Thoughts on Snow/Ice Thursday

9:30pm…

The National Weather Service has much of Eastern Oregon under a Winter Storm Watch for Thursday.  Hard to believe it’s November 11th!

MarkWarningsWinter WX

That’s because moisture will ride over the top of the chilly airmass in place over us.  Here is a look at my current thinking and forecast:

MarkSnow_TextPanel  MarkSnow_TextPanel2

So what has changed in the past 24 hours?  It’s cold!  The cold airmass is sure pouring in quickly this evening.  I see at 4pm over Salem at 850mb the temp was around zero which is pretty close to what models expected.  Low level temperatures were a bit warmer than modeled today, but seem to have lowered down a closer to where we expected them to be at 9pm.  Gov’t Camp is in the upper teens and 850mb temps were forecast around -11…close enough for me.

Assuming models are doing okay on the thermal profile of the atmosphere, what do they show for tomorrow night and Thursday?

1. Precipitation arrives somewhere between midnight and 7am Thursday.  Our RPM is really fast, but the more reliable WRF-GFS has it into the metro area around sunrise or just before.

2. Sticking, or even “in the air”, snow is very unlikely in the metro area.  Our RPM is too warm at the surface and higher up.  The WRF-GFS, which may have had precip placement issues in the past, has generally done very well with the thermal profile of transition events like this.  It shows temperatures over the metro area rising above freezing from 2,000′-5,000′ tomorrow afternoon and never dropping back down again.  Take a look at the sounding for 7am Thursday:

wrf_gfs_7amThurs

So I have no idea why it is producing light snow totals over us…it can be ignored for now.  The MM5-NAM at 4am Thursday is a little closer to snow, nam_4am  but it seems to run too cold often so I bet it’ll warm its forecast a bit the next 24 hours.  Not sure why that model is producing snow too.

3.  Isolated spots of freezing rain are possible to start Thursday morning in the metro area, but I sure don’t see a metro-wide ice storm.  Cloud cover doesn’t thicken up until later Wednesday night so temps may drop below freezing under mainly clear skies away from the Gorge wind.  This will be closely watched by forecasters like me.  It’s pretty simple…if the temperature is 34 or under when the precip starts, then freezing rain is likely, at least for a brief period.  That said, for roads to freeze up we’ll need temps down to 30 or lower.

4.  Cold rain the rest of Thursday...high temps in the 30s, a breezy east wind, and rain at times will make for a miserable winter-like day.

5.  A big November snow/ice storm in the Gorge.  East wind isn’t going away in the Gorge through the weekend and a ton of moisture is coming.  I’m thinking 6-10″ is likely in the central/east end with a good 1/2-1″ ice accumulation at the west end.  Maybe as damaging as what we saw back on March 1st.  Could be some big sleet drifts too like we saw at that time around Multnomah Falls.

6.  Cold air is here to stay for awhile.  The 00z models confirm what the ECMWF showed earlier, a 2nd surge of cold air from the north late Friday and Saturday since the northerly flow around the upper high is going to dominate over the undercutting flow from the southwest.  Interesting stuff since that would mean the snow-covered ground east of the Cascades would stay in place.  Winter is arriving early!

One last thought…

If our forecast is about 5 degrees too warm???  The best November snow/ice storm in 30 years will arrive Thursday in the Portland Metro area and the snow/ice will be slow to leave.  Let’s hope that doesn’t happen.

Chief Meteorologist Mark Nelsen

131 Responses to Thoughts on Snow/Ice Thursday

  1. alohabb says:

    Never mind that. Old broadcast. Whoops.

  2. alohabb says:

    Huh. Mr Carson just said mostly rain tomorrow with pockets of snow/frz rain.

  3. GTS1K' says:

    Oh, boy…

    Can’t wait for snow/ice (especially ice) since I just got power back after almost 14 hours without it – Internet and phone out, too.

    Good thing gas for the generator is relatively cheap these days.

    Today’s project is to bring in more firewood.

    35.2 and still blowin’ pretty good.

  4. Ok a Winter Storm Watch just went up for Cowlitz County! How close to Kelso/Longview are we talking all? Snow/rain/ZR what! I want to sub teach Thurs. not feeling comfortable about it! Yes I have a safe snow SUV! Not liking icy roads & I live on a hill!

  5. Marc (East Vancouver) says:

    Within 18 hours, KPTV still not worried in he slightest. Cold rain still in the forecast unless you’re in the gorge. I trust KPTV. School and work as usual tomorrow.

  6. tomnepdx says:

    NWS not holding back at all, but I’d rather them err on the side of caution rather than have something surprise the city. Looks like they’e forecasting PDX to barely get above freezing tomorrow, too. I doubt that’ll be the case though; I say Portland makes it to about 36 or so.

  7. Goducks09 says:

    Mark… Come out, come out wherever you are!

  8. W7ENK says:

    Winter Storm Watch issued for Northern Willamette Valley

    WINTER STORM WATCH
    NATIONAL WEATHER SERVICE PORTLAND OR
    1103 AM PST WED NOV 12 2014

    http://inws.wrh.noaa.gov/weather/alertinfo/19309581

  9. Andrew (Beaverton) says:

    Winter Storm Watch
    URGENT – WINTER WEATHER MESSAGE
    NATIONAL WEATHER SERVICE PORTLAND OR
    1103 AM PST WED NOV 12 2014

    …FIRST BOUT OF WINTER WEATHER THIS FALL FOR PARTS OF SOUTHWEST
    WASHINGTON AND NORTHWEST OREGON…

    .AN ARCTIC FRONT HAS BROUGHT STRONG EAST WINDS AND A COLDER AND
    DRY AIR MASS TO SOUTHWEST WASHINGTON AND NORTHWEST OREGON.
    MOISTURE FROM A PACIFIC WEATHER SYSTEM WILL LIKELY SPREAD IN FROM
    THE SOUTHWEST LATE TONIGHT INTO THURSDAY…BRINGING A WINTRY MIX
    OF PRECIPITATION IN COMBINATION WITH CONTINUING BRISK EAST WINDS
    TO THE NORTHWEST OREGON COAST RANGE…CLARK COUNTY…NORTH AND
    CENTRAL WILLAMETTE VALLEY…SOUTHWEST WASHINGTON AND NORTHWEST
    OREGON CASCADES AND CASCADE FOOTHILLS. THE PRECIPITATION WILL
    LIKELY BEGIN AS SNOW…THEN TRANSITION SLOWLY TO SLEET AND/OR
    FREEZING RAIN THURSDAY AFTERNOON INTO FRIDAY MORNING.

    ORZ006-WAZ039-130315-
    /O.EXB.KPQR.WS.A.0008.141113T1400Z-141114T0600Z/
    GREATER PORTLAND METRO AREA-GREATER VANCOUVER AREA-
    INCLUDING THE CITIES OF…HILLSBORO…PORTLAND…OREGON CITY…
    GRESHAM…TROUTDALE…VANCOUVER…BATTLE GROUND…CAMAS…
    WASHOUGAL
    1103 AM PST WED NOV 12 2014

    …WINTER STORM WATCH IN EFFECT FROM THURSDAY MORNING THROUGH
    THURSDAY EVENING FOR THE PORTLAND AND VANCOUVER METRO AREAS…

    THE NATIONAL WEATHER SERVICE IN PORTLAND HAS ISSUED A WINTER
    STORM WATCH FOR SNOW…FREEZING RAIN AND GUSTY EAST WINDS…WHICH
    IS IN EFFECT FROM THURSDAY MORNING THROUGH THURSDAY EVENING.

    • TIMING…PRECIPITATION WILL BEGIN AROUND DAYBREAK
      THURSDAY…STARTING MOSTLY AS SNOW OR A MIX OF SNOW AND
      SLEET…BEFORE TRANSITIONING INTO A MIX OF SLEET AND FREEZING
      RAIN LATER IN THE AFTERNOON AND EVENING.
    • ACCUMULATIONS…SNOW ACCUMULATIONS COULD REACH 4 TO 6
      INCHES…WITH UP TO A QUARTER OF AN INCH OF ICE POSSIBLE IN THE
      LATE AFTERNOON AND EVENING HOURS. THE MAIN THREAT FOR ICE
      ACCUMULATION WILL BE FOR AREAS CLOSEST TO THE COLUMBIA RIVER
      GORGE.

    • WINDCHILL…BRISK EAST WINDS WILL CONTINUE THROUGH LATE
      THURSDAY…WHICH WILL ALLOW WIND CHILLS TO FALL WELL BELOW ZERO
      AT TIMES. THE LOWEST WIND CHILLS AND THE STRONGEST WINDS WILL BE
      FOR LOCATIONS CLOSEST TO THE COLUMBIA RIVER GORGE.

    • IMPACTS…THE COMBINATION OF SNOW AND ICE TOGETHER WITH BRISK
      EAST WINDS WILL MAKE THE THURSDAY MORNING AND EVENING COMMUTES
      VERY DIFFICULT.

    PRECAUTIONARY/PREPAREDNESS ACTIONS…

    A WINTER STORM WATCH MEANS THERE IS A POTENTIAL FOR SIGNIFICANT
    SNOW…SLEET…OR ICE ACCUMULATIONS THAT MAY IMPACT TRAVEL.
    CONTINUE TO MONITOR THE LATEST FORECASTS.

    &&

    $$

  10. W7ENK says:

    Winter Storm Watch for Greater Portland Metro area

    WINTER STORM WATCH
    NATIONAL WEATHER SERVICE PORTLAND OR
    1103 AM PST WED NOV 12 2014

    http://inws.wrh.noaa.gov/weather/alertinfo/19309908

  11. W7ENK says:

    Blizzard Watch just issued for the Gorge.

    BLIZZARD WATCH
    NATIONAL WEATHER SERVICE PORTLAND OR
    1103 AM PST WED NOV 12 2014

    http://inws.wrh.noaa.gov/weather/alertinfo/19310195

  12. Hal in Aims says:

    power went out about 90 minutes ago……..now on generator……up to 35 from 30 at 530……..stiff easterly breeze……

  13. Garron near Washington Square says:

    I’m really nervous about the impending “forecasm”! I merchandise a grocery store, and I think I really under estimated my grocery order for last night! I don’t get another truckload until Saturday, I’m guessing we’ll be out of stuff by tonight. I’ll be working OT Saturday, almost guaranteed!

  14. Upper Air Analysis
    Portland – The Dalles – Spokane
    As of 9 AM
    —— 850mb —- 925mb
    PDX: -3.6c ……. -2.6c
    DLS: -10.8c ….. -9.5c
    GEG: -11.4c ….. -8.6c
    *850s -12c to -13c over south Central Washington banked up against Cascades.

    12z GEM
    In agreement with the NAM/GFS with bringing the low in south of PDX somewhere around North Bend-Florence-Yachats. Next the second cold shot for Saturday is looking good, if not colder than the GFS. Another low moving onshore near the same area Saturday with cold east wind continuing.

  15. Ryan says:

    I’d be surprised if we don’t at least get a taste of snow in the morning.

  16. Tyler Mode says:

    Looks like a lot of the moisture stays south leaving us mainly dry and cool.

  17. Jason Hougak says:

    I c…c..ant feel my ffffingers Lloyd their numb

  18. Jason Hougak says:

    Blizzard warning for the gorge?

  19. Jane - Forest Grove says:

    So I asked the Magic 8 ball “Do I get to stay home and sleep in tomorrow?”

  20. paulbeugene says:

    Really tricky forecast coming up.

    Looking at the 12Z model runs this morning. 4km WRF mm5 has low center headed to somewhere S of Newport toward Florence.

    Model soundings show temps above freezing to about 750mb by 4am Salem southward.

    If models are correct then snow really going to happen south of Salem or even Woodburn except from Dallas northward along east side of Coast Range.

    If models are too warm with the soundings then Salem or even Eugene could start as snow tonight. Best moisture/precip will be Salem south but that is where the warmth will be, too bad.

  21. Boydo3 N. Albany says:

    European Space Admin. just landed spacecraft on a comet. That’s right, a comet!

  22. Mark says:

    I was in Coeur D’ Alene, ID and Spokane, WA yesterday. Interesting to start out at 22F in the morning, and end in Tigard, OR at 39F, the temp slowly rising as I moved back towards the metro area. I couldn’t help but think how much a blanket of snow in the Columbia basin would help the cause for some snow, keeping the airmass just a wee bit cooler. Unfortunately, it’s bare everywhere until you hit the 4k+ elevation in Idaho and northern Washington… And even then it’s just not that thick. Will be interesting to see how quickly the overall airmass modifies as a result.

%d bloggers like this: