Wasatch to Get Some Too

Some HUGE storms have struck other regions of the Northern Hemisphere in recent days.  Previous posts describe 2+ meter dumps in the southern Limestone Alps of Europe (Another Alpine Dumpage Update) and Japan (Gosetsu Chitai Dumpage).  Adding insult to injury, huge snowfalls overnight in northern Pennsylvania and southern New York, including 44" at Newark Valley with snowfall rates of 4-5" per hour.

Snowfall reports received as of 8:30 am. An intense snow band set up overnight around the Binghamton NY area, producing snowfall rates of 4-5" per hour. Among the highest snowfall totals thus far: Newark Valley NY 44", Litchfield PA 43", and Binghamton NY and Vestal NY 41" pic.twitter.com/zopzr501Ao

— NWS Eastern Region (@NWSEastern) December 17, 2020

Lord have mercy!  

I can't promise snow totals of that magnitude for the storm that is developing today, but let's have a quick update on where things stand. 

We are currently in the prefrontal stage of the storm with the latest radar imagery showing the heaviest precipitation in the northern Wasatch as of 1625 UTC (0925 MST).  

As of 0900 MST, Alta-Collins has picked up .06" of water equivalent, but not enough snow on the board yet to tick off an inch.  The water numbers from the automated weather stations at Snowbasin show .02" or less by 0900 MST but the latest snow stake photo shows about an inch of snow.  Basically, things are just getting going.

In the Salt Lake Valley, we're presently in a "virga storm" situation with dry air at low levels.  The photo below, taken at 0820 MST shows snow virga falling aloft, but much of the snow sublimating before reaching the valley floor.  I did get hit by a few flakes while I was out on my walk.  

For the Salt Lake Valley and central Wasatch, we will remain pre-frontal today with southerly flow and periods of precipitation increasing in frequency and intensity as the day goes on.  Snow may mix with rain at times at the lowest elevations.  This morning, I saw a mixture of snow and "slush" as I was walking at 5000 feet elevation, but it changed over to snow when intensity increased.  The NWS is expecting impacts for the evening commute in Salt Lake County, so be alert.  The CDC recommends that you wear a mask when social distancing is not possible and the Utah Highway Patrol recommends that you slow down when the roads are wet, slushy, snowy, or icy.  

The HRRR is bringing the front through the northern Salt Lake Valley between 0200 and 0300 UTC (1900-2000 MST).  Should be an all elevations storm at this stage.  I like seeing the Salt Lake Valley and the central Wasatch covered in HRRR precipitation!  

We are having some networking problems and our usual products are not all available this morning.  Below is the NWS forecast summary is below.  2-4" for Salt Lake City, 3-5" for Ogden, 4-6" for Park City, and higher amounts in the mountains.  

Source: NWS

The Utah Avalanche Center is still advertising 8-14" for the central Wasatch, and that seems reasonable based on what I have.  Maybe we can do a bit better if things come together.  I'm inclined to think that less than 8" is unlikely for Alta from this one.  Tomorrow is a likely deep powder day, although the meager natural snowpack means low-tide conditions and as noted in the Utah Avalanche Center report, the backcountry avalanche hazard will likely be high.  The green light will not be on.  Let's be careful out there. 

Gosetsu Chitai Dumpage

As we await our next storm on Thursday, we once again look elsewhere for big dumpage.  

Today it is Japan's Gosetsu Chitai, or heavy snow region.  Some huge totals are coming in from the Echigo Mountains of central Honshu.

RECORD-BREAKING!! #Snow has been piling up at an unprecedented rate in #Japan. Fujiwara had 162cm (5.3feet) in 48hr. This is due to the combination of unseasonably cold Siberian air and unseasonably warm ocean temperatures. 150cm (4.9feet) is still possible into the next 48hr. pic.twitter.com/aTR6L7hGev

— Sayaka Mori (@sayakasofiamori) December 16, 2020

Below are observations tabulated by the Japanese Meteorological Agency and run through Google Translator.  The big winner is at Fujiwara in Gunma Prefecture with 128 cm (50 inches) in 24 hours, 196 cm (77 inches) in 48 hours, and 203 cm (80 cm) in 72 hours.  

Coming in second for the 48 and 72 hour totals is Tsunan with 149 and 173 cm (59 and 68 inches), respectively.  Tsunan is a long-term observing site at 452 meters above sea level (1483 feet) and 37˚N with a mean annual snowfall of 1349 cm (531 inches).  To put this into perspective, this would be like the Diablo Foothills in the Bay Area getting as much snow as Alta.  

I've identified each of these with thumbnails in the image below.  Sea-effect storms in this region come in two flavors.  Some produce the heaviest snow very near the Sea of Japan.  Others can penetrate inland and dump more precipitation on the mountains.  With such heavy precipitation at Fujiwara, well inland, this is definitely a case of the latter.  

For more on the snows of Japan, see my recent article with Sento Nakai of the Nagaoka Snow and Ice Research Center, which appeared earlier this year in the Bulletin of the American Meteorological Society (available here).  

Thursday Storm Must Come Through

The snow accumulation season has gotten off to a slow start.  In my view, the Thursday storm must come through to get the Nordic season off life support and help more with the upper-elevation snowpack.  The time has come.  Let winter begin.  

The forecasts are optimistic.  The GFS has a productive, slow moving frontal system moving across northern Utah on Thursday.  The forecast below is for 5 PM Thursday afternoon.  Temperatures are low enough that even if the storm starts out as rain at the airport, it should be cold enough to snow at Mountain Dell and the lower trailheads in the Cottonwoods and Mill Creek.

Water and snowfall totals for Alta from todays 6Z initialized GFS for 8 AM Thursday through 4 PM Friday are .91 and 12.8 inches, respectively.  The NAM is a bit less enthusiastic with 0.54 and 7.6 inches, respectively.  

The downscaled SREF is unusually excited, with all but 2 members producing 12" or more (including the light snow prior to Thursday's main event), with a maximum of about 28 inches. The mean is about 17 inches.  Deducting the mean from the weaker pre-Thursday events and you have a mean storm total of about 15 inches.  

One of the things I like about the storm is the frontal passage Thursday afternoon and evening looks to be quite productive.  That will be good for all elevations, and we need snow everywhere right now.  

The downscaling we do sometimes overdoes the snowfall at upper elevations in those periods, so perhaps the higher SREF members are overly optimistic.  I suspect to get to 2 feet or so at Alta we will need the post-frontal northwesterlies to come through big time.    

Personally, I like the 8-14" forecast advertised this morning in the Utah Avalanche Center advisory.  That seems like a good number for the upper Cottonwoods.  This will be a significant event for the valleys as well and should help with Nordic skiing at Mountain Dell.  

Recent Precipitation Extremes

Here are a couple of ongoing examples of precipitation extremes for your entertainment this Thursday.  

We've discussed the heavy snowfall in the Alps in previous posts.  I've found a new winner for extreme snowfall during the event, the Connyalm at 2105 meters in the Gailtaler Alps of East Tirol in Austria, just to the north of the Porzehütte site we've discussed previously.

The time series below shows a remarkable increase in the height of the snowpack (HS) from about 20 cm at about 1800 CDT on 4 December to nearly 300 cm at 1200 on 9 December.  

Source: https://avalanche.report/weather/stations

If you prefer US units, that's an increase in snow depth of about 110 inches in 114 hours (4 3/4 days).  Remarkable stuff.  

The camera at that location was down when I tried to pull it up.  Here are a couple of photos from the region to remind you of the beauty of snow.

Source: https://www.megacam.at

https://www.megacam.at

Shifting gears to Utah, it's quite remarkable how dry it has been since July 1.  From then to yesterday (December 9), total precipitation at the Salt Lake City International Airport was only 1.52 inches, easily the lowest on record.  

Source: NOAA Regional Climate Centers

In fact, there's only one other year under 2 inches for that period since records begain in 1874, 1958 (1.80 inches).  In addition, 1.52 inches is actually less than what Las Vegas averages for July to November (1.92 inches).

The US drought Monitor now shows a huge chunk of the state in exceptional drought, including Salt Lake City and the central Wasatch.  

Forecasts are more optimistic for the coming week than they have been in a while, with a series of troughs coming through.  Let's hope they produce.  

What It's Like to Ski 2 Meters of Fresh Snow

With the recent snowfall of 2 meters (80") or more in the Carnic Alps and surrounding region, one might wonder what it's like to ski in so much snow.  

Not as good as you might think. 

The reality is that powder skiing, like many things in life, requires some level of moderation, or what many call the Goldilocks storm.  In other words, not too big, not too small, but just right.

Where the threshold is for too big is somewhat ambiguous as it depends on the condition of the underlying snowpack or surface (alpine meadows in the Alps often serve as the bed for glide avalanches) and the characteristics of the snow during the storm.  As storm totals go over about a half a meter (20") you can have great skiing when conditions are right, but as the storm rages on and accumulations deepen, it becomes increasingly difficult to maintain momentum except on the steepest hills, where avalanche hazard is likely to be high.  

When you get a meter (40") of snow, especially if it falls in a day, it's pretty unlikely you can safely ski anything steep enough to slide except perhaps under the best of conditions in the lowest density snow (and I wouldn't tempt fate in such a situation).  Two meters in two days and you've got a good snowpack for the rest of the season, but otherwise you're probably hunkered down or interlodged.

I've skied twice in conditions where two meters of snow fell in two days.

Crystal Mountain, WA

The first was in the early 1990s at Crystal Mountain in Washington.  They received two meters (80") of snow in two days and 65" in 24 hours, the latter a record for the State of Washington and indicative of unusually dry snow for the Cascades.  

I have vivid memories of skiing after that storm, although psychologists will tell you that memories change.  I remember driving at high speed through Seattle to pick up a buddy and then up to Crystal.  I can't remember if we got the first chair for the public, but if we didn't, we were close.  We waited forever at the base.  Not only had we gotten up there early, but it's pretty much impossible to open a ski area when you get 2 meters of snow in two days.  In fact, they only opened one chair, the lower lift that takes you to the base of Rainier Express.  

After riding that chair, we were the "tip of the spear" breaking trench out northward to the only terrain that *might* be steep enough to ski.  It was like a breakaway during a road race rotating through trail breaking responsibilities with competitors with the chasing peloton gaining minute by minute.  

At the time, I was probably skiing on a pair of slalom racing skis, possibly the Salomon 2S.  Long and skinny, as were all skis at the time.  The snow was so deep and I sunk in so far that turning was not an option.  I just pointed them straight down, tried to maintain speed, and bounced up every now and then to make sure I wasn't going to run into anything and to cough out snow.  I survived to the bottom, looked back up the hill, and, other than a few others who made it down like me, saw most had fallen and augured in.  Many spent the morning looking for lost skis.  

We took a few more runs on the same hill, which became more manageable with time as it was cut up, and then went home.

Disappointed.

Myoko Kogen, Japan

In January 2017 I was on a difficult business trip to the Nagaoka Snow and Ice Research Center.  Following the science meetings, I spent a few days in the high-mountain and especially snowy Myoko Kogen region near Joetsu.  I ski toured on the first day, afterwhich the heavens opened up and we got about a meter of snow in two days in Akakura Onsen where I was staying and a reported two meters on the upper mountain.  It might have been closer to a meter and a half, but who's counting?  

On the first day of the storm, I had a great day at Seki Onsen, a small ski area with a couple of lifts, including a single chair that, I kid you not, they were loading every other chair.  I think Powder Mountain called Seki the "soul of skiing."  It was a great experience.  

On the second day, I skied at Akakura Onsen, a ski resort that is the epitome of "deep not steep."  Average annual snowfall of 500+ inches but, as it turns out, pretty damn low angle.  I think our options were limited, however, since travel was getting pretty difficult at this time.  

I began the day with some Kiwis who were staying at my lodge.  I took a photo of one of them getting an "official" measurement of the new snow depth next to the top chair as we waited for it to open.  

During this time, patrollers were out begging everyone not to ski off piste or enter the backcountry.  Terrain traps were likely to be death traps.  The possibility suffocation in a tree well or from inversion was very real.  

We weren't first in line and thankfully, the two pistes off the top had been skied the prior day and were already somewhat cutup when we got there.  That made the skiing possible in the low-angle terrain, although it was a struggle for many.  

The Kiwis then decided to do some sidecountry skiing.  I had brought my touring pack and gear, but was not going to succumb to powder fever and we split for the day.  It's painful to ski low-angle cutup, but going home is mandatory.  

After skiing, I had an iconic walk through the winter wonderland of Akakura Onsen.  I regularly use several of these photos in talks.

Later that day, the Kiwis arrived back at the lodge.  All were safe, but they had to perform a rescue of a snowboarder who had fallen into a creek bed and nearly suffocated.  

The storm continued that evening, quickly filling up the walkway into the Myoko Mountain Lodge where I was staying.  

The next day I was flying out of Tokyo.  That morning, through the Herculean efforts of the lodge owner, we were able to get out and he was able to transport me inland to the first train station that was actually open.  Remarkably, it wasn't that far away.  Maybe 10 km.  Sea-effect storms, even big ones, sometimes decay rapidly with inland extent. 

Another Alpine Dumpage Update

Some incredible snow totals continue to come in from the south side of the eastern Alps.  The biggest increase in the Height of Snowpack (HS) that I could find was at the Porzehütte, an Austrian Alpine Club hut in the Carnic Alps just north of the border of Italy.  I grabbed the screen shot below fortuitously when they peaked at around 2.34 meters, which represents more than a 2 meter increase in less than 24 hours.  

Source: lawis.at/station

I don't know how to access tabular data to get precise numbers for total water equivalent, but a guesstimate from the graph yields about 400 mm, so we're talking some serious concrete with 20% water content if those numbers are accurate.  

The Carnic Alps, as well as the Julian Alps and Dolomites to the south, are one of the wettest parts of the Alps and prone to heavy precipitation.  An analysis of average annual precipitation in the Alpine region shows the highest values along the northern and southern "rims" of the Alps.  In the central and eastern Alps, precipitation actually decreases as you move into the Inner Alps, despite the terrain getting higher.  

Average annual precipitation (mm) in the Alpine Region. Source: Isotta et al. (2013).

There are also two precipitation "hot spots" on the southern rim.  The first is in the Ticino, Lombardia, and Piemonte regions of Switzerland and Italy.  The second is in the Dolomites, Julian Alps, and Carnic Alps of Austria, Italy, and Slovenia.  These precipitation hot spots are produced by flow interactions with the Alps and the surrounding mountain ranges, which focuses vapor transport and precipitation dynamics in these areas.  

In addition, these are areas that receive the greatest fraction of their precipitation on days with moderate to high precipitation intensity, so their precipitation climatology is biased to big events.  

Fraction of precipitation from moderate to high precipitation intensity days. Source: Isotta et al. (2013).

In contrast, moderate to high precipitation intensity days produce a lower fraction of the precipitation along the northern rim.  Thus, the southern rim and hot spots get their precipitation when Mother Nature hits home runs (big events), whereas the northern rim scores with lots of base hits (lots of smaller events).  Note that this doesn't mean that the northern rim doesn't see extremes, because it does, but it tends to see more frequent smaller events than the southern rim.

A few photos of this event from @weathertoski are provided below.  The area is still seeing snow and will see periods of snow, possibly heavy again on Tuesday, until Wednesday.  Impressive!

Potentially historic snowfalls for some southern parts of the Alps: https://t.co/PGoKdcOhGN pic.twitter.com/CJbv9b51Gj

— weathertoski (@weathertoski) December 6, 2020