Wednesday, April 27, 2022

The Great Salt Finger Lake

Given the meager snowpack that generally exists in northern Utah, it's no surprise that the Great Salt Lake is expected to drop to historically low levels this summer.  

Last year the lake dropped to its lowest measured elevation at Saltair, 4190.4 feet.  A look at the observations collected at Saltair by the UGSS since last year shows that the lake reached its maximum elevation in early May and dropped about 2.5 feet through fall.  


The recovery during the winter and spring has thus far been pathetic.  We currently sit at about 4191 feet, nearly 2 feet below where we were last year.  The runoff situation isn't great again this spring.  About the only silver lining is that recent storms have helped the snowpack in the Bear River Basin, which is now running ahead of last year by a bit.  

However, that's not going to help a lot and I suspect we'll make a run at 4189 feet by early fall.  

I've been preparing some material on the future of the Great Salt Lake for the 2nd edition of my book Secrets of the Greatest Snow on Earth.  I'll be including a bathymetric map of the lake based on work by Dave Tarboton at Utah State to illustrate what will happen as the lake shrinks.  The deepest portion of the lake lies along a northwest to southeast axis.  As the lake shrinks, it will become increasingly confined to a narrow channel along this axis.  Basically, the Great Salt Lake becomes the Great Salt Finger Lake.  

At about 4170 feet, the lake becomes two salt ponds.  That may sound crazy, but the lake is currently down about 20 feet from its most recent high stand in the late 80s.  Another 20 feet and we are there. 

The Modis image below was taken on September 27, 2021when the lake was near its minimum and historical low elevation.  It corresponds quite well with the 4191 foot contour above with a small arm of water wrapping around the north and east side of Fremont Island and a sliver of water along the Jordan River as it flows through what was formerly Farmington Bay to the east of Antelope Island.  

The implications of the withering Great Salt Lake are more dust, less lake-effect snow, and the demise of one of the most important bird habitats and ecosystems in western North America.  

Tuesday, April 26, 2022

The Weather Whiplash of the 2021/22 Season

I hope you enjoyed the Gift from the Gods last weekend.  What a long strange trip this season has been.  It was the best of times.  It was the worst of times.  Weather whiplash for sure.

I'll summarize with the Snowbird SNOTEL measured snow water equivalent (SWE) of the snowpack.  At this elevation, the season got off to a good start with SWE increase of 4.7" from October 8 to October 27.  

Then the spigot turned off and we only added 1.3" from October 27 to December 9.  The snow faceted on the north half of the compass, forming a persistent weak layer that would haunt us for a significant part of the winter and in many areas melted out on the south side.  

The storm track returned in December and Mother Nature added 15.7" of SWE to the snowpack through January 7.  That was a pretty good run and the only period outside of October that the snow accumulation rate that exceeded climatological expectations [i.e., the slope of the median (green) line] for more than a few days.  

We then lived on that snow until early March.  From January 7 to March 5, Mother Nature only added a scant 2.1" to the snowpack.  I have heard rumors it was the least snowy February on record at Alta.  I haven't seen the numbers for Alta Guard yet, but before this year, the minimum there was 34" and the resort reported 26" based on their snowfall history page, so chances are we set that dubious record.  

From March 5 through today, we've seen a series of storms interspersed with ablation (snow loss) events.  The SWE trace (black line) during this period shows ups and downs.  In the net, the SWE increased about 10.2" during this period, a rate that was still less than median for the period.  However, if my calculations are correct, the Snowbird lost 2.4" of SWE during those ablation events.  Without those losses, the accumulation for the period would have been 12.6", very close to the median SWE increase for the period of 13.1".  

I see that period from March 5 to April 25 as perhaps an example of the future Wasatch spring snow climate, with the snowpack ripening earlier, significant losses occurring on south aspects, and the frequency and severity of ablation events on north aspects increasing.  

My grade for the season is an incomplete.  I'd like to give it a C+, but due to a foot injury, I haven't done much skiing other than groomers since early February and had to sit out the storm cycle this weekend.  Thus I lack the ability to properly asses the season and encourage you to input your grade and justification in the comments below.  

Thursday, April 21, 2022

Gift from the Gods

The next three days are going to be exciting and interesting for weather and snow lovers as a major spring storm moves through the region.  

Today a surface cold front slowly sags into and intensifies over the Great Basin.  The GFS forecast valid 0000 UTC (6 PM MDT) this afternoon shows the front extending across central Nevada and northern Utah very near the Salt Lake City.  For much of the day, we will see strong southwesterly pre-frontal flow, possibly with dust (I assume you haven't had enough of that).  

The northern Wasatch Front will probably see a shift to westerly or northwesterly flow late in the day, but it's unclear if that will happen in the Salt Lake Valley.  Right now I'd say the odds favor that not happening, but I can't rule it out, especially for the northern part of the valley.  It will, however, be a dry front this afternoon, so the main impact will be on winds and temperatures.  

The models differ on the exact movement and position of the front overnight, although they keep it over northern Utah.  The GFS forecast valid 1200 UTC (0600 MDT) Friday morning has a disorganized surface front over northern Utah with the precipitation band to its northwest is filling in nicely.  The flow at upper levels and for the central Wasatch remains strong and out of the southwest. 

On Friday, the GFS does two things.  First, it develops widespread showers ahead of the frontal precipitation band by 1800 UTC (1200 MDT).  At that time, the frontal band is moving into northwest Utah and its leading edge is over the West Desert.  Note the accompanying surface wind shift in the lower right-hand panel below.    

That afternoon, the frontal band moves in and the flow shifts to northwesterly, with widespread precipitation over most of northern Utah by 0000 UTC (1800 MDT) Friday.  

Friday night is the post-frontal crap shoot with mountain induced precipitation over and upstream of the Wasatch Range and a chance of a little lake-effect involvement. 

By and large, Saturday looks like a gift from the gods.  Our GFS derived forecast for upper Little Cottonwood shows a total of 1.35" of water and 18" of snow for Alta-Collins through 9 AM Saturday, with some additional precipitation during the day.  

The ECMWF model is just a bit below that.  By 23/18Z (1200 MDT) Saturday the SREF has 3 low members under five inches to give one heartburn, but 18 out of 26 members generate 10 inches of snow or more.  

Make some turns for me. 

Tuesday, April 19, 2022

A Quick Update

It's been a while since I did a post, but I've been busy working on the 2nd Edition of Secrets of the Greatest Snow on Earth.  It's coming along nicely and I'm hoping to get it to my publisher by the end of May.  

I have good news and bad news on the forecast front.  The bad news is we just had a frontal passage in the Salt Lake Valley and it has come loaded with dust.  

The moisture lags the surface front by a good ways and is pretty scant at that.  We'll see a few valley showers and mountain snow showers later this afternoon or evening, but the latter won't add up to much. 

The good news, however, is that the system coming in late Thursday night/early Friday morning and affecting us through Saturday looks more potent.  Below is the downscaled NAEFS plume showing some healthy totals with a mean of between 20 and 30 inches.  

Don't bet the house yet.  The GFS is a bit more subdued (and it tends to be wet), with just over an inch of water and about 16 inches of snow.  Regardless, keep your fingers cross for another April dumpage, just in time for the weekend.

Wednesday, April 13, 2022

Bits and Pieces

It's been a pretty good April storm cycle so far.  Totals at Alta Collins per automated measurements:

4 PM Monday 11 April - 4 AM Tuesday 12 April: 11 inches
4 AM Tuesday 12 April - 4 PM Tuesday 12 April: 2 inches
4 PM Tuesday 12 April - 4 AM Wednesday 13 April: 6 inches

I suspect the skiing was pretty good yesterday and will be excellent this morning where untracked.  The northern Wasatch also got hit pretty well.  Snowbasin is reporting 15 inches in the last 48 hours and has announced they will reopen for skiing Friday through Sunday.  It's never over until it's over.  

I'd like to summarize the forecast through Friday afternoon as "dribs and drabs" but that seems unfairly discouraging for April, so I'll say "bits and pieces" instead.  Currently radar shows snowshowers moving into the northern Wasatch from the west.  

This general pattern will continue this morning, with the northern Wasatch likely to receive the most snowfall and the central Wasatch intermittently getting into the action. For example, the GFS shows westerly flow at 700 mb (10,000 ft or crest level) across northern Utah at 1800 UTC (1200 MDT) today with the heaviest precipitation in the northern Wasatch (color fill).  

Through Friday afternoon, a series of weak systems will move through northern Utah with the large-scale crest-level flow fluctuating between westnorthwest and southwesterly.  Expect periods of mountain snow through Friday with occasional breaks and snowfall heaviest at upper elevations in the northern Wasatch.  Temperatures will also be increasing, so getting on it quickly will be important as it is April and the sun has no mercy for fresh dendrites.  

The GFS-derived accumulated precipitation and snowfall graphs below for Alta-Collins shows the situation well with a pulse of snow this morning and early afternoon, then a break, then a couple more small pulses before a few inches Thursday night into Friday morning.  There's another brief period of snow Saturday evening.  

The timing and strength of these periods of snow can't be forecast precisely.  I guess the operative word for this pattern is unsettled, with conditions becoming more mild as temperatures rise (note the the warming trend on Mt. Baldy in the upper right panel).  

Enjoy it while it lasts.

Tuesday, April 12, 2022

Graupel is Good

 The storm delivered as forecast (I love to say that!) in most areas including 11 inches through 8 AM at Alta-Collins.  

Here at the University of Utah, the ground was sprinkled this morning with some beautiful graupel particles.  Below is an example of a pea sized, conical-shaped graupel particle outside the Student Life Center. 

Graupel forms as tiny supercooled cloud droplets collide and freeze on an ice particle.  Typically it has a higher fall speed than snowflakes (3 meters per second compared to 0.5 to 1 meter per seconds) and requires a fairly strong updraft to form.  Radar imagery overnight suggests that the convective cell moving over the University of Utah at 12:40 UTC (6:40 AM, see below) may have produced it, although there were one or two other cells that moved through the area earlier.  

We are now solidly into the unstable, postfrontal flow, although as shown in the time-height section below, the flow direction below and at crest level is predominantly westerly to west-northwesterly and perhaps not quite optimal for Little Cottonwood.  

Nevertheless, periods of snow will predominate today and, given the April sun, we will probably see some strong snow showers this afternoon, possibly with thunder and lightning.  Expect to seem some graupel or pea-sized hail as well.  My best guess is 3-6" more for Alta Collins, although the hit-and-miss nature of what we will see later means there's a wide range of possibilities.  A direct hit by a strong cell would really add up, for example.  

Monday, April 11, 2022

The Gathering Storm

It's hard not to look at the satellite loop below and not get excited.  There's a deep cyclone making landfall on the Pacific Northwest coast with the concomitant cold front pushing across eastern Oregon.  

Source: College of DuPage

As I type this, it's pretty easy to find the front.  It just blasted through Rome in southeastern Oregon, resulting in a wind shift from southwesterly to northwesterly and a 10˚F drop in temperature in an hour. 

Source: MesoWest

The pattern being forecast by the HRRR model for today is, however, not straightforward, due to the effects of terrain on the storm system.  The forecast for 1800 UTC (1200 MDT) is pretty consistent with the observation and shows a cold front (blue line) extending across northwest Nevada into southwest Idaho, with Rome being in the post-frontal environment.  

However, as the cold front moves eastward across northern Nevada, a sharp windshift known as the Great Basin Convergence Zone develops ahead of it (dashed yellow line).  The forecast for 2100 UTC (1500 MDT) shows this feature is forecast to form just south of Salt Lake City and may result in a wind shift in our area before the arrival of the cold front.  At this time, precipitation occurs both ahead of the front (prefrontal) and behind it (frontal).  

This pattern persists through 0000 UTC, with prefrontal showers becoming more widespread in the central Wasatch and environs.  Again, the flow ahead of the front has shifted to northwesterly in the vicinity of the Great Basin Convergence Zone.  

By 0300 UTC, the front has reformed along the Great Basin Convergence Zone.  This is an example of discrete frontal propagation with the front jumping ahead of its earlier position.  Frontal precipitation now covers the central Wasatch and most of the Salt Lake Valley.  

All of that might be an example of TL;DL, but it shows some of the complexities of how cold fronts move through the Great Basin.  We will see if it verifies.

The GFS is jacked about precipitation in and around the Wasatch Range this evening, generating more than 0.5" of snow-water equivalent in the central Wasatch and western Uintas in the 3-hour period ending at 0300 UTC (2100 MDT).  Although there may be a little rain this afternoon in Park City, snow levels will come crashing down later today and this evening, so much of this precipitation will fall as snow.  

Our GFS-derived forecast product below shows the burst of snow with the complex frontal system beginning just before 6 PM MDT with 1 inch of water equivalent and 13" of snow forecast through 4 AM Tuesday.  Snow showers add an additional 0.5" of water and 10" of low density snow during the day on Tuesday, bringing the total to 1.5" of water and 23" of snow through 6 PM tomorrow afternoon.  

For an ensemble perspective, the SREF members generate 0.65 to 1.5" of water and 9 to 24" of snow through 0000 UTC 13 April (6 PM MDT Tuesday), so the GFS may be an upper-bound forecast.   Note that most of the spread develops after the frontal passage, which is not unusual as the post-frontal environment is often more difficult to forecast.  

I expect 12-20" at Alta Collins through 6 PM tomorrow.  Ski conditions tomorrow morning will depend a lot on how things bond to and bury the frozen coral reef that currently covers the Wasatch Range.  Low end amounts will probably yield quite a bit of bottom feeding.  High-end amounts should result in pretty good conditions that will get better as we add more snow.  Keep in mind that we are in low-tide conditions in many sun exposed areas.  There will be hidden hazards.  

Also, our snow algorithm is going for very low density snow tomorrow (5% per the GFS).  I'm not sure if that will verify.  It's April, and the sun, even through clouds, is pretty caustic.  Additionally, we could see convective storms with riming and possibly graupel, which is higher density.  This is why I've cut the upper-end snowfall amount to 20" rather than about 24 as suggested by the GFS and SREF.  You won't complain if that ends up being low.  

Saturday, April 9, 2022

It Ain't Over 'Til It's Over

Lenny Kravitz doesn't ski.  I know because he played the closing day concert at Ischgl Ski Resort in Austria in 2019 and said so.  Perhaps he's learned by now.  If not, he could think about taking advantage of the return of winter to Utah.

We start with the situation yesterday when spring was full on.  Knowing we were going to see cooler temperatures and stubbornly firm snow this weekend, I spent a few hours running laps at Alta.  Conditions were about as good as they get for spring skiing with firm but very carve-able groomers at the opening bell and very few people on the hill through the morning, enabling one to ski at maximum warp. 

By about 1 PM, things were getting softer and crowds were picking, but by then my foot and ankle had enough.  I suspect the skiing was fun in the afternoon, especially on steeper off piste that for the most part was relatively bump free.

This weekend we are trending cooler.  It will take a while longer to soften up today and you may need to seek out south or west facing terrain for that to happen.  Tomorrow looks like a slap in the face with 700-mb (~10,000 foot) temperatures dropping to about -13˚C tomorrow morning leading to a very hard freeze.  I'm not sure there will be much softening on the snow tomorrow.  Perhaps on south or southwest aspects, but it will be a struggle.   

Then a real spring storm comes in for late Monday into at least Tuesday.  Temperatures rebound in southwesterly flow on Monday and by late in the day it appears mountain snow showers will be developing.  The GFS forecast for 0000 UTC 12 April (6 PM MDT Monday) shows a strong cold front draped across northern Nevada and southeast Idaho, with the prefrontal showers over the Wasatch and Uintas.  

By 0600 UTC 12 April (0000 MDT Tuesday), the GFS is all in for heavy frontal snowfall over the Wasatch Range and has temperatures cold enough for precipitation to be changing to snow on the valley floor.  

This is followed by a period with heavy post-frontal mountain snowshowers, and probably some valley snow as well.  Below is the GFS forecast for 1800 UTC 12 April (1200 MDT Tuesday).  

Our GFS-derived forecast over the next week for upper Little Cottonwood is below.  Mt. Baldy (11,000 ft) temperature drop through Sunday morning, bottoming out at 2˚F, recover ahead of the front, and then drop during and following the frontal passage.  Heavy snowfall accompanies the front Monday night and continues through Tuesday.  Totals by 0800 MDT Tuesday morning are 1.25" inches of water and 15.5" of snow for Alta Collins.  By 0000 MDT Wednesday morning, the GFS puts out another 0.32" of water and 6.4" of snow.

The SREF is also pretty excited.  A few members produce some light snowshowers later today or tonight.  Adjusting for that, the range of forecasts from all 26 members is 8 to 25 inches of snow for Alta Collins for the Monday night/Tuesday period.    

By and large, this looks like a pretty good April event.  Don't hang up the skis yet.  It ain't over 'til it's over.

Addendum 9:21 AM Saturday:

Seeing some photos from this morning suggesting we didn't get much of a freeze up there last night.  Perhaps we can maintain spring conditions today.  It will be a race between the sun and the transport of colder air into the area as the front is now through.  

Monday, April 4, 2022

A Visit From the Pacific Jet

There's a storm coming in tonight but the big story for the mountains isn't snow, but wind.

As shown by the GFS jet-stream level forecast for 1800 UTC (1200 MDT) tomorrow, the Pacific jet will be penetrating across a low-amplitude off the Pacific coast and southeastward into Utah.  Jet stream level wind speeds at that time exceed 60 meters per second (120 knots).  

I used to fly a decent amount between Salt Lake City and Denver, and in patterns like this I used to plan on there being no drink service and the fasten seatbelt sign being on the entire flight.  It's a recipe for mountain-induced gravity waves and turbulence.  

The time-height section for Salt Lake City shows a lot of black flags at upper levels from 0000 UTC Tuesday (6 PM MDT Monday) to 1200 UTC Thursday (6 AM MDT Thursday).  Winds at 650 mb, roughly the altitude of Mt. Baldy and other 11,000 foot peaks, maximize from around 0600 to 1200 UTC Tuesday (Midnight to 6 AM MDT Tuesday) as a cold front pushes through the area. 

Our Little Cottonwood forecast product has gusts on Mt. Baldy reaching over 70 mph overnight tonight and remaining above 50 mph through 11 AM MDT Wednesday (see center left panel).  I won't be surprised if they go higher than that.  Typically this product underestimates the peak gusts.  

On the plus side, there will be some snow.  The GFS is putting out 0.68" of water and about 6 inches of snow for Alta-Collins through noon MDT Tuesday.  This is, however, on the high end of the SREF forecasts, which max out at 6 inches.  

Bottom line: Expect an angry storm with 3-7 inches of snow that may end up in Wyoming.  

Saturday, April 2, 2022

Dwindling Snowpack

I haven't been touring due to a foot injury and haven't been in Big Cottonwood Canyon for a couple of months.  We went to Brighton and Solitude today for a few hours of laps today, however, as my son is saving his last Alta/Snowbird Ikon day for what he hopes will be a powder day.  

The day of peak daily median snowpack at the Brighton SNOTEL is April 16.  At the Mill D North SNOTEL it is April 1st.  So to see the snowpack so devastated was quite remarkable.  South aspects are bare, even to the summit of Reynolds Peak. 

And elsewhere the snowpack is remarkably thin for this time of year.  Below is an extreme example on the Solbright trail from Solitude to Brighton, which is on a south aspect.  The end is nigh for the Big Cottonwood "Interconnect."  

Most of January and February were very dry and there was no March miracle.  In fact, March provided a good example of how intensifying warm waves are altering the snow hydrology of the Wasatch Range.  The snow water equivalent graph for Brighton is below.  From 1 to 22 March, it increased 3.2 inches.  The increase in median snowpack water equivalent in that period based on the previous 30 years of records was 2.1 inches, so we were doing decently during that period.  However, the last March heat wave resulted in a 2 inch decline.  

The net for the month of March ended up being only 1.7 inches.  Median is 3.9 inches.  What a disaster.

Friday, April 1, 2022

Cardiff Resorts to Open in 2023/24

A new ski resort is being planned for the central Wasatch and scheduled to open in 2023/24. 

It will be unlike any other ski area in Utah.

Taking a page from club skifields in New Zealand, the resort will consist of two surface tows that will extend up an area of private land that exists in upper Cardiff Fork, beginning at about 9000 feet elevation and going to approximately 10,000 feet to a ski run known today as Power Outage on the north side of the ridgeline between Cardiff Peak and Mount Superior.  

Accessing the lifts will require skinning or hiking, which is the case at some club fields in New Zealand.  For example, accessing the Temple Basin skifield in Arthur's Pass requires a 45 minute walk to get to 3 rope tows.  To access Cardiff Resorts, one will either need to do the long schlep up Cardiff Fork or access from Alta via Cardiff Bowl and Pass.  There is some talk of providing snowmobile tows up Cardiff Fork for an additional charge.  

The resort will, however, only be open one day a year.

April Fools Day.