Snowbasin Forecast Guidance

For a long time, I've neglected our friends in the northern Wasatch, but that is changing this year as we will be conducting a major field campaign focused on that region this winter.  More on that in a future post.  In preparation for that campaign, we just dropped a new Snowbasin forecast guidance product on weather.utah.edu.  It's available from a link along the top bar or directly at https://home.chpc.utah.edu/~steenburgh/ml/hrrrsnowbasinforecast.html.  It should update regularly, but we're not watching things all the time, so always check the dates before using.  

This new Snowbasin forecast guidance is based on the HRRR and uses machine learning to improve the prediction of several variables.  There's a graphical product (the example below is from last season):

and a tabular summary:

We provide wind forecasts for three locations: Ogden Peak (OGP), Strawberry Gondola Top (SB2), and the Boardwalk snow-study plot (SBBWK).  The first two are on the Snowbasin Ridge line and very wind exposed.  The latter is in a wind sheltered mid-mountain area.  We provide temperature forecasts for the aforementioned locations plus the Middle Bowl observing site (SNI), which is near the bottom of the Middle Bowl chair, and the main base area (SBE).  All of these forecasts are based on machine learning algorithms applied to the HRRR.  

There is also the height of the 0°C wet-bulb temperature level, which is a rough estimate of the top of the melting layer (snow level is typically several hundred feet below this).  This is based on a profile from the HRRR just upstream of Snowbasin and referred to as the wet-bulb-zero level or WBZ.  The precipitation fields, including snow-to-liquid ratio/water content, hourly and totally precipitation, and snowfall amounts, are for the Boardwalk site.  Water equivalent precipitation is directly from the HRRR. Snow-to-liquid ratio/water content are based on a new machine learning algorithm developed by Michael Pletcher, a graduate student in my group.  We apply these to the water equivalent precipitation to obtain the snowfall forecasts.  

The graphics are organized so that the precipitation related plots are plotted on the left and the temperature, RH, and wind plots are on the right.  From top to bottom, the precipitation-related plots include:

1: Hourly water equivalent (bars) and total water equivalent (black line) at Boardwalk.
2: 700-mb temperature (purple line) and relative humidity (green line) over Boardwalk.  These are useful for estimating cloud conditions at crest level, which is typically just below 700-mb at Snowbasin.
3: Wet-bulb zero level (black line) and 1000 ft below the wet-bulb zero level (green line) with color-fil between.  This is based on a high-resolution profile just upstream of Snowbasin and provides an approximation for the melting layer.  We use the profile upstream of Snowbasin so we can have data down to roughly the elevation of Ogden and because the National Weather Service provides a very high resolution profile from the HRRR over the Ogden airport.  Color fill is used to indicate the elevation of key locations at Snowbasin.
4. Hourly snow-to-liquid ratio (bars) at Boardwalk with light blue used for non-precipitating period and dark blue for precipitating periods. Inclusion of non-precipitating periods allows one to have an estimated snow-to-liquid ratio during periods when the HRRR doesn't produce precip (but Mother Nature might). 
5. Hourly snow (bars) and total snowfall (black line) at Boardwalk.

From top-to-bottom, the temperature, RH, and wind plots are:

1. Hourly temperature at OGP, SB2, SBBWK, SNI, and SBE following the embedded legend.
2. Hourly RH at OGP, SB2, SBBWK, SNI, and SBE following the embedded legend.
3. Hourly wind speed (red line), wind gusts (blue line), and wind direction (black dots) at OGP. Wind speed and gusts based on the left-hand y-axis.  Wind direction the right-hand y-axis.
4. Same as 3 except for SB2.
5. Same as 3 except for SBBWK.  Winds at this site will be weaker and more erratic, and that is evident in this plot.

The primary strengths of this product are its intentional design for Snowbasin and the use of machine learning to improve the HRRR forecasts, which are too low-resolution to adequately capture local effects.  The weaknesses are that its based on one model (the HRRR), rather than an ensemble, and we are not currently using any machine learning to improve the water equivalent forecasts (that could be done but I only have so much time in the day).  One, however, can also consult our experimental plumes from the RRFS Ensemble (https://weather.utah.edu/index.php?runcode=2025100306&t=rrfsqsf&d=PL&r=SNI) and Utah Snow Ensemble (https://weather.utah.edu/index.php?runcode=2025100300&t=ensgefsds&d=PL&r=SNI).  In doing this, one should recognize that the plumes are for the nearest grid point to Middle Bowl, not Boardwalk as in the HRRR-derived product above, and that the RRFS, and Utah Snow Ensemble have different terrain representations.  As a result, the product above is for about 8000 feet, whereas the RRFS plumes are for 6864 feet and the Utah Snow Ensemble for 8282 feet.  This can be important to consider during events with marginal snow levels.

Comments appreciated.  Criticism ignored.  Actually, that's not true, but like all of our online products, we do what we can with limited time.  Yes, we know the web page is not mobile-device friendly.