Cold Showers Today; But Lots of Dry Weather This Week

9pm Sunday…

It was quite a dramatic weather day for some of us. A classic post-frontal (behind a cold front) unstable airmass flowed into western Oregon and western Washington today. That gave us an early spring mix of hail, downpours, bright sunshine, and a few lightning strikes. At 3:15pm one thunderstorm was moving across the West Hills and our system detected a lightning strike around the Cedar Mill area.

Sure enough, a cedar tree was hit in the Cedar Mill neighborhood. Thanks to Alex for this pic

And thanks to all of you that sent in hail pics. Late this morning 1/2″ to 1″ deep hail fell around the Seaside to Astoria area on the northern Oregon coastline. This one is from Lauren Masak in that area.

We get these hefty showers in early-mid spring for a couple of reasons. 1) The upper atmosphere in our area reaches its coldest point in late February and March, lagging the surface temps. In Portland our average high temperature has climbed from the mid 40s to mid 50s since early January. Warming below (compared to wintertime) plus just as cold above means more rising motions = hefty showers. 2) Sun angle is climbing rapidly. We are getting as much energy from the sun now as we would in very early October. A few sunbreaks and the surface warms quickly. That leads to “warm” bubbles of air rising through the chilly atmosphere overhead.

A large upper-level low is sitting off the West Coast; it won’t move much the next two days. Most of the energy and rain is headed south of us into California.

That cold upper-low drifts south and dies over the Desert SW Wednesday and beyond, leaving high pressure to take over for at least a few days Thursday-Saturday. By Saturday the ECMWF looks like this…

Other than a weak system passing by NEXT Sunday, the ECMWF operational model is mainly dry for about a week starting Wednesday. Ensembles from the same model show many members with mainly dry weather during that time. In general it appears the first half of March will end up being significantly drier than average; quite a change from what we’ve seen since December.

The one chilly trough passing through a week from now has been forecast by the GFS recently to bring much colder air for a couple of days. But…it is the GFS and it’s been trying to do that for a couple weeks… Most recent runs just have typical mid-March snow showers down to 1,500′ or so. Not much ensemble support for snow to lowest elevations either. That said…it is interesting that next Sunday is one year from the day we saw a morning dusting to 2″ in the metro area.

So if you have outdoor plans this week, you sure won’t get soaked. But I’d aim for Thursday-Saturday for the best chance of totally dry weather.

This evening I started working on my winter recap presentation I do each year for the Oregon AMS. This year ANYONE can easily watch the meeting since it’ll be on Zoom and Facebook. It’s 7pm Thursday the 18th. If you’re a weather geek and want to immerse yourself in an hour of weather stats, maps, charts…this is your chance! A couple of initial thoughts:

  1. What a slow winter!…Until those four days in mid-February. I have almost nothing to talk about for November, December, & January. At least we had a wind event and snow close call that month.
  2. This was the warmest La Niña winter on record in Portland! Although the urban heat island likely has something to do with that number. We’ll see how the regional numbers look when they come out this week.
  3. We’ve now gone through 7 winters without a regional “arctic blast”. Winters have been easy on our gardens recently…only 24 in Portland this year.
  4. Portland has seen measurable snow now for 6 consecutive winters. 4 of those were “big” snow years, but in two it just barely happened. We are due for a ZERO year I suppose.

Chief Meteorologist Mark Nelsen

32 Responses to Cold Showers Today; But Lots of Dry Weather This Week

  1. tim says:

    To w7, Tropical tidbits daily sst updates and since march 1st enso has been warming quickly. latest 3.4 is 0.17C.

  2. tim says:

    La nina is weakening rapidly with near neural sst now, it could be a very hot summer on the way.

    • W7ENK says:

      Not sure where you’re coming up with that, official observations from BOM Australia (the world’s leading authority on ENSO conditions) certainly don’t indicate anything even remotely close to what you’re claiming.

  3. Roland Derksen says:

    According to the forecast, we may approach the 60F mark for the first time this year on Saturday. I’m somewhat skeptical of that- but even if it does happen, it doesn’t mean winter will be over. In looking over my records last year, I saw snowflurries on the first 2 days of April.

  4. tim says:

    Will the UW models be useing the new gfs v16?.

  5. tim says:

    Anyone notice Uw models have been slow to update the past few days? nothing new just annoying.

    • Tanis Leach says:

      I don’t know if this is still going on, but a few weeks ago, they said they were doing a computer upgrade/maintenance (can’t remember exact word used)

    • Joshua lake oswego says:

      Not really on topic, but GFS v16 is going live a week from today. You can already view the data now, but it will replace the v15 operational model on the 17th. Let’s see if some of the supposed improvements are noticeable in our forecast area.

  6. tim says:

    I have family members that belive weather satellites and radar are fake and don’t show what is really happening and that democrats control them that’s why they never watch the weather report, crazy.

    • Larry says:

      Hopefully that kind of stupidity doesn’t run in the family.

    • Anonymous says:

      You could always point them to Cliff Mass and ask them to follow his blog because he’s a top weather expert and conservative. You can even link them to his blog posts ranting about politics as proof. I don’t find anything wrong with being conservative, but ignoring science altogether for conspiracy theories is unhealthy for everyone. Might as well get them exposed to some of it through someone they may trust.

  7. JohnD says:

    Question for “Ken in Wood Village”:
    Would you care to summarize your experience of the February winter storm out your way? I know that Troutdale “officially” received 14” of snow. No doubt similar where you are.
    Did you live where you currently are in 2008? I’m sure I’m much older than you; but we lived in Troutdale during that winter. Of course the events that year were more protracted. But the high point then appeared very similar to what transpired there last month. I drove out to observe. E.g. Half buried cars; huge snow banks, berms; etc. My what that East Wind can do!
    I recorded 34” overall during the entire 2008-09 winter. We had several “events” in addition to the 10+ day biggy in Dec. I recall, for example, a nice fluffy 3 incher one Sunday evening in January then, for example, that was completely gone the following morning when a south wind kicked in!
    Anyway just fun stuff—if you care to compare.
    We live in inner SWPDX now. I felt extremely grateful that the precipitation stayed mainly as snow where we are in February—with many not so fortunate. I recorded 6” snow-sleet+1/4” ice at the end. No doubt the totals here would have been similar to what they officially were at the NWS (10.1”); but the character of the precip was sleet during a period of high intensity—before changing back to snow.
    In all, quite a 4 day winter storm! No doubt significant by any standards. And post effects lingering much longer—especially, of course, in zones which experienced primarily freezing rain.

  8. Anonymous says:

    I know it’s way too early for anyone to make any predictions or guesses about winter 2021-2022, but I’m crossing my fingers for a front loaded winter with some December and January snow events versus the seemingly February (and March!) only snow events we’ve gotten the past few winters. A widespread event where the entire Portland metro area sees decent snow (and only snow) is at the top of my wish list for next winter.

    • Larry says:

      Me too. It feels weird to have more winter action in March than December sometimes. I’d like to see some normalcy.

  9. Mountain Man says:

    Things are starting to cook, not just simmer on the day 7 in the models today. One of the things I love about spring is the battle with winter. Mark made a perfect point or two about that. Anyway beautiful spring weather, a brief moment of real winter for a day or two, day 7 to 8 and then back to spring. I love it! Got up to 57 last week, had an inch of snow yesterday afternoon (two different showers dropped a half inch), got down to 27 this morning, and now I’m looking forward to the late week 50’s again. Now, perusal of all available ensombles at the moment, there’s a reasonable chance, after you guys in the lower elevations get into the low 60’s, you could have a dusting of snow or at least slush about a week from now. It looks very possible with agreement between models and ensombles ever agreeing more on the very cold but fast moving trough.

  10. Ken in Wood Village says:

    It’s been awhile but I have enough money to buy a subscription to a paid weather site. The free ones are not giving me enough information on what it happening in the atmosphere.

    I see the NWS has said the possibility of thunderstorms mainly along the Coast but I’m seeing on the HRRR a line of showers (maybe thunderstorms) coming up the Willamette Valley. In the past when shower come up from the South. Normally when they come up this way, they can be fairly strong. This happen back on June 26th, 2019.

    The one thing that’s going to help is the sun. I looked at the Satellite picture and there are clouds and a couple of showers around the Portland area right now but those will move out and the skies will clear and the atmosphere will warm up. This should give fuel for the showers/thunderstorms to build up.

    At least that is my thinking. We’ll see if my thoughts are correct!! I’m keeping an eye on this all day 🙂

  11. Tanis Leach says:

    Separate Question for everyone: In your opinion which class should I take. I can only take 1 or I’ll be overloaded (I have 3 additional classes)
    ATS 412: Atmospheric Radiation
    ATS 499: Mesoscale Meteorology

  12. Tanis Leach says:

    Thanks for the update Mark!

    Quick statistical analysis since I did this about 2 weeks ago but didn’t post this yet.

    Chance of another 10 inch winter (unadjusted/adjusted): 5.1%/1.5%
    Applies from Multnomah county to Cowlitz county along I-5.
    No snow winter (unadjusted only): 9.3%
    Chance of low <20°F: 96.9% (note that this changed since I now look back to 1940 rather than 1950 from my earlier forecast)
    Chance of arctic blast (minor or major): 89.5%
    Chance of -12°C: 84% (only going back to 1973)

    Take these with a grain of salt since they are just based off the frequency of how often they’ve happened in the past. Any winter condition must have the corresponding atmospheric condition.

  13. Roland Derksen says:

    No lightning here that i know of yesterday, but we did see some hail briefly on a couple of occasions. Rather cool as well, so the mountains are really loaded with snow.

    • Ken in Wood Village says:

      There were a few lightning strikes yesterday. I happen to be in Beaverton visiting a friend when that storm came through. It dumped a lot of hail and 3 lightning strikes. Only one hit the ground so my lightning detector only picked the one up but the other two were cloud to cloud. 🙂

  14. Ken in Wood Village says:

    I think there is an outside chance of thunderstorms later today. I would keep an eye on the sky’s today. 🙂

  15. 5OClockCharlie says:

    These night-time temps sure are cold. My heat-pump keeps switching to supplemental heat. There goes my energy bills for another month 😦

    Euro seems to think we’ll get a trace-2″ Sunday-Monday. The surface temps and sky temps seem to support that.

    Strangely the GFS 6z and 12z have backed off on snow in the valley. Seems it’s confined to the foothills.

  16. W7ENK says:

    With regard to Point #2…

    This was the warmest La Niña winter on record in Portland!

    Wasn’t the last La Niña Winter also the “warmest La Niña Winter on record” in Portland? 🤔

    • Tanis Leach says:

      20-21: 43.58°F
      17-18: 42.63°F
      50-51: 43.03°F

      17-18 the last la nina winter, was the 2nd warmest la nina winter at the time.

      Interestingly, the 50-51 winter had a larger departure from average (2°F) compared to this winter (1.48°F)

  17. W7ENK says:

    Crazy, my lightning detector goes out 50 miles, and it didn’t see that strike!

    And we didtnt get any of that action on the Eastside. Just some menacing clouds and a quarter inch of large raindrops. No hail, no thunder, just raindrops.

  18. Anonymous says:

    Nice post I do think we are due for a very cold winter especially with 7 years without an arctic blast I am thinking next year it happens record cold temps dec Jan maybe even historic similar to Going back to the 30s or late 1800s we will see

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