Stormy Christmas

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.

Nature’s Firehose

Before I get to the upcoming Atmospheric River set to blast the Wasatch starting later this weekend, I’ll hit the short term real quick.

With cold temps and a quick-hitting shortwave scooting through Utah this (Friday) evening, I’m expecting a burst of nice low-density snow in the mountains. I’ll go 3-6″ for the upper Cottonwoods, 2-4″ for the PC resorts, and 3-5″ elsewhere.

Now for the good stuff! Nature’s firehose will be cranking up beginning late Saturday night, with precip rates and wind speeds increasing into Sunday morning, and the storm ending late Monday night. There will not be a ton of large-scale lift provided by the atmosphere but the sheer amount of water being transported in the nuking upper level winds, and then being forced to rise over the Wasatch, will provide all the ingredients to drop some serious precipitation. This is an Atmospheric River. So what will the conditions be like on the ground?

-Snow levels will be high: getting as high as 8,000ft on Sunday. The bases of many resorts will get rain.

-Winds will be howling Sunday morning through Monday morning

-Snow will be of the Sierra Cement variety. I wouldn’t be surprised to see periods of 5:1 snow-water ratios

-Avalanche conditions will be quite dangerous in the backcountry

As for snowfall totals, I’m going to stick with exactly what Trey went for yesterday. Near the snow line, these totals won’t be valid of course, but I anticipate these amounts at mid-mountain and above. Trey went for 18-36″ in the upper Cottonwoods and northern Wasatch, with 10-20″ on the PC side (above the snow line). Most important in these kinds of storms though is the amount of liquid equivalent in the snow that will fall…important for covering up rocks for skiers, and for storing water in our snowpack for lakes and rivers. I’m anticipating 3-5″ of liquid in the upper Cottonwoods and Logan area mountains…that’s a lot of water from one storm. 

So it’s gonna be a wet, warm, and windy storm…and one we definitely need. As Trey said, get out there and surf that beautiful new snow!


Long Term also still looks good for a nice cold storm Christmas Day by the way. Santa put Utah on the nice list!!!

Going BIG!!!

Looks like we were able to squeeze a couple inches out of some snow showers this morning. Forecaster Peter Veals was reporting 1-2″ on the ground in Upper Little Cottonwood, which helped freshen things up a little. Looking ahead we have a very exciting forecast.

A strong upper level jet max will slam into the Pacific Northwest this weekend bringing with it a very moist/unstable airmass. This will help place Nrn Utah in a favorable region for prolonged, strong northwesterly flow. Several favorable ingredients will likely come together to provide an extended period of snow at higher elevations:

1. Strong jet max penetrating the inner-mountain west – 160 knot jet max

2. Moist northwesterly flow in the mid-upper levels – favorable for additional orographic enhancement particularly in the Cottonwoods and westerly/northerly facing aspects. 

3. Long duration – 48 hours


A few concerns also exist, though:

1. Warm airmass – Snow levels will be 7500-8500 feet. Cooling effects during heavier precipitation will be able to overcome this at times, though.

2. Jet location – Nrn Utah will be more on the Anti-cyclonic side of the jet. Preferred location is directly underneath and just north of the jet max.


With all this said through Tuesday I’m conservatively expecting 1.5 – 3 FEET in the Upper Cottonwoods and resorts in the far North like Beaver Mntn (particularly above mid-mountain where snow ratios will be slightly better). 10 – 20 inches should fall in the Park City area at mid-mountain and above. Base locations may see periods of rain and snow due to the warm airmass. Unfortunately areas farther south will be the big losers for this storm cycle. Totals will be marginal at best with < 6 inches at resorts such as Sundance, even at the highest elevations. 

How will it ski? Due to the warm air mass snow densities will be quite high (probably average 7:1 – 10:1 above 9000 feet). So while we aren’t talking blower pow, you should still be able to surf the higher density snow with your fatties. MOST importantly, this is adding much needed water to the overall snowpack and coverage should drastically improve.

An Oasis or a Mirage?

The Cottonwood resorts were able to squeeze all of 1 inch out of the very weak disturbance last night and cloudy skies have been the rule today.  Matt L was thinking that there might have been more, but alas, it was only enough to produce some wisps as you cruised down the groomers.  A shearing, negatively tilted trough will come onshore in California tonight, adding more to their much-needed totals. 

The trough really falls apart tomorrow though, and the moisture and lift just aren’t going to come together for Northern Utah.  I think an inch or less is a good bet Wednesday.  Like Matt L mentioned, Brian Head might be able to get to 6 inches or so as they will have more moisture to play with.  The shreds of the trough will hang around Thursday, bringing grey skies and maybe another inch to the Wasatch.  Beaver Mountain and the Logan-area mountain will do better Thursday, with 1-4 possible by Friday morning.  

Looking forward from Friday, the large scale pattern will begin to shift from what we have seen this week.  According to the current GFS, the polar jet over the eastern Pacific will become fairly static as a deep long-wave trough sets up over the Central Pacific.  Such a pattern will keep the proverbial firehose pointed right at Oregon and Washington.  Enough of this moisture will make it inland that Northern Utah could do pretty well in the moist WNW flow from Sunday to next Tuesday, albeit with high freezing levels. The ECMWF ensemble likes it too, with virtually all the ensemble members on board with the idea of a strong, wet westerly jet hitting the northwest US. 

The only question is whether we will end up too far south to get it!  This setup lookssimilar to the one that really gave our season a kick in the pants last February, where the Cottonwoods did well, low elevations got rain, and areas from Logan, UT to the Tetons just got hammered. 

In short, don’t bank on it yet, but the 5-7 day outlook is hopeful.

Dense powder is still powder

As anticipated, the first part of this storm came in like concrete; shallow clouds and warm temps are a recipe for dense snow. We are now entering into the cold phase of this storm, so the snow that falls tonight and tomorrow should finish us off with a nice right-side-up snowfall.


Before I get into the forecast though, here’s a look at how snowfall totals are coming along throughout the Wasatch for this storm:

Alta Collins and Top Cecret: 4″

Snowbird: 5″

Thaynes Canyon Snotel (PC resort): 2″

Snowbasin: 7″

Ben Lomond Peak Snotel: over 10″

Tony Grove Lake Snotel: 3″


All of these locations came in at over 10% water content, so like I said, quite dense, but the skiing on the 5″ at Snowbird today was surprisingly good! Creamy powder is still powder, and it is also very good at covering up rocks and building a base. On a final note, you can’t ignore that huge number on Ben Lomond! It appears that during the pre-frontal W/SW flow, orographic precip generation went big up there. I say over 10″ only because there is no board to sweep at snotel sites, and settlement of the snow makes it impossible to say just how much fell. Needless to say though, they’ll likely be the winners for this storm.


Now for the forecast, I’m gonna stick with the storm total numbers that others before me have put up. We’re just shy of verifying within our ranges, so the additional snow that it appears will fall should push us into those ranges. Periods of snow will continue through tomorrow (Sunday), with things winding down in the afternoon/evening. One wild card with the cold upper-level temperatures though, is lake-effect, and there is a chance we could see a band Sunday. This would give us a few more inches in the Cottonwoods than forecast if were to happen.


Long range still looks similar to what Trey described, with a shot at a fairly weak storm in the Tuesday-Wednesday timeframe. In the mean time, get out and enjoy the snow!

Snow. Finally!

As I write this early Friday evening, precipitation can be seen moving into radar range..when was the last time we could say that?! As I’m sure many of you have noticed, it’s been unseasonably warm. Today we broke another record high at Salt Lake Int’l Airport. Why’s this important? It means any pre-frontal precipitation will fall as snow only at very high elevations. The bulk of precipitation is expected to be associated with the frontal passage, however, so snow levels will lower during the heaviest precipitation. A few quick model numbers for the Nrn Wasatch: GFS = .2″ qpf, ECMWF = .5″ qpf, NAM = .4″ qpf, GFS (4 km) = .6″ qpf,  NAM (4km) = .8″ qpf. If we grossly used a 10:1 snow ratio that would yield about 2-10 inches for the model solutions. So what are we calling for?


Like Ian said in his forecast below, we’ll likely see modest accumulations with the front overnight tonight followed by additional accumulations Saturday PM. Overall, I’m sticking with the 6-12 inches for the Upper Cottonwoods as we’ve called for the last several days. Lower totals in lower elevation areas like PC: 3-7 inches (higher amnts possible above mid-mountain). This storm will be “right side up” so it at least has that going for us. Groomers will probably be great, but off trail you’ll risk hitting crust or hidden rocks. 


Long range

Another storm is on tap for mid-week! Unfortunately, it looks like the bulk will miss us once again, but any snow is welcomed. And it could still be decent: ECMWF gives us solid accumulations, GFS and ensembles not so much. We’ll hopefully have a better idea once we get this storm out of the picture.




Rummaging for Scraps

One of the most impressive storm systems in years is already making its impact felt along the Pacific Coast.  The National Weather Service has issued just about every kind of warning it can issue, from high surf and wind to blizzards.  Places in Washington State have already totaled up 10 inches of water.  Too bad it was just that- water.  At that particular station what snow was present has now been washed away.  And that is only 1000 feet below treeline!  Not great for skiing, although the storm will finish with lower snow levels.  

As the previous post mentioned, it would be great if the Sierra Nevada didn’t exist right now.  They will doing their best to remove moisture from the air these next few days.  That’s fine. California needs it much more than we do.  Utah is most likely to get snow between Friday evening and Sunday morning as the Pacific trough passes over us.  The biggest variable in my mind for snow amounts is how long the moist northwesterly flow behind the trough lasts.  It is during this post-trough NW flow that the Cottonwood Canyons can really get it. Looking at the GFS and EC I think something around 7-14 inches is possible in the upper Cottonwoods, with 4-9 elsewhere.  That 14 is a little bit on a limb, but I think the potential is there due to the cool, moist NW flow. The storm should be all snow at the resorts, with the bottom of Snowbasin and Sundance being the only possible exceptions Friday night.  

Right now it looks to me like Saturday will be the better day to ski, but I say that with low confidence.  Never turn your back on a model indicating moist northwest flow.

The long range doesn’t look great with split flow dominating.  

Relief is on the way!

Jeff and I went for a tour along the Park City ridgeline today, and it felt like a March day. The south aspects were getting slushy (even up high), and it was very much a short-sleeve affair while climbing. Despite the toasty temps though, it is December and the sun angle is very low, so the high elevation slopes facing more toward the north still had great snow! Surprisingly great snow. This warm spell (December heat wave?) will persist for a few more days unfortunately. In fact, tomorrow through Thursday will be even warmer than today. Thursday will likely be the toastiest day this week…getting about as warm as it can get in December. Skies will definitely be bluebird on Monday, and for Tues-Thurs, there should be a reasonable amount of sun, although some weak disturbances passing to our north may bring some periods of clouds. Now for the good stuff..relief from our snow drought is in sight!

I think we’ve gotten to the point (as far as model predictability goes) where I can say with reasonable certainty that we will be getting a storm late week/this coming weekend. The devil is in the details though, and here is what remains uncertain where we stand now, 5-6 days out:

-Timing: the ECMWF has the show starting much later and ending earlier than the GFS. This affects snowfall totals greatly; you need a long duration storm for lots of snow.

-Where the best large-scale rising motion will be: if it doesn’t set up over Utah, we won’t get very much snow.

-Which direction the upper-level winds will be coming from: the preferred corridor for moisture transport into Utah is through NorCal/S. Oregon…I’m a bit worried with our moisture tap coming from the southwest. The model solutions will shift around in the coming days, and if things move north (over the High Sierra Nevada), we could miss out on the Grade A pacific moisture.

-Temperatures: right now the temperature trend during the storm looks great (starting warm, ending cold), but the model soutions will shift around as I mentioned, so we’ll keep an eye on this.

So all we can say is that a storm is very likely; we’ll let you know as soon as the details and strength of this storm come into focus.

Same ole Same ole

It looks like we’ll continue with warm and dry conditions through mid-week, unfortunately (although this is perfect biking weather…gotta find some good with the bad). The models are continuing to depict a strong trough impacting our area late next week, but run to run consistency has been lacking. Significant timing and amplitude differences exist between the GFS, EURO, and ensembles, however, at least all the models are showing some kind of trough by next weekend. As good as things were a couple weeks ago, this latest drought (As Matt mentioned) has now pulled us behind in snowfall totals :(. It’s still VERY early in the season, though, so things can change. In the meantime, enjoy this pleasant weather and shred some groomers!


Warm and Dry

Well, the prognosis is still not good for snow in Utah over the next 5 days.  Some flurries are possible Saturday, and thats about it.  The one silver lining to all the warm weather and clouds has been that weak layers in the backcountry are healing.  Other than that, though, I can’t think of much good that is coming from this pattern.  

It doesn’t really feel like it, but we are only slightly behind average for snow in the higher elevations of the Wasatch right now.  Most stations are 75-90% of their normal snowpack water content.  Up by Logan they are above average.  If you want a deep snowpack you can drive to Jackson though. They have been doing fairly well the last couple weeks, with 50% more season snowfall than the Cottonwoods.

In long range model dreamland there is a good, wet trough making its way into Utah on Thursday next week in the deterministic 12Z GFS.  Who knows if it will happen.  We can hope..