A very cold system will bring snow showers to the region later today into tonight with mostly light accumulation. Models have been keying in on the possibility for two sets of atmospheric rivers to bring the region tremendous amounts of precipitation over the next 10 days.
Before I begin, it’s important to note that atmospheric rivers are very volatile and if the jet buckles or points slightly to our north or south, that the forecast amounts could change dramatically. So none of this is guaranteed, but it is worth exploring the possibilities.
Today we will see a very cold follow-up system drop through the region. It is currently 15F at my house on the bench and almost all mountain locations are in the single digits. These temps will drop even colder for tomorrow morning. BE PREPARED! As for snow, generally it looks like 2-5″ of snow in the mountains today and tonight as snow showers become more widespread this afternoon and evening. The Cottonwoods could get the benefit of some lake enhancement and could see slightly more. The NAM is calling for up to 8″ for the Upper Cottonwoods by tomorrow morning:
Not sure I buy it, but is definitely possible. Tomorrow could be a bit of a sleeper powder day if this comes to fruition.
We should have a break Wednesday into early Thursday with temperatures warming significantly on Thursday ahead of the next system.
The first AR event will push into the region starting on Thursday night. We should see snow levels rise with this system as mild air moves in from the Pacific. Starting with such a cold airmass means that there could be pockets of low elevation snowfall or even freezing rain if we can’t fully mix out the valleys before precip starts. Snow levels should rise up to between 6-7k feet. For Park City, it looks to remain snow in town at this time, but snow levels are always tricky so no guarantee.
The mountain snowfall should continue off and on thru Friday, then perhaps a break late Friday into Friday night. Then a second wave pushes in for Saturday and brings more heavy snowfall to the area. We should start to clear out by Sunday. Total snowfall with this first wave should be significant for the high elevations. Currently, the NAEFS plumes looks like this:
If we ignore the light blue lines (which represent the canadian ensembles) as they seem to be erratic, we find that the mean snowfall for the Upper Cottonwoods thru Sunday AM is about 35″. Usually this is overdone. The Euro is showing about 2″ of liquid for this same time period. All things considered, I think 10-30″ is possible for the mountains of Northern Utah with this system. The highest elevations that are favored by a westerly flow could easily see higher amounts.
The screaming message is that it seems likely that we should get a good shot of base building snowfall.
After taking a bit of a break Sunday and perhaps Monday of next week. It looks like we have a good chance for a second, perhaps even stronger AR event. Models have been very consistent in the last few days with handling this system. Too early to know what snow levels will look like, but precipitation amounts through the end of next week look off the charts. When you couple this second AR with the first one, you get a total GFS forecasted snowfall that looks like this:
A huge swath of the mountains is “off the charts” snowfall. This map actually portrays a 10-day maximum snowfall of 148″. Now, before you go running around telling people that we are going to get 150 inches of snow, it’s important to point out that this is almost certainly overdone and I expect this model to come back to earth. As mentioned earlier, these atmospheric rivers are hard to forecast and there’s a solid chance we get missed completely. The Euro is much more conservative and is portraying plenty of precipitation for us, but it’s certainly nothing mind-boggling like we are seeing from the GFS.
I think getting excited is ok, especially for this first AR event as it’s much closer and confidence is higher but it’s important to note that none of this is guaranteed and the forecast could change rapidly. I’ll try to update often if anything changes over the next 10 days. Who needs sleep anyway?
I’ll leave you with this 10-day loop showing total QPF. Notice the Sierras getting slammed…