A local Volkswagen dealership had a deal where they would make your car payments for a year if it snowed on Christmas this year. Thankfully for those of us who ski, it looks like the dealership will be out of luck this year. The outlook for this next week is a good one if you are a skier.
First things first, we are soon coming to the tail end of a very nice storm for all of Central and Northern Utah. Water managers and local skiers love storms like this. They might not provide blower pow, but man do these storms cover up the rocks quickly. With temperatures dropping steadily since last night, snow densities and snow levels are dropping, improving the skiing. The Wasatch will see between 0-3 inches of snow between now (3:30 pm) and when the precipitation ends this evening. The Bear Rivers near Logan look to get 2-4 more up high. While the snow totals for this storm have been impressive, it is really the water totals that make it an exceptional event:
Tony Grove Lake (near Logan): 5″ water, 24″+ snow
Beaver Mtn Ski Area: 12″ snow
Ben Lomond Peak (near Ogden): 4.6″ water, 18″+snow
Snowbasin: 2.7″ water, 17″ snow
PowMow: 2.4″ water, 14″ snow
Alta/Snowbird: 4″ water, 27″ snow
Brighton: 2.4″ water, 17″ snow
Park City: 1.7″ water, 12″ snow
Not only did Alta get a lot of snow, but no rain either. Once again Little Cottonwood delivers. Looking back at the pre-storm forecast, things panned out pretty well for both water amounts and snow amounts. Snowbasin and PowMow undershot their forecasts, and the error was primarily in the snow density forecast as opposed the the forecast water amount.
This storm was a good example of how snow amount forecasting can be very hard relative to simply forecasting rain. Most forecasters take from the model just a water amount, and then apply a snow ratio to that water amount for each phase of the storm to get actual snow amounts (the models aren’t good at converting water to snow themselves). In situations where at some point in the storm you might get anything from rain to 6% powder, you have 2 big sources of error: the amount of water that will fall and how much snow each unit of that water will turn into. In this last storm the water forecasts were quite good, so much of the difficulty was in forecasting the rain/snow line and snow densities.
Speaking of snow density, our next storm will arrive on Christmas morning. Unlike the last system, temperatures will be cold and blower powder is a distinct possibility. The models have been a little squirrely on this one, but things look promising for what I call a “checkmark storm.” These storms often bring awesome pow riding as the storm comes in warm and goes out cold, often with a good fetch of NW winds that keep things piling up in the Cottonwoods in either lake-effect or post-cold frontal showers. Even though both the GFS and ECMWF are liking this solution, the snow ranges will be big due to the potential for prolonged moist NW flow. Like I said 2 weeks ago, never turn your back on moist NW flow if you are forecasting for the Cottonwoods! Here are some amounts for Thursday morning through Friday afternoon:
Upper Cottonwoods: 12-24″
Northern Wasatch: 8-16″
Park City: 6-12″
If you are planning when to ski, Thursday (Christmas) looks like the main storm day, but Friday looks even better with more and fluffier snow from Thursday night.
After that there might be another trough Sunday, but its all over the place.