Wasatch Weather Weenies

If the snowfall history page on Alta's web site is correct, they've had 102" of snow this April.  During this past week, the Alta-Collins peaked at 161", which I suspect is the highest since the epic 2010/11 season. The SNOTEL data from Snowbird shows a roughly 8 inch increase in water equivalent for the month.  We now sit just below 60 inches of snow water equivalent, about 15 inches above average. Source: NWS Having missed the entirety of our most recent storm cycle, I'm forced to reminisce about 2010/11, which still reins supreme, with a larger increase in snow water equivalent for the month and a snow water equivalent of almost 75 (see cyan line above).   I got a reminder from Facebook this morning of just how great that season and April was.   Meanwhile, in the valley, the Salt Lake City International Airport is now up to 6.73" of precipitation since March 1st.  That rates as the 5th wettest March–April period on record. For those of y...

I'm still out of town and you continue to reap the benefits.  Through 4 AM MDT, another 9 inches overnight at Alta–Collins. Total snow depth is now at 149" and approaching the Big One-Five-Oh.  I believe that puts it at the deepest snowpack of the season, although I haven't done an exhaustive check.  

I hope you people are happy for my sacrifice.  I sit this morning in a coffee shop in central Pennsylvania with a light rain falling and leaves on the trees.  Winter is thousands of miles away. Meanwhile, in the Wasatch Range, the Steenburgh Effect is working wonders.  Alta–Collins has received 15 inches of snow since yesterday morning, with 9 inches overnight. Source: MesoWest With temperatures falling overnight, and now sitting at 23ºF, I bet there are some good turns to be had at upper elevations. Make some for me.

I am currently on travel, which is good news for you, because it means the Steenburgh effect is en force.  I haven't had time for a proper look at the models, but did notice that they are looking active for this week, as evinced by the NAEFS ensemble plumes for Alta. As we mentioned a week or two ago, it ain't over until it's over.  Keep the skis waxed and get on it before it's baked. Last night I received the Charles Hosler Alumni Scholar Award from Penn State's College of Earth and Mineral Sciences for contributions to the development of science through teaching, research and administrative leadership. Dr. Hosler served his country in WWII and Penn State as Prof. of Meteorology, Dean of Earth and Mineral Sciences, VP of Research, Dean of the Graduate School, and Provost. He also signed my acceptance letter to Penn State in 1985. It was an honor to sit with him and receive the award from Dean Bill Easterling. I'm pretty shocked about the whole thing ...

Another day, another front, another gasp of lake effect.  Radar imagery this morning shows some lake-effect precipitation over the Salt Lake Valley and the central Wasatch. Alta-Collins is now up to a storm total of 8 inches.  Some of that is from yesterday's and yesterday evening's non-lake-effect convection, but some of it is lake effect.  Might be some decent spring skiing up there today. The fact we've had a couple of brief lake-effect episodes this month shouldn't be a surprise.   We are in the heart of the spring lake-effect season .  A curious aspect of lake effect produced by the Great Salt Lake is that it's not most common during the heart of the ski season, but instead during the shoulder seasons.  The primary peak in lake-effect frequency (and amount) is in November, and the secondary peak is in March and April (depending on if you are looking at amount or frequency). Average number and amount of precipitation produced at Snowbird by G...

Meteorological radars are designed to detect precipitation, but any objects of sufficient size and number concentration will give you a return. This morning's radar loop, for examples, shows returns that are almost certainty from birds leaving their roosts along the wetlands surrounding the Great Salt Lake.  Note in particular the plume-like development and dispersion of echoes from near the southeast shore of Farmington Bay and the Bear River Migratory Bird Refuge. To the west, you can see some echoes created by precipitation.  Some April showers are on tap for today.  

April showers bring May flowers.  The combination of abundant moisture and good large-scale forcing yielded a solid frontal precipitation band that swept through northern Utah last night.  Below is the KMTX radar image from about 0100 UTC (1900 MDT) yesterday evening.  Something for everyone. Source: NCAR/RAL About all we missed out on was severe thunderstorms.  There were some lightning strikes in the area, as indicated below, but I didn't see any strong wind or hail reports on the SPC web site this morning.  That's probably for the best.  It is only in the warped mind of a meteorologist that one is disappointed when severe weather doesn't materialize. Source: lightningmaps.org Rainfall reports reported to the National Weather Service show accumulations over .9 inches at several sites along the east bench.  The airport came in with 0.65 inches.  Those are good totals for a relatively brief storm.   As of 7 am, Alta-Collins has ...

I got some odd stares this morning carrying my umbrella on the bus, but I know better.  A juicy airmass is in place over the Great Basin and, with good dynamics later today, we're in for a wet period later today and tonight. First, let's take a look at the moisture that we have in place upstream.  The 1200 UTC (0600 MDT) sounding from Elko shows a near saturated atmosphere through most of the troposphere, with the exception of a dry layer just above 500 mb. Source: SPC The total precipitable water in this sounding is 15 mm (0.6 inches).  The sounding climatology shows values of 0.6" are near, but not quite at the upper-limit of prior observations at Elko.  There are a few days in mid-to-late April with values reaching about 0.65-0.67".  Nevertheless, 0.6" is pretty high for April. Source: SPC If we look at the return interval of the precipitable water forecast produced by the North American Ensemble Forecast System for 1200 UTC (0600 MDT) this mor...

Today marked the last day of lift served skiing at Alta and the end of an era for the resort as General Manager Onno Wieringa retires after this season. Onno was a strong supporter of weather research and forecasting efforts in Little Cottonwood Canyon and the Wasatch Range.  Alta was the first ski area to begin supplying weather observations to the "Utah Mesonet," predecessor to MesoWest  (special thanks as well to Alta Ski Patrol, especially Howie Howlett and Titus Case).  Before the advent of MesoWest, weather observations were sparse to non-existent across most of the Wasatch Range.  Today, we get observations from nearly all of the ski resorts and they make a huge difference.  The Alta-Collins site, in particular, provides very high quality snowfall and snow water equivalent measurements that are used by everyone who forecasts in the Wasatch Mountains including the Utah Avalanche Center, National Weather Service, UDOT, utahskiweather.com, opensnow.co...

Greenhousing is a commonly used word in the snow and avalanche business.  It may be 12 letters long, but for powder skiers, it is essentially a four-letter word because it leads to snowmelt and melt-freeze crusts. Although I didn't do an exhaustive search, it's actually quite difficult to find a good definition or explanation of greenhousing.  It is not defined, for example, in the National Avalanche Center Encyclopedia , and isn't in the indexes of the avalanche books that I have on my shelf.  One can, however, find discussions of the importance of the  greenhouse effect , such as this passage from The Avalanche Handbook by David McClung and Peter Schaerer: "Conditions leading to the formation of wet-snow avalanches by radiation in the spring are governed by the net radiation balance of the snow surface. The net balance includes both long-wave (terrestrial) and short-wave components (sunlight). Direct sunlight warms the snow cover, making wet-snow avalanche...

Spring is the time of strong cold-frontal passages, as defined based on large, rapid temperature changes, especially in the Intermountain West.  This is quite clear if we look at the frequency of strong cold-frontal passages across the western United States by month, which shows a peak in the late spring (May).  There is a similar peak in the Intermountain West, but it is more pronounced and reaches a maximum in June. Source: Shafer and Steenburgh (2008) There are two major reasons for the spring peak.  One is that it is still a synoptically active period, with frequent trough passages.  The second is that surface heating is also quite strong, which leads to daytime frontal intensification.  As a result, the frequency of strong frontal passages is highest in the late afternoon (~1800 local standard time) and shifts to later in the day as one moves from winter to summer. Source:  Shafer and Steenburgh (2008) Intermountain fronts strengthen during ...

This weekend's storm provided a wonderful exclamation point for the ski season.  Really, I was feeling depressed about how the season was going out with a whimper rather than a bang.  From March 5th to April 8th, there was only one day during which Alta recorded 10 inches of snow (March 27th) and we suffered through the hottest March on record.  Corn is fine, but I'd rather be skiing powder.  For April, Sunday was as good as it gets, and I liked it so much that I did a dawn patrol yesterday morning to get in some more turns before class. My season now feels complete, although it's never over until it's over.  I've skied good (not great) powder on Memorial Day weekend in the Wasatch.  It happens. And, while we're talking about it not being over until it's over, we turn our attention to California.  The models continue to show this prolonged period of southwesterly large-scale flow over the eastern Pacific and western US in which California continues...

I had the good fortune to be able to ski tour with my son today.  We found some of the best April snow that I've ever skied.  Bottomless, right-side up, hero snow.  My personal favorite, especially in April.  A few shots of the kid getting the goods.

Morning has broken and the GOES-16 visible imagery is simply beautiful and shows clearly the two frontal bands that will influence our weather today and tonight, the first over northern Utah and the Salt Lake Valley right now (as if you needed a weatherman to tell you that) and the second moving across northern Nevada.   Source: College of DuPage Talk about well defined.  Really, you aren't going to see two more distinct frontal systems than that in the Intermountain West. Radar imagery through 1406 UTC (0806 MDT) shows the frontal band progressing across northern Utah with a well defined back edge.  Perhaps I will be able to get in a bit of gardening today after all. One thing that I noticed in the overnight model runs is how colossally bad the 0600 UTC 3-km NAM forecasts were for this morning.  The end of the loop above shows a very wide and broad frontal precipitation band over the Salt Lake Valley and surrounding area, but the 3-km NAM has nothing ...

I love spring storms, so I'm feeling like a kid in a candy shop today. Winds picked up yesterday and gusted strongly overnight in advance of a developing trough and surface front over Nevada.  After midnight, peak gusts at upper-elevation locations in the northern, central, and southern Wasaatch are 82, 77, and 70 mph, respectively.  In the valleys, the Great Salt Lake Marina hit 60 mph and a sensor near the juncture of UT-201 and I-80 in the Salt Lake Valley hit 63 mph. Winds as I write this have actually slackened just a bit.  Obs from the juncture of UT-201 and I-80 show two periods of strong winds overnight, on prior to midnight, the other from about 1:30-4:30 AM. Source: MesoWest With the development of the front and surface trough over Nevada today, as well as daytime surface heating, we will see strong winds today.  Given the prolonged nature of the event, dust is likely as well.   The models are still calling for two fronts to move through n...

The latest model forecasts are advertising what I'll call a "cold front double whammy" for the weekend with two pronounced frontal passages. The 0600 UTC initialized NAM shows precipitation associated with the first front over northern Utah at 1200 UTC (0600 MDT) Saturday morning.   And then the precipitation associated with the second front over northern Utah merely 18 hours later at 0600 UTC (0000 MDT) Sunday.  Time-height sections show each of these features quite well.  Keep in mind that by convention, time increases to the left in these time-height sections.  Thus, you can see the pre-frontal southerly flow and low-level dry air that will predominate through late tomorrow on the right side of the diagram.  Tomorrow could be quite windy with blowing dust and perhaps some elevated convection and a slight chance of a thunderstorm.  The bottom falls out with the frontal passage.  Note how the freezing level (blue line) drops, bottom...

When I was an undergraduate at Penn State, Craig Bohren was my physical meteorology professor and my advisor.  He had two major influences on my career.  First, sometime perhaps late in my junior year, he told me that I had pretty good grades in math and physics and that I should think about going to graduate school.  Up until that time, I hadn't considered it.  In hindsight, it was only a brief comment, but one that completely changed my life path. Second, Craig taught in a very unconventional way.  The usual approach in physical meteorology is to subject students to long derivations and heinous interpretations of mathematical relations for cloud and radiative processes.  The approach can be very dry and unappealing.  In contrast, Craig almost always began with an example, typically a photo taken on his walks to, from, and around campus, and then insisted that we explain the subject. One day he came in with photos of manure heaps, and asked us to ...