Slow Warming This Week, Lots of Cascade Snow

February 26, 2017

8pm Sunday…

Today was a perfect example of what I call “conversational snow”.  That’s a snowfall that either does or doesn’t stick, gives us plenty to talk about, but doesn’t have much effect on our lives.  In the lowest elevations of the metro area the old rule held out for the 3rd or 4th time this winter…cold showers coming in off the Pacific with a southerly or southwest wind don’t give us significant or life-altering snow.  Hillsboro, Portland, Vancouver, & Troutdale all stayed above 36 degrees during the morning fun…too “warm” for snow to stick.  IF the showers/airmasses are cold enough…I think it was March 2009, then it’s possible to get heavy/wet sticking snow right down into the city, but the atmosphere overhead has to be colder than today.  In the hills around the metro snow stuck briefly in heavy showers.  This is from Timothy Rotter in SW Portland around 4pm near PCC Sylvania:

photo_timothyrotter

And if you went up at any elevation (well below 1,000′) and got under heavy showers, you likely saw more than this.  That includes the Coast Range and foothills of the Cascades.  Our John Hendricks got this image during the morning hours in the West Hills.  I think this location is somewhere around 700′.

photo_john

The next 48 hours we transition from the cold northerly flow into a slightly milder westerly flow of air coming more directly off the Pacific.  Remember this is the 2nd system that has dropped in on us from the north, the previous one was Friday.  IF there are any leftover showers tomorrow morning, there’s no reason snow couldn’t stick down around 1,000′ or even a bit below, but in the case of tomorrow AM the showers look very scattered = mainly dry.  Best chance will be along the west slopes of the Cascades and foothills.  That includes the hills in the west end of the Gorge.  The sticking snow level gradually climbs from around 1,000′ or just below tomorrow morning to around 2,500′ by Wednesday afternoon.  Between now and Wednesday we’ll see LOTS of clouds (especially Tuesday/Wednesday) and occasional very light rain showers in the valleys.  Meanwhile the westerly flow overhead means the mountains will scoop up LOTS of moisture.  Powder alert!  Take a look at snow forecast through Tuesday…a very heavy snowfall with quality snow due to the cold air.  12-20″ likely on Mt. Hood

rpm_snowaccum

With the clouds and light showers, it’s pretty obvious March will be coming in like a lamb, not a lion.   The saying of course refers to early March sometimes starting more like winter, but always ends on a calmer spring note.   Regardless, I think the fork is coming out this week, I don’t see much winter left!  Maybe something like this morning again, but that’s about it.

Fork2

Chief Meteorologist Mark Nelsen


Snow Level Around 1,500′ This Morning

February 26, 2017

As expected a mild southerly wind is blowing west of the Cascades this morning and has lifted the snow level up above 1,000′, actually closer to 1,500′.  Here’s a good picture from home this morning at 8:45am.

Bottom of pic in the canyon is about 900′ elevation, top of the trees in the distance is around 1,400′.  So the sticking snow elevation (the SNOW LEVEL) is up above 1,000′ in this location:

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Always remember SOUTH WIND = NO SNOW in the lowest elevations of the Portland Metro Area.  Okay, one time out of 10 we’ll get a dusting in this pattern.  Or with a really cold airmass coming onshore a couple of inches can fall in the hills in this pattern, but it’s very rare.  You either want calm conditions or of course the favored snow pattern with cold air already in place (calm) or pouring in out of the Gorge.

Enjoy your Sunday!  The steady rain/snow is about to change to showers and sunbreaks, it should be a much brighter afternoon.

I’ll be back at work this evening and see you on-air at 10pm.

Chief Meteorologist Mark Nelsen