Chilly March Weather Ahead

We have 3 more days of mild weather on the way; soak it up since there will be a dramatic change on Sunday. Chillier temps and more “normal” March conditions begin on Sunday.

Models have come into much better agreement tonight that we get a fantastic spring-like day on Saturday. Offshore flow, no cloud cover, and 850mb temps up around +4 should push temps to 60 or a bit higher. We MIGHT see our warmest temp so far this season; and Pearson Airpark should get it’s first 70 degree temp of the season (inside joke for that warm ASOS sensor). That will make the big change Sunday and Monday even more noticeable for the general public.

A sharp cold front and then upper-level trough swings through Sunday afternoon and Monday. That drops 850mb temps down to the -5 to -8 degree range, depending on which model you follow. My forecast on the graphic is based on the GFS being a bit too cold in the end. A -8 will bring sticking snowfall down to sea level in early March at nighttime and with solid showers.  The 00z ECMWF just came in and it’s not quite as cold, but still a -5 deg at 850mb Monday afternoon.  We’re now into that time of the year that showers and sunbreaks combined with those cold temps will still mean highs well into the 40s, maybe even 50.

Of interest is also the following system Tuesday night and Wednesday.  With cold air in place snow levels could be quite low during that time.  This time of year everything would have to work out just right to get snow down to the hills around the metro area, but it’s happened many times in my 19 year career forecasting weather here in Portland.  But once again, it’s VERY tough to get sticking snow down in the lowest valleys where most of us live.  The latest measurable snowfall AT PDX is March 8th.  We’ve had traces later in the year than that.

Chief Meteorologist Mark Nelsen

66 Responses to Chilly March Weather Ahead

  1. Matthew says:

    I don’t think this has any chance of snow fall on the valley floor.

    1# We will have a warm onshore flow.
    2# -4 to -5c at 850 is hardly cold enough during even the winter.

    So no, I don’t believe it will go below 1,500 feet. I only have seen snow in Portland once in my life.

  2. Sandi (Wilsonville) says:

    Front page Oregonian story about snow in early March 1989:

    Story continues:

    • Justin (Brush Prairie) says:

      That was our last real March snowstorm. 3.5″ in downtown Portland and as much as 14″ elsewhere in the metro area.

  3. Mr Data says:

    http://www.youtube.com/watch?v=EOSlkHY1oU4 (Portland Oregon March 2006 nighttime snowfall. 2 inches in 1 hour.

  4. Stevengibson says:

    So whats the lowest it will go?

    • Rob "Wrath" S.E. Portland says:

      Sticking snow 1,500′
      Wet snow down to 1,000′
      A mix possibly to 500′

      I think this would be nighttime hours only and this is only IF the GFS solution is correct, but don’t bank on it being as cold as advertised.

    • dabears (Hillsboro-Tanasbourne) says:

      Rob, if the GFS were to actually verify as it’s been showing, the snow level would probably be under 500 feet in some heavier showers. The real question I think is if and to what extent the GFS is overdoing the cold.

  5. imperiet says:

    I have a stupid question.

    00z, which means midnight GMT right? Why then does it run at 20 GMT-8 for us?

    • timmy - scappoose says:

      we arent in the time zone that it initiates from

    • dabears (Hillsboro-Tanasbourne) says:

      Timmy, 00Z would mean 4pm for us. The 00Z runs (or at least starts showing up on the internet) well after this. Imperiet has a good question that I’ve always been curious about as well.

    • ..we are 8 hours west of GMT (Greenwich, England, where time begins, apparently); midnight there is 4pm for us (-8)

  6. yevpolo1990 says:

    GFS on board with -7/-8 850mb temps…
    Euro is around -5 or so
    What i say is:
    Keep an eye on euro and see what it keeps spitting out, if none of the models really change their perspective just with in the middle of it all and stick with -6/-7.
    I have a feeling westside folks can be in for a suprise!

    • dabears (Hillsboro-Tanasbourne) says:

      I don’t really see how this event favors the westside over anyone else like you’ve been implying.

    • yevpolo1990 says:

      we always are colder at night than really anyone else in the metro, we always hit 32 first

    • yevpolo1990 says:

      then who else hits 32 first in the metro besides hillsboro/beaverton area?

    • Timmy_Supercell (Hillsboro) says:

      Perhaps the faulty KVUO station? lol

    • dabears (Hillsboro-Tanasbourne) says:

      Definitely areas like Brush Prairie can get colder than us. Beaverton doesn’t usually get *that* cold, though Hillsboro is definitely one of the coldest.

    • yevpolo1990 says:

      eh brush prairie is way out there..

    • Rob "Wrath" S.E. Portland says:

      Actually if we’re talking in terms of distance Brush Prairie is closer to Vancouver than Hillsboro is to Portland. It’s nearly half the distance.

      And what this proves is…. Not a thing. 🙂

    • yevpolo1990 says:

      true true rob

    • Andrew Johnson says:

      Hillsboro did pretty well in March 2006. I was in Hillsboro one evening during March 06′ and a very heavy snow shower came through and dumped about 1 1/2 in the Tanasbourne area.

    • yevpolo1990 says:

      i remember that nicely! 🙂 ^^^

    • dabears (Hillsboro-Tanasbourne) says:

      That is definitely what I like to hear! Hopefully we can do it again.

  7. Eternal Yamcha (SE Milwaukie) says:

    March is quickly becoming my least favorite month… Honestly.

    2009, 2008 and 2006 all had terrible Marches. 2007 took the sting off a bit, but it was the most bipolar month I’ve seen in a long time (pretty big temperature swings day-to-day.) March 2009 was perhaps my least favorite March and could rank among my least favorite months (weather wise) of all time.

    Why? The warmest temperature we hit in March, 2009 was 61 degrees. ONLY 61. Sure we hit it twice, but that’s pathetic. The day with the highest temperature ABOVE average was only above by 6 degrees. Again, horribly pathetic. Sure we “flirted” with snow, but that means “we saw snow down to relatively low elevations but not quite the valley floor” and we had BELOW average rainfall.

    I highly, highly doubt we’re going to see snow down to the valley floor. We might see the snow level drop to it, but only when there’s 0 moisture around. We’re at the time of year that we need basically a near-perfect set up to give us snow and honestly? I really just don’t see it happening. What’ll likely happen is that we’re gonna be cold and DRIPPY for an extended period of time and give me another reason to dislike March.

    The only way that I’ll be satisfied is:

    1. We actually see snow at the lowest levels. None of this “Snow showing up at 1,000 feet under showers” stuff either. That’s actually my least favorite weather unless it’s combined with…

    2. Thunderstorms/Hail. I’d like to see some sort of cold core thunderstorm activity come out of this. If it’s gonna be cold and showery, we better see some good thunderstorms/showers and hail outta it or…

    3. A good soaking. We’ve been at-or-below average rainfall in March all the way back to 2005. My definition of a good soaking is any day that we see more than .5″ of rainfall.

    4. At-or-above average temps. Of course, if we swing away from the cold after a bit of disappointment and start hitting temps in the 60s with sunshine, I’ll be happy with that. I’d like to see an upper-60s or 70 degree day this month.

    Don’t get me wrong, I’m kinda glad that we’re gonna see some cold air moving in. I just don’t want it to stick around and be gray and drippy the entire time. I want to see some action, or this cold air can move out of the way and usher in warmer air. Seriously, I am really tired of our rather bleh Marches and I don’t feel like being teased with the possibility of snow when we might not see it here on the valley floor.

    Note: This isn’t intended to start anything, I’m just venting my frustrations about former months and am rather anxious and worried that THIS March won’t be anything different.

    Note^2: If you wanna see what I consider a good March and one that had a fair trade off of cold/warm? Look at March 2005.

  8. Cliff says:

    A little bit slow, but march will come in like a lion.

  9. PaulO says:

    18Z GFS onboard and maybe a bit colder?

  10. Ryan (Walnut Grove) says:

    Let the model riding commence!!!

  11. dabears (Hillsboro-Tanasbourne) says:

    How disappointing. The 18z completely removes all hints of cold and 850 temps don’t even get below -1C.

    Nah just kidding, it’s still there and looking good so far.

  12. WEATHERDAN says:

    We had a similar situation to this in 2006, early cold, mild late winter, followed by a record cold trough in the 2nd week of March. Salem had a record cold high of 38 degrees that day and 2 inches of snow. When summer came though it was very hot all summer long. Will history repeat itself? Only time will tell.

    • Andrew Johnson says:

      In the past decade or so it seems as if March has delivered more goods than February! March 2006 was great. I also picked up a dusting of snow sometime around March 8th or 9th last year I think.

  13. Precious says:

    I’m sure the snow boarders and skiers will be happy with anything “white” coming their way…as for me, love the already-spring we’ve been having!! Last year was the pits in Sherwood with over 16 inches of snow December through January, and didn’t like it that we all had to dig ourselves out of our driveways. Where’s a snowplow when you need one? Obviously, we can’t afford that here. When I retired in 2005, I thought my hard work had ended…ha ha ha.
    Mark, you are a wonderful weatherman. Between you and Drew, I know I am NEVER left in the cold when it comes to your forcasts!!! Keep up the good work!

    • Rob "Wrath" S.E. Portland says:

      Jeez… How is that possible to just steer right into an the ice. 30-40 ships too. 😆

    • Rob "Wrath" S.E. Portland says:

      Into the* ice.

    • Rob "Wrath" S.E. Portland says:

      I didn’t explain very well and that unfortunately happens too often when my neck is acting up. Rather frustrating. So basically it’s been unusually cold and the ships out of port were trapped as the waters became increasingly colder and ice formed trapping them. I believe that’s right….

    • W7ENK says:

      Actually, my friend in Estonia just took a ship to Sweden from Tallinn (capital of Estonia) about two weeks ago. I asked him about the ice and he told me that the ships are designed to break it as they travel, but apparently the ice is too thick now in some spots? That’s pretty wild!

      I’ve mentioned a couple times on here about the really COLD winter they’ve been having…

  14. Rob "Wrath" S.E. Portland says:

    12z has warmed things just a tad.
    http://wxweb.meteostar.com/sample/sample.shtml?text=KPDX

    12z ECMWF still is not in total agreement with the GFS. I almost wonder if the 18z and 00z tonight also are slightly warmer.

    • Jesse-Orchards says:

      I don’t think the 12Z is noticeably warmer. Really no change worth mentioning. Still gets us down to -8c at 850mb, still gives us our best chance(granted, it’ll be slim) of valley snow early Monday morning.

    • Rob "Wrath" S.E. Portland says:

      Yeah it’s just a tad. BUT I do wonder we may be losing momentum on this deep, chilly trough. Maybe it’s a bit warmer as the EURO shows. 00z will be critical tonight.

    • Jesse-Orchards says:

      We’re not losing momentum on anything, the trough’s gonna come. The GFS is probably just overdoing it per the usual, that’s all.

      I suppose we could call every model run critical. :p

    • Rob "Wrath" S.E. Portland says:

      I think I was hoping for the 518 thickness and -39c 500mb temps. Yeah GFS is notorious for that. 18z runs soon and I CANNOT wait! Okay, I can.

    • Ben Randall says:

      Is over water trjectory possible …. I think 500ft snow lvls during the day then sea lvl during the night

    • Rob "Wrath" S.E. Portland says:

      I’m thinking 1,500′ at best for sticking snow. Now if you can manage to get directly under a heavier shower during the overnight hours you could briefly see the snow level lower under 1,000′, but that won’t be the common theme. The sun is warming every day now too. Also there looks to be light onshore low-level flow which kills any chance of snow below the foothills. I think 850mb temps will end up around -3 to -5c anyhow which is too warm even during Winter.

  15. pappoose in scappoose says:

    Sorry boydo3, I scraped ice off car windows this AM and the cool weather isn’t here yet. I think early next week your prediction of, “I don’t think we are looking at a freeze, although some frosty nites might be showing up”, will be blown out of the water. (Or maybe out of the snow).

    • boydo3 N Albany says:

      Healthy debate is good.

    • dabears (Hillsboro-Tanasbourne) says:

      I can debate you that the sky is green, it wouldn’t be healthy.

    • boydo3 N Albany says:

      I’m going steelhead fishing for the next few days. By monday we should be looking at snow……..in the mountains. So then it’s off for some powder skiing. Wet cold showers early next week in the flat lands. No snow.

    • pappoose in scappoose says:

      The fishing won’t be any good. The water will be too cold and clear with the snow and freezing temperatures.

  16. PaulO says:

    GFS 00z and 06z keep the cool weather coming. Hopefully we will see something active and exciting before spring returns. Monday night still looks cold.

  17. Karl Bonner says:

    Offshore flow and sun only gets us to 60 on Saturday? For some reason that seems a little weak. It would be more believable if the lower Columbia Basin were somewhat on the cool side (e.g. 55 in The Dalles, low 50s further east) and PDX got enough east wind coming through the Gorge near sea level. The trouble is, it’s getting harder and harder for the east side to stay cool during sunny weather; the sun is simply too high in the sky by now. About the only way I could see it happening was if there was some moderately cold air coming in from the northeast, similar to the pattern two weeks ago. Without the cold air, I’d expect that many places in the Basin would hit the low 60s.

    And with the offshore flow, that would likely mean 62-65 in Portland and Eugene, perhaps even a degree or two warmer. I’m no expert on the subject but I have a strong sense of intuition about this.

    Keep in mind that in the past decade we’ve had three years where 70-ish temps happened in the first half of March. Granted, that was a perfect-case scenario, but it seems to indicate that March ridges are supposed to warm us up quite a bit.

    • Karl Bonner says:

      Another note: if this exact setup gets us to 60 in the first week of March, the same pattern in the 3rd week of February probably wouldn’t get much above 55 if even that. Now to be fair, it is true that over the course of late winter and early spring, the potential temperature under a strong ridge increases more slowly west of the mountains than it does on the east side. Our average highs go up about 5 degrees per month, and the highs under a ridge increase only slightly more rapidly, going from perhaps 3-7 above average in mid- February to 10 or 12 above average by early April. (Keep in mind I’m talking about typical ridge days, not the unusually warm ones!)

      In contrast, the Basin gains about 8 or 9 degrees ever month to its averages, and ridge temps probably much more. In February it usually doesn’t warm up too much in the Basin; they are likely to stay pretty close to seasonal average for highs and with cold nights. But when the change does come east of the mountains, it can happen very quickly. I remember as a teenager a couple times when The Dalles had some sunny days in late February that barely broke 50, but within just two or three weeks we started hitting the mid-60s. There seems to be an abrupt “flipping point” somewhere around the first or second week of March where all of a sudden sunny weather starts bringing highs that are way above average rather than at or slightly below average.

    • Jesse-Orchards says:

      Tune in next time for part 3 of Karl’s 37-part novel:

      “Unseasonable Warmth and High Sun Angles – Why I love them, and how they changed my life.”

    • Rob "Wrath" S.E. Portland says:

      I really like Karl’s post here.

    • pappoose in scappoose says:

      I agree Karl, if we have full sun Saturday we should easily break into mid 60’s.

  18. W7ENK says:

    Snow?

    Really, I have nothing useful at the moment, and in all actuality, I’m just tagging this post so I can read the notifications in my e-mail. Sorry.

    TAG!

  19. Jake-(Gresham) says:

    Good to hear the Cascades are going to get some much needed snow soon! 🙂

  20. Justin (Brush Prairie) says:

    Mark, the record for PDX is actually from March 25, 1965. And PDX had measurable snow later than March 8 as recently as 2006, when 0.3″ were measured on March 10.

    Downtown Portland of course had a 5.2″ snowstorm on April 1, 1936, but that was a long time ago.

    • Rob "Wrath" S.E. Portland says:

      I don’t know how you know all of these historical records, but you do time and time again. This type of info is invaluable to the blog.

      Good night all.

    • Mark Nelsen says:

      Yeah, I really screwed that up. I was thinking of the latest 1″ on the ground. I have that on a weather graphic I occasionally use. Shooting from the hip and attempting to be credible don’t go together very well.

  21. Rob "Wrath" S.E. Portland says:

    A very deep, sharp trough with 500mb temps bottoming out at -39c Portland and -40c Bellingham.

  22. Sandi (Wilsonville) says:

    Thanks Mark! Sounds intriging with that cliffhanger.

  23. Rob "Wrath" S.E. Portland says:

    Mark, thanks for the mini-update.

    More in a few minutes… Oh golly. I wonder what you’re implying…?

    Snow?
    Hail?
    T-STORMS?

    I may need a strong tranquilizer tonight…. 😮

  24. AdamInAumsville says:

    First?

    Come on snow!

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