if anyone mentioned it in a earlier thread but there’s a great interview with George Taylor in the Tuesday edition of The Tribune. Whoever did the interview obviously has a differnt view than George has, and I found it facinating how said person tried to throw some subtle and not so subtle barbs at George’s beliefs. George’s responses were very profesional as would be expected and he ended up making him/her look rather inmature and ill-informed.

  34. Hey Mark..are you going to do another last one for the winter snow total post??????

  35. as much as i wish it were warm…i love statements like this:

  36. Ice says:

    I also thought winter was over.. I hope this would be the last freeze/frost…

  37. Jesse-Orchards says:

    It’s been almost one whole year since we’ve seen a cool summer.

  38. Sean (Lebanon, Indiana) says:

    Hey Rob, in reading what some forecasters have been saying is that the Pac NW is going to stay this way (Below to Much Below Normal) for at least the rest of the month. Man, talk about some crazy weather. This last weekend we were 20 degrees below normal for highs, and have had lows in the 20s the last two nights (hopefully the roses which were budding weren’t killed). But, now with temps rebounding back into the lower to middle 70s this week it will be nice.
    I can’t remember a time when there was a chance for snow down to 500ft in the middle of April! Even during all the years that I lived there! Truly markable to see how this pattern is evolving, hopefully this doesn’t mean a cooler summer for you guys. Though it has been awhile since that has happened there.

  39. Nof at work Hillsboro says:

    loop worked, WOW…if only this had materialized 3 months ago. Oh well it’ll be a nice tease.

  40. TheTriforce Silverton 360ft says:

    from hot to cold. Welcom to the Extremes of Oregon! Cmon over for some “Global Warming” Al Gore.
    By the way: The loop is broken. No image when I load it so sorry Dr Rob. 😦

  41. Thanks for the update Mark.
    I want you all to look at the following links.

    Showing how the pattern evolves with the high out near 145W but nosing far north into the Arctic and the flow back around plunging the colder air directly south through the NW Territories, British Columbia back over the PNW.
    This is the 500mb height model showing essentially upper level temperatures. This is showing an absurd -36c to -39c cold pocket aloft. This is extremely cold and not typical for really any time of the year over our region. In fact if I am not mistaken we haven’t seen any 500mb temps progged this low all last Winter. Also with that cold of airmass moving overhead with ANY sun breaks we should fire off convective showers of hail, graupel, ice pellets, or maybe even some t-storms very easily. As we are heading into mid April the sun is growing progressively stronger all the while. I imagine the convection temperature will be somewhere in the 40-43F range. With any convective moisture that will only aid in lowering the snow level due to the heavy yet brief precip rates. This will be interesting to see how all of this plays out.
    – Dr. Rob

  42. wendy-silverlake,wa says:

    500 FEET. LOWS 30 TO 35.
    AROUND 45.
    this is insane. Wasn’t winter suppose to be over? Wondering how we are going to get my son to his t-ball game Saturday morning. Last weekend they played in 80 degree weather and this weekend they will be playing in snow. Go figure.

  43. Sean In Tigard says:


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