Tuesday, November 7, 2023

Some Updates on weather.utah.edu

I'd like to share a few updates that we've made to products on weather.utah.edu since last winter. 

The Little Cottonwood forecast guidance derived from the HRRR (https://www.inscc.utah.edu/~steenburgh/ml/hrrrlccforecast.html) and GFS (https://www.inscc.utah.edu/~steenburgh/ml/gfslccforecast.html) has been updated with retrained machine learning algorithms that include last season in the training dataset.  An example from the GFS is below.  

We also added a temperature forecast for the Collins (9662 ft) observing site, which is a bit more representative of mid-mountain conditions than Mt. Baldy, which is still included as it is useful for ridge-top temperatures.

The new snow-to-liquid ratio (SLR) algorithm is based on a technique known as a random forest trained with observations from Alta-Collins.  It is more accurate and should produce a somewhat wider range of SLRs (up to about 25:1 if conditions are right) than the technique we used last year.  We thank Alta Ski Patrol and Alta Ski Area for continuing to provide access to weather observations and snow measurements so that we can produce products like this.  

We also updated the SLR algorithm used in our experimental HRRR snowfall products, and example of which is below.  

This also uses a random forest, but trained with data from 12 snow-safety sites in the western continental United States.  We thank everyone staffing those sites for providing data so we can develop products like this.  

I get a lot of requests for "point forecasts" from this product.  I'm trying to move away from autogenerating those.  Instead, you can do it dynamically for any point in the continental US at https://www.inscc.utah.edu/~steenburgh/hrrrqsfts/hrrrqsfts.html. This link is also available if you click on "Point Time Series" under HRRR-Snow (Experimental) in the left hand nav bar on weather.utah.edu.  Below is an example for Paradise Ranger Station on Mt. Rainier.  They will take a minute or two to pull up.  I recommend that you compare the elevation of the HRRR grid point (printed in the second graph) to your site as sometimes there are large differences that can be important for interpretation.  

We are also working on products from the Rapid Refresh Forecast System (RRFS) which the National Weather Service is currently testing and developing to replace the HRRR.  The RRFS is run at comparable grid spacing to the HRRR (3 km) and is currently run as a small ensemble with six members.  

Remember that these are experimental products and not official forecasts.  Feedback appreciated.  


  1. The only feedback I have right now is DEEP thanks for the wonderful diversion provided by weather.utah.edu. I'm stupified how I could exist for so many decades without my daily fix.

    I guess I do have feedback that the upper LCC guidance point forecasts are integral to who I am. In addition to being the CENTER of the universe, this point location is KEY, in case you were thinking it might not be.

    During cold season I wake up and go to sleep checking (when storms are rumored)

    and (when storms are known in the next 36 hours)


    And it goes without saying the NAEFS plume

    Since you dissed the SREF I've been skipping it but I still visit on occasion.

    On the point of point forecasts, its highly entertaining a few times a year to see how much snow the periodic monster ARs produce at the Central Sierra Snow Lab

    I could go on ... you get the idea.

    It seems your point is all the points I just listed can be got via the instructions you provided. Fair enough. Leaning new navigation routes is a small price to pay for the invaluable data you provide.

    In case you are wondering I'm taking a few days off to rest my arthritic knee and the miserable weather today caused me to choose lounging. Plan is for tomorrow to be day 11 on the Collins Glacier.

    Btw, super impressive your first turns were Ballroom. Day 10 Saturday was two laps of Ballroom stem-christies, hence the arthritic knee rest. I can remember at least one occasion when conditions were worse.

    Thanks always for everything you do


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  3. I just tried to create a point forecast for 111.5719W 40.3573N and got a server error. Is this operator error on my part or is it a server issue? Thanks for all your work.

    1. Be sure to use a negative for west longitude and to put the lon and lat in the right boxes. Direct link that will pull up our most recent downloaded and processed run: https://www.inscc.utah.edu/~steenburgh/hrrrqsfts/hrrrqsfts.cgi?inittime=&plon=-111.5719&plat=40.3573&units=English

      I just tried and it worked. I have seen that error before from time to time though.

  4. And just like that, Jim gets a private database of every secret stash in the Wasatch. Well played, my friend. Well played :)

    1. I like to think that a distinguishing characteristic of what we do is to *not* keep it private. And it's free!

    2. That was totally tongue in cheek - hope it came across that way. If I were you, I couldn't resist making a heat map of coordinate request. Thanks for all you do!