A Snowy Night Ahead

February 21, 2018

6pm Wednesday

Here we go again!

“Snow v3.0” is about to arrive.   This system is very similar to yesterday’s where a surface low pressure system slides south through western Canada, than slides south along the Washington/Oregon coastline.  This one should move right onto the Oregon coast and slide into SW Oregon.  Anywhere north and east of the low pressure center has a decent chance of sticking snow during the night.  That means that this time those of you in the central/south Willamette Valley may FINALLY see a snowfall.  Remember that Salem/Albany still haven’t seen measurable snow so far this winter.  You can see the movement of the low in the slideshow:

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HIGHLIGHTS

  • Light snow develops the next few hours across NW Oregon, spreading east and south
  • Expect 1-3″ almost all inland locations from SW Washington down into at least the central Willamette Valley
  • Trace-2″ is possible along the beaches themselves
  • ROADS WILL BE SNOWY FOR THE THURSDAY AM COMMUTE
  • PARTLY CLOUDY THURSDAY = NICE MELTING AGAIN IN THE AFTERNOON, LIKE TODAY

One weak band of snow flurries just passed over the metro area and now we see deeper moisture/snow moving onto the north Oregon coastline.  By 10pm, snow should be falling along the north/central coastline and into the Coast Range.  In fact by 10pm snow may have begun in the metro area too.  Recall yesterday it showed up 8 hours ahead of schedule!

Temperatures are in the mid 30s at this hour, but more important is the dewpoint.  We’re in the mid-upper 20s which means falling snow will evaporate into the “dry” air, cooling the airmass.  The result is that we’ll have no problem getting snow to stick anywhere north of that low pressure center.  In the southern Willamette Valley there may be just enough southerly breeze (like with last night’s system) to keep the sticking snow level off the valley floor.  We’ll see how that plays out.  Luckily models are in slightly better agreement with snow accumulation up north.  Here’s the GEM  snow contour, with the snow forecast from each model on the table.  This is the main reason we’re forecasting 1-3″.

Now our 00z RPM just came in with better accumulation in the metro area:

 

So we’ll see how this plays out, at least it’s happening when most of us will be asleep and hardly anyone will be on the roads.  It’s also kind of nice that we’ll be able to drive around like normal once again tomorrow afternoon.

Tomorrow night, assuming skies clear out as expected, we’ll likely have another very cold night.  This morning at the last minute it cleared out at PDX, allowing the temperature to plummet to 23.  We have the same setup for Friday morning.  Maybe a late season 19?

Chief Meteorologist Mark Nelsen

 

 

 

 


Round 3: Snow In Valley Tonight

February 21, 2018

10:30am Wednesday

That was a fun drive home last night.  Freeways were mainly wet/slushy until I made it around the “Gateway Turn”.  I-84 suddenly turned icy in the usual spot past the I-205 split.  Colder/drier air from the Gorge had already frozen the freeway out there.  Then the last mile to my home wasn’t plowed.  5″ new on the road…I’m glad I didn’t take the snow tires off when it was 60 degrees!

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Just a quick post to let you know what’s up for tonight and tomorrow AM.

All models show another “BC Slider” (or is it “Yukon Slider”?) coming down along the Oregon Coast tonight.  Timing is perfect if you want more snow, the bulk of the precipitation falls in the middle of the night.  Check out the trusty ECMWF model, showing 1-3″ in most of the Willamette Valley and metro area tonight.

ecmwf

Several other models show heavier totals around Salem, I’ll look at it in more detail this afternoon, but here’s the main message:

  • EXPECT ONE MORE ROUND OF SNOW…LIKELY 1-3″, IN MUCH OF THE LOWLANDS TONIGHT.
  • THURSDAY MORNING’S COMMUTE WILL LIKELY BE SNOWY, WITH SNOW/SLUSH ON MANY ROADS

This appears to be the last snow event for now since Friday night’s wetter system has a strong southerly, warming, onshore wind arriving at the same time as the precipitation.

I’m headed outside to enjoy the sun, and play with the snowblower I thought I wouldn’t use this winter…8″ snow on the ground here.

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Chief Meteorologist Mark Nelsen