Wasatch Weather Weenies

 The forecast for the next 10 days is pretty depressing and discouraging.  I'll call it a WYSIWYG forecast (What You See Is What You Get).   As far as the large scale is concerned, there's little change from what we've experienced over the past three weeks.  Ridging off or near the Pacific coast with short-wave troughs rolling over the ridge and diving into Utah.  These troughs bring in some cold air and can partially or fully mix out the air pollution, but are moisture starved, dropping some flurries or an inch or two of snow.  I'll summarize the situation with the 10-day accumulated precipitation through 0000 UTC 9 February (5 PM MST Tuesday 8 February) from the ECMWF high-res model and the GFS.  The ECMWF puts down a spec of 0.10" of water equivalent for the upper elevations of the central Wasatch for the entire 10-day period.  The GFS even less. If we're lucky, perhaps one of the troughs can generate a bit more than predicted by these mod...

In the 1970s and 1980s, numerical weather prediction had reached a point where it was being increasingly used for operational forecasting, but would often fail to predict high impact weather events.  Of particular note were nor'easters, strong extratropical cyclones that develop along the U.S. east coast and can bring crippling snowfall to metropolitan areas.   A look back at the literature during that time reveals many papers describing forecasts busts.  Lance Bosart wrote an especially important paper on the President's Day Snowstorm of 18-19 February 1979, which affected the mid-Atlantic states.  He noted that "the storm is noteworthy because of the failure of operational prediction models to signal the intensity of the event."  Source:  https://journals.ametsoc.org/view/journals/mwre/109/7/1520-0493_1981_109_1542_tpdsof_2_0_co_2.xml We've come a long ways since then, but challenges remain today, including the details concerning the track of the sys...

 If you are an Olympic enthusiast and/or weather junkie and are looking for real-time weather information for the venues, the english version of the Beijing 2022 Weather Portal is available at https://olympic.weather.com.cn/en_dongao/.   There's a pretty nice display with real-time data for the Yanqing Alpine Center showing station locations with access to wind, temperature, and humidity information.   As I type this, it's almost midnight in Beijing.  Current temperature at the downhill start is -17.2˚C (1˚F).   Winds were almost 30 knots as well.  BRUTAL.  Climate is what you expect, weather is what you get, but cold and windy is a very real possibility during these games.   I've noticed that the time series of observations from the site are frequently old.  It seems to key off of the local time at my location, whereas Beijing is ahead of Utah time.  I've found the best way around this is to change the time in t...

If you follow ski racing, you know that this Friday and Saturday should each have featured a men's downhill and Sunday a slalom on the famed Hahnenkamm in Kitzbuhel, Austria.  Instead, the meteorologists won the day and the Saturday downhill and Sunday slalom were switched due to anticipated heavy snowfall on Friday night and Saturday.   Indeed the Saturday snow did materialize and Dave Ryder won Great Britain's first world cup race as he unleashed a great second run and the top skiers from the first run flailed in the difficult conditions.   It's GOLD for @daveryding in the Kitzbühel Slalom @fisalpine World Cup!! BRITAIN'S FIRST EVER ALPINE SKIING WORLD CUP GOLD - laying down a marker for @Beijing2022 next month! 👏👏👏👏👏 pic.twitter.com/HVvz2ceaKE — GB Snowsport (@GBSnowsport) January 22, 2022 Ryder learned to ski on plastic slopes in England and has been knocking at the door for a win for a long time.  Great to see him get his first win at the age o...

The 2022 Olympic Winter Games start on February 4th.  The host city is....Beijing, China?  Weird.  Beijing is not widely known for much related to snow and winter sports.  Does it even get cold there?  Let's take a look.   Beijing is in east Asia, just inland from the Yellow Sea.  It is about 680 miles from Pyeongchang, South Korea, identified with the thumbnail below and host city for the 2018 Olympic Winter Games.   As is the case for much of east Asia, the winter climate of the region during winter is dominated by semi-permanent high pressure centered over interior Asia.   Source: NOAA/NWS Climate Prediction Center This means the wintertime climate of Beijing is quite dry.  In February, the average precipitation (water equivalent) in Beijing is only 0.19" (1971-2000 normals from  https://en.wikipedia.org/wiki/Geography_of_Beijing ) compared to 1.30" in Salt Lake City (1991-2020 normals from  https://www.weathe...

  Although it's only a brief flirtation with the storm track, we will see a trough passage tonight and tomorrow, one that will bring a bit of snow for skiing and some wind to clean out the smog that's occupied the valley for far too long. Tonight, the upper-level trough rolls over the large-scale ridge that is presently off the Pacific coasts and drops into Utah.  At 1200 UTC, the upper-level trough axis is nearly over Salt Lake City.   For the central Wasatch, expect periods of snow to develop tonight a bit before midnight and continue into tomorrow morning.   There will also be some snow at times in the Salt Lake Valley.  NWS forecasts are calling for a trace to 2 inches of snow in the northern valleys.   We might do a bit better than that on the east bench, but this doesn't look like a big event for accumulation.  However, we haven't seen snow around here in a while, so heads up for the morning commute.   For the central Was...

Air quality over the past three days has deteriorated as pollution has built up in the valleys and basins of northern Utah.  Below are time series of PM2.5 (top) and wind direction, speed, and gust (bottom) from the University of Utah.  PM2.5 concentrations at this site tend to fluctuate daily and are typically lower at night when there is easterly to northeasterly outflow from Red Butte Canyon and higher in the afternoon when there is westerly to southwesterly upslope flow from the Salt Lake City metropolitan area.  You can see these swings very clearly below, with peaks in PM2.5 in the afternoon and valleys at night.   You can also see that the weak trough passage on Friday did provide some ventilation of the valley with PM2.5 concentrations on Saturday afternoon considerably lower than on Friday afternoon.   However, that was only a partial mix out and since then we have seen PM2.5 concentrations rise each day.  Yesterday afternoon, we peaked a...

If you are out and about in the backcountry this weekend, you may encounter surface hoar , beautiful but weak ice crystals that form on the snow surface when it cools below the frost point.  We saw plenty of it yesterday at lower elevations during our ski tour.   Surface hoar is sometimes described as recrystallized powder, but as I understand it, that's incorrect.  Surface hoar is created through the growth of new crystals.  The formation process is similar to frost.  The snow surface cools below the frost point and ice crystals grow from the deposition of atmospheric water vapor onto the snow surface.  This process becomes highly effective under clear skies, when the snow surface can become quite cold, and when there is a strong temperature inversion.  It is also very effective near open water where there is a source of water vapor.   In contrast, recrystallized powder, or  near-surface facets,   form through the metamorphism...

How to describe forecasts for the next 14 days?  Awful?  Dismal? Pathetic? It's not impossible that some trough sneaks through the grips of the high-amplitude ridge and gives us a few flakes, but for the most part, it looks like a lock that we're going to see well-below average precipitation and mountain snowfall over the next two weeks.   On average this time of year we should be getting about 3.5 inches of water equivalent and 40 inches of snow at Alta every two weeks.  We'll be lucky to get 0.5 and 5 and if the majority of models are right, we'll get close to nothing.   Here's an example, the Euro over the next 10 days.  No precipitation in the central Wasatch.  Source: Pivotal Weather And how about the CPC 8-14 day outlook. Source: CPC A good forecast if you're into valley pollution and hate snow.  For the rest of us, it sucks. Below is the mean water equivalent in the Jordan River Basin (including the central Wasatch) based on SNOTE...

  The Internet is a blessing and a curse.  So much information at your fingertips.  But alas, interpreting studies is fraught with perils and there's also a lot of misinformation out there.  In fact, there's plenty of snake-oil salespeople, some of them highly trained, making good money on uncertainty and misinformation.  Even amongst ethical scientists, the value and applicability of papers published in the peer reviewed literature varies.  If you want to get to the bottom of critical issues, from COVID to climate change, can you do it?   I personally am skeptical of the ability of most people to ignore expert guidance, sift through data and publications on complex matters, and figure it out for themselves.  This is not to put experts on a pedestal, but instead to recognize the realities and complexities of interpreting data and scientific studies, as well as our vulnerability to cognitive biases.  The reality is that it takes time, pra...

The upper-level pattern is locked in for the for the foreseeable future. Below is a 12-day loop of GFS analyses and forecasts from 1200 UTC (5 AM MST Tuesday) 11 January through 1200 UTC (5 AM MST Sunday) 23 January.  Color fill is the wind speed at jet-stream level (250 mb).  The Pacific jet is raging , extending from Asia across the western and central Pacific.  Apologies for not including a color scale, but at times maximum winds along the jet core locally exceed 200 knots.  What a beast.   However, the jet splits near through this period near Hawaii.  There are some variations in the extension of the jet, but for the most part, Intermountain West is left under a ridge or split flow with just some synoptic debris , or weak troughs floating around.  These are the leftovers spit out from the exit of the Pacific Jet.  Let's take a look at some ensemble forecasts.  Below is the mean 500-mb geopotential height forecast from the Global Ense...

The air quality has fluctuated dramatically at the University of Utah, on the east bench in general, and in Parley's canyon over the last two days.   PM2.5 observations from our mountain meteorology lab site at the mouth of Red Butte Canyon show low concentrations, indicative of good air quality, through the morning of 10 January (Monday).  On Monday, the inversion and the pollution began to build.  PM2.5 concentrations peaked at about 11 ug/m3, at the upper end of good.   Source: Mesowest However, they then dropped in the evening, with a couple of brief spikes to higher values.  On the morning of 11 January (Tuesday) they then climbed again, this time reaching higher values and topping out at 27 ug/m3, solidly in moderate.  Then they dropped overnight again.   These observations reflect both a trend and a daily cycle.  The trend is the buildup of pollution in the Salt Lake Valley as emissions continue to pour into the persistent va...

Pretty pathetic forecast covering at least the next 10 days or so.  Essentially a flatline for mountain and valley precipitation in some models.  Shall we start with the ECMWF for a change of pace?  Total accumulated precipitation in the central Wasatch a big goose egg over the next ten days, with just a skiff of snow in the western Uintas and Bear River Range.   Source: Pivotal Weather GFS?  How about a tad over a trace for the Wasatch Crest. Source: Pivotal Weather Cutting back to 7 days for our NAEFS ensemble product, there are 7 members (out of 52) that generate 4-9 inches of snow, mainly from a weak trough that rolls over the ridge and affects Utah late Thursday and Friday.  The rest of the members are 0-3 inches of snow.   About the only positive is that trough later this week comes close enough to stir up the inversion and mix out the pollution.  The GFS forecast below valid 0600 UTC 14 January (11 PM Thursday) shows decently stro...

As anticipated in Monday's post, a messy storm has arrived in northern Utah.   Let's start with the big picture.  The 6-hour GFS forecast valid at 1200 UTC (5 AM MST) this morning shows high integrated water-vapor transport (IVT) values associated with an atmospheric river curving anticyclonically (clockwise) from near Hawaii over a high-pressure system off the coast of California and across Oregon and Idaho towards Utah.   Source: CW3E A closeup for the western U.S. shows atmospheric river conditions extending into northern Utah.   Source: CW3E This pathway across Oregon and southern Idaho is one of two key ones for atmospheric river penetration into northern Utah as it minimizes water vapor loses to precipitation over high barriers such as the Sierra Nevada.  The other key pathway comes up the lower Colorado River Valley and through western Utah.   This morning's 1200 UTC (5 AM MST) sounding from the Salt Lake City airport shows satura...

It was a great run during the holidays for northern Utah.  From December 22 to January 1, Alta recorded 70 inches of snow.  All resorts and backcountry areas benefited, as did the Nordic skiing.  Mountain Dell has great cover heading into 2022.   Then, the sun came out in the Cottonwoods over the weekend and it was nice to see it.  Yesterday was spectacular in the backcountry, with amazing conditions.   I exit the holiday week tired but happy.  I can't remember the last day I didn't ski tour or skate ski! The week ahead promises some snow, but it looks messy.  I'll summarize in three parts.   First is tomorrow when we are in predominantly zonal (westerly) flow at the tip of a decaying inland-penetrating atmospheric river.  Expect some snow to develop during the day, especially in the northern Mountains.   Second is late Tuesday night and Wednesday when a weak trough passes through, driving what will probably be t...