First Snow in The Passes This Week

October 10, 2017

7:30pm Tuesday

After 5 months of warmer than normal temperatures the month of October has been much different.  We are only 10 days into the month and we’re running well below normal.  In fact with the clouds and rain arriving just after midday, we ended up 7 degrees below average for the date.  A cold front is passing through the region right now, the leading edge of a much cooler airmass.  This begins a 3 day period of showers in the valleys.  Of course just like last month we’ll likely see a few thundershowers at times along with hail too.  But this time the airmass is colder which equals lots of Cascade snow!  That’s one reason I quickly finished up work in my garden the last two days, planted garlic, shallots, & cover crop.  I think we’re done with the warm season!

Take a look at the ECMWF model forecast of snow level over the next 6 days

The snow level (lowest elevation we expect snow to stick) should linger around 4,000′ through Friday night, then quickly rise well above all ski areas Saturday through at least next Monday.  With several disturbances giving us waves of showers, the snow is going to be piling up relatively deep up around 5,000′ and above.  Here’s our forecast for snow totals plus Cascade driving conditions

Yep, I think we could see up to 2 feet of snow at Timberline, and possibly up around 10″ or so down at Government Camp…that’s spread over the next 3 days.  Of course in October snow levels go up and down so most or all of that will melt this weekend and early next week.  But this should be the earliest measurable snow at Govy we’ve seen since October 2009; quite a change after the past few years

There will also be some snow (just a bit) over some parts of the High Desert of central and eastern Oregon…most likely Thursday and/or Friday.  Plus the first snow of the season could fall in the Wallowa Valley…winter is getting closer

Looking farther ahead, a strong “zonal” flow sets up Sunday through much of next week.  That means a Pacific jet stream will consolidated and flow mainly west to east, instead of this north/northwest flow bringing us the chilly showers right now.  Now typically that’s a very wet pattern for us in Fall.  But in this case Sunday and Monday the jet will be to our north, then sag south over us Tuesday through the rest of next week.  The result is a nice dry spell centered right over this weekend…good timing.  Note the ECMWF ensemble 24 hour precip forecast for the next 10 days:

You see not a single ensemble member has rain over us during that period, but they all are quite wet NEXT Wednesday-Friday.  Pretty good agreement the middle/end of next week will be a soaker.

To summarize

  • The next 3 days will be cool & showery in the lowlands and snowy above 4,000′ in the mountains
  • Cascade passes will be snowy at times the next 3 days, although only the summits will be icy since the snow level doesn’t go much below the passes….you’ll run into snow only near the summits
  • Saturday through Monday = dry, with varying amounts of morning fog to afternoon sunshine each day
  • Tuesday & beyond next week = back to wet weather

Enjoy the showers…everything is back to normal in the Pacific Northwest!

Chief Meteorologist Mark Nelsen