Sunny Sunday

Today was a lovely day to get out for a hike and check out the new snow, if nothing else. The Albion Basin trailhead parking was bustling today with intrepid skiers heading up towards Grizzly Gulch to make a few turns on the little bit of new snow that fell at the beginning of the weekend. Remember, most resorts are now closed to uphill access so they may prep for the season. Brighton has a few access routes but remember to check with the resorts and observe all signage before heading onto ‘inbounds’ terrain and this time of year treat all terrain just like the backcountry.

Just a brief shot of precipitation on the NAM-12km simulated radar. Just one three-hour frame.

Looking ahead to Monday’s weak precipitation event, it seems like the models fire up a brief period of snowfall for the mountains as a weak wave of instability rolls through the larger-scale ridge that has established itself over the southwest. A so-called ‘dirty ridge’ generally leads to a period of cloud cover and extremely limited precipitation amounts. The NAM 12km has just over a dusting to an inch along the central Wasatch, with perhaps 2″ or so for the northern Wasatch. The bulk of what falls will happen on Monday afternoon.

Just a dusting expected around here. Want more? Head north – the bullseye continues to sit over the Jackson area.

Ridging follows into the coming week, with borderline temps up high (To be honest- I’ve got to agree with Trey here, it’s not looking good for the target dates). Keep your fingers crossed that at the least snowmakers have temperatures conducive to putting down some of that man-made white gold so we can get back to sliding on snow sooner than later!

What does the future hold?

Storm totals:

Alta Collins: 15 inches

Brighton Crest: 17 inches

Snowbasin: 12 inches

Tony Grove: 15 inches

Despite the Wasatch not having much in the way of a moist northwesterly flow behind the cold front, most locations still did very well with this storm. The high moisture content of the pre-frontal and frontal precipitation periods made up for the slightly less favorable post-frontal period.

University of Utah students monitoring the storm from Antelope Island using the DOW7 (Doppler On Wheels)
University of Utah students monitoring the storm from Antelope Island using the DOW7 (Doppler On Wheels)

Forecast

Unfortunately, it’s not all good news – at least the near term forecast looks relatively quiet. The storm track will move farther north once again, which means the Tetons, Sawtooths, and Pacific NW will continue to reap most of the benefits. If you want to do any skiing the next couple weeks, I’d suggest taking a trip north. Many locations up there are already well above average in terms of snowpack. On the other hand, it looks like another slow starting ski season for us.  A very weak short wave trough will clip Northern Utah on Monday, but I’m not expecting more than maybe an inch or 2 at most.

"Death ridge" over the Western U.S. next week
“Death ridge” over the Western U.S. next week

Following this weak disturbance, ridging will quickly build across the West. This means relatively clear weather and warming conditions. Because we’re already well into November (low sun angle and solar radiation), I also think valley locations could become inverted. This is a double edged sword – not only are we remaining dry, but also temperatures in the mountains will be too warm for snow making. I hate to be the bearer of bad news, but right now I’d anticipate any opening dates scheduled for next weekend to be moved back (obviously this is resort dependent).

Storm Update and Forecast

The storm system that began to impact the region is finally starting to shut down.  The cold front associated with the storm system swept through this morning and brought with it crashing temperatures and heavy snowfall, as we expected.  Totals have been adding up fast in the mountains.  Here are a few reports as of 2:30PM MST:

Alta: 11″
Snowbird: 10″
Powder Mountain: 8″

With the cold, moist northwesterly flow expected to continue for a few more hours, I expect an additional few inches in the Upper Cottonwoods. Below is a screenshot from the MTX doppler radar valid for 2PM MST.  It nicely shows the area of orographic enhancement to the southeast of SLC, over the Cottonwoods.Screenshot 2017-11-17 14.18.43

The webcams near the base of Alta near this time show that it was in fact nuking:

mtspcam

The Forecast:
The weather will remain quiet through the weekend.  On Monday and Tuesday we expect a small system to make its way through the region and bring a few inches of snow to the mountains.  After that, its looking like we ridge up through Thanksgiving.  There are some signs in the long range models that we return to an active weather  pattern in about 10 days, so keep your fingers crossed.

The First of Many

Hey there fellow snow lovers and winter mountain sport enthusiasts!
Glad you stopped by for this year’s edition of Utah Ski Weather. As Tom mentioned, we will be here every day of the ski season bringing you the most up-to-date weather to help you plan your adventures and when to use a perfectly timed “sick day”.  Without further ado, lets get right to the forecast.

The Set-Up:
Last night southerly winds kept the boundary layer well-mixed, and temperatures remained mild thanks to a mid-level cloud deck which mitigated the typical radiational cooling we experience on a clear, calm night. This morning and afternoon, these strong southerly winds have persisted. This wind pattern is typical of a pre-frontal environment.  Soon we will see a change as the deepest trough of the season will move through by mid-day Friday.

Currently, the precipitation is falling to our north and west, colocated with the region of strongest baroclinicity (temperature gradient). Surface observations show that winds have already shifted to north-northwesterly near Boise, giving a preview of whats to come for the Wasatch.

Current radar image from weather.gov
Current radar image from weather.gov

This trough is not lacking moisture – the Sierra Nevadas have already seen 5″(!!) of liquid near Squaw Valley.. Not to mention winds absolutely ripping, with gusts exceeding 100 mph.  Unfortunately, the current environment does not favor strengthening of the system as it progresses eastward, but considering it is mid-November, I don’t think we will be complaining about any snow that falls.

The Forecast:
The precipitation associated with this frontal passage (FROPA for you weather weenies) will be both the pre-frontal and post-frontal variety.   And to make matters worse, the models are closing in on a solution where there will be two distinct bands of heavy precipitation, one centered over the central Wasatch/Cottonwoods, and the other near the UT/ID border.

The precipitation will begin to fall this evening as rain in the valley and bases of the mountains, with freezing levels hovering near crest-level.I am hesitant to even mention this, but there is also a SLIM chance for some lake-enhanced showers this evening.. In other words, don’t get too excited about that component.  Overnight, the precipitation will intensify through the early morning hours with snow levels dropping down to the benches. This burst of precip will still be pre-frontal and has the potential for scattered convection given some forecasted mid-level instability. Expect locations like Brighton to do especially well in this set-up. The FROPA should arrive by 10-11 am tomorrow, with winds shifting to the northwest and freezing levels reaching the valley floor.

Time-Height cross-section at KSLC showing theta-e (K) lines and shaded relative humidity (%). Time progresses to the left. Courtesy of weather.utah.edu
12 Z NAM KSLC Time-Height cross-section. Black contours show constant lines of theta-e (K) and shaded contours are relative humidity (%). Time progresses to the left. Courtesy of weather.utah.edu

Precipitation will persist in the mountains through around midnight and could be orographically enhanced by the northwest flow being lifted by the terrain.  Any moisture that can be squeezed out in the overnight hours into Saturday A.M. will be considered bonus.  On Saturday subsidence will dominate, shunting off any moisture and dynamics that would produce exciting weather.

The Bottom Line:
While this is the first of many storms, we are especially excited for what base might begin to be built.  This is a tricky forecast since we are dealing with a mixed bag of pre-/post-frontal and possible lake-effect precipitation, not to mention the placement of the north and south bands of heavy precip could throw a forecast out the window in a hot minute. Total liquid water content is forecasted to be anywhere between 1.5″ (ECMWF 12Z) and 3.5″ (GFS 18Z – Sorry to burst your bubble, but this won’t happen).  I like Tom’s forecast, but I am feeling a bit more optimistic, so I’m going to up the ante to 10-18″ for the Upper Cottonwoods resorts given the persistent, deep moisture available through tomorrow evening.  I am feeling less certain about the east side of the Wasatch, so I am going to say 7-13″ at PCMR from precipitation of the pre-frontal and spillover varieties.

If this is a sign of things to come, you’re in for a long season of fun storms and busted forecasts.

Enjoy!

Hype is Building

Welcome back skiers (and boarders)!  After a long, hot summer and dry fall, we’re back in action here at Utah Ski Weather.  For those of you who aren’t familiar with this site, we’re a group of graduate students in the Atmospheric Sciences program at the University of Utah with a passion for snow, skiing, and mountains.  We’ll be posting a forecast blog every single day of the ski season.  Be sure to follow us on Twitter (@utahskiweather?) and Instagram (utahskiweather) for updates throughout the season.

Now on to the impending storm.  Tomorrow will be mild with strong south-westerly winds ahead of the cold front.  Initially, when precipitation breaks out around midday, snow levels will be very high, ~8k to 9k feet.  Precipitation will continue on and off throughout the day and night across the region before the cold front sweeps through early Friday morning.  We expect a period of heavy precipitation to be associated with the cold front.  Snow levels will drop to the valley floor as we transition into the post-frontal northwesterly flow on Friday.  The gif below depicts the storm’s evolution nicely:

18Z GFS forecast.
00Z GFS forecast.

For totals, I expect a general 8-14″ above 8k feet in the northern and central Wasatch.  Higher totals are possible in the Cottonwoods, where I wouldn’t be surprised to see a report of 18″.  Below is the the forecast from the high-resolution NAM-3km for the Upper Cottonwoods:NAMMG_ALTA2017111518F060

Keep in mind that this model tends to overdo precipitation.  Some of the research we’ve performed here at the U has shown that it often forecasts 2x the amount of precipitation that is observed.

A considerable amount of uncertainty exists beyond this system.  Let’s hope that mother nature corporates and provides us with some early season pow.

Thanks for a Great Season

With the usual rowdy send-off, Alta shut down the lifts on Sunday, and once Brighton closes this coming Sunday, Snowbird will be the only resort still open in Utah. While they will probably stay open through at least the end of May, we are hanging up our forecasting hats for the season.

It was a pretty awesome one, despite an extremely warm February and record warm March. The savior for us was the fact that precipitation was well above normal…one of the wettest in recent memory at many sites. This should mean that the high elevation snowpack will last for quite a while for those that like their summer skiing. Thanks for visiting our site, and we look forward to seeing you again when the snow starts flying in the fall!

-Peter

One Last Storm?

Yesterday’s storm ended up being a disappointment for the mountains. We weren’t expecting anything much, but I know I was holding out hope for a shower or two up in the mountains. Alas, all we got was some dust on the snow. The frontal passage in the valley dropped temperatures by 20°F, and the temperature difference was still strong in the mountains with Alta-Collins seeing a 13°F cool-down in one hour. And high temperatures today were much cooler than they were for the last few days–the first day since Sunday that we didn’t break 32°F.

We have one more day that won’t break the melting point in the mountains (at least in shady spots–the sun is intense), and then we’re back to spring temperatures. By Sunday mountaintop temperatures will be flirting with 40°F, though the 50s will hold off for a while. We have another storm on the docket, though details are still a few days away.Screenshot_20170414_210853

The spread on this ensemble highlights how there is a general concord on timing with a storm arriving Tuesday afternoon. However there is no consensus with precipitation amounts, and small changes in how the atmosphere evolves will lead to diverging storm totals. Another thing that’s up in the air (pun not intended) is the temperature of the storm. While most guidance leans towards a very high snow level at least for the first few hours of the storm, I can’t rule out something colder and snowier.

Springtime Lull

With temperatures steadily increasing in the valley this week, it’s feeling solidly like spring (even summer, for those of us from cooler climates!). The next few days should bring some fairly dynamic conditions, with a weakening trough approaching from the west.

GFS 500 mb Height Field Thursday into Friday
GFS 500 mb Height Field Late Thursday showing mid-level SW flow and the approaching trough

At first glance, it seems like this might be a trough that delivers a decent snowfall, but a closer look at the models show energy dissipating as the trough moves inland, with little moisture associated with it in the first place. We can expect temperatures at elevation to climb into the 50s for Thursday on the warm southwesterly flow as winds increase, especially at mid-elevations. Clouds will increase throughout the day with what moisture and lift is available, with the potential for mixed rain/snow showers overnight into Friday.

NAM Time-Height, noting the passage of a shallow front early Friday.
NAM Time-Height, noting the passage of a shallow front early Friday.

There’s some decent mid-level instability overnight into Friday morning that could produce periods of heavier snow showers in the upper Cottonwoods and high on the Park City ridgeline, though that support will be short lived. If snow showers continue into late Friday and Friday night, they will likely be light and sporadic. I’d say it’d be reasonable to expect 1-3″ at upper elevations with a trace to 2″ at mid and lower elevations. Being spring, surprises can happen, but the models have been indicating this system weakening for a few cycles now.

Back to April

Oh what a day it was on Sunday…I had one of my best powder days of the season, and I heard many other skiers saying the same. Some bold claims were made:

 

Unfortunately, after our brief blast of January conditions, the April weather is coming back. We will get brushed by a storm Tuesday, which will bring us mainly just some clouds. Wednesday looks to be beautiful, sunny, and warm, with above average temperatures…definitely the best day to get outside this week.

 

Screen Shot 2017-04-11 at 4.20.39 PM
The GFS model forecast for Wednesday…big ridge of high pressure with blue skies and warm temperatures.

Clouds will begin to increase late Thursday as our next storm moves in on Thursday night, which does not look overly impressive. It should be good for some snow in the mountains and a cool-down, but probably not a powder day. The storm looks to exit the area early Friday, and the temps begin to warm up again.

Beyond that, the next potential for precip could be early next week, but confidence is low on that. Most of the remaining open ski areas in the Wasatch will have their closing days on Sunday, so make sure to get on it! Snowbird, as usual, will likely be open through at least Memorial Day.

Wet and Wild

I woke up this morning with a view of snow on Mount Van Cott. Overnight snow levels must have dropped to ~6000′ with the heavy showers that affected northern Utah in the early morning hours. While a lot of water fell from the sky this morning, not all that much snow made it. The coating on Van Cott was gone nearly as soon as the sun came out, and Alta only had ~4″ of snow from the nearly three-quarters of an inch of water.

This weekend we get more than one shot at good snow, however. First was this morning, and then there were the thunderstorms this afternoon. Next is a broad area of moderate precipitation moving in from the west. This radar clip is the very image of hope. There is a lot of moisture downstream, so if all goes well the Cottonwoods will get a good soaking tonight. And, since snow levels are at 7700′ feet right now (and are only going to drop further), most of the incoming precipitation will be snow.Screenshot_20170408_190320

As far as amounts go tonight, the consensus forecast for tonight through tomorrow morning is for around an inch of water. With mountaintop temperatures being what they are, ratios aren’t going to be the best, but they’ll be pretty good for mid-April. The high elevations in the Cottonwoods can look forward to 8-12″ of snow through the end of the day Sunday, while lower spots will have to make do with 4-8″. This is exactly the sort of refresher we needed to cap off the spring.

SREFPL_CLN2017040815F087
An ensemble of probabilities for tonight at Alta-Collins in SWE