The Jet Stream Is Broken

An upper-level trough is moving through Utah today (Thursday) and tomorrow, bringing with it some convective storms and eventually cooler temperatures.  

Snow from the last storm is now almost gone.  The Mount Baldy webcam at Alta this morning shows the snow line has tretreated to nearly 10,000 feet with substantial losses even at upper elevations.  Although the Mt. Baldy summit is obscured, considerable rock and dirt is exposed in the Ballroom at center right of the photo.  

Source: Alta.  Photo from about 7:45 AM 22 October 2026

Se, we are essentially starting over from here. 

The situation for today and tomorrow is a bit of a crap shoot.  Today, snow levels will be too high for much in the way of accumulations.  Perhaps if we get a thunderstorm or thunderstorm complex today it can lower the snow levels down onto our highest peaks, but the RRFS ensemble shows the wet-bulb 0.5 level sitting over 11,000 feet until later this evening.  Thus, any snow accumulations will be limited.

The various ensemble members have differing ideas about what will happen tonight and tomorrow, which reflects uncertainty in the trough structure and movement.  For Alta-Collins (about 9300 feet in the RRFS ensemble), forecasts range from 2 to 11" through Saturday with a mean of 6".  I'm not optimistic this storm is going to produce sufficient snow for me to consider getting on skis for the first time this season. 

After that, all I can say is the jet stream is broken.  I don't currently have a good North Pacific plot on weather.utah.edu, so I'll use Tropical Tidbit's 250 mb wind speed analysis for that region to illustrate this.  Below is the GFS forecast valid 1200 UTC Monday. An intense jet extends off the coast of Asia, but splits immediately east of Japan.  The pattern over the central and eastern North Pacific is a mess of closed lows and what I'll call "synoptic debris" with the main poleward jet extending across Alaska and northern Canada and a sub-tropical jet down near Hawaii.  

Source: Tropical Tidbits

 Local snow for us in such a pattern would depend on one of those closed lows tracking properly through our area.  Not impossible.  Some of the Utah snow ensemble members do this, but most are giving us lighter precipitation and snowfall amounts through the end of October.  About 10% of the ensemble members give us 20" or more of snowfall by 1 November.  The rest are below that.     


We will see how this plays out. 

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