Wasatch Weather Weenies

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...

It's been an active 48 hours over northern Utah thanks to the Saturday showers and thunderstorms, remnants of Rachel, and several other precipitation drivers. The plot below shows the estimated precipitation over northern Utah for the 48-hour period ending at 1400 UTC (0800 MDT) today (Monday, October 12.  Everyoen got some, but the biggest amounts are on the Alpine Ridge above Little Cottonwood Canyon and over the south slope of the Uintas where there are local accumulations of more than 3.5 inches.  Most of the central and northern Wasatch has seen at least an inch.  The lightest accumulations are in the northwest Salt Lake Valley (<0.5").   Source: MRMS Big Cottonwood Canyon was closed for a while yesterday due to flooding on the road. 🚧 Uphill Restriction Alert 🚧 SR-190: @SLCO_OOTS @UtahDOT are restricting uphill traffic due to flooding and debris on road. 📍: traffic will be turned around at mouth. ‼️ETO to uphill traffic: UNKNOWN https://t.co/tAZHyS...

Tropical Storm Rachel is currently well off the coast of Baja California, but it and its remnants are expected to affect the southwest United States this weekend and Monday.  The latest track and intensity forecast shows Rachel moving on a northeastward path, ultimately making landfall somewhere on the northwest coast of Baja or the California Coast near San Diego as a Tropical Storm.  By 5 PM Sunday, Rachel is forecast to be a post-tropical cyclone as it moves into Utah.   Source: NHC A post-tropical cyclone has lost its tropical characteristics, including its warm core and symmetrical storm structure, but maintains a low-level circulation and in some cases evolves into a mid-latitude frontal cyclone through a process known as extratropical transition .  In this case, Rachel is forecast to maintain a low-level circulation all the way to Utah because it is gaining the assistance of a strong upper-level trough that is digging down the Pacific Coast, as evident i...