Wasatch Weather Weenies

Nothing gives me heartburn more than the hyping of winter storms days in advance in Utah.  The devil is in the details and snowfall at any given point in our state is strongly dependent on frontal position, wind direction, and the like.  With those words of caution, let's take a quick look at forecasts for the storm later this week and this weekend.  As I mentioned yesterday, there will be a period of warm-frontal precipitation in southwesterly large-scale flow Thursday afternoon and evening that should some snow to the mountains.  Then, things get interesting. The 6Z GFS forecast shows a developing trough and strong cold front over the Great Basin and northwest of Salt Lake City at 1500 UTC (8 AM MST) Friday.  We are in the strong southerly flow ahead of the front, with precipitation primarily lagging it.  At 700-mb (roughly crest level), strong southwesterly flow reaching over 30 m/s (60 knots) covers much of western Utah.  If happening...

The models have been advertising a fairly exciting period of weather for this week and weekend the likes I'm not sure we've seen for some time.  It's a complicated enough situation that I struggled with how to describe it in this post, and ultimately decided to simply use the GFS forecast time-height section for Salt Lake City for a summary (click here for information on time-height sections and remember time increases to the left).  Through Wednesday, we're in the doldrums, but early Thursday we have a weak warm-frontal feature moving through northern Utah that might bring a bit of snow to the mountains.  Then things get interesting as a deep upper-level trough digs southward out of the Gulf of Alaska and parks itself along the Pacific Coast.  This leads to a period with strong southerly flow developing Thursday night and persisting into Friday.  Any snow available for transport at that time will surely go for a ride and we may see some dust as well. ...

The Winter Olympics have wound down, leaving only memories of great performances.  One thing that struck me about these games is that the women's events were equally or more compelling than the men's.  In fact, when I think about the most memorable performances I saw, which are admittedly heavily biased to alpine skiing, nordic skiing, and biathlon, they were all by women.  Thus, here's my list of top bad ass performances during the Olympics.  Marit Bjoergen, women's 4x5 relay: Bjoergen appears 3 times in this list as she cemented her place as the greatest Winter Olympian of all time at these games.  She skied the anchor leg in this race, schooling the younger Stina Nilsson of Sweden.   Marit Bjoergen, 30-km mass start: As far as endurance races go, this is about as dominating as you get.  Bjoergen pushed the pace from the start and was a locomotive for 30 km, winning by near 2 minutes.  The performance was the epitome of "a confident a...

I've had a busy morning with no time to write, which is a shame given the weather.  I can share one quick observation from the storm today.  The radar is showing some orographic effects in the post-frontal northwester flow from 1738–2032 UTC (1038 AM – 132 PM MST).  Note, for example, the persistent echoes on the western (windward) sides of the Oquirrh and Wasatch Mountains, which contrasts with the shadowing seen over the southwest Salt Lake Valley.  Clearly better skiing above the Kennecott Smelter than at the open pit mine. 

Over the past week and in forecasts for the next 10 days the overall pattern remains in some ways similar to what we have seen all winter.  The flow is very high amplitude, with strong upper-level ridges and troughs.  This can be seen in the dynamic tropopause analysis below, which is essentially a map of jet stream level winds with areas of locally low tropopause pressure (warm colors) indicating ridges and areas of locally high tropopause pressure (cool colors) indicating troughs.  What has changed, however, is that the mean ridge position has shifted upstream to what I'll call its "happy place" over the central Pacific Ocean.  As a result, we will see several amplifying upper-level troughs digging into the western U.S. over the next 10 days.  This is a much colder pattern than we have seen all winter. It is also a more "active" pattern.  Forecasts for the next 7 days show a series of weak but frequent storm systems moving through.  Total accu...

In 66 years of women's cross country skiing, the US has never won a medal, let alone a gold medal.  That just changed. 

Lake-effect snows added a bit of frosting to the President's weekend winter storm last night.  Alta is reporting a 22" storm total, but only 3" overnight.   In the end, I think the storm did a little better than anticipated through yesterday morning and a little worse than anticipated yesterday and last night.  Such is the post-frontal crap shoot. There are reports of more than 20 inches (through yesterday afternoon) in Sandy and Cottonwood Heights, so this was an event in which storm totals did not increase significantly with elevation up the canyon.   Temperatures this morning are bone chilling in the mountains.  The latest from MesoWest shows predominantly teens in the Salt Lake Valley, which isn't all that bad, but above about 8500 feet, most stations are at or below zero, with a -12ºF at 11,000 feet.   Source: MesoWest Ski touring on days like these requires constant movement.  I recall doing a huge day several years ago i...

Finally, a great storm.  All elevations, all locations.  Some cherry picked storm totals so far based on reports to the NWS (time of measurement in parentheses): Smithfield, Cache Valley (4 PM Sun): 12" Ogden (5 PM Sun): 2" West Valley City (6 AM Mon): 5.2" Salt Lake Airport (5 AM Mon): 3.6" Cedar Hills, Utah County (5 AM Mon): 9" Powder Mountain (5 AM Mon): 12" Brighton Crest (5 AM Mon): 16" Alta-Collins (3 AM Mon): 14" Spruces (4 AM Mon): 10" Through 8 AM, Alta Collins is up to 18", blowing my 7-14" expected through 9 AM out of the water.  With the KMTX radar up-and-down overnight (and currently down), getting a good handle on the action is more difficult than usual.  One thing that caught my attention is described in the tweet below, issued last night.  From 8-10, Alta-Collins recorded 6" of snow (3"/hr mean rate) and I saw some tweets of impressive accumulations near Alpine as well.  During this period, ...

Exciting weather is happening and on the way, so it seems fitting to organize this post around the six questions to answer when forecasting .  1. What has happened? This "winter" has thus far been like 3.5 consecutive Novembers rather than a typical November, December, January, and February sequence.  The average temperature at the Salt Lake City International Airport for 1 December - 17 February was 37.8ºF.  That's just a shade lower than the November mean of about 40ºF.  As everyone knows, we're well below average for snowfall and snowpack, especially in the lowlands.  The photo below was taken this morning looking up City Creek Canyon and indeed it looks more like a scene you might see after a November snowstorm than one would expect in mid February.    This context is important as I suspect most people are entirely unprepared for what is coming.  It will probably seem like the first storm of the year. 2. Why has it happened? This ...

Much to talk about today.  I'll split this post into two parts, Powder Fever/Real Winter and Olympic Dreams. Powder Fever/Real Winter Wow, what a morning.  Yesterday's storm blew away my expectations for both snowfall amount and water equivalent.  The Utah Avalanche Center reports 12-18" of new snow in the Cottonwoods and along the Park City Ridgeline.  This morning is bluebird.  It's hard to imagine a better ski day after all the pain and suffering of the winter to date.  I suspect many dawn patrollers were out this morning and that it will be powder panic in and around the Cottonwoods this morning.   In the backcountry, the buried weak layers still give me heartburn.  Check the avy report and don't let powder fever cloud your decision making. The models have also been shifting to higher totals for the storm sometime late Sunday to Monday, as evinced by the downscaled NAEFS plume for Alta.  Totals currently being spit out by...

Sidelined with a broken bone in my hand this week, you reap the benefits. Alta Collins has recorded 0.49" of water and 8" of snow through 7 am this morning (the 18" snow interval depth is spurious in the data below, so it's unclear if we may have ticked up or down from the 8" at 6 am). While not a big storm it's pushing toward my arbitrary "deep powder" threshold of ten inches.  It's also pushing the upper end of predictions. The radar imagery shows we'll add more to that total, especially in the next hour or two. Nice to see it snowing in the lowlands as well.  Campus was covered in a thin blanket of white at sunrise this morning. Make a few turns for me.

In times like these, one learns to appreciate the smaller dumps in life.  My usual definition of a deep-powder day is a 24-hour snowfall of at least 10 inches, but we've only had one of those at Alta since December 3rd! On the other hand, recent dribs and drabs have certainly helped the skiing some, even as we continue to lose ground to climatology for snowfall amount and snowpack water equivalent.  The 6" of quick snow Saturday afternoon and 7.5" yesterday did create some smiles.  Maybe 6" is the new deep powder day. You'll be hearing some talk of a pattern shift probably in the coming days, and indeed there are some changes afoot.  The GFS forecast valid 5 AM MST next Tuesday, for example, has a trough over the northwest U.S. and a ridge over the east, something we haven't seen a lot of this winter. Similarly, the ECMWF model has a trough in the west (with some differing details) as do most (but not all) GEFS ensemble members. Penn State E...

You can always count on the Winter Olympics to serve up some good weather stories.  So far in PyeongChang, it's cold and wind. Let's talk about the cold first.  The average temperature in PyeongChang during the Olympic Period is 22.1ºF, making its climate easily the coldest to host the Winter Olympics since Lilliehammer in 1994.  Note that the numbers below for sites other than PyeongChang are from Wikipedia and for the entire month of February. PyeongChang 2018: -5.5ºC (22.1ºF) Sochi 2014: 6.0ºC (42.8ºF) Vancouver 2010: 5.5ºC (41.9ºF) Turin 2006: 6.4ºC (43.5ºF) Salt Lake City 2002: 3.6ºC (38.5ºF) Nagano 1998: 0.0ºC (32.0ºF) Lilliehammer 1994: -5.3ºC (22.5ºF) Some of these sites have outdoor venues that are higher (and colder).  However, if you are a reporter returning to the host city each night, you are frequently experiencing a warmer climate.  There's no escape from the cold in PyeongChang.  Even in the Gangneung Coastal Cluster, near sea le...

Skate skiing on the "Greatest Snow on Earth" at the Utah Olympic Park late yesterday left much to be desired. Following up on the previous post , let's take a deep dive and see how unusual this year has been so far for snowfall and snowpack. This is perhaps an even more challenging topic than temperature.  Measurements of snowfall and snowpack are spotty and continuous records going back to before 1990, when most SNOTEL stations were installed, are difficult to find.  In addition, snowpack is strongly influenced by changes in vegetation and human activity around observing sites, not to mention factors such as wind transport.   For snowfall, our best option is the meticulous record kept by snow rangers and avalanche professionals at Alta Guard, which is being extended and maintained today by the UDOT Avalanche Safety Office in Little Cottonwood Canyon ( big hat tip to them! ).  Observations were collected at the Atwater study plot above the Town of A...