Wasatch Weather Weenies

Today's basin-wide snowpack snow water equivalent analysis is quite remarkable.  Much of the interior western US is in the red, signifying <50% of the 1971-2000 average. Most impressive are the low numbers in Utah and Colorado where there are many high elevation basins that are typically just past peak snowpack in late April.  Observations from these states show only a few sites above 50% of average snowpack SWE. At the Spud Mountain SNOTEL in the San Juan Mountains (10,660 ft), the snowpack was completely gone a few days ago. The few sites in the San Juan Mountains that are above 50% of average snowpack SWE are all at or above 11,000 ft.  At Wolf Creek Summit (11,000 ft), snowpack SWE was running near average through February, when Mother Nature put on the breaks for storms and flicked the warming switch.  At this high altitude location, the average peak snowpack SWE occurs around May 1, but this year it appears like they are looking at a late March...

Today was the last day of lift served skiing at Alta.  My son coaxed me up for a few runs as he hates to miss the last day.  It's been a sub par year during which I have struggled mightily with a balky back, but we still had fun and made the best of it.  Here's to hoping next year is better. A highlight of the day was spotting these old Olin Comp SLs in the lift line. I actually sold a couple pair of these back in the day (1980s).  At the shop I worked at, we got a $10 commission on these babies, instead of the $1-$2 we got for other boards.  They were the Comp $L instead of the Comp SL for a starving college student. As the season concludes, I'm amazed that problems persist with the rascally facets (a.k.a. depth hoar) that developed earlier this year.  At least two slides during last week's heat wave failed on the old depth hoar (see here ,  here , and here ).  I didn't bother checking out this slide that pulled out above the ent...

Beautiful loop above of a developing upper level trough as it exits the Intermountain West and moves over the Great Plains today.  This is an infrared satellite image, but the wavelengths sampled are strongly influenced by the distribution of water vapor and temperature in the upper troposphere (usually above about 6 km).  As a result, it only sees the highest clouds and color contrasts in other areas reflect differences in water vapor and temperature.  The protrusion of red extending into central Kansas at the end of the loop is in the heart of what is typically called the "dry slot," where the upper levels have very low relative humidities.    In addition, flow around the developing low has also produced a beautiful isolated region of what is probably locally dry air in the upper troposphere over western Kansas.  Call it the eye of the storm if you will, although tropical cyclone aficionados will likely grimace.

With rain pelting my window and a cool, moist airmass in place, I slept like a baby last night.  In the mountains the storm delivered largely as advertised, laying down about 6" at the Alta-Collins site overnight, although snow water equivalents (SWE) were a bit higher than expected, totaling just over an inch.   Some of the SWE fell as rain early in the storm.  In fact, as the front moved in, snow levels looked to be near 11,000 feet.  About .35 inches of SWE fell before temperatures at Alta-Collins fell to below freezing.     The storm is now much colder with snow showers continuing over the Cottonwoods.  Fairly strong west to west-northwest winds are blowing at crest level, with gusts over the last 3 hours on Mount Baldy in the 60–70 mile per hour range.  Looking at the latest radar loop, I can't help but ask the question, "is this lake effect?" Precipitation is falling mainly over high topography downstream of the Great Salt...

As is often the case over the Intermountain West, we're seeing a nice surface frontal boundary develop during the day over eastern Nevada and southern Idaho.  Although a front was largely indistinguishable this morning, note the clear wind shift and contrast in temperature that currently exists from the southern Snake River Plain to near Elko Nevada. Frontal passage at Jerome, Idaho was quite apparent in the meteogram as temperatures were climbing in the pre-frontal environment, but dropped abruptly with frontal passage. I suspect we'll see further frontal strengthening (in terms of the abruptness of the temperature contrast) over the next few hours. Kudos to MesoWest for collecting and integrating surface observations from all over the western United States.  They are indispensable for frontal analysis!

Things are starting to get interesting to our west.  The regional radar shows scattered showers, some fairly heavy, over Nevada and Idaho. A close up from the Boise radar shows the linear nature of some of the stronger precipitation features. At the moment, however, there is no well defined surface front in this area, although one may develop during the day today over eastern Nevada.  I think we'll see a better organized front with a sharper airmass transition and wind shift develop later today. Looks like we will pick up a decent amount of valley rain with the frontal passage, and it is badly needed.  There's a chance we may get some showers ahead of the front as well if we can bubble up some pre-frontal convection.  Thunder and lightning?  Perhaps.   Mountain snow is also in the cards, but snow levels look to be quite high.  The forecast 700-mb (crest-level) temperature is around -1ºC as the front comes in this evening, and fa...

The next couple of days look to be quite interesting for northern Utah.  After three days of record breaking maximum temperatures (the 86ºF, 88ºF, and 86ºF observed at KSLC on Sunday, Monday, and Tuesday were all records for their respective dates and close to the all-time record high for April of 89ºF), change is coming. A deep surface and upper-level trough has developed off the coast of California and has tapped into moisture from the tropics and subtropics.  This moisture has streamed northward and is now pushing into southern California and the desert southwest. 1200 UTC 22 Apr – 1200 UTC 25 Apr 2012 IR satellite loop with GFS 925 mb (~750 m MSL) wind vectors and integrated water vapor We're near the end of the wintertime "rainy season" for that part of the world, but they will get some, especially later today and tonight as the upper-level trough sweeps across the region.   Places like Los Angeles and Las Vegas will see rain tonight, and panic ...

What a difference a year makes.  The contrast between last spring and this spring is staggering.  At Alta-Collins for example: 23 April 2011: Snow depth 181 inches, maximum hourly temperature 35ºF 23 April 2012: Snow depth 90 inches, maximum hourly temperature 59ºF Need I remind the skiers out there that the Alta-Collins snow depth reached a maximum of 207" on April 30th last year.  207"!  Further, the snowpack didn't drop to 100" until July 2nd.  In fact, there was more snow at Alta-Collins on July 4th last year than there is today . Utah skiers have experienced close to the full range of the Wasatch snow possibilities in just two years.

We've seen bad and good snow years over the past decade in the Wasatch Mountains.  Is there a trend? Detecting and determining the cause of snowpack trends over the western United States is a difficult task.  There are a number of reasons for this including: The lack of reliable, continuous snowpack and snowfall records in the early 20th century.  As a result, most analyses begin in about 1930 or 1950, which is a relatively short period.  Further, throughout the historical record, snowfall and snowpack observations have their warts, which complicates quality control and trend attribution.   There are large, natural year-to-year and slowly varying decade-to-decade variations in climate and snowpack characteristics, which complicate trend analysis.   Non-climatic factors can contribute to the observed trends and variations, including changes in observational techniques or locations, land cover (e.g., increased tree cover), and land use (e....

It was a spectacular day yesterday in Utah.  Temperatures were well above average, with the 80ºF high at the Salt Lake City International Airport.  The unofficial maximum temperature at the base of Alta was 64ºF. Overnight temperatures at Alta were about 5ºF warmer than Friday night.  The window for decent corn will probably be earlier and shorter today than yesterday.  At the Salt Lake City International Airport, today's record high is 83ºF.  We have a good chance of equaling or topping that as it should be a couple degrees warmer today.  In case you are wondering, the all-time record high for April is 89ºF.  

Not only because spring snow is slow, but also because the models are hinting at a possible return of winter late next week.

" Skiers will eventually find that the Brighton Basin, or the heads of the [Cottonwood] canyons within a short radius of this winter paradise, offer the best skiing to be found in the Wasatch Mountains. " - S. D. Green, U.S. Weather Bureau Meteorologist, 1935 Today we conclude our discussions of the snow climates of northern Utah by answering a question that I am frequently asked.  Is there a place in Utah with a better climate for deep-powder skiing than the Cottonwood Canyons? No.  Or maybe better put given the uncertainties, probably not.   The S. D. Green quote above pretty much sums up the situation.  Green was the original Wasatch Weather Weenie, a meteorologist and an avid backcountry skier .  Some of his photographs are part of the ski archives in the University of Utah Marriott Library .  He and the early ski pioneers recognized pretty quickly that there was something special in the upper Cottonwood Canyons.   S. D. Green ph...

Sharp Peak in Utah's Oquirrh Mountains A few readers have contacted me asking about the snow climate in the Oquirrh and Stansbury Mountains west of Salt Lake City.  The Oquirrh Mountains flank the western Salt Lake Valley, reaching elevations of up to 10,620 feet, while the Stansbury Mountains are the next range to the west and reach 11,031 feet at the summit of Deseret Peak. To my knowledge, there are no long-term, publicly available snowfall records from the upper elevations of either mountain range.  It is possible that Rio Tinto/Kennecott has such records as they have explored ski area development on their land in the Oquirrhs at various times over the past few decades, most recently a few years ago (e.g., here , here ).  Others have proposed resorts in the Oquirrhs as well (e.g., here ).   SNOTEL observations from the Rocky Basin site at 8900 feet in the central Oquirrhs show that average snowpack SWE reaches a maximum of about 25 inches in early-mi...

In an earlier post, we discussed some of the remarkable weather contrasts that existed between the Cottonwood Canyons and the Wasatch Back during the day on Sunday.  This included a pronounced cloud shadow that formed over the Wasatch Back and Park City Mountain Resort (PCMR), as well as the occasional spillover of precipitation across the Wasatch Crest.  Also, it was readily apparent that the snowpack at PCMR was substantially thinner than that found in the Cottonwood Canyons. Dorothy, we're not in Little Cottonwood anymore. Although the lack of snow at the base of PCMR on Sunday is partly related to elevation (the area pictured lies between 7000 and 8400 ft) and aspect (east to northeast), even on elevations and aspects similar to those at the resorts in Little and Big Cottonwood Canyon, the snowpack was markedly thinner.  This is confirmed by SNOTEL observations from Sunday at Snowbird in Little Cottonwood Canyon (31.5" SWE and 78" snow depth @ 9640 ft) and Thayn...

A weak baroclinic trough is moving through this morning, but it has produced a nice period of steady rain over northern Utah.  Note how the radar coverage filled in nicely as the system approached Salt Lake City, giving us a good soaker. With fairly continuous radar coverage, one can see some of the areas where the radar is partially blocked by the topography, leading to lower radar reflectivities (see red lines) farther from the radar. Unfortunately, this is one of the challenges when operating a radar in complex terrain.

The Wasatch Weather Weenies don't spend much time on the Wasatch Back during winter.  We like being in the Cottonwood Canyons where there's a greater variety of storms and a deeper snowpack.      However, thanks to some free lift tickets from a friend, we ran laps yesterday at Park City Mountain Resort (PCMR) where we got a great look at some of the leeward effects of the Wasatch Mountains. As shown by the 1800 UTC (1200 MDT) 15 April 2012 NAM analysis, yesterday featured large-scale northwesterly flow at crest level and through most of the troposphere. This led to the development of low clouds over the western (windward) slopes of the Wasatch Mountains, including the Cottonwood Canyons (in lower left-hand corner of red box below).  In contrast, a pronounced cloud shadow was found downstream of the Wasatch Crest (right side of red box). Early in the morning, this led to beautiful sunny skies at  PCMR, with low clouds hanging over the Wasatch Cre...