Still Looking Chilly

A busy afternoon/evening; Steph is off today so I got all the shows.  It makes for a long day but it was nice to have some good changes to forecast and track.  By that I’m referring to the warm weather tomorrow and the cold weather early next week.

I don’t see anything significantly different from last night at this time.  IF we had significant moisture around either early Monday morning or early Tuesday morning I could easily see us getting snow down to the city.  But I sure don’t see that.  Our RPM is really pathetic on moisture Monday morning and the GFS doesn’t look wet early Tuesday morning.  After that temps warm and our brief flirtation with low snow levels is over for the week.   Now I admit that we could get some nice convective showers moving in from the northwest Monday afternoon.  That may give us the most meteorological fun.  They would probably contain hail and could even change to all snow, especially after 5pm in the lowest elevations.

Due to the lack of any good vorticity maximum, surface low, or anything “organized-looking”, I’m not too excited about even more than a trace below about 1,500′.  It could end up being a real waste of a very cold polar maritime airmass.  In the past (2006 anyone???) we’ve seen vigorous and heavy showers with a similar setup.   The big difference then was strong westerly flow up above with lots of moisture following a cold front.  This time a surface ridge is building in ahead of the next system and the cold trough is passing through quickly instead of sitting over us for 2 days.

So I’ll do some forecast percentages:

100% chance of at least a dusting to 1,500′

50% chance of a widespread dusting to 1,000′

30% chance of widespread dusting below 500′ in the Portland Metro area.

5% chance of no school Monday morning at more than 1-2 local school districts (do your homework!)

30% chance of a hard freeze; less than 25 degrees in Hillsboro or 28 @ PDX  (only chance is Tuesday morning).

Chief Meteorologist Mark Nelsen

52 Responses to Still Looking Chilly

  1. Karl Bonner says:

    It would definitely be fun to get a little dusting of snow, especially with all the spring flowers and early trees already in active mode. Phenologically speaking, it’s somewhere between about 3/15 and 3/25 depending on which plants you’re talking about. My eyeball estimate is that almost half of all the cottonwood trees along the river now have at least some green on them, and perhaps 5% of the total have what I would call a solid canopy, meaning the entire tree is covered with decent-sized leaves (though still not as large, and certainly not nearly as dark, as they get later in the spring).

    If I had to guess, I would say that the peaches and plums are the furthest ahead of schedule. The flowering plums hit full bloom between Feb. 15 and 20 this year. I think March 10 is normal for them. The saucer magnolias, however, only became really profuse in the last two or three days. And they are typically pretty solid by about Paddy Day. So instead of being only a few days behind the plums, they are two weeks this year.

    And the early maples (bigleaf and the other one with the green-yellow flowers) are probably the least ahead: usually by about the 20th the flowers are getting widespread, while this year they currently look to be about one week away still. (There are a few specimens that came out VERY early, such as Feb. 25 or even the 20th in one case! But they are the exception rather than the rule. And I haven’t seen a single bigleaf maple emerge yet although some of them look really close.

    I’m curious what things would look like right now if it had been a little warmer during the February ridge and during last weekend. Keep in mind we were dipping into the high 20s down this way a couple weeks ago, and that can really damper plant progress. Without the chilly wind things might have been about 5 degrees warmer in both night and day. Also last weekend was a great setup for some mid-60s in favorable spots. If only the clouds hadn’t spoiled things! I really hope we don’t go into an extended cold period with highs struggling to get much beyond 48-50 and near-freezing nights. That could really jeopardize our early schedule.

    One more interesting note. Last year the flowering plums didn’t start to fade out until the first week of April. But right now many specimens are already somewhat past peak, perhaps comparable to April 1? Keep your fingers crossed for more warm weather – if you think it’s early now, imagine the prospect of things being really green and leafy by the very end of this month. It makes me think of the time I visited California in late March and all the leaves were well out.

  2. flurball says:

    I see “dabears” aren’t done spending money 🙂

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

    00z looks a tad warmer, just very slightly so, at least the WRF-GFS anyhow.

    500mb thicknesses appear to peak around 519-520dm

    850mb temps peak around -6c to -7c

    500mb temps peak around -36c to -38c

    To perhaps enhance the chances for convection the cold core/pocket aloft moves directly over NW Oregon/SW Washington. If we can manage sun breaks maybe some good hail storms and isolated lightning strikes.

    • Stevengibson says:

      So no snow now lol

    • Rob "Wrath" S.E. Portland says:

      I really doubt the valleys were to ever see snow anyhow. Going to have to be 1,000′ maybe down 500′ if you’re lucky enough to get a heavier shower overnight.

    • Stevengibson says:

      i sit about 600′ so hopefully that extra 100′ help some!

    • dabears (Hillsboro-Tanasbourne) says:

      Wow. It’s not warmer, and stop downplaying this. I’ll bet you $100 right now (seriously) that some valley spots will see snow.

    • What “valley spots” are we talking here??


    • dabears (Hillsboro-Tanasbourne) says:

      Anywhere west of the gorge, below 500′ and within 50 or so miles of PDX.

  4. dabears (Hillsboro-Tanasbourne) says:

    Forest Grove is at 69! Gonna be a close call for 70. 67 here. Can’t believe how warm it feels.

  5. dabears (Hillsboro-Tanasbourne) says:

    The 18z is nice and cold. It’s starting to look like we could get a second snowstorm Friday into Saturday as well.

  6. muxpux says:

    man, this is like the weather in the midwest/south. 65 one day and bright sunshine, then possibly snowing 2 days later.

    fun stuff.

  7. Timmy_Supercell (Hillsboro) says:

    So hows everybody liking this month of Maych? 🙂

  8. Battle Ground Brian says:

    1:30pm @ BG Lake

    Temp 65.5 Low:39.0 this morning
    Hum: 28%
    Winds: SE 5-10mph

    Some areas like Scappoose, Hazel Dell may hit 67 or 68 for todays max temp. Closer to 60-62 in windy areas closer to the Columbia. Great downsploping in Clark Co. this afternoon.

  9. Warm 64.3° with light NE winds

  10. W7ENK says:

    I’m sticking to my default…

    “I’ll believe it when I see it!”

    • weathergirl - colton - 1000 ft says:

      Hey W7ENK – think I saw you on the freeway yesterday – do you drive a blue car? Small world!

    • W7ENK says:

      Indeed, I do. One with lots of antennas… 😆

      I just hope I wasn’t driving like an @$$.

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

    60.1 here

    I see a station very near me is reporting 62 with upper 50’s throughout Gresham.

    Hmmm 12z is nice…. Maybe an overnight snow level of 500-750′? C’mon moisture….

    • Mark says:

      Ah, Rob, you started at 1500 feet, now you’re down to 500 feet!

      Tomorrow will be…..sea level!

    • dabears (Hillsboro-Tanasbourne) says:

      Rob, I think it’s pretty obvious that the overnight snow level will be under 500′. The question is the timing of the moisture.

    • Rob "Wrath" S.E. Portland says:

      Nah I can’t go lower than 500’…. Very cold air mass for sure, but it’s traveling over 1,000 miles of warmer waters, relatively speaking of course which as we know will moderate things just a tad too much. Now if this cold air were to be dumping southeastward down the British Columbia Coast and we set up a short-over-water trajectory, then I’d think sticking snow at sea level would be possible.

    • Rob "Wrath" S.E. Portland says:

      I should say well over* 1,000 miles.

    • Jesse-Orchards says:

      Rob, Mark has talked about this before. 500′ is just a weenie snow level to forecast. Either put it at 1,000′ or put it at 0′.

      Personally, I think there will be some lucky areas, under heavy showers, that see sticking snow to sea level.

    • Jesse-Orchards says:

      Rob, as Mark has said before, 500′ is just a weenie snow level to forecast. Either put it at 1,000′ or put it at 0′.

      Personally, I think some areas who happen to see heavy precip at the right time of day will see sticking snow to sea level.

    • Mark says:

      Jesse, I don’t think it’s that big of a deal to forecast a 500′ snow level. I personally only remember Mark talking about forecasts like 200′ and 300′, most notably from Rod Hill back in the day. I personally like the 500′ snow level, as at many times, I’ve had no sticking snow down at 250′ feet in Beaverton, but a couple hundred feet up on Cooper Mountain, it’s a whole ‘nother deal.

  12. Jesse-Orchards says:

    12z looks as cold as ever. The event is getting quite close now – you can see theleading edge of the trough currently over Southern Alaska/Northern GOA speeding ESE toward our Coast. I would still expect a small degree of moderation from the GFS, but it looks likely at this point that we fall to at least -7 to -8 at 850mb, with sub-520 thicknesses.

    • Mark says:

      Yup, it looks as if the strength of the cold is relatively set. Now, we just need to figure out the timing of this thing and how much precip. there will be.

    • dabears (Hillsboro-Tanasbourne) says:

      It seems like the cold has been extended as well. I can see it snowing into Wednesday now if we’re lucky.

  13. Warming up nicely…up to 53.5° from an overnight low of 33.4…

    Light, variable wind…Pressure falling at 29.98″

  14. Ben Randall says:

    I will disagree with mark , I think everyone will get a snow surprise Monday Morning trace-2 inches

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

    58.6 here with very breezy to gusty NE winds.

  16. Timmy - scappoose says:

    Just arrived in LA at LBC, pouring down rain! Great.

  17. pappoose in scappoose says:

    I love the percentages Mark, it reminds me of old times when I watched Bob Lynott break down the chances of snow.

  18. sds says:

    We have a saying here in Clark Co.–when the snow melts off Silver Star Mt., then it is safe to plant your corn seed! I don’t think that is going to work this year.

  19. am i being monitored? if so why mark?….

  20. yevpolo1990 says:

    lets hope coast ran….

  21. Mr Data says:

    Sorry for getting upset as I was upset about an earlier incident from the winter still and it just confused everybody. :-[ ^^’

    (best smiley I can find if my text ones fail)

    (warning sound ad)

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

    PDX/TTD-DLS nearing 3mb of offshore flow. We’ll here’s hoping for a surprise vortmax or shortwave to sweep in Monday night.

    Good night all.

  23. pgiorgio says:

    Good luck on getting some exciting weather. 5% doesnt seem too good for a widespread snow though.

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

    Mark, thanks for the update.

    50.2 here with increasing NE winds.

  25. Tyler in Hazel Dell says:

    Snow or no snow—at least we have some exciting weather! I’d be happy with some strong showers Monday with maybe some hail! Will make for a great time lapse!

    Headed to Silver Star tomorrow, probably little or no snow (4,300′).

  26. W7ENK says:

    Hey, these are better chances than we’ve had pretty much all winter long! I’ll take what I can get. 🙂

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