Utah Ski Weather

It has been a good week for the mountains for sure. There were a few smaller storms and a few bigger ones, and the holiday weekend has seen mostly fair weather with some showers adding a few inches to the total. Alta-Collins has made it up to whopping 134″ of depth. That’s 11 feet and 2 inches or 3.4 meters.

For a while now we’ve been able to see a big storm on the horizon to look forward to. Right now that isn’t the case. There are hints of something next Monday, but that’s far away and doesn’t seem all that impressive. But it’s not like we’re having an early spring. The weather pattern we’re getting into is characterized by persistent troughing. The atmosphere can be thought of as a composition of a lot of waves. Some of these waves move quickly around the Earth, others move slow as molasses, and others even go backwards. The fun weather tends to happen at the transition points between troughs and ridges of the larger waves. Have a look at how the waves will be tomorrow:

This is a representation of the waves in the atmosphere halfway up (and green shading for humidity). Notice that Utah is right in the middle of a large and deep trough. The winds are weak and the jet stream is well to our south. Troughs can be like ridges in that they can be a bit stagnant. However, they are significantly better than ridges for winter enthusiast for a few reasons. First is that we’re north of the jet stream and it’s cold. Second is that there’s a lot more (relative) humidity around. Third is that cold air above 40°N land in late February can be a recipe for popcorn showers.

These ingredients together mean that I think it’s going to be a good week. It’ll give the snowpack a chance to settle, and the clouds will keep that late February sun at bay (it’s as strong today as it is October 24th). Plus we’ll have weak showers that keep thing fresh all week long. Below is an ensemble forecast for the Cottonwoods, and it shows how we’ll get an inch or two several times this week just from pop-up showers and weak disturbances (the CMC members in this case is out to lunch and should be ignored). One of the troughs we’re under is one of the really slow ones, so it’ll be a while until we’re back into a super stormy pattern. But I’ll take this over a ridge any day.

TLDR:  More snow tonight (see totals below) with snow levels around 7500 ft but lowering. A small break on Fri with a strong cold front and mountain/valley snow Fri evening, bringing another 8-12″ by Sat morning and snow showers through Sun morning.  Read on for details.

We’ve been in warm, wet southwest flow over northern Utah today.  For some visual proof, check out the orographic (mountain induced) clouds that formed due to air rising up the southwest side of the Lone Peak area.  As an added bonus, we even got some breaking mountain waves (likely “Kelvin-Helmholtz” waves due to the presence of wind shear) over Lone Peak this morning.

For Backcountry or “Sidecountry” Users (This does not apply to inbounds at ski areas or near highways)

THE FOREST SERVICE UTAH AVALANCHE CENTER IN SALT LAKE CITY HAS ISSUED A BACKCOUNTRY AVALANCHE WARNING THROUGH 6AM FRIDAY FOR THE WASATCH, BEAR RIVER, AND WESTERN UINTA RANGE. CONSULT WWW.UTAHAVALANCHECENTER.ORG FOR MORE DETAILS

Tonight/Tomorrow:  As of 4pm temperatures are pretty warm with many mountain stations above freezing (especially those below 8,000 feet).  But, snow level corresponds to wet bulb zero (level where the wetbulb ~ 32?F/0?C) and snow levels appear to be ~7,500 feet.  Luckily, the snow level will lower through this evening as cooler air comes in.  The recent snow to this point has been dense/heavy but will also get less dense  overnight tonight.  Winds have been very strong and will continue to be strong through tomorrow evening.  Expect the following amounts (above 7,500 ft) by mid-morning tomorrow:

• Salt Lake Area 8-12″
• Pow Mow: 10-12″
• Snowbasin: 6-8″
• Sundance: 7-9″
• Beaver Mountain 4-6″

Friday Night / Weekend:  Friday will dry out a little until ~ 5pm when a cold front and associated snow (mountain/valley) will arrive.  Expect periods of heavy snow (and strong winds) Friday evening with an additional 8-12” falling across northern UT mountains from the cold front passage until resort openings on Sat.  Scattered snow showers will continue off/on Saturday with another 5-10” by mid-day Sunday.  After that we dry out with no significant chance of snow.  See below for a summary:

-Tyler

TLDR: A series of storm systems are on the way with A LOT of snow forecasted for the mountains. A winter storm is currently impacting the state of Utah with heavy, wet mountain snow and valley rain. A cold front will barrel through Friday with heavy snowfall rates during the evening, and snow showers will linger for a few days afterward. By Sunday, the mountains should be measuring snowfall in FEET rather than inches.

 Avalanche Danger and Winter Storm Warning:

First of all there is an AVALANCHE WATCH effective now through Thursday morning, at which time it is expected to transition to an AVALANCHE WARNING. There also is a Winter Storm Warning in effect from now through Friday morning at 5Am for the northern Wasatch Mountains as 1-2+ feet of snow and dangerous driving conditions are expected. Be VERY careful in the backcountry the next couple of days.

Wednesday – Thursday:

A low pressure system off the coast of California and the “coupling” of the polar and subtropical jets have brought a lot of moisture into the West and Intermountain West (see water vapor imagery below from http://weathernerds.org. Already today, we have received a fair amount of snow in the mountains. As of 4PM, Alta has reported 6″ of snow, and Brighton has reported 3″. During the remainder of this evening through Thursday we can expect heavy, wet snow to fall in the mountains, with some of the lower mountain elevations switching to a rain/snow mix at some point during the night. Keep in mind that with some near-surface cold pools in place, some regions at lower elevations may not see a transition to rain/snow at all. Nevertheless, this wet, heavy snow (along with strong, gusty winds) is the reason why avalanche danger will be high over the next couple of days.

In the early hours Thursday morning, heavy snow should taper off a little bit. However, mountain snow is unlikely to stop altogether. During the late afternoon on Thursday, though, the remnants of the closed low currently off the California coast will move through Utah as an open wave, and heavier snow showers will resume (likely around 2-4PM). This heavier activity should last through the late evening (~midnight). Through Thursday evening, we can expect the following snow totals in the higher elevations:

• Beaver Mountain: 15-20″
• Snowbasin: 15-20″
• Pow Mow: 11-16″
• Park City Area: 10-15″
• Cottonwoods: 18-23″

Friday:

During the day Friday, conditions should be cloudy but relatively calm. However, most models are showing a cold front pushing through our area Friday evening, with very heavy snow for a short period within the baroclinic zone. So, for at least an hour or two Friday evening, we might see some pretty impressive snowfall rates in the mountains (and valleys too), especially given that the airmass will be colder and allow for better snow ratios.

The Weekend and Beyond:

After the front passes, things will “dry out” a bit. However, we’ll still see plenty of mountain snow showers throughout the day on Saturday and Sunday as we will still be under the influence of a long wave trough that doesn’t seem like it wants to move anytime soon (we might be under the long wave trough through the end of the month). Through Sunday, snow totals should be VERY impressive. The GFS currently is forecasting over four feet, yes FOUR FEET of snow in the upper Cottonwoods from now to the end of the weekend! While that may be a little bit of an overzealous forecast and might need to be downscaled, this is for sure; there will be a TON of snow in the mountains over the next several days! Here’s a pretty cool look at what the deterministic GFS model is forecasting for snowfall totals over the next 72 hours (through Saturday afternoon):

One other interesting note… as of now, we are well above our median accumulated snow water equivalent (SWE) for the year in the mountains according to data from https://www.nrcs.usda.gov/. The black line below represents the current (“2019”) season, and is compared to the median, minimum and maximum SWE over a 30 year timespan.

Enjoy all the powder up there in the mountains over the next several days! More importantly, though, stay safe (especially those of you going out to the backcountry!). Check back tomorrow for more details on our upcoming storms.

-Pete

Yesterday’s cold front passage brought ample snowfall from the North-Central Wasatch all the way down to Southern Utah. Most resorts south of Ogden (sorry PowMow and Snowbasin) got 10+ inches of the good stuff, refreshing our ever-deepening base depths.  Here are some 24- and 72-hour storm totals courtesy of OnTheSnow

The recent snowfall has put our snow water equivalent values well above normal for this time of year.. A welcome change from the past few seasons, especially last year which was abysmal to say the least.

Short-Term Forecast (Monday – Thursday):

The next few days look relatively calm over the state of Utah as a ridge builds in.  We should be experiencing relatively quiescent weather through Wednesday evening, which is when our next system will be moving into the area. The plot below shows the 500 mb heights and vorticity valid Thursday (Valentine’s Day!) at noon.  Note the area of red and yellow vorticity shading over Utah, indicating a strong system.

This cold system should contain ample moisture and will result in frozen precipitation at all elevations. Timing of the frontal passage currently looks poised to move through Northern Utah around 5 pm on Wednesday evening (shown as Thursday 00 UTC on plot below).  The trough is forecasted pass to our south, which will bring strong southerly winds to the area.

NAM 12 km time-height cross section via weather.utah.edu

According to the most recent model guidance, precipitation should continue in the mountains with intermittent showers into the weekend.  While we are getting out of our range of confident forecasting, it looks good for another fantastic holiday weekend.. Here are some too-early snow and liquid precipitation forecasts from the NAEFS ensemble

More details tomorrow!

-Taylor

Today turned out to be a bit of a surprise powder day at the resorts. 8-12″ were reported in the Upper Cottonwoods. After a break in precipitation during the day, an intense front entered the region just a couple hours ago. It’s been absolutely dumping with strong winds at my place in SLC.

Snow should continue through the evening and begin to taper off during the overnight hours. Expect totals of 8-14″ with up to 18″ in the Upper Cottonwoods. Tomorrow will be another powder day. Expect early morning canyon closures before the resorts open.

We’ll have a brief break from tomorrow through Wednesday morning. The next system will being to impact Utah during the day Wednesday. The details aren’t iron out with this system yet, but it looks like another 1-2 ft + is a good bet.

There will be little rest for the weary as yet another system is looking likely for the weekend. We are in one of the better patterns in recent memory and there are no signs of it ending anytime soon. Get out and enjoy the powder and stayed tuned for details on the upcoming storms.

A weakening low pressure system currently over the Intermountain West is providing cloudy conditions over Utah’s mountains today with a bit of snowfall as well. Only up to a couple of inches of snow are forecast for today through this evening, though, as the decaying trough ejects out of our area.

In the meantime, a Winter Weather Advisory has been issued for the Wasatch Mountains from 12Pm Sunday until 4AM Monday morning. A Winter Weather advisory for snow means that periods of snow can cause difficulties traveling on roads with poor visibility. From the National Weather Service office in Salt Lake City:

As a side note, there also is a Winter Weather Advisory for the valleys (and a good portion of the state of Utah).

Sunday and Monday

It should be relatively quiet Sunday morning through the early afternoon as shortwave ridging briefly moves through. There could be a few passing snow showers, but little accumulation is expected during that time. The real fun begins on Sunday afternoon/evening as a cold front associated with an upper low moves through Utah. Between 2-4PM, heavier snow showers should develop just ahead of and along the cold front as is moves into northern and central Utah. 700 mb temperatures (seen below) will be plenty cold for precipitation to be all snow, even in the valleys.

HRRR forecast analysis shows heavy snow along a convective line associated with the baroclinic zone (area in which cold/dense air is separated from warmer/less dense air) moving through Utah.

Another look at the HRRR forecast radar without the rain/snow mask reveals relatively strong reflectivity values (>25 dBz) as the line of snow moves through. Contour lines of frontogenesis at 700 mb (crest level) show that these stronger reflectivities are associated with the cold front.

Snow showers should linger behind the low pressure system as a small warm air slowly moves through under a middle level cold pool. This instability (warm air under cold air) should allow for additional accumulations in the mountains and parts of the northern Utah valleys. So how much snow will we get? Here’s a breakdown of what we can expect as of right now through Monday evening:

• Beaver Mountain: 15-20″
• Powder Mountain: 20-25″
• Snowbasin: 16-21″
• Park City area: 10-15″
• Cottonwoods: 17-22″
• Sundance: 7-12″
• Brian Head: 8-13″

Long Range

After next Monday, things look very active still. There is a lot of model agreement on another strong winter storm with a ton of moisture arriving next Wednesday into Thursday. Furthermore, the overall pattern for the second half of February looks very favorable for storms to pass through our region as models forecast us to be in a generally trough-like pattern. See the 500 mb geopotential height and anomalies animation below showing that the West and Intermountain West will generally have troughs passing through the area for the foreseeable future.

Let’s hope we make good use of the “troughy” pattern and keep the winter storm train rolling! Check back tomorrow for an update on forecast storm totals for the storm Sunday/Monday, and we’ll keep you up to date on the potentially big storm Wednesday/Thursday.

-Pete

Sunny skies returned to northern Utah today after a chilly start to the morning. Most valley locations met high temperatures in the 30s this afternoon, while warming at higher elevations was aided by warm air advection (but not really that warm) this afternoon as southerly winds picked up. This afternoon, Mt. Baldy warmed up to 6 F compared to a temperature of -6 F about 24 hours ago. Sustained winds up at Mt. Baldy are now around 40 mph with gusts to about 60 mph as of 3pm.

The sun will not last for much longer though as more storms are moving in over the weekend. On the GOES-17 pre-operational satellite loop below, we can see the components that will bring change to our weather this weekend, as highlighted well in Marcel’s post yesterday. There is a small circulation off the coast of California as well as what will become a much larger system working westward and southward out of British Columbia. Over the next few days the former will wrap around the latter and be ejected into the Intermountain West and approach Utah on Saturday.  The larger system will follow and bring impacts to northern Utah on Sunday afternoon.

Clouds will filter in this evening and overnight, and snow should begin midday tomorrow at higher elevations. It will be cold enough to snow at all elevations tomorrow but the higher snowfall amounts will be confined to the mountains. The highest intensity of snowfall is expected in the late afternoon to early evening hours as moisture moves in.

Snow totals (Saturday noon through early Sunday morning):

• Cottonwoods: 4-8″
• Rest of Wasatch: 2-5″
• Wasatch Front : generally less than 1″

We could see a brief lull in precipitation Sunday morning between storm segments, but snow will pick back up Sunday afternoon as a cold front moves through (looking to be close to 5pm local time on Sunday). Snow will continue overnight into Monday along with cold air similar to what we have experienced the past couple of days. Storminess looks to continue through the following week or so as we make our way into another holiday weekend.

Check back with us tomorrow for a more detailed look at expected snowfall totals on Sunday and into Monday. Be safe on and off the slopes this weekend with the new snow and be aware of avalanche conditions!

-Lucas

TLDR: Some additional snow overnight but amount and location will depend on finicky lake-effect showers…but generally < 5”.  Becoming sunny late Thu-Fri but cold on Thu.  Next notable chance of snow appears to be Mon-Tue.

Storm Details:  WOW! What a great storm cycle that began late Sat and is winding down but should officially end tomorrow around noon.  Since we should get a little more snow, I’ll hold off on doing comprehensive storm totals across all Utah ski areas, but here is a quick approximation (NOTE: snow water equivalent (SWE) is generally from SNOTEL sites while snow totals either come from ski resort reports or snow accumulation equipment…so take snow totals as best guesses).

From Sat evening through this morning or afternoon:

Park City Area:        ~5″  SWE  and ~45-50″ snowfall

Little Cottonwood:  ~6″ SWE  and ~55-60″ snowfall

Big Cottonwood:     ~5.5″ SWE and ~60-65″ snowfall

Ogden Area:              ~4″ SWE and     ~35-40″ snowfall

For those who hit the slopes today, the newest snow was right-side-up and skied wonderfully (if you could get to the resorts).  Some are posting pics on our twitter feed at https://twitter.com/utahskiweather.  So how much will fall tonight?

Tonight/Tomorrow

We are in post-cold front moist northwest flow, which favors the Cottonwood (especially Little Cottonwood) Canyons in what are generally orographic (or mountain enhanced) snow showers.  We also have an environment conducive to lake-effect snow showers and have seen some lake-enhanced precipitation already today (check out our twitter feed for some radar imagery, https://twitter.com/utahskiweather )  The problem is both these phenomena are notoriously difficult to predict since weather prediction models have a hard time resolving the fine-scale meteorological processes at play.  The “rules of thumb” and other pieces are currently in-place, but those are not a guarantee.  See below for a quick look at the times, locations, and research driven probability for lake effect.  I predict another 4-6” by tomorrow at noon for the Cottonwood Canyons, and 1-3” for the Park City, Provo, and Ogden area mountains…maybe 2-4” for Snowbasin.

Next, it will be cold tonight through tomorrow with 10,000 ft temperatures getting to -20?C (below 0?F).  Getting to -20?C is pretty rare and puts us in the very cold for Utah category.  The good thing about these cold temperatures is they increase the odds for lake effect, so not all bad.

Mid / Long Range

Temperatures will warm slowly Fri and Sat with sunny skies Fri and increasing clouds Sat.  A weak storm will move through late Sat-Sun but right now totals look in the 3-6” range.  After that a storm slated for Mon-Tue looks to be a better snow producer.  More details as we get closer.

-Tyler