It’s certainly spring.

Today was certainly an interesting one out in the Wasatch. If you made it out, chances are you found some of the heavy, wet creamy goodness to be had. While not bad skiing, it’s a pretty clear indicator we’ve moved into springtime snow with limited cold air support. 

NAM Time-height for Salt Lake City, UT
NAM Time-height for Salt Lake City, UT

Looking forward to the weekend: we’re moving into drier conditions for a few days, while an active pattern remains upstream to our west. Warmer temperatures and sunshine should prevail through Sunday, with the next trough digging in to the region for Monday. At the moment models have this event wrapped up pretty early Monday, and the model trend has been weakening. Deterministic output only produces 4-8″ from this little wave. We’ll see how it develops as it comes into range of the higher resolution HRRR on Sunday.

GFS Meteogram into early next week, Alta, UT
GFS Meteogram into early next week, Alta, UT

Sun should work to soften surfaces both days this weekend, making for pretty great skiing. The active pattern appears to continue into early April, so we’ll keep our fingers crossed for just a few more great powder days while we can get them.

Complex System

Showers have entered the region out ahead of our next storm system.  Expect southerly winds to increase as we head into the early evening.  Between 5 and 6 PM I expect a fairly strong cold front to push through the the Salt Lake Valley.  It’ll cross through the northern Wasatch an hour or two before then(3-4 PM) and the southern Wasatch an hour or two after then (7-8 PM).  The time height cross section from the NAM 12-km below highlights this frontal passage nicely:

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NAM-12km time height cross section for SLC

I wouldn’t be surprised to hear a rumble or two of thunder as the front passes through.  Associated with the front will be a band of steady precipitation.  Models are forecasting this band of precip to stall somewhere in Utah as the low pressure system closes off in southern Utah.  Uncertainty remains as to where this will happen – hence why we aren’t confident in snowfall totals.

As we head into Friday winds will shift to easterly, which could lead to very strong winds in the valley.  Periods of precipitation will continue throughout the day tomorrow, but the easterly flow may limit accumulations at resorts on the west side of the Wasatch.  With so many small scale features at play combined with high uncertainty, the high resolution NCAR Ensemble appears to be a useful toll in forecasting snow amounts.  Here is its output for the Upper Cottonwoods:

NCAR Ensemble for Upper Cottonwoods
NCAR Ensemble for Upper Cottonwoods

Accounting for the low snow ratios and uncertainty in this system I am going with 6-12″+ for the Cottonwoods and Northern Wasatch.  This system will sit and spin in southern Utah, providing them with additional snowfall.  I expect totals in the southern Wasatch to range from 10 to 20 inches.

We clear out for this weekend, then another storm early next week.  An active spring pattern looks to continue for the foreseeable future.

Next Storm to Arrive Thursday

Wednesday will offer up mostly clear skies across Utah as a ridge of high pressure builds into the area.  Quality skiing conditions can be expected tomorrow afternoon with light northerly winds around 10-15 mph and base temperatures in the mid to upper-30s.  By Wednesday evening, high clouds will begin to stream into Utah ahead of our next system.

GFSMG_ALTA2017032818F180

GFS Meteogram for the Upper Cottonwoods

Southwest winds will increase Thursday afternoon ahead of a cold front. A few isolated snow showers will be possible before the front arrives. The cold front will arrive Thursday night with a band of moderate to heavy snowfall expected along the cold front.

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GFS 6-hour precipitation rate and type through Saturday morning

Behind the cold front, winds will shift to the north to the northeast. Snow showers will continue through Friday afternoon before tapering off Saturday morning.

Snowfall Forecast (Thursday PM – Sat AM)

  • Upper Cottonwoods:  12-20″
  • Northern Wasatch: 10-18″
  • PCMR & Deer Valley: 9-15″

Overall confidence in this forecast is lower than normal, as a slight shift in the low pressure center’s position could lead to lower totals. 

Storm, Bluebird, Storm, Bluebird

The past 4 days have followed the pattern of a storm day followed by a bluebird day & tomorrow looks to be no exception. After a lovely bluebird ski day, another storm is on tap for Monday. Right now it looks like snow will begin for the mountains during the morning hours and pickup during the afternoon. It should be a “last chair” kind of day, or for those of you wanting to get out in the backcountry things should be filling in quite nicely for a post-work tour. Of course, as always, refer to the Utah Avalanche Center whenever venturing into the backcountry.

What am I thinking in terms of totals you ask? Well first I want to quickly recap the last couple of storms to impact Northern Utah. Both of these featured more precipitation (albeit of the rain variety) in the valleys than in the mountains! While not unheard of, it’s certainly more common to see the reverse due to orographic enhancement. Unfortunately, both of these events featured weak forcing over the Wasatch and the best upper level dynamics were displaced on 25-50 miles to far to the west. What about this storm? I’d anticipate better orographic enhancement this time around but nothing to write home about. For totals I’m expecting 6-12 inches with the Cottonwoods falling at the upper end of the range.

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ECMWF model forecasted snowfall totals for this week

Thing will clear out Tuesday/Wednesday before yet another storm impacts Northern Utah on Thursday/Friday.

THIS is what Spring weather should be

Yesterday’s storm was quite impressive, and probably came as quite a shock to those of you already in warm-weather mode! Alex’s forecast verified well, as snowfall totals above 7,000ft were generally in the 5-10″ range. This isn’t a super impressive storm by that metric, but Salt Lake airport saw its wettest March day EVER with nearly 2″ of liquid falling. That’s 1/8 of our normal yearly precipitation in a single day! And curiously, <1″ of liquid fell at many sites in the mountains. A particularly strong band of precip set up across the state, and the airport happened to be located under the band.

 

Today is a nice break in the action, with bluebird skies and light winds. I suspect the skiing was pretty good this afternoon before things heated up.

 

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The view from Snowbasin this afternoon

Fortunately, this break will be short-lived, and another storm rolls in tomorrow (Sat) morning. It won’t be very cold, or very strong, but it’ll be a nice refresher. Expect 4-8″ at most resorts by Saturday night.

Precipitation Forecast from ECMWF model
Precip forecast through Saturday night from the EC model

The next storm comes Monday, and it looks strong, but quick-hitting. The pattern looks to remain active after that.

Snow Returns!

An upper level trough currently centered over central California will swing through Utah Thursday.  Temperatures aloft will cool, allowing for snow levels to drop down to about 6500′ by Thursday afternoon.  A band of snowfall will likely occur with the passage of a cold front, before snow turns more showery during the afternoon.

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IR Satellite Imagery across the Western U.S.

Snow showers will wind down Thursday night as skies clear out, leaving sunny skies on tap for Friday.  The freezing level by Friday afternoon will climb close to 9,000′.   Another storm will enter Utah Saturday.  Stay tuned!

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NAM Cross-section of Wind and Relative Humidity

Forecast Snowfall (valid Wed. night – Fri. morning)

  • Upper Cottonwoods 5-10″
  • PCMR & Deer Valley 4-7″
  • Northern Wasatch Front 5-10″

-Alex

Winter Returns!!

Hope y’all haven’t put the skis and heavy jackets away quite yet cuz winter’s coming back! After a 2 week + drought for snow in the Wasatch, the switch has finally been flipped and winter’s coming back with vengeance. The first of a series of storms (at least 3 – see below) to impact Northern Utah will begin late tonight/early tomorrow.

Screen Shot 2017-03-21 at 9.31.19 PM

Expect a couple inches of snow by the end of Wednesday at high elevations above 9000 feet. Otherwise temperatures will still be a little too warm for snow in areas like Park City below mid-mountain. The good news is that 700 mb temperatures will be cooling and the GFS has been trending a little colder (-7C, though NAM is warmer around -3C and European in the middle at -5C). Overall, it won’t be blower by any means but certainly colder temperatures than we’ve seen of late with fairly significant accumulations above 7500 feet. Right now I’m expecting 6-12 inches – though if the latest European model run were to verify then we’d probably hit the upper end of the range if not a little higher.

On Friday things will clear out for what should be a beautiful bluebird day. Then on Saturday storm #2 moves into Northern Utah producing a quicker hitting snowfall – however, totals still should be decent. Sunday will provide another brief break followed by storm #3 into Monday-Tuesday.

European model snowfall totals for the next 10 days
European model snowfall totals for the next 10 days

Summary

Wednesday – Dust on crust

Thursday – Storm day (could be getting good in the afternoon)

Friday – Bluebird

Saturday – Storm day

Sunday – Break in the action

Storm on the Way

It’s been a while since a nice, cold storm has come through. Instead it has been hot, sunny, and dry. The snowpack has taken a hit even in the Central Wasatch, which isn’t surprising considering it hasn’t dropped below 0°C at Alta-Collins in over a week (granted observations there are hourly, so a brief lapse could have occurred between an observation).

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Also there has been no real precipitation in the last week. This might change today as showers have been popping up over the valley and mountains this afternoon. The radar at the time of writing shows a bullseye over the Central Wasatch. The problem is that, if there isn’t a cold outflow from the storm, then this would be rain everywhere but the highest elevations.

Screenshot_20170320_154045

These afternoon showers should continue for the next three days. The thing is some of the storms will have lightning in them, so you will have to be very careful when going out. They can pop out of nowhere when you are in the mountains.

The next cold storm will pass through Thursday. It’s still too far out to go into specifics, but we’re looking at 5-10″ or so in the higher elevations. How far down the snow level will creep is very uncertain, but right now a good estimate is 7500′. Thursday’s storm won’t do much for our lower elevations, but the resorts should get a little refresher.

Hope on the Horizon

It’s been an extraordinary stretch of spring (summer) weather the past few days. We’ve set record highs at Salt Lake City on 3 days, and these highs are equal to the average highs for late May…pretty incredible.

From the Salt Lake City NWS office
From the Salt Lake City NWS office

We’ll stay well above average for the early part of the work week, but fortunately there is some hope on the horizon. Temperatures will begin to cool as a we transition to a colder and stormier pattern.

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Euro ensemble forecast precipitation at SLC. Looks like it will start stacking up late Tues/early Wed. models.weatherbell.com

Monday and Tuesday will be very warm with the chance of a shower or two. Then Wednesday into Thursday, accumulating snow looks likely at most resorts. Beyond that, the models keep us in a fairly active pattern, so hopefully more snow and no more of these ridiculously warm temps.

This morning finally saw a slight re-freeze at upper elevations as temperatures fell just below freezing above 9000ft. This was the first in a few days, with an overall unsupportive snowpack to contend with lately. The bottom line is while we’re not quite in the clear yet, the weak storm this weekend will help usher in a shift in the pattern towards cooler temperatures at upper levels, with a little more damage (via warmth and rain) before things start improving.

Temperature, Dew Point at Alta Baldy from the NAM 12km
NAM 12km – Temperature, Dew Point at Alta Baldy summit

Here’s the gist of it: Sunday morning will see a weak shortwave trough push through the region. Expect cloudy skies in most areas, with the chance for rain showers below 9,500 ft or so. Rain showers will likely be more persistent in the mountains than the valleys, with the chance for a trace to an inch or two of snow at the highest elevations.

GFS Time-Height RH/Theta-E at Alta, UT
GFS Time-Height RH/Theta-E at Alta, UT

The above model data indicates the freezing level (thick blue line) staying well above the Alta base elevation until Wednesday, falling with the incoming mid-week storm. Temperatures at 700 mb will finally fall below freezing by Wednesday morning, with precipitation falling as snow to most ski area base elevations.

Details are still fuzzy this far out, but we’ll update you as we’re able – at the moment, 6″ above 9000 ft in the central Wasatch seems to be a reasonable lower bound for snowfall totals by Thursday AM.

-Mike