Brief Freezing Rain or Snow Monday AM

10pm Sunday…

Our cold spell is about to come to an abrupt end in the next 12 hours.  The lowest part of the atmosphere over the western valleys of Oregon and S.W. Washington is still quite chilly this evening with many of us below freezing.

During the night a strong southerly and/or southwesterly flow will be developing.  By 4-7am up at 2,000′ models say the southwest wind will be blowing around 30-40 mph transporting in much milder air.  That’s in advance of a relatively strong cold front approaching from the northwest.

Now typically if we have a juicy front approaching with a dry and cold airmass at the surface, it’s quite possible to get some sort of snow/ice storm.  But this time it’s much different from last week.  This system is coming in from the northwest and gusty southerly wind arrives by tomorrow morning.  The easterly Gorge wind that would often transport very cold and dry air into the Portland metro area has died down to just an easterly breeze that is barely making it out of the Gorge.  I was just at a house about 200′ above the Columbia River in Corbett and I can vouch that it IS just a breeze at this point.  So the “freezer door” is now shut and the atmosphere will quickly moisten and go above freezing overhead by 4-7am.

At the same time precipitation will be arriving.  Between 4-7am SOMETHING frozen will likely fall for many of us.  There could be spots of snow from the metro area north but I think it’s more likely we’ll get areas of freezing rain for a couple of hours at the beginning of the Monday AM commute.  In this case it can’t last long with the mixing southwest wind arriving both above and the Gorge wind nearly dead.  So the main message is:  Be very careful if you are out and about between 4-7am; what appears to be rain may be freezing on the roadways in some spots.  Or there could be light snow accumulation at first as well.  You can see the 4-7am precip forecast from the WRF-GFS this evening:

or_pcp3-15-0000

IF that were all snow, that would imply an inch or so accumulation.  But I think freezing rain is more likely for the spots that remain below freezing since the airmass above appears to be mainly too warm for snow (for most of us).  Check out the snow forecast from our RPM model, which implies at least a dusting for many of us before the changeover to regular rain:

rpm_snow_00z

And the WRF, which holds the snow in the higher elevations only:

or_snow3-15-0000

Beyond 7am temperatures should warm above freezing quickly.  In fact by tomorrow night at this time we’ll be around 50 degrees with a gusty south wind!  It’ll feel “tropical” after the last couple of weeks…

For you folks in the (central/eastern) Gorge, you’ll likely get a mix of freezing rain/snow through tomorrow evening before a changeover to rain tomorrow night.  A gusty WEST wind there by Tuesday means high temps in Hood River and The Dalles will surge well into the 40s…the melt will be on!

Chief Meteorologist Mark Nelsen

 

26 Responses to Brief Freezing Rain or Snow Monday AM

  1. Ron says:

    As much as I don’t mind winter i am ready for the melting to begin here in the Gorge/Upper Valley.

  2. Wendy-Silverlake, WA says:

    So is there an inversion or something? Everything below us is completely white, and we have 36 degree rain and most of our snow melted overnight. The kids are just staring out the window wondering what they heck, no school and no snow to play in.

    • Tyler Mode in Battle Ground says:

      Yes, warm air is moving in aloft (up to 5,000′ or so) and will slowly erode the cold below you from above.

    • Tyler Mode in Battle Ground says:

      If you can, take pictures!

    • sds says:

      Still freezing here at 250 foot level at 10:30 this morning 6 miles up the Lewis River valley out of Woodland and 3 inches of new snow making it a beautiful winter wonderland. I know it should start raining soon, but it sure is pretty now.

    • sds says:

      Just an update at 4:30–it is raining lightly and the snow has packed down to 2 inches over the still frozen ground. Temp. has risen to 34 degrees–maybe we will melt out by tomorrow!

  3. Scooter says:

    The rain is back the snow will soon be gone, and fear not all you consumers there is still a whole week to satisfy your addiction to shopping, get those tire chains off and get out there. Merry Xmas.

  4. Marc (Brush Prairie, WA) says:

    Feeling very nostalgic this morning. Not often do we get surprise snow events these days. Went to bed with KPTV and others predicting warm rain this morning. Woke up to a winter wonderland.

    • JERAT416 says:

      36 and light rain here in Parkrose. Was only about 32 when I got here around 5:30. Still no Pineapple Express though.

    • marinersfan85 says:

      No one predicted warm rain until this evening. They also said it could begin as snow especially the farther North you live.

  5. chiefWright (Marquam 350') says:

    Very fast warmup here:

    4 AM: 27 degF and calm
    6 AM: 40 degF and winds SW 15 mph

    The mets have certainly made lots of waffle in the last two weeks (and there’s so much batter between all those lovely models), but they’ve been pretty close within 12 hours (albeit somewhat shifty greater than 12 hours) of an event like this morning or last Thursday afternoon.

    Perhaps we’d prepare more appropriately to our highly uncertain weather if they went back to being wrong more often?

  6. W7ENK says:

    Woke up at 4:45a to the sound sleet out my window, was 30°. Quickly switched over freezing rain for a bit, but by the time I left the house the temperature had bumped up to 33° and most everything was just wet. Reached downtown without a hitch, and it’s 39° with light to moderate rain.

    It’s over, folks.

    • JJ78259 says:

      It’s over for the fall but winter is coming. There is bound to be a few more Polar Vortexes before Weather Dan come out of hibernation. It was 26 degrees this morning in San Antonio that’s enough of that stuff!!!

    • Tyler Mode in Battle Ground says:

      Heaviest snowfall since last January here in Battle Ground! Now just rain and 34, as predicted.

  7. angela says:

    Still snowing heavy in Vader, Wa. (next to Castle Rock) big fluffy flakes!

  8. muxpux (Longview) says:

    2″ new here in Castle Rock. That makes a bit over 9″ for the month.

  9. Paul D says:

    Once again Mark is spot on. It snowed a bit at my place in Hillsboro, and now it is 32 degrees and raining.

  10. Tyler Mode in Battle Ground says:

    Snow and sleet in Battle Ground. Quickly coated everything again. Temp is 31.1. Dewpoint 28.8

  11. W7ENK says:

    NWS doesn’t sound too sure of what’s going to happen tomorrow. They’ve basically issued a Significant Widespread Uncertainty Warning for our this area…

    • Diana F. says:

      Yup NWS has been non-stop, cya gobbledygook today.

      It’s been quite amusing and revealing (and yes educational) to read each report in its many versions through the day and night, as each even unfolds. I’ve made it a point to do this since our weather turned up the drama, way back, let’s see…….snow events ago?

      NWS has been preaching the ‘ole “when y’all gits up in the morning’, look out yer windah to see what weather ya gotz”- forecast.

      Masterful gibberish, lol…..and sure goes to show how difficult our weather can be to predict!

  12. Longview 400 ft says:

    Currently 31.3
    The temp has hovered around this for quite sometime.

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