Wasatch Weather Weenies

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....

October is a great month in Utah and this weekend has been a beauty.  Fall and winter seasons were in evidence this morning in Big Cottonwood Canyon.  Although past peak, golden aspens were still in abundance.   Then there's the snow on the high north aspects. I'm curious to see how much of that snow can survive this week.  Under clear skies, it can be hard to melt snow this time of year on shady north aspects, but the models are advertising a late-monsoon moisture surge later in the week with mild 700-mb temperatures, cloud cover, and snow levels that could be above 10,000 feet on Thursday.    That's a recipe for rain on snow to at least 10,000 feet so maybe we will lose some of that high north snowpack before the trough swings through and temperatures fall.   We shall see...

The operational implementation of the Rapid Refresh Forecast System (RRFS) and RRFS Ensemble Forecast System (REFS) has been postponed again to November 3rd.  That operationalization also includes sunsetting several ancient NCEP forecast systems including the NAM, HREF, SREF, and HiresW.  Those modeling systems will live for a few more days.   Per the NCEP Service Change Notice Update released on October 15, the delay is to include changes to precipitation type products produced during model postprocessing due to overforecasting of freezing rain and underforecasting of ice pellets.  These are issues that have been a thorn in my side for the HRRR and RRFS snow products for some time.   In the case of overforecasting freezing rain, we've seen this frequently in the HRRR and the RRFS.  An example is below.  Apologies for the lack of a map, but the black circle is Alta and the area of pink , purple, and light blue around it denotes an area of fo...

  For the first time in almost four years and potentially for the last time, I will be offering Atmos 6250: Mountain Meteorology during spring semester 2027.  The class is designed for graduate students in the atmospheric and related sciences who are pursuing research in or related to mountain weather and climate.  There are no exams.  The course involves a mixture of lectures, student presentations, and group research projects based on student backgrounds.  If you are a graduate student at the University of Utah and are wondering if the class is right for you, check out the syllabus from Fall 2022 at  https://utah.instructure.com/courses/805483/assignments/syllabus or drop me an e-mail (jim.steenburgh@utah.edu).  That year the class involved a field experience at Storm Peak Lab.  I'm still working on what we will do in Fall 2027, but it may involve a field experience using a research radar in northern Utah.  

Weather.utah.edu is now launched.  If you haven't had a chance to checkout the new layout, head over there now.   We continue to build out the system.  Recent updates include adding dynamic time series for HRRR Snow and the reintroduction of the RRFS Snow Ensemble. Dynamic time series for HRRR Snow are at the bottom of the HRRR Snow menu (see Point Time Series).  Or you can go to it directly:  https://weather.utah.edu/hrrrqsfts.html .  From that site, you should be able to extract a time series, focused on snow, for any point in the continental US.   Leave the initialization time blank, input your favorite longitude and latitude, and then bookmark the result.  Going to that bookmark should pull up the latest available run.  Always check the initialization time since these are experimental products and sometimes products are old.   The resulting web page will include summary information, a graphical time series, and a tabu...

 " The rain fell on the Earth four days and four nights " -Genesis 7:12 (paraphrased) I suppose its blasphemous to paraphrase the bible, but by the time the current storm is over tomorrow, it will be about a four-day event, so it seems appropriate.   Below are gauge-measured precipitation totals for the first 3 days of this storm (i.e., from 1500 UTC/0900 MDT Saturday to 1500 UTC/0900 MDT Tuesday). Many stations, even in valley locations, are over an inch.  2+ inches at many locations along the east bench of the Wasatch Range from Orem to Ogden.  Some statiions over 6" in the Wasatch Range.  This data hasn't been quality controlled and a few big amounts might need to be adjusted, but the normally somewhat reliable Timpanogos Divide and Snowbird SNOTEL stations are at 7.00 and 7.30 inches, respectively.   Source: Mesowest The Collins snowstake has about 8" of dense snow on it this morning.   Snowbird has 10" on theirs, giving them early b...