Wasatch Weather Weenies

 I'll be away from the blog for a couple of weeks.  Enjoy the snow and the March sun!

Many people are likely suffering from spring fever this weekend with sunshine and mild temperatures along the Wasatch Front.  Saturday's high temperature at the Salt Lake City International Airport was 56F and the National Weather Service is going for 61F for today (Sunday). Source: NWS.  Downloaded at 8:41 AM MST Nevertheless, the snow held up fairly well at Alta yesterday, although I only skied until 1:30.  If you are wondering, the record high for today is 68 and for the month is 69 (set on Feb 28).  We should fall short of these.  A look at that forecast though does show something "different" on top for Monday night when a surface cold front and upper-level trough will move through northern Utah.  The GFS forecast valid 0600 UTC 27 February (11 PM Monday night) is shown below, showing the front draped over northern Utah. Mountain snow and some valley rain look to develop Monday afternoon. Snow levels will likely fall to the valley floor by about 11 PM. ...

It's too early for a full monthly recap, but the numbers for the first 20 days of February are worth a look. Total precipitation at the Salt Lake City International Airport through yesterday was 2.93" which rates as the 7th most on record *for the entire month.* Source: https://xmacis.rcc-acis.org/ We can climb up a little higher before the end of the month (and will probably get some more today and tonight). It has also been warm.  For the first 20 days of the month, the average temperature was 40.5F, which rates as the 9th warmest.   Source: https://xmacis.rcc-acis.org/ Finally, despite all of that precipitation, we've only had 1.2" of snow for the month at the airport.  Snowfall has been scant at the lower elevations, even as the snowpack has really benefited at upper elevations.   Speaking of upper elevations, the Snowbird snotel now sits at 33.8" of water equivalent (black line below).  This is 142% of median for the day.  That's a ...

The phrase atmospheric river is a relatively new one.  The phrase "tropospheric river" was first used in a paper by Reginald Newell and coauthors in 1992 to describe narrow "filaments" of strong water vapor flux or transport in the atomphsere.  Then in a 1994 paper, Newell and Yong Zhu termed these features atmospheric rivers, a phrase that has caught on and is now widely used not only amongst scientists, but also with the general public.  Hereafter, I will abbreviate atmospheric river to AR for convenience. In Utah, however, the phrase is being used to describe many situations that do no reach AR criteria, including today.   ATMOSPHERIC RIVER: Another subtropical train of moisture will move in today. Brunt of the valley rain will be This afternoon into Wednesday morning. Rain totals look healthy and mountain snow totals will be around 1-2 FEET for the Cottonwoods. #utwx pic.twitter.com/XciepWzobZ — Matthew Johnson (@KSL_Matt) February 20, 2024 ARs are defined...

  Zermatt, Switzerland It is not unusual to hear people make comparisons between Alta and Zermatt when it comes to transportation.  One often hears statements like "Alta should be like Zermatt" or "we should have a train like Zermatt."  This article is not to argue against transportation upgrades (I am likely supportive of a well designed mountain transportation system for the Wasatch), but to instead discuss some of the limitations of these comparisons and the unique challenges facing Little Cottonwood Canyon.   Alta is a small town.  The population for the 2010 census was 383.  This dropped to 228 for the 2020 census.  I'm not sure how confident to be in either of these numbers, but we are talking about less than 400 permanent residents.  It has five lodges [Snowpine (58 rooms), Alta (57 rooms), Goldminer's Daughter (89 rooms), Alta Peruvian (80 rooms), Rustler (85 rooms)], some condos, and some additional rental units.  Down the road,...

Correction : Total screwup on my part.  The times for the races indicated below are Central European Time not Central US Time.  You would think that I would know that (duh!).  Thus the races aren't in the evening, but in the morning and early afternoon local time.  Apologies! World cup cross-country skiing returns to the US for the first time in 23 years with racing this Saturday and Sunday. Source: @FISCrossCountry More than 30,000 fans are expected for the races, which will be held at Theodore Wirth Regional Park .  In fact, the event is sold out. Snowfall in the Minneapolis area has been scant this season, but Mother Nature provided several inches of natural snow this week that will help beautify the event (which could have gone on with artificial snow).  Forecasts suggest a dry weekend although there will be some wind for the Saturday sprints.  Race-time temps should be  25-30F each day. On the Women's side, the US team is having an amazing se...

This is the second part of a blogstorm examining a new paper by Michael Wasserstein and I examining snowfall extremes at Alta.  The paper was just published in what is known as early online release and is available at https://journals.ametsoc.org/view/journals/mwre/aop/MWR-D-23-0206.1/MWR-D-23-0206.1.xml , but may be paywalled if you don't work at an institution with a license for American Meteorological Society journals or have an American Meteorological Society membership (apologies).  However, we are summarizing the key findings in this blogstorm.  In Part I , we examined the relationships between flow direction and heavy snowfall at Alta, highlighting that heavy snowfall can occur from a wide range of flow directions, but most commonly for SSW or WNW flow for Liquid Precipitation Equivalent (LPE) and the latter for snowfall amount.  The bias toward WNW flow for snowfall amount reflects that such flows are typically colder and feature higher snow-to-liquid ratios,...

Michael Wasserstein and I have a new paper out examining our favorite research topic: Snowfall extremes at Alta. The paper was just published in what is known as early online release and is available at  https://journals.ametsoc.org/view/journals/mwre/aop/MWR-D-23-0206.1/MWR-D-23-0206.1.xml .  It may be paywalled if you don't work at an institution with a license for American Meteorological Society journals or have an American Meteorological Society membership (apologies).  However, we'll hit some of the highlights in this special two part Wasatch Weather Weenies blogstorm, beginning here with Part I.   The inspiration for this work was a paper by Larry Dunn, a long-time meteorologist and avid skier, that was published as a NOAA Technical Memorandum in 1983.  Many of the relationships between flow (especially wind direction) and local snowfall enhancement at various locations in the Wasatch Range that are used today are based on this paper.   Mich...

I suspect the skiing yesterday was very good.  I had to sit it out due to a balky back.  Hope you were more fortunate.  The big weather story today is really from SoCal where some big rainfall numbers are coming in from the LA Basin and environs.  Below are 24-hour totals as of this morning with seven sites in the Santa Monica Mountains and Beverly Hills coming in with more than 10 inches of rain.   The analysis below shows the situation at 0000 UTC 5 Feb (5 PM MST Sunday) with a deep cyclone just off the central California coast and strong integrated vapor transport directed toward the Santa Monica and San Gabriel Mountains.  It was a great recipe for heavy orographic precipitation development.   Utah will be seeing bits and pieces of that storm as the trough moves through the western US.  As I looked at things this morning, I had no idea how to summarize the next few days.  The system is so broken up over the western interior that...

 Precipitation moved into northern Utah last night producing lowland rain and upland snow.  As of 6 AM, the Alta-Collins automated sensor was up to 6" of moderately high density snow with .66" of water (11% water content).  High density at this stage is good to smooth things out and bury the hard underlying surface.   Radar at 6:46 AM showed widespread precipitation over the Great Salt Lake and much of northwest Utah.  The Cottonwoods and the central Wasatch were seeing some snowshowers, but were in a bit of a lull.   That lull should, however, be short lived as the trough moves in from the west.  The HRRR, for example, keeps the central Wasatch on the edge of the action through about 1500 UTC (8 AM).   But then it swings the trough in with widespread precipitation over all of northern Utah by 1800 UTC (11 AM). So, snow today, possibly heavy at times, especially with the trough passage.  It is fairly mild out there this morning...