Wasatch Weather Weenies

Yesterday's cold-frontal passage probably brought more dust to the central Wasatch than snow.  Frontal passage at the University of Utah featured the usual wind shift and temperature drop, but also a spike in PM2.5 associated with blowing dust. Peak concentrations at the U reached almost 15 ug/m3, which equates to a moderate air quality level.   Cameras at the University of Utah caught the post-frontal dust and gravity-current-like nose of the cold front passing through the Salt Lake Valley. Post-frontal dust and gravity-current-like nose of cold front that just passed through Salt Lake shows up well in this video. Watch carefully for the moonset too. pic.twitter.com/qr27dhAiu8 — Jim Steenburgh (@ProfessorPowder) March 29, 2021 And check out the terrain induced flows over western Nevada with dust from the Carson Sink providing a great tracer.  Large dust storm pushing south through the Nevada desert towards the California border. @NWSReno #NVwx pic.twitter.com/aYd...

I hope you enjoyed the cooler and somewhat snowier weather over the past week as it appears that things will be changing moving forward.   Over the past week, I finally got out and got some ski touring in and enjoyed skiing powder again.  Yesterday provided a weather potpourri of low visibility and occasional snow and graupel showers with the cloud over acting to preserve the powder through the day (thankfully).   The graupel was generally light, but during one heavier period, we were treated to graupelfalls over some of the cliffs where we were touring.   The snow over the past week on upper-elevation north-facing aspects survived quite well thanks to a progression of cold troughs.  Forecasts for the next week are not as optimistic.  The GFS and other models forecast a strong frontal passage Monday, but without a lot of moisture.   Thus, it will be cold, but likely a dust on crust event.  The remainder of the work week looks d...

It has not been a great snow season across Utah and southern Wyoming.  The vast majority of SNOTEL stations sit below median snowpack snow water equivalent.  Source: NRCS However, if you look carefully, there are some sites that are above average and in a few cases well above average.  In particular, check out sites along the north slope of the Uintas, over the Tavaputs Plateau in eastern Utah, and along the Laramie Mountains of eastern Wyoming.   These are sites that are relatively dry, with low median peak snow water equivalents of 15 inches or less, but got creamed during the period of the Front Range Blizzard in mid March.  One outlier event has made their whole season.   For example, Hickerson Park on the north slope of the Uinta Mountains has a low median peak snow water equivalent (< 10 inches), picked up over 4 inches of water equivalent during the Front Range Blizzard period, lifting them to median peak SWE (note that the green box is ...

There's gonna be some great skiing out there today.  The Utah Avalanche Center reports 12-17" in Big Cottonwood and 16-20" in Little Cottonwood.  That makes this storm a nice little overproducer and puts it into Goldilocks territory.  Radar still shows some snowshowers this morning.  I decided to skip this morning's powder panic in the canyons and instead reflect back on yesterday, which provided a great example of why I prefer a dusk patrol over a dawn patrol. I woke up with the frontal passage and enjoyed a breakfast of Tirolean Kaiserschmarrn, a high-density pancake that one shouldn't eat unless large calories are needed for ski touring.  Seeing the snow was just beginning, I enjoyed a morning tea and watched the World Cup finals.  No globe for Shiffrin this year, but it's hard not to like Austrian Katherina Liensberger who soars through slalom gates with a big smile on her face and won the slalom globe and final race of the season.   I then to...

We are entering the time of year when we see the strongest cold-frontal passage.  This is due in part to the fact that (1) we actually get cold frontal passages this time of year and (2) the high sun angle drives processes that increase and sharpen the temperature contrast across the front.   The cold front that will move across northern Utah tonight and tomorrow looks to be a good one, but the timing as currently forecast is off for Salt Lake City to maximize the sharpness and intensity of the frontal temperature drop.   Below is the NAM forecast for 1800 UTC (1200 MDT) tomorrow showing a shift from prefrontal southwesterly flow and post-frontal westerly flow across the front, which is draped over the Salt Lake Valley.   Because of the frontal passage, the change in temperature from this afternoon to tomorrow afternoon will be dramatic.  The forecast high for the Salt Lake City International airport for today is near 70˚F, whereas tomorrow aftern...

Several months ago, Alex Nabaum contacted me for snowfall data from Alta for a project he was working on. I get such requests from time to time, but this one was different because Alex is a professional illustrator and was interested in integrating this data into the concept for a poster he was working on. I'll let Alex tell the story behind his poster and encourage you to check it and some of his other offerings out at  https://www.skiposters.art/ .  40 years of Alta Snowfall Season Totals, Hidden in This Poster Alex Nabaum Poster © 2020 by SkiPosters.art I’m a professional illustrator, skier and lover of ski resort history. Especially Alta’s. My grandfather Sherman Nabaum was chairman of the Winter Sports Committee that raised money to get skiing started at Alta in the late 1930’s. A few years ago I went searching for ski resort posters to hang in my house, but was disappointed with the posters available.  Albeit beautiful, they all looked so similar.  The unique ...

It's been a while since we took a look at the proposed transportation alternatives for Little Cottonwood Canyon.  We last visited this issue on June 9, 2020 (see Little Cottonwood Canyon Transportation Alternatives ) when public comment was being sought on three proposed alternatives: enhanced bus with no additional roadway capacity, enhanced bus with roadway widening, and a gondola from the mouth of the canyon.  All three include bussing enhancements along Highland Drive and Wasatch Boulevard. UDOT actually received, identified, and evaluated 19 proposed alternatives from the public comments including everything from direct gondola to Snowbird and Alta from the gravel pit (eliminated as it would traverse wilderness areas) to a tunnel loop system with autonomous vehicles (eliminated due to a lack of existence of a fully operational system currently).  A full run down is available in the addendum report issued in late November 2020 .  Below is a summary of the five cu...

If you are looking for oddities in the snow climate of the western United States, the area near and immediately east of the Continental Divide is a good place to start.   First, let's talk about the snowiest month of the year, as illustrated in the plot below from Brian Brettschneider.  Most of the western United States and Canada west of the Continental Divide sees their snowiest months in December, January, or February.  However, near and east of the Continental Divide, the snowiest months are late in the cool season and in many areas in February, March, or even April.   Snowiest month of the year (now featuring Canada). pic.twitter.com/nA2GvHhsGE — Brian Brettschneider (@Climatologist49) March 5, 2021 Focusing on the Front Range region of Colorado, based on average snowfall, the snowiest month in Boulder is March (16.1").  The least snowy month from November to April is actually January (9.7").  One of the reasons for this is that the late wint...

Following up on the previous post ( Decimated Low-Elevation Snowpack ), our woefully warm, windy, and dusty weather continued through yesterday when once again we hit a high of 70˚F at the Salt Lake City Airport.  So, maximum temperatures for the last four days were 62, 70, 60, and 70 and the average temperature for the 4 day period was four day period was 51.9˚F, the 2nd highest on record behind only...wait for it...2020.   Source: NOAA Regional Climate Centers An unfortunate aspect of our snowpack observations is that there really aren't any in sites in lower elevation or south aspect areas that experience the most snow loss in these situations.  Thus, we are stuck with sites in locations that tend to preserve snow, but even then, lower elevation sites suggest a ripening (warming to 0˚C through depth) and net loss of snow (note that sublimation could have contributed to these losses in addition to melting).  For example, the Little Bear site at 6,458 feet just...

A few numbers to summarize our current warm wave. Yesterday's maximum temperature of 70˚F was only the 4th time 70˚F has been observed in Salt Lake City on or before March 6.  Other years with a maximum temperature of 70˚F on or before March 6th are 1879 (70, March 6), 1921 (71, March 3), and 2020 (70, March 6).   Going back for the past two days, the average maximum was 66.0˚F, 6th warmest on record. For the past three days, the average maximum was 63.0˚F, the also good for 6th. For the past four days, the average maximum was 63.0˚F, 3rd warmest on record. And finally for the past five days, the average maximum was 61.6˚F, 5th warmest on record.   Thus, this warmth is not unprecedented, but it is on the high end of what has been observed in early March.   Additionally, it is occurring during a season in which the snowpack is below average, especially in the lower elevations.  As such, the low-elevation snowpack has been decimated anywhere that ge...

The phrase cold pool is used for several meteorological phenomenon, including topographically confined layers of cold air that are confined by a warmer layer aloft.   There are two types of cold pools: diurnal and persistent .  Diurnal cold pools form during the evening or night and decay with surface heating the following day.  Persistent cold pools occur mainly in the winter and last through at least one daily heating cycle or more.  Colloquially, persistent cold pools in northern Utah are known as inversions.   There is a remarkable transition in the characteristics of cold pools in northern Utah from February to March.  During this period, days are getting longer and the angle of the sun relative to the horizon at a given time of day is increasing, resulting in a dramatic increase in the amount of solar energy intercepted by the Earth's surface and available to heat the lower atmosphere. Through about the end of February, especially when the...

The past few days I've been watching the models closely to see if the southern-branch storm that will bring some snow to the upper elevations of central and southern Utah tonight and tomorrow might give some love to the central Wasatch.   Every now and then the models give a glimmer of hope, but the latest GFS keeps the precip to the south.  Most impressive with this storm is the very sharp transition in relative humidity and precipitation southeast of the central Wasatch.   This is consistent with the vast majority of downscaled SREF members, 21 of which give little to no precipitation for Alta-Collins.  If you must cling to hope, there are 4 that give around 4-5 inches and one that gives just over 8.  There's also the Euro, which does bring precip into Salt Lake County tomorrow morning.   Source: pivotalweather.com So, this really is a forecast of location, location, location.  If the storm stays to the south, it's probably a complete ...