Doug Jacobs sent in this nice looking picture from Grass Valley. The picture was taken today, and he wondered how I possibly could call for a 10,000' freezing level. Of course if you are reading this blog you probably know the answer. First you need to know where he is. Grass Valley is on Highway 97, maybe 25 miles south of Biggs Jct. near Maryhill. It's at about 2,400'. That puts them at the "intersection" of the low clouds and land over there in Eastern Oregon. They have been in/out of the top of the fog layer much of the last week. When the layer is deeper, they just see low clouds there, when thinner, they get fog. In fact the temperature there has been between 20 and 25 degrees for the past 5 days! Now that's REALLY boring weather, but it does make for a frosty scene doesn't it?
Back here west of the Cascades, nothing has changed dramatically in the last 24 hours. The airmass coming through the Gorge has cooled though. Troutdale is running 3 degrees cooler, Corbett is 2 degrees down. This also dropped the high temperature at PDX 6 degrees from yesterday! Since Saturday, it seems like PDX has been getting a bit warmer than I would have expected based on the airmass pouring out of the Gorge…the strong offshore gradient must have allowed some slight mixing of the warmer air above. Weakening gradient has now kept the airmass more homogeneous, so I went only for a high of 45 again tomorrow.
Speaking of gradient, it's been a slow and painful process the last 24 hours. We've gone from 10 millibars PDX-DLS easterly gradient down to 7.2 right now. I expect a drop to 4-6 mb. by tomorrow at this time. The wind has sure been slow to respond. Gusts are still reaching around 60 mph at Corbett and 30-40 mph at TTD. I notice we haven't seen a gust over 40 at Troutdale since 6am though, so progress is being made for those of you that are REALLY sick of the wind. Today is day #6 of strong easterly flow…just one more to go! I think Thursday will just see gusts 30-40 mph at the west end of the Gorge as the surface high continues to weaken.
Looks like a significant pattern change coming up this weekend, but to what? What a tremendous mess in models beginning this weekend and continuing next week. The general idea SEEMS to be for a longwave trough to become established along the West Coast, similar to what we saw in December. However, model runs are all over the place…which makes me want to curl up in a fetal position, cry and murmur…ecmwf…ecmwf. The GFS as of 00z suddenly now seems to want to be ridgy next week, a huge change. The ECMWF sure looks similar to last winter, with cool storms coming at us from the west. It also isn't quite as cold/deep with an initial shot of modified arctic air dropping over us Sunday though. The GFS is definitely colder, in fact I realize our 7 Day forecast doesn't represent an airmass that cold (highs 35-40). But Drew and I decided with model uncertainty that our current weekend forecast is a good blend. As for snow, from what I see now, there's no moisture around since the cold air just "drops in" Sunday and Monday. The ECMWF would have a big snowstorm by Tuesday as a surface low approaches the cold air over us, but the GFS is just plain dry. I assume both of these will change with future model runs…it's only Tuesday! Mark Nelsen
Extra: I've updated some of the peak wind gusts from the weekend storm down below. The NWS reported 77 on their "Rooster Rock" sensor (which is 3 miles west at the Corbett exit). Also a 67 in SE Troutdale. Small town rumor says someone in Corbett measured 92 mph, but I haven't tracked that one down yet.