Monday, November 12, 2012

American Fork Gets the Shaft!

We just received this morning's visible satellite image from MODIS.  This is the first visible image since the storm and, although there are some high clouds, they are thin enough that you really can't miss where it snowed and where it didn't.  Check out the lack of snow cover north of Utah Lake around Saratoga Springs and American Fork.


  1. Oh yes we did get the Shaft. I live in American Fork up near highland and Cedar Hills and we got maybe 3 inches total. Points toward the freeway got 2 inches and under. I was hanging out with some family in Sandy Sat night and they easily had 18 inches and driving back home to our couple inches was truly saddening!! Even Provo got more than us!

  2. The lake effect snow just didn't want to make it down there and if any snow did come down, it went further south. The Utah Lake effect kicked up and gave Provo a little more, but particularly Spanish Fork and Spanish Fork Canyon.

  3. Yea I live in Lehi by Thanksgiving Point and we only got 4 inches and most of it has melted. We usually don't get the big snow down here unless the storm comes from the west/southwest (which is a rarity). I'm guessing the Traverse Mountains create a nice block from the northern/northwestern storms and lake effect.

    The satelitte though is impressive and interesting that everyone got snow around us but not us.

  4. There might be some other things at play too, besides the storm just having missed those spots. That part of Utah Valley has subsidence effects when surface winds are northerly, which can cause a fair amount of sublimation and/or melting of falling snow before it reaches the ground. Look at the area just west of I-15, where air comes through the gap (lack of downsloping). You can see there is a band of snow cover all the way down to Utah Lake, with another area of apparent subsidence and bare ground to the west of that. Once in a while you can see this gap effect in southwestern Salt Lake Valley in southerly winds, where near-surface air moving through the gap remains colder and more saturated compared to areas where it has descended from a higher elevation. Also, the warm soil temperatures combined with daytime solar radiation which could penetrate thin snow cover more than deep snow, resulting in greater melting in these areas. For those who live down there, does this compare with what you saw?

  5. Before I moved to south Lehi over four years ago, I used to live in west Murray near the Jordan River and I bemoaned the fact that the central Salt Lake Valley always fared poorly during warm advection precipitation events. There was always a doughnut hole in the radar coverage where I lived. We had to wait until cold advection commenced before we saw appreciable snowfall. Well, southern Lehi is worse. The only appreciable snowfall here occurs during warm advection patterns (overrunning events). As soon as the wind turns northerly and cold advection begins, the accumulating snowfall ends.

    During this event we got about 0.5" that melted by Friday evening, then about 1.5" by Saturday morning that was gone by Saturday afternoon, then another 0.5" by Sunday morning that was history by noon. So yes, we often get the shaft and this event was no exception. Eventually I'll purchase my own weather station and start documenting what an abysmal microclimate I live in.

  6. Ugghh....I went up to Corner Canyon to groom for nordic skiing. Left my house this morning at 0430, all excited with 18" of snow in my yard at 4,800ft. I go out to 6,100ft at Traverse Ridge and there is only 6" or so.

    Any insider scientific beta? David had a good explanation, but does that mean that Traverse Ridge area typically has poor snow accumulations?

    1. I would say it all depends on wind direction, and which side of the ridge you are on. I have a friend that lives up in the Suncrest development, at the 6,000 foot elevation on Traverse Ridge. I call it snowcrest because they usually get a lot of snow up there. But if you are on the downwind side of the ridge, it is a completely different story.

      Even in cases where the radar imagery shows almost uniform reflectivity over the whole area (implying that there might not be large topographic effects on the storm itself), there are usually places that seem to get very little snowfall on one side of this ridge or the other. It seems like a downsloping wind of as little as 1,000 or 1,500 feet vertical descent can be enough to sublimate much of the snow falling over a given location. Maybe someone has data on sublimation rates vs dewpoint depression or something, that is probably a major factor around here in regard to snowfall microclimates.