Between Snow Storms Today

December 23, 2008

DSCF0012 I was a bit negligent in posting yesterday…probably due to exhaustion and the fact that forecast-wise there wasn't much to talk about for today.  The other is that I REALLY wanted to get home due to generator issues and other things (2 kids stuck in a house alone with my wife).  So at midnight I made it down my rural road which had one lane plowed with 3 foot berms on each side.  I get to my driveway and…nowhere to park!  My wife had left the snow shovel, so at midnight I spent 30 minutes digging through the (relatively light) snow, just enough to nuzzle the SUV into a little parking spot.  Then it was a 500 ft. trudge through about 2 feet of snow in the pitch dark, stumbling into the powder, in jeans and hanging onto bananas and a bottle of wine.  You can imagine the scene.  No electricity at home and the family was camped out by the woodstove all asleep like it's Christmas Eve!  To make this long story short, the power just came back on and internet access is restored.  I am just amazed at the snow depth.  I still have 21" on the ground about 2 miles east of Corbett at 1,000' elevation…I don't get much drifting here because of very little wind, so I assume that there must have been 22-24" before it compacted the last 24 hours.  That includes 13" on top of the thin ice layer Sunday too.  You see the picture…that's my dog;  the Prius is on the left and the Odyssey minivan is on the right.  They won't move for a long time!  I'll put some other pictures in the viewer photos on the sidebar.

I haven't spent the usual enormous amount of time staring at maps today, but enough to confirm what I was already thinking, with a few changes…

Offshore flow continues tonight and early tomorrow ahead of an approaching weather system…keeping us relatively cold through morning.  I see temps are approaching freezing in spots at 1pm, so that forecast is looking good.  I doubt we'll see a dramatic drop tonight, just staying in the mid-upper 20s.  That sets us up for some snow in the morning as precipitation from the approaching California storm merges with the cold front coming in from the northwest.  Last night I said 2-4" and at this point that seems a bit high, considering that the freezing level should rise to about 1,500' from 4pm tomorrow through early morning Christmas Day, and the heavier precip comes with that slight warming.  Maybe 1-3" is a better bet.  Christmas Eve itself (tomorrow evening), should be a bit sloppy with a rain/snow mix due to a good southerly wind blowing up the Valley.  Not exactly a real warm wind, but enough to change those of us below 1,000' to that sloppy mix.

Then the fun returns Christmas Day itself.  Looks like a surface low slides right over the top of us or just to the south during the morning hours, turning our surface wind easterly again (cold), then light north by late in the day.  There is a good burst of precipitation at the same time…SO…I think Christmas Morning we'll probably see widespread 2-4" snowfall, with some spots up to 6" if we stay chilly enough.  Maybe Steve Pierce can confirm, but I don't think we've ever seen such a White Christmas! 

I think the higher elevations and Columbia River Gorge could see another foot of snow from tomorrow morning through Christmas night!  Down here in the metro area I see snow, then rain/snow mix or all rain, then more fresh snow Christmas Day.

I didn't look too far beyond Christmas since I spent the morning shoveling, BUT, it's obvious there is going to be a quick change to mild and wet westerly flow late Friday and the weekend.  50 degrees isn't too far away for those of you tired of the snow…

9pm Update:  This will be brief, since I need to get organized for the 10pm show, but I see precipitation is moving in quickly this evening.  Some below have mentioned the KPTV tower temp is above freezing at the top.  Yes, but just barely and the dewpoint at that elevation is below zero.  That means evaporational cooling should drop temps down below freezing at that elevation soon after the precipitation starts falling.

Just looked at 00z maps…there seems to be a slight northward trend in the 00z WRF-GFS and 00z MM5-NAM in the low pressure center location for Christmas Day.  The 00z NAM would give us no snow, but the 00z WRF still could.  Just another wrinkle in the forecast. 

What continues to be very clear in the longer range is that the snow threat ends Friday.  After that it's back to wild, wet, and warm Pacific weather systems.  Enjoy the snow while it lasts!

Mark Nelsen