Wasatch Weather Weenies

I like the looks of the storm on tap for late tonight and tomorrow.  It's a pretty good front that is going to usher in the coldest air of the season so far for northern Utah.   We'll start with a look at the GFS forecast valid 0900 UTC 26 October (3 AM MDT Wednesday) when a compact upper-level trough is centered over southeast Oregon and the preceeding cold front is draped across northern Utah.  At 700 mb, roughly 10,000 feet or crest hight of the Wasatch Range, there is about a 12˚C (22˚F) temperature contrast across this front, so it's a whopper.  By 1500 UTC (0900 MDT), the trough is over southwest Idaho and the front is draped over Salt Lake City.  We will be post-frontal by this time with steady rain on the valley floor and snow intensifying in the mountains.  Woo hoo! By 2100 UTC (3 PM MDT), the cold air is into northern Utah in earnest with 700-mb temperatures over the Salt Lake Valley below -6˚C.  This will mean some flakes down to bench ...

I'm a big fan of Cody Townsend's The Fifty , which documents his efforts to ski all the lines in the book Fifty Classic Ski Descents of North America .   I've skied a few of these lines and dreamed of skiing a few others.  Some are beyond either my physical or technical abilities, or the suffering to powder ratio is too high to interest me.  Cody and cinematographer Bjarne Salén do a remarkable job capturing footage of their adventures and bringing me along for the tour.  I keep thinking about all of the parameters they are dealing with including the snowpack, weather, route finding, climbing hazards, and ski challenges, and yet they are also shooting some great footage (and carrying all that gear).  It's an impressive accomplishment.   The latest episode, Tragedy and Triumph in the Split Couloir , documents their attempts to ski the extremely challenging (and often snow starved) Split Couloir on the 14,058 foot Split Mountain in California's East...

The last week of October is going to be an interesting one for mountains of the western United States.  I've been watching forecasts for a cold trough to drop into the Pacific Northwest for about a week now.  It's going to bring significant October snows to portions of the western United States.   It's worth a look at the origins and forecast evolution of this trough.  It all began with the formation of a midlatitude cyclone off the coast of Asia late last week and over the weekend.  This cyclone built a ridge that was over the Behring sea at 1800 UTC 22 October 2023 (1200 MDT Sunday, orange line).  Just east of this ridge was a weak trough and jet streak that I've circled in red. These represent the incipient cold trough.   Both the ridge and the incipient cold trough are forecast to amplify through 0000 UTC 24 October (1800 MDT Monday) with the trough digging southward over the Gulf of Alaska.  By 0000 UCT 25 October (1800 MDT Tuesday)...

 NOAA released an updated seasonal forecast yesterday, which immediately got everyone in a lather with much of Utah being "in the green" for January to March precipitation.   But let's all take a deep breath here.  First, these outlooks have never been very reliable (or all that useful for skiers).  Remember the outlooks from last season?  My "favorite" was the one issued by Accuweather last September. That didn't age well in the Sierra and Utah that's for sure.   Second, let's talk a bit about what the NOAA seasonal outlook actually means.  It is a probabilistic outlook, meaning that they are not forecasting those areas in green to definitely receive above normal precipitation.  Instead in the first two shades of green, they are saying that the odds are  leaning to above normal .  For example, southern and central Utah are in the first shade of green, which means they are giving a 33–40% chance of above normal precipitation....

The Salt Lake Tribune published an article this weekend discussing plans for Olympic Venues assuming Salt Lake is awarded the games again, which is looking likely (see Utah Olympic Venues Coming into Focus as Organizers Get Creative ).    Perhaps most surprising and disappointing is that Snowbasin may not be interested in hosting the men's and women's downhill, super G, and combined events.  Perhaps they are just posturing for a better deal with the Olympic committee, but that would be a major loss if it happens.  As far as Olympic downhills go, the Grizzly and Wildflower downhills are pretty good ones.  There's a decent amount of vertical and they are steep and technical.  Not all Olympic downhills are so challenging.  The terrain is scenic, and access for spectators is excellent.   Top of John Paul Tram and start house for the Grizzly Downhill The options outside of Snowbasin appear to be limited or simply less exciting.  Per the Inter...

The storm is over.  Automated observations from Alta-Collins indicate a storm total of 15" and a settled snow depth this morning of 12".  The High Rustler cam shows it's white.  If I squint, I think I see some tracks on Nina's.   By and large though, this puts us solidly in ski purgatory.  Enough snow to whet the appetite, but not really enough to ski.  I'm sure some people will get out, but the current snowpack situation is below my tolerance level and I'm not inclined to risk injury.  Additionally, the forecast looks ridgy.  The NAEFS downscaled ensemble forecast is pretty much a flatline for the next 6-7 days, although there is one plucky member that generates six inches.   There is always hope.   I suspect, however, that most of the snow on sunny aspects will melt out over the next several days.  It will survive on upper-elevation shadier aspects, but likely facet and weaken.  Expect heterogeneous avalanche c...

As of 7 AM this morning, the automated Alta-Collins measurements are showing what looks to be 9 inches of new snow (based on 2" through 1600 MDT yesterday and 7" overnight) and a total snow depth of 8 inches.  This from about 1.28" of water.   Overnight radar imagery (hopefully not mangled by blogger) showed bonafide lake effect for a time overnight that looked strong enough to perhaps produce a bit of lightning and thunder.   That has now transitioned to more widespread precipitation with a flow direction that is a bit more northerly than I'd like for Alta magic to kick in, as evinced by this morning's 1200 UTC (0600 MDT) sounding. Source: NOAA/NWS/SPC I'm inclined to think another 1 to 3 inches today and then you can stick a fork in it.   I'm sure that will be enough to get some diehards out, but that's not enough snow for me.  I'll continue to recreate on the brown ribbon of flow in the lower to mid elevations.  

Great Salt Lake Effect forecasts from computer models have historically exhibited poor reliability for a few reasons.   One is that many computer models have had insufficient resolution (or grid spacing) to adequately resolve the Great Salt Lake and surrounding mountain effects.   Another is that the Great Salt Lake is simply very sensitive to small changes in the ambient flow and surface conditions, so when you look at a handful of model runs, they don't always capture the full range of possibilities. Let's take a look at how these issues are manifest in current model runs, starting with the GFS. The effective grid spacing of the GFS is 13 km.  At it's current level, the Great Salt Lake is about 25-km wide, meaning that in northwesterly flow, the GFS at best has two or three grid points that include lake characteristics.  In addition, the GFS is unable to distingish between the Stansbury, Oquirrh, and Wasatch Ranges, so it cannot separate mountain effects ...

Enjoy today's mild weather because things are gonna change. I can feel it.   By tomorrow morning, we will be in colder air.  The GFS shows that by 1200 UTC (6 AM MDT) tomorrow morning the surface cold front is through and we are in colder, westerly flow.   Temperatures and snow levels will be dropping overnight and in the wake of the cold front.  Our GFS-derived forecast product for upper Little Cottonwood shows forecast highs for Alta-Collins today in the low 50s, fairly close to yesterdays 54°F max, and then temperatures falling overnight and remaining in the low 30s tomorrow.   Concurrently, the wet-bub zero level drops to below 8000 ft by 9 AM tomorrow morning and near 7000 ft by 6 PM tomorrow afternoon.  That puts the snow level around 7500 feet in the morning and perhaps 6500 ft by afternoon.   The GFS generates periods of snow with and following the front, adding up to about 8" at Alta-Collins by  6 AM Thursday.  Th...

October is my favorite "bonus" month.  Everything about the month is a bonus.  If it snows, the skiing is a bonus.  In Utah, if it doesn't snow, there's a good chance the weather is great for hiking or mountain biking.  The colors start to change and the views are wonderful.  Southern Utah is more tolerable.  It's hard to say anything negative about October.   And today was the epitome of October.   Blue skies, mild temps, beautiful colors.   The new BST from Mueller Park to Wild Rose is such a pleasure to ride this time of year.  Much of the trail was dense and moist.  Almost as if someone had oiled it.  Views were spectacular both up mountain and down mountain. Residents of Bountiful and North Salt Lake are fortunate to have such a great trail to ride.  I feel jealous whenever I go there given the unfinished trail plans in the Avenues.   The colors this year seem especially vibrant.  I think...

We have a sublime WYSIWYG (What You See Is What You Get) forecast for this weekend.  Currently, parked under and upper-level ridge. Tomorrow we're parked under an upper-level ridge.   Sunday we're parked under an upper-level ridge. You get the point.  "Severe clear" is the operating phrase.  Enjoy the fall colors.  

October is coming in like a lion with thunderstorms late yesterday and more action overnight.  Dawn broke this morning with a light coating of snow at Alta.  I'm surprised nobody has put a skinner in yet.  Source: Alta Ski Area Looks like trace amounts at the base, but perhaps 2-3" up high, which may include a bit of snow from Saturday night.  It's unclear if the Collins snow-depth sensor is working yet, but the gauge came in with 0.38" of water equivalent in the last 24 hours.  I mentioned in the previous post the possibility of snow, but was leaning toward a few inches and was inclined to have low expectations for the event.  The models, however, have been trending toward a wetter event.  The GFS, for example, is putting a low moving precipitation band directly over the central Wasatch today.   It then brings a cold, moist secondary trough trough Utah tomorrow.   Telescoping down to Little Cottonwood, the GFS generates a remarkabl...