A Much-Needed Soaking

The past 48 hours have been a much-needed soaking for our parched mountains. Unfortunately that soaking came primarily in the form of rain for elevations below 8,000 ft. Cooler air has been working in and snow levels have been dropping throughout the day, but the precipitation is wrapping up and should be finished by this evening. So probably a net loss of snow and snow-water-equivalent (SWE) in the lower and middle elevation snowpack , but a huge boost up high. Some (approximate) totals from high elevation sites:

Alta-Collins: 15″ Snow, 1.8″ SWE
Snowbasin-Boardwalk, 5″ Snow, 1.5″ SWE (some rain likely)
Timpanogos Divide SNOTEL: 2″ SWE
Snowbird SNOTEL: 2″ SWE
Ben Lomond Peak SNOTEL: 3.6″ SWE
Powder Mountain: 1.1″ SWE
Brighton Crest: 18″ Snow
Brighton SNOTEL: 1.5″ SWE

Above the snow line, it looks like there are some nice creamy turns to be had, and things are filling in nicely:

 

Short Term Forecast
The next storm is following hot on the heels, but unfortunately it doesn’t look to be a major snowmaker. Expect a brief lull tomorrow (Thursday) with some lingering clouds, and then snow showers beginning tomorrow afternoon/evening up along the border in the far northern Wasatch/Bear River Range. These showers will intensify and spread down to the central and southern Wasatch briefly Friday morning, before tapering off later Friday. I’d say 3-6″ up near the border (Beaver Mountain), with 1-3″ in the central Wasatch/SLC/Park City resorts.

ECMWF model forecast
Precip forecast from the Euro model for Thursday AM thru Friday AM
GFS model forecast
Precip forecast from the GFS model for Thursday AM thru Friday AM

 

Long Term
A ridge builds in over the weekend and looks to last into the early part of next week. This means sunshine and warm temps. Enjoy!

Quick Update

As expected, snow levels have remained very high so far.  Accumulating snow has been generally confined to 8.5k+ ft.  Where is has been snowing, most resorts are reporting anywhere for 4-7 inches of dense, pasty snow.

Tonight the cold front associated with the storm will swing through.  It’ll be accompanied by a band of moderate to heavy precipitation and dropping snow levels.  The precip should taper off around 10-11AM.  Additional accumulations of 6-12 inches above 8k ft and 4-8 inches from 6-8k ft are expected.  The simulated radar output below depicts the cold front moving in from the NW and the associated band of precipitation:

hrrr_2018011002_ref_slc

Adding this much water to an unstable snowpack will likely lead to dangerous avalanche conditions. Be safe and enjoy the fresh snow!

Finally, A Legit Storm

A storm will make its way across Utah over the next couple days, dumping significant snow over the high terrain.

Precipitation will break out tonight over most of Utah out ahead of the system. The precip will be accompanied by southwest winds, which will work to pump mild air into the region. Therefore, snow levels will be fairly high for the first half of the storm. We expect them to remain around 8k ft through Tuesday night, meaning that resorts with lower elevation base areas (PCMR, Deer Valley, Snowbasin) will receive rain at the bottom. The HRRR animation below depicts two periods of pre-frontal precipitation:  one overnight and then another during the day tomorrow.

hrrr_2018010902_ref_slc

The cold front associated with the storm system will swing through Tuesday night, dropping snow levels to the valley floor.  We expect precipitation to continue until midday Wednesday in the moist, northwesterly postfrontal flow.  For totals, I expect a general 1-2ft above 8k ft and 6-12 in from 6-8k ft across the entire Wasatch.  The Upper Cottonwoods should do well because of their high elevation and favorable orientation for northwest flows.  If anyone gets 2ft, it’ll likely be them.

The NAM-12km meteogram for the Upper Cottonwoods shows the full evolution of the storm:

NAMMG_ALTA2018010818F084

Most SREF members produce between 1.5 and 3 inches of precipitation, giving us confidence in this forecast.SREFPL_CLN2018010821F087

Long Range:
Behind this system we expect a weak secondary trough to brush northern Utah on Friday and then high pressure takes over until the middle of next week.  Things start to get exciting around Wednesday, the 17th. That pattern change we’ve been talking about is looking good.

eps_m_z500a_noram_25

On Deck: Winter

It was a gorgeous Sunday for the Wasatch with sunny skies and some freshies at some resorts! The following time lapse from Snowbird’s Hidden Peak shows some beautiful clouds throughout the day – starting with low clouds rolling over the Oquirrhs, then fog and low clouds burning off across the Salt Lake Valley, a few clouds forming on the southern side of the Broads Fork Twin Peaks, then fog creeping southward across the Salt Lake Valley nearing sunset.

Hidden Peak time lapse of January 7, 2018. (http://prismcam.com/demos/snowbird-peaks/)

While today was sunny and beautiful, we will start our transition into a much needed wetter week on Monday. High clouds have already started moving into the area (visible in the last few seconds of daylight on the time lapse), and clouds will continue to increase throughout the day on Monday.

While models have not come to complete agreement on the exact details of the snowfall potential this week, confidence is high that we will see accumulating snows in the mountains. Let’s look at the time-height section for the most recent run of the NAM and point out a few features:

Jan 8, 2017 00Z NAM 12 km time-height section from weather.utah.edu
Jan 8, 2017 00Z NAM 12 km time-height section from weather.utah.edu

First, notice the large area of green shading (moisture!) for the next several days in the area. Also take a look at the blue freezing level line and the wind barbs. Then, check out around 12Z Wednesday – looks like a decent cold front to me!

With decent moist SW flow near mountain height, it’s looking like we will see precipitation in the mountains beginning late in the day Monday. However, with the freezing level being fairly elevated, those resorts favored with SW flow (Snowbasin, Sundance) may have more rain than snow at mountain base due to their low elevations (say, compared to Alta). Nevertheless, much needed precipitation will be happening Monday night into Wednesday morning. We can expect a wet (read: rainy) beginning of the week in the valleys and the lower elevation resorts while upper elevations should be getting some decent snow.

At this time, Wednesday morning’s cold front looks to be strong enough to drop snow levels to valley floors. During this frontal passage we can expect snowfall rates to increase in the mountains, and this will likely be a period of heavy snows for a good portion of N. Utah. Then, a switch to more NW flow with a moist column sticking around through Wednesday should keep snow going, especially in the mountains.

I’m going to hold off to let Monday and Tuesday Utah Ski Weather forecasters hone in on more of the details (including expected snow totals) as more model runs come out, but I’ll leave this recent plume for Alta-Collins here!

NAEFS plumes for Alta Collins (from weather.utah.edu)
NAEFS plumes for Alta Collins (from weather.utah.edu)

So this might FINALLY be the week to get out those powder skis. A friendly reminder to be safe both in-bounds and out-of-bounds this week as avalanche danger is sure to increase. Check out the Utah Avalanche Center (https://utahavalanchecenter.org/) before you go and keep up whatever method you do to solicit snowfall in the Wasatch!

An Active Week for Snow-lovers

TLDR:

First, I wrap up Saturday with some storm statistics. Next, we have at least two promising systems headed our way: a weak blast Monday night and a two-punch of snowstorms Wednesday. To end, there are some signs that more active weather will follow.

The Wrap-Up:

Snow is in the forecast–again–and we wrap up a day of fresh powder, albeit one with relatively moderate amounts. To sum it up…

  • Park City resorts saw 1.5-2 inches mid slope
  • Cottonwoods took 3-4 inches on mid-upper slopes
  • Snowbasin and other north Wasatch resorts outdid many forecasts with up to 6 inches of fresh pow since 10AM Saturday

With that, here are snapshots of active skiers at a couple of the resorts today:

Another snapshot, taken via Alta's Sunnyside Mtn webcam (courtesy media.alta.com)
Another snapshot, taken via Alta’s Sunnyside Mtn webcam (courtesy media.alta.com)

The Sunday Ski:

Currently, the day’s storm is moving to our east as a tongue of drier air enters the area. See below’s GOES East water vapor imagery taken earlier this evening:

GOES East Water Vapor Imagery taken at 5:30 PM MT this evening. Note pockets of dry air (dark blue and orange) building over northwest Utah and central Nevada (courtesy weather.cod.edu)
GOES East Water Vapor Imagery taken at 5:30 PM MT this evening. Note pockets of dry air (dark blue and orange) building over northwest Utah and central Nevada (courtesy weather.cod.edu)

In addition, this drier air accompanies a high pressure system, which holds place as an early week system approaches from the southwest (more on that in the next section). Think blue skies for your Sunday ski.

ECMWF relative humidity valid at 9AM MT Monday. Note dry air (orange) arching across the central intermountain west (courtesy weather.us)
ECMWF relative humidity valid at 9PM MT Sunday. Note dry air (orange) arching across the central intermountain west and accompanying a short-lived high pressure system (courtesy weather.us)

The Short-Range Forecast:

There are a few promising systems in the short-range forecast, thanks to a deep trough (a lot to ask for this season!) pushing through mid-week. To explain, I’ve separated what I think is each potential storm and numbered them in the order they pass this week:

  1. Weak pre-trough shortwave: Timing and strength – late Monday night, a quick blast with little precip according to the GFS model. In addition, the European model predicts a later timing and a bit stronger blast. (medium confidence)
  2. Strong Low centered far to our south: Timing and strength – late Tuesday night through Wednesday early evening, a stronger system than the first. Furthermore, the Euro forecasts an earlier passage with more widespread and long-lasting precip. (medium confidence)
    • GFS 500 mbar Relative Vorticity (shaded) valid at 11PM MT Tuesday (courtesy tropicaltidbits.com)
      GFS 500 mbar Relative Vorticity (shaded) valid at 5AM MT Wednesday. Note deep trough south of UT associated with system (2) (courtesy tropicaltidbits.com)
  3. Moderate post-trough shortwave: Timing and strength – Wednesday early to late evening. Another blast but stronger than storm (1). Also, the GFS prefers (3) over (2) as our larger-accumulating storm. (medium confidence)
    • GFS Relative Vorticity (shaded) valid at 5PM MT Wednesday. The strong trough is associated with the strong comma-shaped vorticity signature centered over southern Kansas. System (3) is related to the strong vorticity signature stretched just west of SLC (courtesy tropicaltidbits.com)
      GFS 500 mbar Relative Vorticity (shaded) valid at 11PM MT Wednesday. System (2) is associated with the strong comma-shaped vorticity signature centered over southern Kansas in the figure. System (3) is related to the strong vorticity signature stretched just west of SLC (courtesy tropicaltidbits.com)
  4. Shortwave to pass north of UT: Just a quick mention in order to be complete. Models show a weak system passing well to our north Friday morning through the afternoon. If it does occur, the storm will be influenced by:
    • how deep our trough (2) digs south in the Midwest, and
    • the strength and position of the high pressure system centered near Baja California.

In short, stay tuned for more details on this storm in the days ahead. (low confidence)

The “Active” Horizon:

From a synoptic (broad-scale) perspective, we might see a next wave push through early the week of the 14th. However, models are tricky creatures and it needs to be said that innumerable factors are in play to form the weather pattern we see 9 days ahead. Therefore, take this and other mid- to long-range outlooks with a grain of salt.

Until then there should be some good skiing this week to keep busy. Get on it! And send us your best pics.

Happy skiing y’all.

-marcel

 

Better than Nothing

There’s a storm coming tomorrow. It’s a storm in the same vein as the others we have gotten this season (a.k.a., not a pattern change). The action begins overnight with increasing cloudiness across northern Utah. Snow should start falling mid-morning in the highest mountains and slowly expand to lower elevations. The winds will be out of the southwest for most of the day and switch to northwest in the evening. As such, areas that are favored in southwest flow will have an advantage in this storm (northern Wasatch, looking at you). Precipitation will taper off after nightfall.

As Alex mentioned yesterday, there won’t be a strong cold front associated with this, so the mountains should do much better than the valleys. Winds aloft will be relatively weak, so it will be nice to experience the snow as it’s falling (though how the roads perform is a wildcard). Exactly how much snow falls is still up for grabs. This ensemble of simulations shows a wide range in the Upper Cottonwoods, with anywhere from 0.7″ of SWE to nothing.

Via weather.utah.edu
Via weather.utah.edu

Temperatures aloft will be on the warm side, so snow ratios will be suboptimal. But the weak winds will work to our benefit and keep more crystals intact on their way to Earth. I’m going with 2-5″ in the Cottonwoods and northern Wasatch with 1-3″ other mountain locations. The Wasatch Front will be lucky if a few flakes fix in towards the end of the storm. In most other seasons this storm would be just a refresher and not get that much attention, but this has been a winter of bad luck.

While this storm represents a continuation of the current pattern, a system unlike anything we’ve seen this winter is on the way for the middle of next week. If we’re lucky the desert southwest will have its first rain of the season, and northern Utah might have several days of precipitation. Whether it will be a pattern changer or just an anomaly before more weeks of sameness is yet to be nailed down, but I’m keeping my hopes up.

Storm Arrives Saturday Afternoon

As Mike alluded to in the previous post, a storm will impact Utah Saturday afternoon through Sunday morning.   Friday will be a warm day across mountain resorts.  Mostly sunny skies are expected with freezing levels close to 10,000′.   Crest level temperatures will begin to cool Saturday morning with light snow showers expected through the afternoon.  The bulk of the snowfall will occur overnight Saturday into Sunday morning.

Today’s simulations have been trending drier.  The storm system is splitting further upstream of Utah.  The storm losses organization as it enters Utah, leading to lower snowfall totals than what the models where showing 24 hours ago.

ecmwf_tsnow_KU_slc_15
ECMWF total snowfall accumulation through Sunday afternoon.

With that being said, there is still considerable uncertainty with snowfall totals.  For the Upper Cottonwoods, ensemble members are generating anywhere from a few inches to 15″ of snow.  Therefore, I suspect model runs will to wobble back and forth between drier and wetter solutions during the next 18-24 hours.

NAEFSPL_CLN2018010412F168
Ensemble plumes from NAEFS showing the snowfall uncertainty with the upcoming weekend storm. Courtesy of weather.utah.edu

Bottom Line

The lack of a defined cold front will favor orographic (mountain generated) snowfall.  This storm will likely be a “cloud storm” for most valley locations.   Northern Wasatch resorts will see the most action during the southwesterly flow component of the storm Sunday afternoon through the early evening.   Resorts favored by northwest flow will see the majority of snowfall occur later Sunday night into Monday morning.

Forecast

  • 4-8″ in the Upper Cottonwoods
  • 2-5″ for Park City side, Snowbasin, Powder Mountain, and Beaver Mountain.

Extended Forecast

Models are hinting at the potential for another storm system impacting Utah Wednesday and Thursday next week.

eps_z500a_noram_25

500 mb geopotential heights from the ECWMF ensemble. Blue shading over Utah represents the possibility of a storm impacting Utah Wednesday next week.

Hope!

Well, at this point I’ll pray to just about anyone or do just about anything to appease the snow gods. We’ve washed our cars, we’ve burned our skis… Perhaps we should try and use the force…? The good news is at least there’s *something* on the way to break up the monotony of warm sunny days in the mountains.

Help us Obi Wan... You're our only hope... Make it snow!
Help us Obi Wan… You’re our only hope… Use the Force and make it snow!

We (and the snowpack) will have to suffer through a few more warm days before getting some redemption this weekend. Snow showers are likely to start to spread across the high terrain Saturday morning as moisture moves into the region, with a little bit of dynamical support and instability moving through late on Saturday. At the moment the trough looks to weaken as it comes onshore and continues to do so as it pulls north and away. This means we’re looking at a pretty quick hitting event with yet again fairly limited moisture. Nothing like the deep tropical taps we saw last year.

GFS Time-Height Section showing moist air (greens) moving into the region Saturday. Cooler, but not all that cold, temps will follow, allowing snow levels to fall along with lighter snow densities at elevation.
GFS Time-Height Section showing moist air (greens) moving into the region Saturday. Cooler, but not all that cold, temps will follow, allowing snow levels to fall along with lighter snow densities at elevation.

In short, expect flurries early Saturday with limited accumulations all day, with intensity increasing and snow level falling into the late evening. Most of the snow will fall overnight towards midnight and the early morning hours, with the chance for some accumulation of snow on the benches and little if any on the valley floor. Snow should be wrapped up by mid-morning Sunday. Snow totals are expected to be around 5-10″ for the Cottonwoods above 8200′ and 2-6″ for the Park City side and Ogden area mountains.

Deterministic GFS snow totals through Sunday.
Deterministic GFS snow totals through Sunday.
Ensemble plumes indicating the significant spread remaining as the event is still 3-4 days out. Should the system weaken faster than expected or pull further north, expect snow totals to drop. Hints at a second storm late in the coming work week.
Ensemble plumes indicating the significant spread remaining as the event is still 3-4 days out. Should the system weaken faster than expected or pull further north, expect snow totals to drop. Hints at a second storm late in the coming work week.

Looking further the models hint at bringing another system into the region late in the coming work week but — as I’m sure you’ve all learned by now, we won’t hold our breath or put any value on a long-range forecast just yet.

In all, Sunday should be a great ski day out there and I hope you all get to enjoy it (I know I will)!

Here’s to 2018

Because I think all us skiers would like to leave the beginning of this season in the dust.  The first month of the 2017-2018 has been underwhelming to say the least, with current snow water equivalent values far below normal for this time of year. The Wasatch has accumulated only half to two-thirds of this typical SWE measured on the last day of the year.  We gotta be better, people.

Utah Snow Water Equivalent, percentage of normal. via wcc.nrcs.usda.gov
Utah Snow Water Equivalent, percentage of normal. via wcc.nrcs.usda.gov

As mentioned by Lucas and Tom, the first week of 2018 appears to continue this depressing trend of menial precipitation. According to the Ensemble Situational Awareness Table produced by NOAA, the NAEFS has a ridge building in, with 500 mb heights 1-2 standard deviations higher than normal for this time of year.  Translation: No precip and possible deterioration of air quality.

NAEFS mean 500 mb heights valid Tuesday night (6Z Wednesday) via http://ssd.wrh.noaa.gov/satable/
NAEFS mean 500 mb heights valid Tuesday night (6Z Wednesday) via http://ssd.wrh.noaa.gov/satable/

In the mean time, I hope you all have a wonderful last day of 2017! Lets hope 2018 brings us more powder days.

Positive Signs in the Long Range

As Lucas pointed out, the next week looks mild and dry.  The total precipitation forecast from today’s 12Z GFS run depicts a bleak and unfortunately all too common picture – no appreciable precipitation over about the next 7 days.

gfs_tprecip_west2_27

Long Range:
Beyond the day 7 period models are beginning to indicate a return to more active weather. The GFS Ensemble system (GEFS) forecasts a high probability of negative pressure anomalies over the state during the 1-2 week period.

gefs_slp_stdev_noram_41

The Climate Prediction Center is also onboard.  They’re forecasting a high chance of wetter (and unfortunately warmer) than normal weather during the 8-14 day period.

 

814prcp.new

814temp.new

Enjoy the bluebird days and stay tuned.