Uh oh. 1/7 forecast.

Posted by
 January 7, 2011

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Good morning!
In yesterday’s forecast, there was a typo. I meant to say the “Arctic Oscillation,” but put Pacific Decadal Oscillation instead. That’s 5am brain for you. Anyway, they both affect the weather in the PNW, but on different time scales. We are currently in the cold phase of both, which is contributing to the storm path being in the incorrect place for pow-pow on Mt. Hood.
But first, today’s weather on Mt. Hood. Temps are above-freezing again this morning, and it’s looking like the snow level won’t fall below 5000’ until after 4pm. However, once the temps start dropping, they’ll drop fast, and the snow level will be at 2000’ by 10pm, falling to 1000’ by Saturday morning. The precipitation will start around 1-2pm, which means we’re probably going to see some r**n today. Heaviest precip will happen between 4pm and midnight, for some r**n, followed by some snow. I think we’ll still see 4-6” of new by tomorrow morning, for a total water value of .5”-.75”. Winds today start at WSW 15-25, building to W 25-35 by 4pm.
Tomorrow starts with light snow flurries and the snow level at 1000’. Heavier snowfall will happen between 1pm and 10pm. Total accumulation 4am to 10pm will be 3-5” with water value of .25″-.5″. Winds tomorrow will be WNW at 15-25 all day.
Sunday brings intermittent orographic snow flurries and sunbreaks all day. Total water value will be less than .25″. Snow levels start at 1000’ and drop to the surface. Winds will be WNW 5-10 in the morning, becoming light in the afternoon.
Monday and Tuesday look cold, clear and calm with the free air freezing level at the surface and light east or north winds on the mountain.
If the forecast holds for Wednesday, the Gorge is ******. Very cold air at the surface clashes with an overrunning warm system containing 1-2”+ of moisture. At this point, it looks like the snow level with this system will be at 5000’, except in the Gorge, where it will be at the surface. Cold air will remain in place through late Thursday or early Friday, meaning well over a foot of snow could fall in the Gorge. This is great if you want to skin or bootpack Hospital Hill, but not so great if you want to drive somewhere. If this forecast holds, expect I-84 to close. On the other hand, the moisture could miss us entirely. Stay tuned.
Have an awesome day today!

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