Wasatch Weather Weenies

As "Covember" ends, it's now a lock that July to November was the driest on record in Salt Lake City with only 1.52 inches of precipitation.  It is now one of only three years with less than 2 inches of precipitation during the period, joining 1958 (1.66 inches) and 1933 (1.72 inches).   Source: NOAA Regional Climate Centers As far as temperature is concerned, July to November was the 5th warmest on record with an average temperature of 66.7˚F, just a shade behind 2013 (66.9˚F), 2017 (66.9˚F), 2012 (67.1˚F), and 2016 (67.3˚F).   Source: NOAA Regional Climate Centers Record low precipitation and excessive warmth is a bad combination and, not surprisingly, the US Drought Monitor has all but far northern Utah in exceptional or extreme drought.   The trend continues to start December.  believe it or not, there's a cold frontal passage tonight and for that we can be grateful as it will stir up the inversion.  On the inversion, precipitation looks ...

I'm starting to get lots of questions again about western drought, persistent ridging, and "the blob", the anomalously warm ocean waters in the northeast Pacific Ocean.   If this is something you are interested in, please see the Weather West blog post " New insights into the Ridiculously Resilient Ridge & North American Winter Dipole " as it should answer most of your questions.  

For outdoors time, ride is an ambiguous word.  It could me snow riding, the favorite form of recreation for most of the readers of this blog this time of year.  Or, it could mean bike riding, which is also a great activity, but perhaps not the activity of choice in late November or early December. Unfortunately, the models continue to favor just weak systems moving through the area and forecasts that give us limited mountain snowfall for the next several days.  I'll show a couple of examples.  The GFS forecast below, valid at 1200 UTC 2 December, has a dreaded "Rex Block" parked over the western U.S.  A Rex block features an upper level ridge to the north of a closed low, sometimes referred to as a "high over low block" by those with a Northern Hemisphere bias.   The Euro isn't much better.  For the same validation time, the ridge/trough amplitudes and positions are a bit different, but overall the pattern is fairly similar.   As a resul...

November 2020.  A month better called "Covember" given the explosion of COVID cases across the country. For Salt Lake Area skiers, the month started out with promise with over 50 inches of snow at Alta.  Since then, however, the Covember doldrums have settled in.  Yesterday I found both overcast and "undersmog" as I walked in the Avenues foothills.  This is not an uncommon scene this time of year when a weak trough and associated warm-air advection move through the area.  Such a situation increases the stability and provides just enough lift for mid-level cloud formation, but insufficient moisture and flow to generate precipitation or scour out the stable airmass over the valley.   If you had asked me a few days ago about snow potential Thanksgiving week, I wouldn't have been excited, but I probably would have thought we'd do OK.  Two troughs were forecast to move through the area, so we'd be bound to get something.  In a case of snatching de...

A lot of people ask me why it seems to be that we never get a good start to the ski season in November.  We all have memories of good starts to the ski season.  Certainly it was better in the "good old days."  But was it? We have relatively short records of November snowfall in the Wasatch Range.  There are actually records for Silver Lake/Brighton going back to 1916, but there are a large number of missing days prior to 1942, in some intermediate years, and then again since 2000.  Thus, I'm going to use Alta Guard, which has a shorter but more continuous record of November snowfall, with only 1972/73 missing.   A look at the November snowfall shows three fairly distinct periods (the plot below is labeled by season, so 1945/46 denotes November 1945).  Pre 1982/83, 1982/83 to 2003/04, and post 2003/04.  The middle period of from 1982/83 to 2003/04 is the fat period when there is a high frequency of heavy November snowfalls and the six largest ...

So far this month, Mother Nature has fulfilled half her bargain.  She's given us snow, but instead of light winds, she keeps giving us tempests.   Crest level winds over the last 7 days in the central Wasatch show winds with gusts at or above 50 mph have predominated about half the period.  On Saturday, the ridge tops in some areas saw gusts to nearly 100 mph, whereas this morning we've seen gusts to over 70 mph.   This is no way to maintain decent skiing. The situation overnight and this morning is one with strong, large-scale, southwesterly flow over Utah.  The GFS analysis for 0600 UTC (11 PM MST) showed 700-mb winds of more than 50 knots over portions of western Utah (lower left panel) and a strong sea level pressure gradient and southerly flow at the surface (lower right).   In that southwesterly flow, there's a nice orographic cloud sitting over the central Wasatch this morning.  Sadly, it does not appear to be producing any snow. ...

Mother Nature has given us enough to start the ski season this year in November, but we're still dealing with low tide conditions.   I'm skiing on some classic old skis that I prefer to think of as skis of seasons past rather than rock skis.  Specifically, I'm on a pair of Kahru Jak BCs that I think I bought in 2005. These skis were ahead of their time.  Light and lively.  124-90-113.  I think this was the first setup I had with tech bindings.  I have a friend who used to tell me if I ever wanted to sell them to give him a call, although this year he suggested they belong in a museum.  That's a bit cruel.  I skied them today and I had FUN, although I need to take a closer look at the bindings, which may finally be on their last legs.   I've been debating whether or not to buy equipment this year.  My "new" gear is about 4 years old and has some decent mileage.  I've been concerned that it will be hard to find anything if s...

What a great night to be a weather weenie.  Heavy mountain snowfall.  Valley thunder and small hail.  It doesn't get much better than that, unless we also got more post-frontal snow.  Let's start with the northern Wasatch. In the pre-frontal environment last evening, it was absolutely lit, with high radar reflectivities developing over the upstream lowlands and extending downstream over the Wasatch Range.   During this period, Snowbasin's Boardwalk site recorded 0.86" of water-equivalent snowfall in two hours .  I looked at their snowcam and inferred a 4"/hour snowfall rate.  Total overnight snowfall reported by the resort was 18", with 1.99" of water equivalent at the Boardwalk site.  That's great high-density base builder and just what we need in November.   Moving to the Salt Lake Valley, the front came through with a strong convective line, lightning, and thunder (apologies for the change in radar color scale, but it's early on ...

Things are looking pretty exciting for the next few days, with a moisture laden storm for Friday night with strong winds, a decent frontal passage Friday night, post-frontal instability showers Saturday, and then another system Sunday.  Did I mention it's going to be windy? Let's talk large-scale setup for Friday night first.  At 0000 UTC 14 November (5 PM MST Friday), the GFS forecast shows a strong upper-level trough and low-level cold front approaching Utah.  Moisture is spreading into northern Utah things beginning to get going over the northern Wasatch in the pre-frontal southwesterly flow.  It's a warm storm to start, but I'm hoping we'll see snow levels at the start of the storm late Friday afternoon near or just below the base of Snowbasin (6500 feet).   The airmass ahead of and with the front is a juicy one.  The GFS integrated vapor transport forecast shows atmospheric river conditions penetrating across California and Nevada into northern Ut...

I was able to get up this morning for a quick lap on the Collins glacier to check out the snow situation.   My ideal first tour of the year is a mild, bluebird powder day.  That's not what I found this morning.  For a while, skinning up above the Watson Shelter, it was snowing hard, the snow guns were blasting, and the wind was roaring down the mountain in my face.  I found myself skiing up with the hood of my shell up and fully zipped.  Welcome to winter! The wind was primarily a blessing, as it smoothed things out and made for good skiing in places.  It was a curse in a few others, but one can't complain.  The snow situation is better than I expected a few days ago before the weekend storm.  Automated observations from the Alta Collins observing site suggest 4" of low-density snow fell this morning.  The gauge measured water equivalent is almost surely too low as is often the case when there's strong wind and low-density snow, but usin...

After months of below-average precipitation, extreme heat, coronavirus, earthquakes, and political stress, Mother Nature finally delivered an overproducer for Utah skiers.  Observations from the Alta-Collins site were a little flaky yesterday, but total snow depth peaked at 23", which is a reasonable guess for new snow amount.  Water amounts, which include the period prior to the one presented below, were around 1.75".   I suspect we did better than that as the Collins gauge typically exhibits undercatch and underreporting of precipitation.  The Snowbird SNOTEL is up about 2 inches since Saturday afternoon, for example.  Despite my forecast, people were out skiing, with one report to the Utah Avalanche Center as I write this early Monday morning.   Most impressive to me was the productivity of the storm from early Sunday morning through Sunday afternoon.  There was a lot going on, so it is impossible to generalize they day meteorologically....

Forget about the Presidential election.  Changes are coming to Utah weather, so start looking at forecasts instead of vote counts.  Indeed, there's plenty to hope and argue about in the forecast below.   I'm having some software problems this morning, so apologies for the garish colors in the loop below which shows either radar or modeled precipitation and the 500-mb (upper-level) flow pattern from 1200 UTC 5 November (5 AM MST Thursday) through 0600 UTC 8 November (11 PM MST Sunday).  The pattern is one that features what we call a "digging" upper-level trough.  That's a trough that instead of moving eastward, moves equatorward and amplifies.   Really, that's not a best-case scenario for snow in the Cottonwoods for a few reasons.  One is that the "dynamics" associated with the upper-level trough pass to our south.  Another is that the flow stays more southerly or southwesterly.   However, this is a deep, cold, unstable trough....

Here we are again with a potential weekend storm in the future.  Assuming the apocalypse doesn't happen in the wake of the election, will you be skiing this weekend? Well, people are skiing now on the lower portion of the "Collins glacier", but will there be enough natural snow to ski this weekend? My view is probably not, although we're likely to get more snow than we've seen from the disappointing storms of recent weeks. The situation this weekend is different than those storms which passed largely to our north.  For this weekend, we are dealing with a trough that is going to "dig" into the western United States and possibly the southwest United States.  Additionally, there is a second trough that moves into the western United States behind it, leaving much of the western United States in the grips of a deep, cold, upper-level trough.  This can be seen in the GFS forecast below.   The good news is that it's going to get cold and it is going to be u...

This week marks my silver anniversary at the University of Utah.  Twenty-five years ago we left Seattle Washington, drove across Snoqualmie Pass into the dry, western interior, and arrived in Salt Lake City a day later to a new home and a new life.  The U has been a great home for me.  I was as inexperienced as they come as a new professor, having just finished my Ph.D. a few months earlier.  One has to wonder what they were thinking hiring me.  I didn't really know what I was thinking when I took the job either, but I got good vibes from John Horel, a professor in what was then the Department of Meteorology, that he would be a great mentor and indeed he has been for 25 years.  John was the best friend and mentor I could hope when I was as a young professor and and remains so as we age into obsolescence.   There have been a lot of highlights and a few lowlights in those 25 years.  John and I contributed to weather prediction efforts for the 2...

 November has arrived and expectations for skiing are climbing rapidly.   There's virtually no natural snow (more on this in a minute), but the hiking right now is fantastic.  Beautiful skies, few people, ideal temperatures.  Here's a view of Mt. Superior from Flagstaff around noon today.   As far as skiing goes, the Collins glacier doesn't go continuously yet.  The lowest 500 vertical feet or so to about 2/3 of the the way up to the angle station was being skied by some today.  Above that, there are segments of man made.   Although proposals for improving traffic in Little Cottonwood Canyon get a great deal of attention, UDOT has been making substantial changes to their avalanche mitigation infrastructure over the past few years.  Most recently, they've been installing Wyssen Towers in many of the avalanche paths above the Town of Alta.   Here's a closeup of one on the Flagstaff face, with the remnants of the Albion ...