The Last Snow of 2017

Warmer and drier conditions have returned to Northern Utah after several days of unstable weather that brought some much needed snow. Ridgelines across the Wasatch observed temperatures up into the 30s today (sounds like a heatwave compared to where I’ve been for the holidays where it has struggled to make it out of the single digits for the last week).  If we check out the SNOTEL stations for the western United States, however, our region is still below average as many other posts have pointed out. The snowiest places compared to climatological normals so far this season are confined to northern Idaho, western Montana, and northwestern Wyoming.

Current SNOTEL snowpack observations as percentage of normal for the water year to date (since October 1st). Northern Rockies are looking great, but the Sierras, Cascades, and pretty much all of the mountains of the Desert SW are looking slim on snow.
Current SNOTEL snowpack observations as percentage of normal for the water year to date (since October 1st). Northern Rockies are looking great, but the Sierras, Cascades, and pretty much all of the mountains of the Desert SW are looking slim on snow. (https://www.wcc.nrcs.usda.gov/webmap)

Looking ahead for these last few days of 2017, there seems to be one chance of a quick storm for northern Utah. As Marcel mentioned yesterday, it’s modeled to enter our area Saturday afternoon. It’ll be quick and hardly a snowmaker for us – maybe a couple inches in the luckiest of places in the Northern Wasatch. Moisture is expected to move out of our area quickly by midday Sunday, but some dust on crust may be in store for New Years’ Eve Day.

NAM 18Z Theta-E time height section showing Saturday afternoon's shortwave that has potential to deposit up ot a couple inches for N. Utah mountatins. (weather.utah.edu)
18Z NAM Theta-E time height section showing Saturday afternoon’s shortwave that has potential to deposit up to a couple inches for N. Utah mountains. (weather.utah.edu)

Ridging and associated calm weather looks to build back into our area for the beginning of the week.  Models are hinting that ridging  may break down toward the end of next week and for next weekend but since it’s so far out we will just need to cross our fingers for another period of more active weather! Have a great weekend!

Placing our Next Bets for Powder

TLDR:
We have another ridge, but it seems to clear out by late next week. There are small chances for powder in between, but I think our best bet comes after a week of patiently waiting.


The Intro:

I heard the Wasatch slopes saw a decent powder day earlier this week, despite the above average temps and accompanying ridge—quite the opposite of what our East Coast brothers and sisters are experiencing. I have to say, it’s hard to enjoy stepping outside to subzero temps from my frozen abode in the Appalachians, where I’m currently spending the holidays.

This pattern stays put over the US for the most part this week. For Utah this means embracing the smog, escaping to the resorts, or daydreaming of better days. To get you started, here’s some powder inspiration via GOES East visible imagery courtesy @NOAASatellites.

In this post I’ll briefly comment on the next chances for powder in Utah that loom in the distance.


The Forecast:

Labeled in the figure below are three waves I think we can watch for.

For orientation, this is a polar view of the northern hemisphere, with the US at the bottom center. Shaded are 500 mbar Heights 12/30/2017 at 5AM Mountain Time. (courtesy tropicaltidbits.com)
For orientation, this is a polar view of the northern hemisphere, with the US at the bottom center. Shaded are 500 mbar Heights 12/30/2017 at 5AM Mountain Time. (courtesy tropicaltidbits.com)
  • #1 and #2: Weak back-to-back shortwaves could brush SLC area. Timeframe late Saturday – Sunday for the first, Monday – Tuesday for the second. Emphasis that these will be weak at best, maybe nothingburgers.
  • #3: Third’s a charm and our best bet for a powder day. This late-week system could drive out the ridge that dominates our area for the next several days. The key feature is an extratropical Low (highlighted in the figure below), which weakens our ridge as the third system approaches from the Aleutian Islands.
ECMWF 3-hour precip forecast 12/29/2017 11PM Mountain Time. Note the highlighted comma-shaped system
ECMWF 3-hour precipitation forecast 12/29/2017 11PM Mountain Time. Note the highlighted comma-shaped feature in the lower mid-latitudes. (courtesy weather.us)

 

Furthermore, both the Euro and GFS come to this solution on their most recent runs. Keep in mind these solutions still have a week to adjust.

Pray, dance, whatever for late next week … and happy skiing!

-marcel

Warm

It was quite warm out today. In the mountains the high temperatures today ranged from the high 30s to the mid 20s depending on elevation. There is an inversion out there (as I’m sure those of you in the valleys are acutely aware), but the inversion top is at about 5900 feet, so temperatures still decrease with height in the mountains.

24-hour high temperatures as of 5:51 PM MST. Via NWS.
24-hour high temperatures as of 5:51 PM MST. Via NWS.

This is somewhat above average, but not outrageous for northern Utah in late December. Today’s highs were somewhere around 2°F above average, with the anomaly varying with elevation. Later on this week the heat will pump up and anomalies will jump to around 10-15°F above normal.

Dec 27, 2017, GFS 2 meter temperature anomaly. Via WeatherBell.
Dec 27, 2017, GFS 2 meter temperature anomaly. Via WeatherBell.

As someone who enjoys spending time in the mountains, I think this is great. Sure, a storm would be nice, and I’d rather the snowpack weren’t being exposed to this heat, but you can be outside in it. Compare that to the midwest and northeast where record cold is making the outdoors inaccessible to those without lots of equipment and planning.

So enjoy the ability to get outside this holiday week. Go skiing or hiking or ice climbing or whatever, just watch how much you’re polluting. There will be high clouds an increasing warmth the next few days before a storm passes to our north on Saturday. The Saturday storm most likely won’t do much for us, but it will at least bring temperature in the mountains back below freezing. Enjoy the last few days of 2017!

Dry through the New Year

With resorts picking up around 1.5-2 feet from the previous few storm systems, the snow pack across the Wasatch is now sitting around 70 percent of normal for this time of the year.  Unfortunately, another upper level ridge is expected to amplify and sit over the western U.S. through the end of the work week.

eps_z500a_noram_15
500 mb geopotential height height anomaly from the ECMWF for Friday afternoon.

A few weak disturbances rotating around the ridge and dropping in from the northwest could bring a few weak showers into the mountains on Friday and Saturday, but any accumulations will be light.

Extended Outlook

Looking into the extended, there is low confidence between model ensemble members.  The European model suggests a pattern change as the upper level blocking pattern breaks down.  This would allow for a progressive pattern with a series of storm systems potentially impacting Utah during the latter half of the first week of January.

eps_z500a_noram_45
ECMWF 500 mb geopotential height anomaly for Jan 6th.

On the other hand, the GFS model suggests another scenario, with the upper level pattern persisting off the west coast of the U.S. The main point to takeaway is the model ensembles in the extended period are in disagreement and there is no clear signal in the potential storm track in the 7-10 day period.  Stay tuned for updates and hope the models trend towards an active pattern!

gefs_z500a_noram_43
GFS Ensemble 500 mb geopotential height anomaly for Jan. 6th.

Merry Christmas!

Waking up this morning to reports of 6+” of fresh snow was exactly what I needed on Christmas morning. It didn’t take long to jump out of bed and head up the canyon, full of excitement. For sure this was one of the best days of skiing we’ve had yet!

Snowbird starting to fill in!
Snowbird starting to fill in!

I’ll keep it short and sweet since there’s not a whole lot to talk about, and I’ve got a whole lot of food to get to eating after a great ski day…

A weak shortwave trough will move through the region on the 27th, though with limited moisture and no real dynamical support is unlikely to produce much in the way of measurable accumulations. Perhaps it’ll shape up differently in the next few model runs but for now I’ll focus on the good news – all the new snow we’ve had.

GFS Time-Height Diagram indicating the enhanced moisture and some instability around the 27th, though the shallow nature of the feature and weak overall support will limit accumulations, if producing any at all. Drier air and high pressure follow into the weekend.
GFS Time-Height Diagram indicating the enhanced moisture and some instability around the 27th, though the shallow nature of the feature and weak overall support will limit accumulations, if producing any at all. Drier air and high pressure follow into the weekend.

For those curious about the future and what’s next… I don’t have a ton of good news and am going to have to agree with Trey – we’re likely to ridge out under high pressure for a handful of days before the models hint at a return to a more active pattern early in January.

A Christmas Gift from Mother Nature

‘Twas the night before Christmas, when all through the house
Not a skiier was sleeping, not even their spouse;
The skis were lined by the door with care,
In hopes that a winter storm soon would be there;

The children were nestled all snug in their beds,
While visions of white dendrites danced in their heads…

Short Term

Tomorrow morning should be a fun one for those that can wait to open presents – especially since mother nature may deliver the best one of all. I see no reason to deviate much from Peter’s forecast of 5-10 inches. I think we may fall on the lower end of that range (outside of the Cottonwoods) with this storm being slightly shorter duration. Nonetheless, no complaints here with snow finally falling the past several days!

hrrr_ref_frzn_nwus_fh1-15

Long Term

Looking longer term I’m more of a grinch on this one. I’m not nearly as optimistic as the others that have posted over the past few days. I’m still not liking the overall pattern with general ridging on the West Coast and a trough over the Eastern U.S. This past week, however, also proved that we can still get good storms in a “relatively unfavorable pattern”, the devil being in the details. Keep burning those skis and washing those cars. We’ve still got a long ways to go. We’ll need over 10 inches of Snow Water Equivalent (SWE) this next month to catch back up with our climatological average. Using a 10:1 ratio that’s about 100 inches of snow, which certainly can and has happened time and time again in the Wasatch. From all of us here at Utah Ski Weather, happy holidays and enjoy the fresh pow!

814prcp.new

A Wet Christmas

The storm that Taylor and Tom forecasted has been awesome. The snow fell hard and fast from last night through this afternoon and is wrapping up as I write this at 7pm. Check out some totals from around the region:

Short Term:
Hot on the heels of our exiting storm, we’ve got another round of mountain snow dropping in for tomorrow night (Christmas Eve). This storm looks to be a bit warmer than today’s so unless the models trend colder, expect rain in the Salt Lake Valley, with a snow line around 6,000ft. More like 5,000ft in the Northern Wasatch. So maybe not a white Christmas in SLC, but a wet Christmas at least.

The bulk of the precipitation should fall tomorrow evening through early Christmas morning, tapering off through the rest of the day. Most of the models are calling for the neighborhood of 0.4″-1″ of liquid with this storm, and despite coming in fairly windy again and slightly warmer, I’m still expecting fairly low density powder. So I’ll go with 5-10″ of snow for most resorts.

Screen Shot 2017-12-23 at 7.02.14 PM
The precipitation forecast from the GFS model for our next storm on Xmas eve/day
Screen Shot 2017-12-23 at 7.01.19 PM
The precipitation forecast from the ECMWF model for our next storm on Xmas eve/day

Long Term:
We clear out after the Christmas storm for at least a few days, but then model solutions begin to diverge on the timing of our next storm. That will come into focus in another day or two. Enjoy the pow and the time off!

Steps in the right direction

As Tom mentioned in his post from yesterday, the large-scale pattern is FINALLY shifting to something more favorable for troughs moving through at regular intervals.  The high pressure has retrograded off to the north west and is now sitting over Alaska, resulting in all-time record high temperatures across the state (it was 33 F in BARROW yesterday).

Short-Term:
Another trough is scheduled to move into the area today with the front arriving later tonight.  Some relatively deep moisture and cold temperatures should result in a decent amount of new snow in the mountains, and even a an inch or so in the SL valley. Lower elevations north of SLC, like Ogden, could see up to 4″ on the ground this weekend. The NWS has issued a Winter Weather Advisory for much of Northern Utah and the Wasatch Front. Given the higher volume of traffic from holiday travelers, be especially careful if you have to be out on the roads.

weather.gov/slc/
weather.gov/slc/

The flow behind the front should remain northwesterly through Saturday night, which could result in additional orographically enhanced snowfall in areas like the Cottonwoods.

Time-height cross section from the NAM 12Z weather.utah.edu
Time-height cross section from the NAM 12Z weather.utah.edu

The resorts in the central and northern Wasatch should fare well from this storm.  It will be likely to see totals between 6-12″ for the Cottonwoods, and 8-14″ for more northern resorts like Powder Mountain. 

NAEFS Ensemble Snowfall weather.utah.edu
NAEFS Ensemble Snowfall weather.utah.edu

Long Term:
The future looks promising with the progressive pattern continuing and the possibility of more snow before the end of the year

Transitioning Into a more Typical Pattern

Hopefully some of you were able to get out and sample some of the fresh powder.  Word is that the traffic up to the resorts in the Cottonwoods was awful this morning– I guess this what happens it doesn’t snow in Utah for several weeks.  Most resorts in the central Wasatch picked up about 6-7 inches of snow with up to 9-10 inches reported in the southern Wasatch resorts.

Short Term:
Another front will swing into the region Friday night.  Precipitation will break out along the front and should continue through midday Saturday.  Once again, this will be a fairly cold and moisture-starved system.  The time-height section from the NAM-12km below shows a nice period of moist west-northwesterly floor along and behind the front:

NAMET_ALTA2017122112F084

Although substantial uncertainty still exists, I expect totals to be similar to yesterday’s system.  I’ll go with 5-8 in the Cottonwoods.  It looks like the northern Wasatch will do a bit better with this system.  I’m expecting 6-12 up there.  The output from the downscaled SREF below depicts the uncertainty for precipitation totals in the Cottonwoods with this system.

SREFPL_CLN2017122115F087

Beyond:
Significant uncertainty regarding specifics exists beyond Christmas, but it does appear that we will remain in a relatively active pattern.  Although there are no major systems on the horizon, most NAEFS members bring an additional storm system through during the late Monday to Wednesday timeframe.  Stay posted.

NAEFSPL_CLN2017122100F168

Today’s Quick Skiff

Today’s quick blast of wintry weather brought a couple inches to most valley and mountain locations. While it was not a huge storm, it got rid of the unhealthy levels of suspended dust that were localized in many valley locations this morning. The main accumulations seemed to be in the ballpark of 1-5″ with  Alta Collins on that high end of accumulations with about 5 inches as of 11PM Wednesday.  While some very light snow showers are still lingering over the Oquirrhs and Tooele area, this storm is mainly a wrap for Northern Utah except for a few overnight showers. It will continue to produce snow in Southern Utah where virtually no snow has fallen so far this season. Winter Storm Warnings by the National Weather Service are in place for areas such as Brian Head and Eagle Point.

Looking toward the holiday weekend, another quick blast of snow is expected beginning on Friday. This storm may have winds that are a little more westerly at and below crest level than the one that passed through today, meaning that some better orographic enhancement could be in store for the mountains – especially on the lee side of the Great Salt Lake. The following NAM time height section shows this pretty well.

From weather.utah.edu
From weather.utah.edu

Beyond Frday/Saturday, we can expect it to remain fairly active and chilly across Nothern Utah, but not near as cold as models were showing a few days ago. Our neighbors to the east will get to endure the Arctic air but we should be not too far from normal in terms of temperature. We could see snow showers in the Wasatch for the next several days but unfortunately not enough to bring us close to where we should be for this time of year. Check back with us for more regarding Friday and keep your fingers crossed for good mountain snows!