Snowy/Icy Gorge Christmas Day

December 24, 2012

A Christmas Day snowstorm is coming for the Gorge, and some spots near/in the Coast Range.

It’s Christmas Eve (Day) and what do you know, it’s still raining…we’ve seen just under 50″ of rain here in Portland this year and it appears it’ll probably go down as the 2nd wettest year on record here!  Of course that would be 2nd after the 63″ we received back in 1996.

Here are the highlights for those just wanting the basics:


  • I-84 through the Columbia Gorge will likely be very snowy after daybreak Christmas morning and through at least early/mid afternoon.  A nice Gorge snowstorm for those of you already there.
  • Hwys. 6/26 will be snowy tomorrow morning over the Coast Range passes (a good 4-6″ new snow), then improve rapidly by midday as the snow level jumps to around 3,000′.
  • I-5 north & south through Oregon and Washington should be okay, just a little snowy over Siskiyou Summit to California. 
  • No snow headed north to Seattle, or at least not enough to affect freeway travel if there is.


No interesting weather through the middle of tonight, we just dry out as the day goes on.  Enjoy the brief dry spell.

  • A very wet storm arrives before daybreak west of the Cascades Christmas Morning.
  • Precipitation may briefly mix with snow in the metro area 3-6am (when we are sleeping), but then all rain as the freezing level jumps quickly after 8am.
  • Sticking snow is unlikely in the metro area EXCEPT possibly out around Banks, Forest Grove, Gaston, Vernonia.  A trace to 2″ possible in those areas if everything works out just right.
  • Just a few degrees too warm elsewhere.
  • It will be ALL SNOW east of Multnomah Falls in the Columbia River Gorge…8-14″ possible from 6am to 6pm!
  • Freezing rain is likely above 500′ west of Multnomah Falls (but not in metro area), heavy ice accumulation (1″) possible up around 1,000′ during the day.
  • After 10am, all areas west of the Cascades (except western Gorge) will see only rain as warmer air moves in, raising the snow level up to around 3,000′.

I’m still on vacation today, but just couldn’t keep quiet when I saw a good setup for a Christmas Day Snow Storm in the Gorge.  I am finally getting tired of the rain, I just noticed we’ve only had one completely dry day this month too.  Hard to believe it’s now the wettest year since 1996 after 80+ days of almost all dry weather;  those people nagging me about “covering up a developing drought” back in early October look REALLY silly now!

Last night was fun with sticking snow briefly in some spots on the east side of the metro area; it’s interesting that without this blog or discussion on Facebook one wouldn’t have known about it via the observations; no metro area official observation showed snow or even a rain/snow mix.  I ended up with a quick 1.5″ here at home.

Nice map for 6am tomorrow:mgWeb_WRF_20121224-120000_ANW_ECONUS_F00250000_PgeneralSfcPres_R4km

Tomorrow we’ve got a real juicy system moving in with a surface low working its way up the coastline; it’s far enough south that it draws in a surge of colder/drier air working across Eastern Washington overnight.  By 10am tomorrow morning, models show 7-10 millibars easterly gradient through the Columbia River Gorge!  It’s going to be a very cold and windy Christmas at the west end of the Gorge.  Gusts 60+ mph are likely there.  BUT, by 7-10am, warmer air will have already worked in to the atmosphere overhead (as noted in the highlights).  So this is a situation where if you wanted snow or freezing rain in the metro area, you need a little longer period of cold east wind to start and/or you need the airmass coming through the Gorge to be colder to start with.  We’ve seen situations like this in the past where the cold air gets pulled towards a surface low offshore and we get a nice ice or snow storm in the metro area.  But this is when it’s truly modified arctic air moving down from the northeast.  Think temps already down in the 20’s in Hood River and The Dalles to start with.  Not from radiational cooling (like we’ll see tonight) but the actual cold airmass.  This time the air will be just a little cooler than what’s already in place today; that’s why it’ll be really tough to get anything frozen outside of the Gorge.

IF we do get a mix or briefly all snow in the metro area, the timing isn’t so great either.  Our RPM has it here by 4am, the WRF-GFS a little slower, but not much.  Most of us will be asleep at that time (I know I will be!).  Any chance for that disappears quickly after sunrise too due to the warmer air moving in aloft.

As for the Gorge, wow…no sign of the snow level rising above the surface until the evening at the earliest.  Think of it this way:  The cold airmass eastside is deep enough to meet the 3,000-4,000′ snow level at the crest of the Cascades.  So whatever falls should fall as snow the entire day as the whole column of air stays near/below freezing; that’s why I went with the big snow totals.  Jesse should be happy in Stevenson, looks like a big dump there! 

For those of you at the west end of the Gorge (like me), it’ll be a thin layer of air right near freezing.  But warmer air above means a Silver Christmas.  Probably marginal for freezing rain near 500′, but around 31-32 degrees at 1,000′.  A narrow band of elevation will see a Christmas Day ice storm with thick accumulation.

I haven’t looked farther ahead on the weather maps, but I work late tomorrow afternoon so I can do that then.  Holidays at a tv station are REALLY slow…

Chief Meteorologist Mark Nelsen