Friday, November 15, 2013

Snow for some

Several days ago, skier's got excited about the "potential" for lots of snow in the mountains. As weather models recalculated the weather, this excitement dried up a bit. There will still be a winter storm, but the snow will mostly stay in the mountains in Northern Utah. Temperatures at upper levels look fairly warm (-8 C at 700 mb) which is a little too warm for it to snow in the valley's.

Below is an ensemble of forecasts for Saturday afternoon (the time I'll be at a football game). The dark red indicates 90% of the models agree there will be over a 0.05 inches of precipitation. Again, this storm looks like it will mostly impact the mountains because of orographic effects. Since the models don't really resolve terrain well, this thin band of precipitation probably should look a little thinner.

From this we will still expect some precipitation during mid-day and afternoon tomorrow. But what kind of precipitation. The left picture below shows relative humidity in the atmospheric column and winds and temperatures at 700 mb (about the top of the mountains). Temperatures are about -8 C at the top of mountains, which is cold enough for snow (because it is below freezing), but not cold enough for us to get much snow at the surface. We can expect rain and some flakes. The right panel shows 6-hour precipitation amounts from the NAM model. 

In Spanish Fork we could see a little snow, but I think it will be mostly rain. Usually it needs to be at least -12 C to get snow in the valley. I like living on the bench in Spanish Fork because it seems winter storms from the northwest get pushed into our little corner of mountains and channeled up the canyon. I like to believe this gives us more snow, but I'll try to keep an eye on it this winter to see if that is true.

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