Dry and mild weather thru Thursday. Storm arrives Friday and last into Friday night. Another storm likely for Monday/Tuesday of next week. A generally colder and stormier pattern has finally arrived.
Short Term Forecast
Not too much change from yesterday's forecast. We will see clouds increase today as a very weak system approaches the area from the west. I think almost all precip will fall apart as it nears Utah and this will mostly just be clouds and light breezes tonight. Wednesday and Thursday look to be very mild as a SW flow develops ahead of our next storm.
The storm arrives Friday and we should see cold air arrive as well with snow levels quickly dropping to valley floors. An earlier arrival of the cold front would make Friday afternoon a good powder day, while a later arrival would mean Saturday morning. These timing details will need to be resolved in the coming days as models are not currently in full agreement. However, we do have good agreement on general amounts. If we look at the GEFS ensembles this morning:
If you read this forecast a lot, you know that I love the above graphs. Not only do they show timing, but they show the range of possibilities put forth from all GFS and GEM ensembles, this gives great insight into how confident a model is in one specific solution. In the case above, we generally have good consensus. The storm should be a moderate winter storm. And when I mean winter storm, I really mean that. No more of this high snow level crap! Cold air and plenty of it means snow for all elevations. We can see ensembles show anywhere from 0.5" to 1.3" of liquid for the Upper Cottonwoods with a mean of about 1". This type of storm should favor the Cottonwoods so other areas will be lower. At first guess, I think this storm could feasibly deliver 5-10" of snow in the mountains with perhaps a foot or more in favored areas like the Cottonwoods. Of course, we'll continue to monitor it, but a moderate snowstorm looks likely.
If you look at the right side of the above graph, you'll also see that I highlighted the next storm which is timing for Monday into Tuesday. After a break late Saturday and Sunday, we should have another good chance for snow in Northern Utah. A lot more model disagreement on this one, which is not a surprise. We should see a good chance for additional accumulations to start next week. Two storms in a row!?! Haven't seen that much this year....
Looking at the maps we can see that the Euro looks good over the next 10 days for accumulation:
Anything in pink is well over a foot of snow. Don't pay too much attention to the numbers as it uses an assumed 10:1 ratio for snow and we should be much higher in the 15+ to 1 range. Also, Euro is fairly low resolution and doesn't pick up topographic influences well. Let's check the GFS:
GFS showing even better and more widespread accumulation in the next 10 days. The difference with the GFS compared to the euro is that it has a third storm system at the very end of 10 days that is not in the Euro model at all. This would be around Thursday the 25th. We'll have to watch this to see which model is right.
As mentioned above, the GFS has a third system around Thursday, Jan 25 and the Euro does not have this storm. Both models then have us dry for the following weekend (Jan 26-28). Long range ensemble heights would suggest the trough reloading for the end of them month which could be a return to storms. Overall, we are finally in a more winter-like pattern for the western US. The eastern half of the country will flip as well with warmer conditions finally bringing them a thaw. After today, I won't have to wake up to news about snow in Shreveport, Louisiana anymore....
Evan | OpenSnow