The analysis loop below shows what happened. The surface-based front made it to Salt Lake City yesterday around 3 PM and the accompanying surface trough has lingered just to our south. The precipitation, however, was less cooperative, providing a bit of snow for the northern Wasatch (1-3" according to the Utah Avalanche Center), but never really making it down to the central Wasatch or the Salt Lake Valley for reasons discussed in yesterday's post.
Currently, the surface trough appears to be draped across the southern Salt Lake Valley, but is a bit amorphous. Note the north winds near and around the airport and the south winds near and around Point of the Mountains.
The Salt Lake Valley will likely see a return of southerly flow today as the surface trough shifts a bit northward. More important, as the upper-level trough finally decides to swing eastward, the precip band gets its act together once again and like Lazarus rises from the dead. Note in the NAM forecast below how the precipitation fills in and the upper-level 700-mb trough intensifies over Nevada. As these features move eastward, we finally get some tonight and tomorrow, along with some post-frontal action late tomorrow and tomorrow night.
That NAM run puts down 0.75" of water and 13" of snow at Alta-Collins by 9 AM tomorrow and 0.94" of water and 16" of snow by 11 PM tomorrow night. For what it's worth, the SREF puts out 0.35 to 1.18 inches of water for the period. The Euro 0.6".
I know what you're thinking. You're not going to get suckered into this again. Fair enough. The past 24 hours haven't been pleasant for my profession. But I think you should be ready. Unlike Friday and Friday night, when there was great uncertainty in the position of the front and frontal precipitation, we can be confident that the front and trough are going to come through tonight and tomorrow, so the issue here is just how productive those features will be. In this case the odds favor a powder day tomorrow. I'll go for 7-14" at Alta by 9 AM tomorrow morning. And, while we're at it, some overnight snow for the valley's too. As always, monitor official forecasts and expect a cluster tomorrow at the bottom of the canyons.
There has been a compact low center lingering just off the Oregon coast today, with an associated surface trough there. Once the trough moves inland it looks like the associated surface low decays, and there is much stronger low-level cold advection in the cold frontal zone. I have noticed this pattern with some other systems too. I think the landfall of the trough core has some substantial effects on the structure and progression of the cold front. In any case, looks like we finally get snow.
ReplyDeleteIndeed! I met friends in the city for dinner at 6:00 driving in from Heber City. On the way down I ran into snow squalls that appeared to be convective in nature. You could make out the cauliflower shaped cloud tops. Driving back at around 9:30 - 10:30, Parleys was getting pummeled. Roads were snow covered and wind was transporting snow drifts across the freeway. Was this a case of orographic lifting leading to convective squalls? It was snowing fairly heavily coming up through the canyon. Once over the summit, it was lighter, but still snowing all the way down into Heber Valley.
ReplyDeleteI saw lightning in one of those convective snow showers east of SLC, I think a little before 7 pm. A couple of strikes showed up on the lightning map. There was a little short-wave embedded in the trough that set some of this off, I think it could be part of the same feature that was visible along the OR coastline on Saturday.
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