Wasatch Weather Weenies

I have lived in Salt Lake City for over 25 years.  During that time, I have been a trail runner, mountain biker, and hiker, although I can no longer do the former.  I recreate in the Avenues foothills probably 3 or 4 days a week, sometimes more.  I've even ski toured in them.   I'm old enough to remember when the segment of the Bonneville Shoreline Trail from Pipeline Pass to Dry Creek was constructed, as well as the segments from Morris Meadow to City Creek Canyon and from City Creek Canyon to North Salt Lake.  All of these trail additions improved the quality of life and access to outdoor recreation for Salt Lake City area residents.   So when I saw plans a couple of years ago to expand the foothills trail network, I was excited.  The Bonneville Shoreline Trail was becoming increasingly crowded.  Lots of bikers and hikers.  The plan included hiking only trails, downhill biking trails, hiking and uphill biking trails, and multiuse ...

Forecasts for this weekend, especially Saturday night and Sunday, are looking good.  It appears rain is likely, and we've reached the time of year where every storm and every drop should be appreciated.   Although we may get get some rain today or Saturday in the form of showers and thunderstorms, the best chance for a soaker is Saturday night and Sunday when the upper-level trough that is currently spinning to our west over Nevada finally decides to head across northern Utah.  The GFS forecast valid 1200 UTC (0600 MDT) Sunday shows the trough with widespread precipitation over much of northern Utah.   The storm will be cold enough for upper-elevation snow.  GFS forecast snowfall for Saturday night and Sunday totals about 10 inches at Alta-Collins.  The downscaled NAEFS has a fairly large range for Alta-Collins, but the mean for the period from 0000 UTC 23 May (1800 MDT Saturday) to 0600 UTC 25 May (0000 MDT Monday) is about 9 inches.   ...

Snowbird announced yesterday that last weekend was their last operating weekend of the 2020/21 ski season.   While we aimed to have another weekend of operations, Mother Nature had other plans. Due to current conditions, Snowbird is now closed for the 2020-21 winter season. Thank you to everyone who joined us—we're looking forward to getting back on snow with you for our 50th season. pic.twitter.com/xJ680WqIrZ — Snowbird (@Snowbird) May 19, 2021 Such a decision is based on several factors, but we'll focus first here on the state of the snowpack as of today, May 20th. SNOTEL observations show a dearth of snow across northern Utah (i.e., north of I-70/US-6).  Only USU Doc Daniel (11.5") above Bear Lake, Lakefork Basin (7.9") and Steel Creek Park (8.9") in the Uinta Mountains, and Snowbird (12") report have more than 2" of snowpack water equivalent.  Most of the remaining sites have nothing.   The duration of snowcover in the spring depends on several fac...

There is a tendency when it comes to SNOTEL observations to focus on the percent of average or median.  That can be useful, but more important for skiing is often the snowpack water equivalent (SWE), as that is what tells you how fat the snowpack is.   A look at the SWE values for yesterday shows a dismal situation across much of California, Nevada, and Utah, with only a few sites still reporting some snowpack SWE.   Source: NRCS If you squint, you can see one of these is Snowbird, which sits at 15.7 inches, about half of the late April peak, 38% of median for the date, and in the bottom 1/5 for the date.   Source: NRCS For snow, there are options to our east (Colorado) and north (western Wyoming and Montana), but to the northwest, the snowpack in the Washington Cascades is fat and healthy.  Many sites report SWE in excess of 35 inches.  Here's one for you...Easy Pass at 5270 feet in the North Cascades east of Mount Baker.  Current SWE i...

When we think about how mountains affect the production of clouds, we often assume that the air rises, cools, and produces clouds on the windward side of a mountain range (i.e., the side facing the flow) and sinks, warms, and dissipates clouds on the leeward side (i.e., the side facing away from the flow.   Source: Whiteman (2000) This is often a good assumption at low levels if the flow is moist and sufficiently strong to surmount the mountain range.  However, there are times when cloud generation occurs on the leeward side of mountain range.   This happened overnight downstream of the Deep Creek, Schell Creek, and Snake Ranges of Nevada.  As shown in the photo below, mid- and high clouds formed or became enhanced downstream (east) of these ranges.  In this instance, it is likely that the flow at low levels was sinking and warming on the eastern/leeward slopes of these ranges as depicted in the schematic above.  However, at mid and upper levels...

Thanks for letting me disappear for a few days to take a break after the end of the academic year.  It was a long one and I needed to reset my sanity.   The limited snowfall in the Sierra Nevada this year created an unusual opportunity for early May corn skiing and mountain biking in the Tahoe area.  We took off last week and did a couple of days of mountain biking, a day of Alpine skiing, and a day of ski touring.   After arriving in Truckee and doing and evening ride on the Donner Crest trail, we skied a day at the famous north Tahoe ski resort that has served as the home or base for many great skiers including Tamara McKinney, Julia Mancuso, Shane McConkey, and Cody Townsend.  Given the limited seasonal snowfall, conditions varied some depending on elevation and aspect... Sadly, KT-22 was closed, so we kept ourselves occupied with laps involving the One Express and Siberia trails, venturing frequently over to the area around Headwall Express (which ...

I've never been a fan of the phrase "climate normals" to describe averages of past climate.  It perpetuates the myth that climate is stationary and it suggests that an average is normal when weather normally fluctuates in a range.  I grimace whenever I hear someone say "normally the high today is 64˚F."   I always wondered who started using this phrase and why.  I don't know the answer to that question, but according to the National Centers for Environmental Information (NCEI), about 100 years ago the World Meteorological Organization (WMO) instructed member nations to calculate climate normals using 30 year periods, beginning with 1901-1930.   So, near as I can tell, we call them climate normals and we average over a 30-year period because we've always done it that way.  That's simply not a good reason, especially now that we are living in a period of accelerating climate change and we know that for some regions, a 30-year average is likely insu...

We suggested a few days ago that the end of the snow accumulation season was nigh.  Observations from the Snowbird SNOTEL show that peak snowpack water equivalent was reached on April 28 (32.7") and that we dropped below 30" yesterday.   Source: NRCS The Alta-Collins snow depth fluctuated around 100 inches for the better part of a month, but is now in decline, having dropped to around 90 inches this morning.   Source: MesoWest Forecasts through the end of the work week keep us generally dry.  We're likely over the crest now even on high north facing terrain.   We got out for some "snirty dancing" on Saturday.  At the start of our tour, it was 47˚F at 7 am.  Disgusting.  Nevertheless, there was a shallow freeze and turns were good on southern aspects where the most recent storm snow had melted out.  Look close and you can see the snirt – dirty snow where dust from storms over the past few weeks has emerged onto the snow surface....