March Offers a S-L-O-W Start To The Meteorologists

8pm Wednesday 

It’s been a very slow couple of weeks weather-wise; hard to find inspirational blog post material.

Putting that fork in winter was definitely the right thing to do two weeks back.  We have slipped back into a weather pattern similar to December with weather weather systems occasionally sliding into the Pacific Northwest.  Precipitation has been well below average across almost the entire western USA the past two weeks.  Portland has only seen .27″ in those two weeks!

hrap-all-nw-14day_percent_anom-3323200

February ended with near normal temps for us…nothing unusual there.  We’ve had a ridge of high pressure over us or just to our west the past couple of days.  Some nice weather has been the result!  By tomorrow that ridge is moving east and you can see a cold upper-level trough approaching.  This is the 500mb GEM (Canadian) ensemble average.  That’s the average of 21 difference ensemble members.

m500za_f024_bg_NA

One would think we have a cold/showery few days ahead (beyond tomorrow) with lots of mountain snow.  But all models show that trough splitting/stretching as it moves over the Western USA.  By Sunday a cold trough is well west of California and what’s left is moving over the Pacific Northwest.

gem_sundayam

That splitting means we get a weak cold front tomorrow night, then a few light showers Friday and Saturday.  Even though snow levels plummet down below 2,000′ by Saturday, there just isn’t much moisture to go around.  Expect only a few inches of snow in the Cascades and higher parts of the Coast range.  Yes, more slow weather.  Although on the bright side we MIGHT see some convection (brief heavy showers) Saturday…maybe.

That cold trough shifts east early next week, likely leaving us with mainly dry weather Sunday through Wednesday.  The same GEM ensembles for Wednesday the 11th

gem_wednesday11th

This gives us some pleasant, but not overly warm early/mid March weather.  All models then are in pretty good agreement another cold troughing “episode” shows up in about 10 days…the following weekend.  Saturday the 14th:

gem_saturday14th

 

Notice with ridging now, plus the first half of next week, that rainfall will remain below normal through the next 7-9 days.  The ensemble average rainfall from the ECMWF shows a half inch or so for the next week, and less than 2″ in the next two weeks.  That’s a bit drier than average, although clearly looking wetter that 2nd week.  The big story here is that I don’t see a long wet period ahead.

ecmwf-ensemble-KUAO-indiv_qpf-3323200

Temperatures will remain near (or even a bit below) average for early-mid March.  There’s no sign of a real intrusion of cold air in the ensemble averages.  But I don’t see any models going for extra-warm upper-level ridging either.  That means no 65-75 degree weather; which can happen this time of year.

To summarize

  1. Other than showers tomorrow night through Saturday evening, there isn’t much rain in the next 7 days.
  2. Near normal temps today/tomorrow turn cooler Friday through Sunday, then warm again early-middle of next week
  3. No sign of widespread frost west of the Cascades until at least Sunday night
  4. The increasing sun angle means even a 55-58 degree partly cloudy day feels warm for a few hours midday through afternoon!
  5. There’s no sign of a stormy March weather pattern ahead

By the way, are still hoping for snow?  I’m sayin’ there’s a chance!

Remember late March 2012?  A stalled front dropped steady/heavy precipitation right over the Willamette Valley.  4-6″ fell in the central/south Willamette Valley and even a few inches fell in the hilly areas around the metro area.  But measurable snow at the lowest elevations west of the Cascades in March IS rare.  Last year was exceptionally cold the first 10 days of the month.  That was mainly due to extensive snow cover left to our north and east from the record cold February.

 

Portland Snow Last Few Times In March2

Portland Snow Last Few Times In March2

More likely is a temperature getting close to 70 at some point this month!

March Warmest Temp

Chief Meteorologist Mark Nelsen

40 Responses to March Offers a S-L-O-W Start To The Meteorologists

  1. Roland Derksen says:

    Some flakes amidst the light rain this morning, but the precipitation didn’t last. Could still see a chance of snow on Friday, however.

  2. Tanis Leach says:

    Just for some weather stats here:

    Last snowfall over an inch: March 8th (1951) (7.6 inches)
    Last snowfall over .1 inch: March 25th (1965)
    1″+ snowfalls in March: 5 (last 1989)

    Last high below freezing: March 3rd (1960, 29F)
    Last high 35 or below: March 4th (1960, 34F)
    Last high in the 30s: March 25th (1955, 39F)

    Lowest I consider thermally possible for March 14th (high): 35F

    Last hard freeze: March 24th (1954, 24)
    Last freezing low: May 2nd (1964, 32)

    Lowest I consider thermally possible for March 14th: 21F

  3. rmlounsbury says:

    Well, it would seem we broke the forks out too soon. We have a legit chance of some brief snow in the valley with this setup. Even if we don’t get snow overnight temps will be cold enough that you’ll need to protect sensitive plants and probably cover those hose bibs up again.

    • Tanis Leach says:

      I will say for Mark what a fork means (missing one but not going back):

      What we are done for:
      Widespread snow and ice storms that shut down for a day or more
      Hard Freeze (below 28) (the most under threat)
      Widespread Flooding (I’d say MOST flooding to accommodate for April Last year)

      What we could still have:
      Windstorm
      Rain
      Quick snow in the morning but gone later.

      So as it stands right now, the fork is fine.

      • W7ENK says:

        Oddly enough, my overnight low temperatures the last two nights have been 27 degrees, after a 28 the night before that, so it looks like he blew that one about hard freezes.

        Also, the number of overnight lows below freezing so far in March (4) is equal to that from all of January. If the current forecast holds true, that number will double by Sunday morning.

        • Tanis GLeach says:

          Not to discount your numbers, I’m pretty sure the numbers being used would be the Portland NWS site. Its lowest is 31 so far.

          When forking Corvallis, I stupidly put 28F, when I should’ve put 25F when I relooked at the data.

        • Tanis Leach says:

          Just responded but made a typo to my name, a Tanis GLeach is me, but was stupid. If there is anyway to change that in moderation, please do that.

        • boydo3 says:

          Better get your forking name right!

  4. Scott Reeves says:

    Looks like models just have a cold rain this weekend

  5. lurkingsince'14 says:

    Please tell me this is model hubris — all winter is a massive joke and then it’s gonna snow in mid-march after a ton of Spring tease weather? What the &!%#?

    The fork has been planted, this somehow turns into 50 and showery amirite Mr. Nelsen?

  6. JohnD says:

    This coming Sat. will already be March 14, after all. Most of we W OR lowlanders already believe the winter ship sailed some days ago (and basically never even stopped here anyway this year.)
    But now this little anomalous looming pattern. I for one will never discount unprecedented winter weather potential. Doubtful this will be that…but maybe a bit early to say yet…
    One thing for sure: I’ve got a Gorge hike planned for this Sat.—in elevation. So cold weather gear will be a given!

  7. Mountain Man says:

    Time for a Mark Nelsen in-depth analysis. All the models have some sort of omaga high with a trough down the back. I actually like the EC this time, which is usually the most accurate. I can’t complain like the rest of you though. Had snow 5 out of the last 6 weekends at my house.

  8. 18z GFS Ensembles for Mid-March were COLD! It would figure our best cold pattern of the entire Winter happens now. Lol.

    Surface Temps

    Mean Temp – Minimum Low/High

    Portland: 22-35°
    Seattle: 24-37°
    Yakima: 12-22°

  9. Joshua Lake Oswego says:

    Interesting possibilities coming up. Saturday morning scores with the GFS (18z) and UKMET. Friday evening for the GEM. A skiff of snow on Sunday says the ECMWF. All very marginal. In any event, should be chilly with some flakes likely in the air at times.

  10. Evan -- Cedar Mill says:

    Haven’t we all learned that the models aren’t doing well this year?

  11. rmlounsbury says:

    Now that we are past the fun-to-watch winter period I hadn’t been watching models all that closely. I took a peak at the GFS operational this morning and noted it is trying to send us some late season Arctic air this coming weekend.

    Anyone watching the ensembles or other models? Is the GFS Op all by itself on this?

    • Tanis Leach says:

      Euro has a modified version of it as of 0z, but their highs are all in the 40s, some ensembles are in the 30s. Its also showing a 50/50 shot of snow on Sunday.

  12. Ken in Wood Village says:

    If we go by what the models are showing now, next weekend could be a very cold. It will be interesting to see how things play out this week with the model runs.

  13. OMK says:

    Drove to the coast this weekend and the passes had BIG flakes. Was even sticking in some spots. It was definitely a first to see snow in the hills and cliffs behind Arch Cape/Manzanita area. The air was chilly and the water temps were frigid! Come on summer!

  14. W7ENK says:

    Looks like the forecast is changing for Denver this coming weekend. I’m flying over for a few days to attend a graduation, and what initially looked like sunny skies with highs mid 60s to maybe 70 degrees and lows down to near freezing, it now looks like highs maybe touch 60 on Sunday, with overnight lows steadily dropping down into the teens by Tuesday morning. Maybe throw a little precip in for good measure? If it snows, I’m screwed, since no one puts winter tires on rental cars. 😥

    That is, if “they” haven’t grounded domestic flights by then. Really hoping that doesn’t happen while I’m there, and then I get stuck…

    • W7ENK says:

      Another day later, and the forecast for Denver continues to deteriorate.

      Looks like I’ll possibly be hindered getting to PDX by snow early Saturday morning, and I’ll be hindered again by snow getting to DIA on Tuesday afternoon. Will reassess once again tomorrow evening and see where things are, but I’m locked into going, I’m obligated. I just have to roll with the punches and take it at this point. Rental car and hotel are non-refundable, package deal.

      Maybe I should just go to PDX after work on Friday and camp out?

  15. Roland Derksen says:

    Foggy and frosty start to the day here- but after that it’s been all sunshine. I don’t mind this slow start at all!

  16. Paul D says:

    Hail in Hillsboro around 3pm!

  17. Evan -- Cedar Mill says:

    Any reports from the West Hills? I’d assume a heavy shower could bring some chunky rain to those elevations.

  18. Roland Derksen says:

    A very brief and light snow flurry here around 7am. The temperature at the time was 34F- I doubt we’ll see anything more.

  19. S L O W indeed. Thanks for the update, Mark.

    By the way, anyone reading this who is in my PDX WX Analysis group if you could pass along this message I would greatly appreciate it.

    I was flagged for spam for posting too many messages too quickly(Radar images) when I was tracking the tornadic supercell in Nashville the other night. This isn’t the first time Facebook has done this to me. The other time was back in 2015 during a severe weather outbreak in my Texas group. Due to this they banned me for 30 days (28 days remaining). Very annoying and frustrating. I did contest this asking for a request for Facebook to review this, so hopefully they will do so and I’ll be able to access my account and groups sooner. If you do get this message info and you do inform my group please also mention my Texas group TheSTORMCenter/DFW as we do have a few members also in my PDX group. Alrighty.

    Thanks!

  20. Roland Derksen says:

    I’ve seen some pretty good snowfalls here in March over the last 20 years- especially in 2002 and 2009. Don’t expect anything measurable soon, but I might see a flurry or two tomorrow.

  21. Ken in Wood Village says:

    The 00Z Euro got a little interesting close to the end of the run 🤔

  22. pappoose in scappoose says:

    There’s a chance! Happy day!

  23. Joshua Lake Oswego says:

    I will bet that PDX gets less than half the rain the ECMWF ensembles are showing for the next two weeks. Any takers? Less than 1” through end of day 3/18. I will also bet that we make it through end of day this Sunday with less than .25”. High res models are putting a nice big hole over the north and central valleys. It was looking promising for a while. Always does.

    We have only had one day with more than .25” since January 30th. .33” in the last 17 days. I already see moss browning in certain spots and grass dying where it has shallow roots and/or water competition near big trees or in rocky/gravelly areas. That usually doesn’t happen until May.

    So Cal looks to get slammed next week. They need it too, but we have no hope in sight.

    • Joshua Lake Oswego says:

      Thankfully for me, nobody took my weekend bet. Parts of the metro area are overachieving for a change. Not PDX yet though.

  24. JohnD says:

    Alaska continues at the moment to be an absolute freezer this season—and for much of the prior weeks/months. Simply beyond me how/why some of that never did advance south—even to US areas typically prone. No doubt some of you have a handle on this.

  25. Anonymous says:

    Anybody else use the fox12 app? The changes they made are horrible!!

  26. Anonymous says:

    It’s interesting that all the measurable March snow has been since 2006 except the frigid late winter of 1989. It seems to me our seasons have changed a little. I’m not one to think it’s directly from man made climate change either. I think there is way too many variables (sun spots, solar activity, normal changing of the Earth over millennia etc).

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