Tuesday AM Update

In a hurry this morning to get a few things done before heading to work…I can tell it’ll be a long day.  Three things pop out:

1.  Snow sometime after 7pm this evening to all areas above 1,000′, probably lower than that far east side of metro area.

Situation this evening is very similar to what occurred November 17th: https://fox12weather.wordpress.com/2010/11/17/a-crazy-weather-night/  This should be fun to watch.

Steady, heavy precipitation as a wave passes by and colder air comes surging in at the surface from the northwest.  In fact no southerly wind but a light north-northwest wind.  Our RPM model shows a changeover to mostly snow in the air even at the lowest elevations, and sticking for sure on the hills.  In this pattern the foothills of the Cascades (and east Valley) are/is favored.  It may even stick in Gresham, Troudale, Camas, Estacada.  Less likely over in the Tualatin Valley as things dry out.  Prime time seems to be 7pm-Midnight.  I can already feel the news freakout…praying that it holds off until 9pm or so.

2.  Precipitation is very close Thursday morning, closer than in previous model runs…could be a dusting?

3.  GFS is swinging dry over the weekend like ECMWF now, we can leave the precipitation out of the forecast.

Chief Meteorologist Mark Nelsen

219 Responses to Tuesday AM Update

  1. Waveguru says:

    No snow in Hood River. They sure have been over predicting the snow up here for the last couple of weeks…

  2. flurball says:

    Precursor to a bust?

  3. Muxpux says:

    Here’s a good cam to keep an eye on,

    That’s KM mountain west of catfishes on the Washington side. 700 feet or so IIRC

  4. Megan says:

    Snowing in the coast range

  5. PaulB/Eugene says:

    Current thoughts

    Low headed toward S OR…may curve a bit to NE as it gets closer…predicting passage between EUG and RBG.

    Best precip currently over SLE…S valley to get more precip in 1-2 hours.

    AST already 39-41F at sea level.

    areas above 500′ looking good for snow late evening/tonight.

    Tough to get snow on valley floor tonight…still looking at least trace at valley floor SLE and points S. Dramatically different as you go above 500-700′

  6. Buoy 46015 at 992mb, considerably lower than forecast…

    36.6F at my home now, dewpoint 35F.

  7. Derek Hodges says:

    The falling temperatures now are nice but largely unimportant. The real cooling comes when we get on the NW side of the low.

    • Jethro says:

      According to the 18z ncep-gfs, that happens between now and 10:00 PM. After that we are pretty much due west of it — then the door is opened for the coast range to start dining on cold showers.

  8. Andrew Johnson says:

    Interestingly I am down to 43 now and Silver Falls State Park (1310′) is 45. I suppose because I am a little bit further north. They are dropping steadily as well though and should pass me soon.

  9. geo says:

    that sensor at gov’t camp is off by a good 2 degrees.( colder)

  10. PaulBeaverton says:

    So I know Mark holds a BS in atmospheric science from UW…Does anyone know if anyone else at Fox 12 weather hold degrees? Just curious.

  11. Christiana in Forest Grove says:

    ALERT 1 – Flash Flood Watch
    AN AREAL FLOOD WATCH IS IN EFFECT UNTIL 10:00AM PST THURSDAY, DECEMBER 30
    Issue Time: 4:09PM PST, Tuesday Dec 28, 2010
    Valid Until: 9:00AM PST, Wednesday Dec 29, 2010
    Back to summary

    FLOOD WATCH
    UNTIL 9:00AM PST
    Urgent – Immediate Broadcast Requested
    Flood Watch National Weather Service Portland OR
    409 PM PST Tue Dec 28 2010

    … Flood Watch Through Thursday For Northwest Oregon…

    .A Series Of Moist Systems Have Dropped Plenty Of Rain Over The Area In The Last Two Days With Another Moist System Approaching
    The Coast Tonight. Runoff From These Storms Is Expected To Cause
    Large Rises On Many Rivers… Some Rivers May Reach Or Exceed Flood
    Stage Over The Next 48 Hours.

    Central Oregon Coast-Central Coast Range Of Western Oregon-
    Greater Portland Metro Area-Central Willamette Valley-
    South Willamette Valley-
    Including The Cities Of… Lincoln City… Newport… Florence…
    Grande Ronde… Tidewater… Swisshome… Hillsboro… Portland…
    Oregon City… Gresham… Salem… Mcminnville… Dallas… Eugene…
    Corvallis… Albany
    409 PM PST Tue Dec 28 2010

    … Flood Watch In Effect From 10 PM PST This Evening Through
    Thursday Morning For Portions Of Northwest Oregon…

    The National Weather Service In Portland Has Issued A

    * Flood Watch For Portions Of Northwest Oregon… Including The
    Following Areas… Central Coast Range Of Western Oregon…
    Central Oregon Coast… Central Willamette Valley… Greater
    Portland Metro Area And South Willamette Valley.

    * From 10 PM PST This Evening Through Thursday Morning

    * Heavy Rain Has Caused Substantial Rises On Many Rivers And
    Another Wet System May Put Some Rivers Into Flood Category.

    Northwest Oregon Rivers Of Most Concern Include…
    Luckiamute River In Polk And Benton Counties
    Johnson Creek In Multnomah County
    Pudding River In Clackamas And Marion Counties
    Marys River In Benton County
    Siuslaw River In Western Lane County

    Precautionary/Preparedness Actions…

    A Flood Watch Means There Is A Potential For Flooding Based On
    Current Forecasts.

    Landslides And Debris Flows Are Possible During This Flood Event.
    People… Structures And Roads Located Below Steep Slopes… In
    Canyons And Near The Mouths Of Canyons May Be At Serious Risk
    From Rapidly Moving Landslides.

    You Should Monitor Later Forecasts And Be Alert For Possible Flood Warnings. Those Living In Areas Prone To Flooding Should Be Prepared To Take Action Should Flooding Develop.

    The Next Update For This Watch Will Be Issued By 900 AM.

  12. PortBlazerFan says:

    Now 43.3 near Clackamas Town Center at 200 ft.. Coast range should be changed over to snow within next 2 hours or sooner.

  13. k5mitch says:

    hangin @ 42.0 F

  14. Boydo3 500' North Albany says:

    Too bad the upper air temps aren’t nearly as cold as the Nov 17th event. But the pattern is similar. Keep an eye on the coast range stations.

  15. Currently 46.1F, just hit 1.00″ of rain and no wind.

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

    KPTV Tower Temps
    As of 3 PM

    T1(1,043′): +4.1c | 0.6c Colder
    T2(1,473′): +2.9c | 0.5c Colder
    T3(1,818′): +2.8c | 0.2c Colder

  17. Snow-Zone/Monmouth-Elv200' says:

    It has been raining hard here all yesterday, last night and all day now again.. the fields are floodings, streams are breaking their banks, the rivers look like there rising fast and are really high, its in the upper 40s and I want snow!

  18. JohnD says:

    Tuning in. Seems like a lot of divergent comments. I guess the usual: Will it or won’t it?; cold enough or not?; where will the main precipitation go?; etc. etc. I guess only time will tell. Like always, what you see is what you get. This is definitely NOT a classic pattern with a cold east wind howling, temps already below freezing, and the storm tracking just south of town. BUT history has shown that we have and sometimes DO have accumulating snow in the current pattern as well albeit the wet variety. And by the looks of things, for those of us that ARE lucky enough, it may actually hang around for a few days–at least on the lawn! Also I AM still optimistic about the mother lode later on!

    • Annie in Vancouver says:

      What “mother load” later on are you referring to??

    • JohnD says:

      “Mother Lode” (mining metaphor for hitting paydirt) = (in this case)getting a big slug of arctic air in here. Some of the heavy hitters on this blog expect that at some point later on–“if” the pattern “retrogrades” rendering it possible for that to happen. For others (like me) it is mostly wishcasting.

    • Annie in Vancouver says:

      Oh, whoops! I misspelled it! Thanks for explaining your thoughts on what the Mother Lode will be!

  19. Buoy 46015 still falling… 994.2 mb

  20. W7ENK says:

    Just hit exactly 1.00″ of rain for the day. Temperature 43.9, down from 49.3 at around 11:30a, dropping slow but steady all afternoon, winds switched to light N-NNW about 2pm.

    I still don’t ‘feel’ snow… 37 and cold, cold rain overnight here in Milwaukie. Green, brown and wet in the morning.

  21. Emz in Tigard says:

    Wind out of the N now.. & down to 44 from a 48 high.

  22. Brad says:

    Something for the wish list…real time KPTV tower temp data.

  23. Jethro (Molalla ~320') says:

    Just drove from south of Canby to Molalla… haven’t seen that much water over the roads since Feb. ’96!

  24. HeatherWeather says:

    45.8 at 2pm now it’s 42.7 Keep on dropping baby!

  25. Karl Bonner says:

    Of course the east end of the city will be favored for some reason OTHER than cool east wind from the Gorge…I assume it would be orographic lift? That would mean more total precip. but where does the slightly lower sticking snow level come from in that equation?

  26. alohabb says:

    Down to 42.6 in Aloha. Was 45 just a while ago

  27. David Mall205 says:

    Just came back from the coast via hwy 26 it was trying to snow at 1600 ft but mostly just chunky rain.

  28. PaulB/Eugene says:

    Unisys 3hr pressure falls:

    http://weather.unisys.com/surface/previous/sfc_con_3pres-1.html

    Low does not look like it is headed to PDX…not yet at least

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

    My barometer is crashing now. A good sign.

  30. alohabb says:

    Ok, lets hold on the snow for a second…with this massive amount of moisture on the ground and temps falling, will we get cold enough for ice to form? Or will the wet ground evaporate before the cold air arrives?

  31. Brad says:

    2 o’clock tower temps really crashing.

    T3 dropped 1.2C in one hour!

    Is that a crow I hear in the distance.

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

    Tower Temps have begun their downward slide.

  33. wendy-silverlake,WA says:

    Oops, I posted this on the other one. It’s confusing having two blogs going at once.

    I just looked at the radar and the rain doesn’t appear to be moving anywhere. Is this going to affect the timing of the front tonight? I’ve noticed in the past that when this happens, things don’t go as planned. Just curious if that is the case or not. Also, how far north is the rain/snow supposed to reach?

    Thanks for any answers you can give!!!!

  34. Andrew Johnson says:

    I’ve dropped 4 degrees in the past hour to 46. Running 3 degrees cooler than SLE now.

  35. Andrew Johnson says:

    N wind really increasing here and the rain is coming down moderately.

  36. WRFGFS from 12Z was significantly too weak, with bouy 46015 at 3 PM showing 995.5 mb, pressure trend -8.3mb, low still apparently well offshore by my eye on the sat img. My home is at 37.1 F dewpoint 35.8F

  37. Yevpolo1990 says:

    http://www.atmos.was…4km_enhanced+12
    The low seems to be bombing, really is getting its act together.

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

    WV Loop shows low pressure near 43 N, 130.5 W moving mainly due east. Northern half of the circulation moves right over the northern Willamette Valley.

  39. PaulB/Eugene says:

    Don’t mess with Mahlon Sweet Airport…it will rule the land of lowland airports tonight in terms of snow….HIO 0.0, PDX 0.0, SLE T, TTD T, VUO T, CVO 0.5, Sweet Home International 0.6, EUG 0.8….

  40. Derek Hodges says:

    43 here, it was 47 earlier. Still raining hard and NW breeze of 5-10mph

  41. kcteach-Gresham-500' says:

    Down to 44.6 here after a high of 48.5.

  42. stevied (North Portland) says:

    Quartz Creek (1,100ft) on Hwy 26 Towards Coast

    1:50pm 41.5F
    2:04pm 39.7F
    2:22pm 39.4F

    Keep fallin’!

  43. Jacob PSE-BPA says:

    Remember Brad says no wishcasting

    Here is My Forecast
    Rain turning to snow around 10pm North of PDX N Clark County to be exact turning to snow in Vancouver around Midnight

    1-3″ in Clark County

    4-6″ above 1000′

    PDX Trace to 1″
    Above 500′ 1-2″
    Above 1000′ 3-5″

    Snow Showers Thursday into the Evening with an additional inch possible

    • Brad says:

      What? 😉 I was just giving you a hard time Jacob. I hope you’re right. The snow grinch has becoming out hard in me lately, so what do I know? I still think we see all rain, and I still think you’re a bit bullish here, but I would happily eat crow to see these numbers verify.

    • Brad says:

      And it’s probably only fair to add my own prediction, rather than just snipe at yours.

      Snow level lowering tonight to 1,000 ft. Mixed rain and snow at times down to the surface. 1-2 inch accum. above 1,000 ft. Lows around 35.

  44. Joe Froncona says:

    After analyzing satellite images and recent model outputs, I have come to the conclusion that the central Willamette Valley will receive 6-8 inches of snow tonight. I would put my certainty at about 82% right now.

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