Wasatch Weather Weenies

A friend send me a copy of Grove Gilbert's 1928 USGS report Studies of Basin-Range Structure  yesterday.  Gilbert was scientific giant who did a number of pioneering studies of the geology of Utah and the western U.S.  He named Lake Bonneville, the historical lake of which the Great Salt Lake is a remnant.  The report appears to have been published posthumously (Gilbert died in 1918).  What caught my attention are the many photos of the undeveloped Wasatch Front, which I've added to the end of this post and which would have been taken probably in the early 20th century.  They are a reminder of how rapidly we have transformed the landscape in the short period of a century (or less).  What will Utah and our beloved Wasatch Mountains look like in 2050 when we are told the population will be twice what it is today? 

Head Blogger, Jim Steenburgh, Hakuba, Japan The Wasatch Weather Weenies began on October 1, 2010 as an invitation only blog for discussing the weather and climate of the Wasatch Front and Mountains, western United States, and mountainous regions in general.  It started out as invitation only because I didn't want discussions to descend to the levels seen, for example, in comments following Salt Lake Tribune articles online.  However, I quickly had so many people asking to read it that I decided to make it publicly viewable and accessible.  Thanks to you, comments have remained substantive and approved for all audiences, and I'm grateful for that.  I'd actually like to see more questions, comments, and suggestions, so feel free to do so liberally.  I consider the Wasatch Weather Weenies to be an educational blog.  Posts sometimes target a more advanced meteorological audience, others a general audience.  There's plenty of graphs and plots (inclu...

A thin veil of altostratus clouds led to an upper-elevation riming event Saturday night that likely threw a wrench at some lift operations in the central Wasatch this morning (Sugarloaf was a late start at Alta, although I'm not sure if that was due to rime or a mechanical). The large-scale setup was typical for these events in the Wasatch Mountains with moist, northwesterly flow spillover over a ridge located near the Pacific coast. This mornings sounding shows very dry conditions at low levels over the Salt Lake Valley, but saturated conditions, indicated by the colocated dewpoint (green) and temperature (red) traces within the cloud layer from about 725 to 650 mb.  This is consistent with cloud bases near about 10,000 ft. Source: SPC The key for rime is that the clouds need to be below 0ºC, but not have cloud top temperatures much below about -8 to -10ºC.  Indeed, this mornings sounding suggests a cloud-top temperature around -10ºC.  At such temperatures,...

With the Olympic Winter Games beginning on February 8, it seems like a good time to take a look at the climate of PyeongChang and the sorts of weather that we might expect in a couple of weeks. PyeongChang is a county in the Gangwon province of South Korea.  On the broad scale, it lies on the eastern edge of Asia, east High Mountain Asia, including the Tibetan Plateau, and between the Yellow and East Seas.  The East Sea is known to many Americans and the Japanese as the Sea of Japan, but the Koreans as the East Sea, so for this post, I will stick with East Sea since they are the Olympic hosts. Olympic venues are concentrated in the Gangneung Coastal Cluster, along the coast of the East Sea, and just inland in the PyeongChang Mountain cluster.  The topography of this region is a mumble jumble of small ranges and mountains.  In a broad sense, the Teabbek Mountains run from south-southeast to north-east, paralleling the coast, with some higher-elevation branches ...

Forget about the weather today.  I just learned of the passing of Warren Miller at the age of 93 .  I find myself surprisingly emotional considering I never met the man, but he had a profound influence on my life. It's probably difficult for younger skiers to understand the anticipation for the screening of a Warren Miller Film in the pre-internet days.  As a youngster in upstate New York, we would travel to Proctor's Theater in Schenectady each fall where Warren would personally narrate that year's movie, shot on location in some of the most spectacular places on the planet.  Today you see footage from many of these places on YouTube after some person's run of a lifetime, but video of skiing in the Selkirks or New Zealand was like seeing skiing from another planet back in the day.  The ONLY way to see it was to go see a Warren Miller movie. Wikipedia provides a chronological list of Warren Miller movies, beginning with his first, Deep and Light , in 1950....

Utah may have the Greatest Snow on Earth, but Japan has the Greatest Snow Climate on Earth.  Nowhere in the world does it snow with such intensity, at such low latitudes, at such low elevations, with such prolific mountain snowfalls. The driver of all this snowfall is the so-called Asian Winter Monsoon, which is characterized by a cold, northwesterly flow from Asia over the Sea of Japan.  This produces copious sea-effect snowfall that inundates northwest Honshu and Western Hokkaido Islands.  Source: Secrets of the Greatest Snow on Earth The snowfall accumulation is relatively punctuated, but incredibly intense.  Compare, for example, the average monthly snowfall at Kutchan, a Japanese Meteorological Agency observing site near the base of Hokkaido's Niseko resorts to that at Alta.  Alta features a broad peak from December through March (the minimum in February largely reflects the smaller number of days), whereas Kutchan features a pronounced maximum, exc...

"Pattern change" is currently on my list of banned words and phrases for good reason as it was being thrown around repeatedly for weeks despite the fact that nobody really knows what it means.  As I've been watching the large-scale pattern for the last several weeks, there has certainly been variability.  Ridges and troughs have formed and dissipated.  There have been some major cyclogenesis events.  However, one thing has remained constant.  The large-scale pattern has been very high amplitude, meaning a wavy jet, especially from the Pacific Ocean to Europe.  That situation looks to continue for the foreseeable future.  Below is the 10-day GFS forecast for the northern hemisphere dynamic tropopause.  The dynamic tropopause separates the troposphere, or the lower atmosphere in which we all live and reside, from the stratosphere and basically sits at jet-stream level.  Note in particular the high-amplitude, wavy nature of the pattern, with...

It was wonderful to see the white stuff return to the valley and the Wasatch Front this weekend.  Everybody got some.  Here are some of the bigger totals as reported to the National Weather Service (water equivalent in parentheses). Bountiful Bench (through 5 PM Saturday): 13.5" (0.87") Bountiful (5 PM Saturday): 10.8" (not reported) Cottonwood Heights (7 AM Sunday): 17.5" (1.64") Holladay (7 AM Sunday): 15.5" (0.91") Summit Park (12 PM Sunday): 20" (not reported) Alta Collins (4 PM Sunday): 23" (1.16") Canyons 8800 ft (3 PM Sunday): 20" (0.90") It was a complicated storm featuring a frontal phase Friday night, a period Saturday and Saturday evening with strong enhancement along the benches, and a period Saturday night when the Little Cottonwood magic kicked in.  There are, however, a couple of key observations to be made.  The first is that the water-equivalents were largest along the east bench of the Salt Lake V...

If you want blower pow, last night was your storm.  From 5 PM yesterday to 6 AM this morning, the Alta-Collins observing site picked up a paltry .32" of water equivalent, but 10" of snow.  That's a mean water content of only 3.2%!   That's a snow-to-liquid ratio of 31-to-1.  If you want a big dump, but don't have a lot of water to play with, that's how to do it.  Really, conditions overnight were only marginally better for orographic precipitation generation than they were yesterday.  The 0000 UTC (5 PM MST Saturday) sounding still showed stable conditions at mid level with strong wind shear from 700 to 600 mb.  The morning sounding is a bit better with northerly flow through depths and colder temperatures aloft, although a weak stable layer remained just above 700 mb.  But the secret to the overnight dumpage wasn't large orographic precipitation enhancement.  There was some enhancement, but .32" of total water and a maximu...

A cold front moved across northern Utah last night bringing much needed snow from the valley floor to the highest peaks.  Powder panic brought gridlock to most (probably all) routes to the Cottonwoods, providing an all-too-frequent reminder that we are loving our canyons to death.  Those who braved the traffic were rewarded with knee deep powder.  I would describe the skiing as good, not great.  A spongy layer of high-density snow to start would have helped reduce the bottom feeding, but this year, beggars can't be choosers.   Snowfall produced by the front went largely as advertised by the models, at least in the upper Cottonwoods.  Alta-Collins had .59" of water and 7 inches of snow through 8 AM this morning.  This compares very well with the NAM forecast we discussed on Tuesday, which put out .64" of water and 8 inches of snow (see Frontal Snowfall Event on Tap for Late Tomorrow and Tomorrow Night ).  The observed wate...

For decades, snowfall forecasts have typically involved the issuance of a range of accumulation amounts, typically (but not always) based on a factor of two.  For example, 3-6 inches, 4-8 inches, etc. I have no idea why.  Perhaps it is a convenience thing.  Maybe people like it that way.  I don't know what that range even means.  Does it represent the middle 50% of possible outcomes, with a 25% chance of more and a 25% chance of less?  Does it represent the middle 80%?  Why always use a factor of two?  Sometimes the range needs to be bigger, especially in longer range forecasts.  And then there is my favorite, "higher amounts in favored locations."  What the hell does that really mean and how do you verify it?  There was a time when snowfall forecasting was truly guesswork, but things are changing.  Computer models are now capable or will soon be capable of simulating smaller storm details, what meteorologists call "cloud...

After another 10-day or so stretch with limited to no accumulations, our next storm will be served up late tomorrow and tomorrow night.  Most of the precipitation for the central Wasatch looks to be primarily frontally forced.  The large scale setup is shown below and features an upper level trough that is initially tilted from southwest to northeast (referred to as "positively" tilted by meteorologists) that closes off and becomes more north-south oriented as it moves inland across the western US.   This has both pluses and minuses for snowfall prospects in the central Wasatch.  The plus is that the front may slow as it drags through northern Utah, extending the period of frontal snowfall, as depicted below in the 1200 UTC NAM forecast.  At 000 UTC 20 January (5 PM MST Friday), the surface front is over Utah County with precipitation over the northern Wasatch.   Frontal precipitation fills in, however, as the front phases w...