Wasatch Weather Weenies

In modern times, it is possible to get a good deal of beta for ski touring from various apps and online sources, but back in the day, the only option was the printed guidebook. For what we call the central and northern Wasatch Today, the Dead Sea Scrolls of the Utah Backcountry is Wasatch Tours, Volume 2 – The Northern Wasatch by Dave Hanscom and Alexis Kelner.   Dave Hanscom is a legend in the Utah Nordic Community who has been heavily involved with The Utah Nordic Alliance (TUNA) and Wasatch Citizens Series nordic race series.  I first met Dave in Japan in 1998 when the two of us were sent to the Hakuba Valley as part of the Salt Lake Olympic Committee advance team.  I liked him immediately and still enjoy running into him from time to time at Round Valley.  I have never met Alexis Kelner, but his research on Utah ski history provided important material for my book.  The Wasatch Mountain Club conservation award is named in his honor, which tells you that ...

Several days ago, I thought the the period through this weekend looked sort of ho hum (see The Week Ahead ).  The models were putting out some fairly modest snowfall amounts, equating to perhaps half of what we might expect climatologically.  Even most of the members of the the normally jacked NAEFS ensemble were keeping snofall totals near or below 15 inches through this morning (12Z 28 January).    Fast-forward to this morning and let's see how things have turned out.  Per the Alta snowfall history, 10" on the 24th, 1" on the 25th, and 9" on the 27th.  Per the Alta-Collins automated snow depth sensor, another 3" yesterday and 10" overnight.  I'm not sure what period the Alta snow history covers each day to splice these together, but we're well above the projections of nearly all of the NAEFSforecast members, except one plucky one that was up around 30" by 12Z on the 28th.   So, dribs and drabs in this case means deep powder.  What a se...

Nine inches of pixie dust fell at Alta-Collins last night.  At the same time, precipitation gauge observations measured only 0.20" of water. That equates to a snow-to-liquid ratio of 45:1, or a water content of a paltry 2.2%.   Precipitation gauges often do not collect as much snow as is falling, yielding higher-than-actual snow-to-liquid ratios.  Still, pretty likely that the snow was at least 35:1 or possibly 40:1, the latter a water content of 2.5%.  That's pixie dust by any measure.   As discussed in my prior post , I expected "dribs and drabs" at times through today (Wednesday).  From a water perspective, 0.2" of water is a "drib."  At average snow-to-liquid ratios for Alta (12:1), that would translate to 2.4" of snow.  Yawn. However, at 40:1, its 8" of snow and at 45:1 you get 9".  Voila! Some meteorologists call snow with snow-to-liquid ratios of 25:1 or greater wild snow .  At Alta, about 6% of days with at least 2" of ...

The anticipated transition to a somewhat drier pattern appears to be underway, although the models are still advertising some snow showers this week.  I'll summarize with the 7-day GFS-derived forecast guidance for Little Cottonwood which shows a few dribs and drabs at times Monday night through Wednesday, then a break until the next system comes in on Saturday night.  Total water 0.6" and total snow 10", which would be about half of average for this time of year.   Those numbers are in line with a super majority of the downscaled NAEFS ensemble members which are heavily clustered between about 0.25 and 0.6" of water and 5 to 12" of snow.   There are, however, a few members going bigger.  There's always hope for more.   The good news is it looks cool so ski conditions should remain generally good, even if a big refresh doesn't happen.  I confess that I feel very spoiled by the last several weeks and feeling a little disappointed.  L...

It was a beautiful day today if you were above the stratus clouds that were hanging around in some areas and tonguing up Little Cottonwood Canyon.  Upper White Pine on a sunny day with a deep snowpack is as pretty as it gets.   However, in the lower canyon and in Little Cottonwood, stratus lurked.   Such clouds can develop in mountain valleys and canyons when a ridge builds in and produces an elevated inversion or stable layer that caps moisture at low levels.  Indeed that was the case today with a stable layer evident in the morning (5 AM) Salt lake City sounding between about 725 and 675 mb, which is just below crest level.   This stable layer likely lowered some by mid morning.  In fact, during our tour we ate lunch right at the top of the cloud layer.  You could feel the temperature cool when the clouds moved in and then warm when they retreated.   In addition, there was just enough humidity in the air to enable ice crystal...

What an amazing winter that we are having.  Per the Alta Snow history, seasonal snowfall through yesterday was 426".  Daily totals over the four days prior to that were 11", 16", 12", and 15".  Looks like another six inches or so overnight too.  All of this on an incredibly fat snowpack.   A change in the pattern is, however, underway.  The parade of storms slamming into California and moving into Utah is about to come to an end.  That parade of storms was associated with an extension of the Pacific Jet across the eastern Pacific and into California.  An example of this pattern from 0000 UTC 15 January (5 PM MST Saturday 14 January) is shown below.   The GFS forecast for 1800 UTC (11 AM MST) Saturday, however, shows the development of a high-amplitude ridge off the Pacific Coast.  Instead of extending to California, the Pacific jet moves poleward over this ridge and into British Columbia.    Utah remains in the northe...

Forecasts look good for another storm Saturday night and Sunday.  The latest GFS forecasts a healthy trough to be over Utah at 1800 UTC (11 AM MST) Sunday with precipitation across much of the state.   The corresponding GFS time-height section for Salt Lake City shows a relatively dry low-level airmass this morning, with moisture moving ain at low levels after 0000 UTC (5 PM this afternoon).  Through about 1500 UTC, moist SSE to SSW flow prevails near and below crest level.  This is a good setup for precipitation not only in the Cottonwoods, but also on the Wasatch Back.   The GFS forecasts the trough to move through between 1500 UTC and 1800 UTC (8 AM and 11 AM) Sunday, after which moist northwesterly flow prevails.  If you wanted to complain about this storm (and you probably shouldn't), the post-frontal northwesterly flow doesn't look especially unstable, although I'm not going to lose any sleep over that because this still loops like a decent ...

Another day, another storm delivering in spades.  What a season! The last 24 hours at Alta Collins is summarized below.  From 7 am yesterday to 7 am this morning a total of 22" (there are wipes of the interval board before 1700 and 0500 that reset the snow interval measurement) and 21" since noon yesterday, so we are quickly approaching the upper-end of my forecast range from yesterday (which was 14–22" through 5 PM today).   Current radar imagery shows the northwesterly flow orographic precipitation machine is operating at full capacity as I write this at about 7:20 AM.   The 12Z HRRR calls for this to taper off this morning, with little to no precipitation at Alta after 11 AM. Do you think Mother Nature got that message?  Maybe not this year.  I'll call for another 2-4" this morning just be safe.  Meanwhile, it's worth a look at just how fat the snowpack is currently across California, Nevada, and Utah.  Below is the current snowpack w...

Some pretty solid numbers coming in for everyone in the Wasatch. Alta Collins up to 1.43" of water and 16" of snow through 7 AM, with the latter reflecting lower densities overall than I expected for this storm in Sunday's post.  A look at reports from around the area shows solid numbers from Sundance to Snowbasin, including the Wasatch Back, although the high snow level may have resulted in some mixed precipitation at the base of Sundance. The time series of temperature and dewpoint from the base of Snowbasin shows the classic "ice cube" effect with temperatures hovering right near 32˚F throughout the period, a consequence of the melting of heavy snowfall preferentially cooling the temperature to the melting point.   We are moving into a bit of a break this morning, although snowshowers may continue at times in the mountains.  The next storm moves in this afternoon and looks to continue into tomorrow.   The next storm features a bonafide trough passage and...

Our winter of wonder continues this week with two storms on tap.   That's not counting todays small appetizer as a weak trough swings through and may give a few snow showers to the Cottonwoods this afternoon.   The first of the two significant storms develops late Monday and Monday evening as an atmospheric river penetrates through southern California and Nevada to northern Utah (see lower right panel below).  Monday night and early Tuesday morning look windy and mild.  Our GFS-derived forecast guidance shows peak gusts on Mt. Baldy over just over 70 mph in the early morning hours on Tuesday with the wet-bulb zero level peaking at just over 7000 feet (that would equate to a snow level near 6000 feet).  Water equivalent precipitation from 11 AM Monday to 11 AM Tuesday is 1.12" with 7" of high-density snow.   The 12Z HRRR run is in and it's not quite as windy (peak gusts near 60 mph), but is is milder, with the wet-bulb zero getting up to just ...

Pinch yourself because these are the days.  Current base depth at Alta 121".  Every SNOTEL station in Utah above median.  Mill D North 204% of median.  Snowbird 206%.  Brighton 184%.  Thaynes Canyon 181%.  Ben Lomond Peak 206%.  Timpanogos Divide 213%.   As of today (January 7), this is the fattest snowpack we have had at Snowbird since the 2010/11 season.  We are in a virtual tie with 2005/06 and just behind 2004/05 and just ahead of 2003/04.  Compared to recent years, we have it awfully good.   Low elevation backcountry access in many areas is in, with the main complication on many trails being some downed timber from the heavy snowfall.   Typically heinous exits in many cases are remarkably well filled in.   And we have the low-angle sun!  This is most definitely the most wonderful time of the year.   The persistent weak layer from the November dry spell seems to be healing. ...