12/24 Mt. Hood snow and Gorge snow

Posted by
 December 24, 2012

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Mt. Hood Snow Forecast – 5000′
4a-8a 8a-12p 12p-4p 4p-8p 8p-4a

Happy Christmas Eve! Hopefully you’re dreaming of a White Christmas, because you’re going to get one. Snowpocalypse is coming to a Columbia Gorge near you. Since there’s only one Columbia Gorge, it’s obviously going to be your Gorge that gets worked over tomorrow. If you have plans to drive I-84 tomorrow, please change them and drive tonight. A powerful low pressure system moves due west of the Gorge over the Pacific, setting up a very strong east gradient by 7am, with 40+mph at Rooster and temps right around 32 degrees in the Gorge (and of course colder in the Upper Valley). With an east gradient that big, cold air will get pulled through the Gorge. Luckily, it’s not bitterly cold east of here, but it looks cold enough to cause trouble.

That east gradient won’t swing around until Wednesday morning, meaning the snow could fall that long, although I suspect it will turn to rain late Christmas day. Precip starts after 4am, with up to 1” of water value giving us 6+” of snow in the Gorge, with 12” possible in the Upper Valley.

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Really, I’m not joking. You don’t want to drive I-84 on Christmas. You might have studs or snow tires, but nobody else on the road does. Of course, I could be totally wrong, and it could all fall as rain. Or maybe freezing rain. Actually, there’s a pretty good chance the Upper Valley will see some freezing rain late tomorrow.

Anyway, on to the Mt. Hood forecast: Today sees snowfall early, quickly transitioning to snowfall mixed with sunbreaks and then clearing early afternoon followed by high clouds late afternoon. Just another inch or two will fall before clearing kicks in. The snow level will be around 1500′. Wind will be NW 35 this morning, 25-30 early afternoon, and 15-20 around 4pm. The wind turns to SW 15-20 overnight.

What causes trouble at sea level on Christmas is good weather on the mountain. However, the snow that falls on Mt. Hood from this system is going to be heavy, not powdery, due to the atmospheric profile. That said, snow starts around 4am with 1.5” water value (WV) falling by 4pm for 10-16” of new snow. Another .1-.2” WV falls overnight, for 1-3” more. The snow level will be at the surface (in the Gorge, anyway) until 4pm, when the snow level rises to 4000′. Worth noting is that temps at 5000′ will be in the mid to upper twenties, despite the low snow level – hence the not-powdery snow. Wind on Christmas will be SW 20 early, rising to SSW 40-50 during the day, falling to SW 30 around 4pm and slowly dropping overnight.

Wednesday sees more snow: About .5” WV between 4am and 4pm, for 5-6” of new. The snow level will be at 2500′ early, falling to 1500′ at 1pm. Wind will be SW 20 early, becoming W 25 midday and WNW 35 in the evening. Another .6-.8” WV falls Wednesday night into Thursday morning for another 6-9” of new snow.

Thursday sees high pressure start building in. Morning flurries give way to partly cloudy, maybe even sunny, skies by 10am. The freezing level will be 1500′ early, dropping to 1000′ mid-morning. Wind will be NW 25 early, dropping to NW 15 mid-morning and holding.

The extended forecast for Friday through Tuesday looks cold and clear. Finally. High pressure and sunshine!

Have an awesome day today!