A Short Post

DSCF0013  This picture has absolutely nothing to do with weather…just a couple of friends smiling for the camera during a commercial break.  I spent a bunch of time this evening cleaning up my school presentation and taking some new pictures in the studio…this would be one of them.  So I didn't have much time to blog.

I don't see any major changes in forecast thinking for this weekend.  It appears to be cold enough to get lowland snow from sometime Saturday night through early Monday morning.  The limiting factor will be moisture showing up at the proper time.  I have a gut feeling that with westerly onshore flow (rain shadow), we have another Dusting to 1" event coming up in the lowlands for Sunday morning…maybe again Sunday night if the moisture holds out.

For fun I checked out the March 1951 maps, when we had 4-10" in the metro area.  500mb heights dipped to about 507 over Portland!!!  An incredibly deep upper level low dropped down and sat just to our north for about 3 days, circulating very cold showers onshore.  I noticed at one point 850mb temps were well below -10.  That must have been fun…Mark Nelsen

88 Responses to A Short Post

  1. stevied (North Portland) says:

    WRF-GFS this evening keeps snow chances for PDX going through Wednesday morning… wow. Quite a chilly spell for March. It actually shows the most snow in PDX between 11pm Tuesday night and 5am Wednesday morning. Maybe 2+ inches.
    Maybe an inch from 11pm-2am Tuesday night.
    http://www.atmos.washington.edu/mm5rt/data/2009030600/images_d2/or_snow3.129.0000.gif
    Then between 2am-5am, maybe another 1-inch +
    http://www.atmos.washington.edu/mm5rt/data/2009030600/images_d2/or_snow3.132.0000.gif

  2. stevied (North Portland) says:

    From NWS this evening:
    THE MORE INTERESTING PERIOD IS SATURDAY NIGHT AND SUNDAY…THICKNESSES SUGGEST THAT THE SNOW LEVEL SHOULD GET NEAR THE VALLEY FLOOR LATER SATURDAY NIGHT AND SUNDAY…PROBABLY ENOUGH FOR AN ADVISORY IN AT LEAST THE NORTHERN VALLEYS…PERHAPS CLOSE TO THE VALLEY FLOOR. TIMING OF LATE AT NIGHT AND EARLY IN THE MORNING WOULD FAVOR SOME STICKING SNOW AT THE VALLEY FLOOR. COLD AIR IN PLACE WILL BE SLOW TO MOVE OUT OF THE AREA WITH THREATS FOR LOW ELEVATION SNOW THROUGH TUE

  3. Runrain says:

    Just had a hail shower develop right over the top of us in Happy Valley. Lasted about 3 minutes. The ground turned white and temp is down to 36.5. The accumulated hail is running down the hill in clumps that look like suds!

  4. Justin (Brush Prairie, WA) says:

    The 00z is impressive cold. 850mb temps get down to -12c, which could easily mean highs in the mid to upper 30’s with a bit of help from cloudcover.

  5. stevied (North Portland) says:

    WRF-GFS this evening doesn’t put but a few snowflakes in PDX, but does have them around. The MM5-NAM was showing much mre in the way of snow in PDX. Let’s see if they can come into some agreement tomorrow morning for the 12z.
    Text output for the 00z GFS shows it colder than previous run, and for a longer period: http://wxweb.meteostar.com/sample/sample.shtml?text=KPDX
    Man, look at the forecast temps for Bellingham!… down to -18c 850mb temps: http://wxweb.meteostar.com/sample/sample.shtml?text=kbli

  6. Bishoy-Beaverton, 300 feet says:

    Well, after looking at the text data, it seems I was reading it wrong. My bad…

  7. Runrain says:

    BLarry: a serious challenge to haiku from Boydo3!!!

  8. Bishoy-Beaverton, 300 feet says:

    Well, would you look at this! The KPTV RPM model is showing an inch or two of snow…
    http://www.cascadeaccess.com/~mnelsen/web_RPM_00z_AccumSnow.jpg
    ..in Clark County!

  9. Bishoy-Beaverton, 300 feet says:

    More specifically, between hours 54 and 96?

  10. Bishoy-Beaverton, 300 feet says:

    Stevied, don’t the 850mb temps look a little warmer to you on the 00Z GFS?

  11. yevgeniy.beaverton says:

    i definately agree, 35 would more reasonable if not 34 degrees

  12. stevied (North Portland) says:

    00z GFS looks good. I don’t see how Mark can keep those numbers for the forecast. I really think he’s going to have to (or should) lower them. 00z GFS shows initial cold air Saturday afternoon/evening, then another shot of cold air Monday afternoon/evening. I see temps on Sunday lucky to reach 40, and Monday the same.

  13. boydo3, N. Albany 500' says:

    For the over 21 group….The Answer is brewin’ in the wind. By Blob Dylun
    The Models are a showing
    some snow and that’s not new.
    And if the wind is blowing
    we’ll hoist frosty brew.
    But if the forecast fails us
    we might just throw a fit.
    And smash the computer monitor
    and chug a Belgian Wit.

  14. SnowFlake (Tigard/Bull Mtn) says:

    that’s only if the SCR (Stupid Coast Range) doesn’t eat it all…..

  15. yevgeniy.beaverton says:

    if you look closely on the map, west side seems to be the big winner of the amounts of snow 😀

  16. stevied (North Portland) says:

    Sorry, posted a bad link in the last one. The 2nd link is correct now…
    ==================================
    SNOW ALERT!
    MM5-NAM this evening shows snow on Sunday in PDX.
    Maybe an inch between 5am-8am Sunday morning: http://www.atmos.washington.edu/mm5rt/data/2009030600.naminit/images_d2/snow3.63.0000.gif
    Then maybe another inch to inch and a half from 11am-2pm Sunday: http://www.atmos.washington.edu/mm5rt/data/2009030600.naminit/images_d2/snow3.69.0000.gif
    So, the MM5-NAM this evening shows 2+ inches in PDX Sunday. Let’s see what the WRF-GFS this evening shows. C’mon, baby!

  17. SnowFlake (Tigard/Bull Mtn) says:

    Looks like it’s time for another snow haiku…..
    Larry…Runrain ??????????????????????

  18. stevied (North Portland) says:

    SNOW ALERT!
    MM5-NAM this evening shows snow on Sunday in PDX.
    Maybe an inch between 5am-8am Sunday morning: http://www.atmos.washington.edu/mm5rt/data/2009030600.naminit/images_d2/snow3.63.0000.gif
    Then maybe another inch to inch and a half from 11am-2pm Sunday: http://www.atmos.washington.edu/~ovens/loops/wxloop.cgi?mm5d2_e_snow3+//72/3
    So, the MM5-NAM this evening shows 2+ inches in PDX Sunday. Let’s see what the WRF-GFS this evening shows. C’mon, baby!

  19. Sandman - Aloha says:

    On my way home I noticed that “crystal” rain is starting to fall here in Aloha. It was confirmed via the splat test. YEH!

  20. yevgeniy.beaverton says:

    tell me about the alert!!! “drool”

  21. **** **** says:

    *** ALERT *** **** ALERT *** STAY TUNED ***

  22. Rob "Wrath" - Elevation 300' -Far S.E. Portland- says:

    Hmmmmm
    Bellingham NE winds. Dewpoint down to 14F ….
    Why do I mention this? I’m wondering if a bit more Arctic air is funneled through the Fraser River valley, then down into eastern Washington thus colder air to creep down through the Columbia Basin setting up a brief cold pool to develop…
    Just something I am keeping an eye on.

  23. Tetraforce (2009-2010 The 1949-50 snow year equailvent) says:

    That could also not be the real Mark Nelso either posting. Anybody can make up his name. Even I could though I wouldn’t.

  24. Tetraforce (2009-2010 The 1949-50 snow year equailvent) says:

    For the public I meant.
    42.8F and cloudy. (sigh) I wish we had more reliable data.

  25. Tetraforce (2009-2010 The 1949-50 snow year equailvent) says:

    Satiliete pictures began after WW2 which just isn’t enough time to develop long-term patterns.
    England has weather records as far back as the 1700s in some spots but for some reason it’s not to the public like here.

  26. Tetraforce (2009-2010 The 1949-50 snow year equailvent) says:

    I’ve learned it’s called sarcasim 8″ of snow. He’s just being funny and I like that humor actually.
    I would like to hear Steve’s thoughts. The only problem I have with his theory is that their isn’t enough records. Decent data only goes back to 1950 and you can’t get any data from the late 1800s.

  27. Jesse-Orchards says:

    Can’t figure out why Mark warmed temps up a bit on the 7-day, especially overnight lows.
    12Z and 18Z GFS, as well as the 12Z Euro, are as cold as ever.

  28. Rob "Wrath" - Elevation 300' -Far S.E. Portland- says:

    Just as this shower started I had some very small hail. Now it has just turned to rain.
    Current upper air analysis
    ————————————-
    850mb: -4c to -5c
    500mb: -23c to -25c

  29. Silverton500 says:

    There will be 8″ of snow SOMEWHERE on Sunday morning.

  30. Tornado Aly (Vancouver) says:

    8″ of snow in the mountains….

  31. Gordon (Working in N. Portland) says:

    Did Mark just let something out of the bag? We know your kidding, but how dare you tease us like that.

  32. Punxsutawney (aka HIO Phil at work by Sunset High ~280' elevation) says:

    ?!!

  33. yevgeniy.beaverton says:

    oo pshh
    sunday will be magical 😀

  34. pgiorgio says:

    ahahah Mark. Not a foot?

  35. Mark Nelsen says:

    Steve is busy putting together his presentation…he’s too busy to worry about the 8″ of snow coming Sunday morning.

  36. Gordon (Working in N. Portland) says:

    What are your thoughts Mr. Pierce?

  37. IceKeeg - workin' in Tigard says:

    Here’s the afternoon NWS discussion regarding the potential event:
    Models are very consistent in dropping an unseasonably cold upper
    trough down out of the Gulf with very cold air moving south across
    British Columbia. 12z and 18z GFS bring very cold air all the way
    into the northern Willamette Valley by Sunday. A cold front moves
    through Saturday and is followed by a second front Saturday night
    with which drops snow levels down very low. The jet remains right
    over northern Oregon with good vorticity advection for continued
    precipitation. This pattern will result in significant snow in the
    Cascades…Coast Range…Willapa Hills and foothills and a Winter
    Weather Advisory will likely be needed. Higher hills of the
    Willamette Valley and Clark County also likely to receive sticking
    snow. The valley floor forecast will be more problematic. The ground
    is pretty warm this time of year and sticking snow more likely to be
    only on trees…roofs and grass Sunday morning. However…if showers
    are heavy enough that could change. If the cold air remains as models
    show into Sunday night and Monday sticking snow may be more likely.
    More to evaluate as event approaches. Schneider

  38. William Johnson says:

    Astoria, Oregon
    3:11 pm
    45 degrees
    Strong showers have been comming in off and on all day now we have a persistant strong west wind comming in at this time i think we are about to get dumped on it is starting to rain goodthe Bald eagles and seagulls are loving the wind they are coasting in it sweet to see.

  39. yevgeniy.beaverton says:

    very nice IMO

  40. Bishoy-Beaverton, 300 feet says:

    18Z GFS is out, and it looks like it’s a little bit cooler with a little less precipitation.

  41. Steve Pierce (Vancouver, WA.) says:

    SPECIAL WEATHER STATEMENT
    NATIONAL WEATHER SERVICE PORTLAND OR
    231 PM PST THU MAR 5 2009
    …LOW ELEVATION SNOW EXPECTED THIS WEEKEND IN NORTHWEST OREGON
    AND SOUTHWEST WASHINGTON…
    A WEATHER SYSTEM COMING DOWN FROM ALASKA WILL BRING SNOW TO MOST
    OF NORTHWEST OREGON AND SOUTHWEST WASHINGTON THIS WEEKEND. SNOW
    LEVELS WILL BEGIN TO FALL BEHIND A COLD FRONT SATURDAY…AND ARE
    EXPECTED TO DROP TO NEAR SEA LEVEL BY LATE SATURDAY NIGHT.
    SNOW SHOWERS ARE LIKELY SATURDAY NIGHT AND SUNDAY…BEFORE
    DIMINISHING SUNDAY NIGHT. SOME ACCUMULATIONS ARE POSSIBLE
    AT LOW ELEVATIONS…ESPECIALLY IN THE OUTLYING HILLS…LATE
    SATURDAY NIGHT AND SUNDAY. IN THE MOUNTAINS HEAVIER SNOWFALL WILL
    BE POSSIBLE THIS WEEKEND…WITH UP TO A FOOT OF NEW SNOW AT THE
    CASCADE PASSES.

  42. boydo3, N. Albany 500' says:

    Seems like we do get a bit less onshore flow and even nne flow sunday nite thru tues. I like the look of this event better than the last (for the mid-valley anyway). We shall see tho.

  43. Rob "Wrath" - Elevation 300' -Far S.E. Portland- says:

    It is going to be close no doubt.

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