Waiting for Snow, Still

Not much change on the weather front.  A weak system will come through tomorrow afternoon and evening.  Some models generate squat.  Others an inch or two.  A game changer it ain't.

A look at last nights Utah snow ensemble shows that storm around 00z 29 Jan with a few of the members producing modest accumulation but the vast majority at 2" or less.  A few ensemble members call for something around 00Z 3 Feb, but most are producing paltry amounts.  

It's only one model forecast, but the ECMWF HRES from this morning has a dreaded Rex block (high pressure "over" low pressure) along the west coast later next week.  

Hope something slips through the net or that the model guidance is just out to lunch.  Even a few inches would be nice.

Waiting for Snow

People keep asking me when it's going to snow.  My response?

How the hell would I know?

Things are grim.  It's OK to be cranky.  

As a scientist, I like to look at the evidence.  I'm doing this at about 7:15 on a Wednesday night part way into a fine bottle of Chianti, which I find necessary to numb sting of the forecasts.

Let's start with the GFS.  A paltry 0.04" of water and 0.7" of snow for Alta-Collins over the next week. 

The Euro?  I don't have an equivalent graphic.  I've looked at the next 10 days.  it might have a few more scraps at times, but nothing to get excited about.

The Utah Snow Ensemble?  Well, the Euro is in it along with 81 other forecasts from the European and US ensembles. It too is pretty grim.  The forecast below covers 10 days.  There's one member that produces just over 20 inches.  There's always hope.  There are 10 members total that produce more than 10 inches.  There's always hope. 

So, 12% of the members give us 10" or more.  Not sure I'd book the private jet from SoCal for a deep powder day based on that.  75% of the members produce 5" or less.  That would be sobering if it wasn't for the Chianti.  

Just how insane is this pattern? The plot below includes 500-mb height contours (the flow roughly parallels these contours with lower heights to the left) and wind speed color fill.  There is practically no flow from Baja California to northern Alaska.  The strongest flow is actually off the SoCal coast, but even there it is < 30 m/s (60 knots).

The closed low causing that weak flow will move across the southwest and give some areas of precip to central and southern Utah and eventually, gulp, parts of Colorado.  For northern Utah, some clouds and maybe flurries with little accumulation.  

Take a look at that image again.   The Pacific Jet want's nothing to do with the west coast.  It takes a hard left turn off the coast of Japan, circumnaigates even Alaska, and then drops down into central North America.  Sucks for Utah. Sucks for Chicago.   

Yes, it sucks, but it could be worse.

Evidence of Top Down Mixing

The pollution layer over the Salt Lake Valley remains today (Saturday) but clearly shallowed over the past few days.

The photo below was taken at 0743 MST Tuesday.

 You can compare that with the one below taken at 0745 this morning.

So, some temporary relief in some upper-bench areas.  

On the valley floor, there was also some improvement, with PM2.5 this morning at Rose Park being lower than it has been in a few days.

All of this is evidence of top-down mixing with the pollution being mixed out from the top down.  Sadly, it has not all been removed on the valley floor. 

What remains after today we will probably be stuck with again for a while.

Stirred Not Shaken

As discussed in the previous post, a weak upper-level trough was expected to move over northern Utah yesterday, but it was unclear if it would crack the inversion (I was skeptical).  Indeed, looking at things this morning, I'll call it "stirred not shaken." Impacts on the pollution are varied.  In the Avenues foothills, there was clear improvement and evidence that the pollution is shallower, as sometimes happens in a weak partial mixout event in which things are eroded from the top down.  

On the other hand, a look at satellite imagery shows evidence of fog or low clouds in portions of the Salt Lake Valley, Tooele Valley, and the area from Bountiful to Layton.  Instead of being bright like the mountain snow, the fog and low clouds look grey, which may reflect that it is thin, patchy, or simply mixed with all of the smog that is still stuck on the valley floor. 

Source: College of DuPage.  Image from 1611 UTC/0911 MST 16 Jan 2026.

As I worked on this post this morning, some of these low clouds moved over campus.  

Air quality during this episode has varied considerably during the day.  At Hawthorn Elementary, one can see the PM2.5 levels peaking each afternoon.  Peak values worsen each day through the 14th (Wednesday).  There was slight improvement yesterday.  

Source: MesoWest

At Rose Park, one sees this same behavior, but peak values are somewhat higher and the nighttime declines are not as large. PM2.5 concentrations this morning are just a smidge lower than the previous two days.  

Source: MesoWest

The question now is what will happen this afternoon.  Temperatures this morning are actually several degrees C cooler above the valley floor than they were yesterday.  At about 7000 ft elevation, for example, it's 1.8°C this morning, whereas it was 5.0°C yesterday.  Thus, the inversion is weaker.  This makes it more susceptible to surface heating during the day.  One possibility is that with a bit of surface heating we start to vent the valley floor and we mix out some of the gunk.  A best case scenario is we vent everything.  I think that's unlikely, although perhaps some areas see some improvement.  

Perhaps more likely is that the pollution remains very stingy over and near the Great Salt Lake.  The lake is a bit colder than the surrounding land surface in situations like this and there can be a lens of cold, polluted air that remains entrenched over it.  That cold and polluted air tends to move into the Salt Lake Valley during the day.  Sometimes it mixes out for a bit only to have the polluted lake air push in during the day.  

We will see how this pans out.  Definitely a tough forecast.  Hope for a full mix out.

We Could Be Screwed

Just another day in the paradise that is the Wasatch Front.  The latest west-facing image from the University of Utah shows a blanket of smog over downtown Salt Lake City.  

Source: https://horel.chpc.utah.edu/camera_pages/wbbw.html

It's tough to get above it without going to the mid elevations.  I hiked this morning to the top of the Avenues foothills and it was unclear if I was completely out of it even at 5700 feet.  

Recent station (filled squares) and mobile (filled circles) PM2.5 observations show values in the valley generally between about 28 and 45 ug/m3.  

Source: https://utahaq.chpc.utah.edu/

The threshold for unhealthy for sensitive groups is 35.5 ug/m3, so we are seeing values that are near or above that.  The DAQ sensor at Hawthorne Elementary is at 41.3 ug/m3 as of 2 PM.  

Is there hope for a mix out?  The best chance is probably on Thursday and Friday.  On Thursday there is a weak upper-level trough moving over Utah late in the day in the ECMWF HRES forecast.

In the wake of that system, the northerly flow increases and crest-level temperatures drop to perhaps -2°C.  Perhaps the cooling aloft combined with the increased flow can at least give us a partial mix out, but other models are less optimistic than the Euro and it's possible we're screwed.  The GFS forecast for Friday afternoon, for example, still has a capping inversion based at about 825 mb.  In that case, we probably remain exiled in hell.  

Assuming we don't or only partially mix out, we could see the development of fog and eventually stratus that's elevated above the valley floor.  That will make for even more depressing conditions, but in some of those situations cloud base raises with time and produces a deeper mixed layer at low levels.  There's still pollution, but there's a bit more dilution that helps to moderate the PM2.5 levels (although they can still be hazardous).  

Hope for that partial mixout on Thursday and Friday.  

LCC Is Back (Temporarily)

January 8 marked the first day this season with an above median snowpack water equivalent at the Snowbird SNOTEL.  Hooray.  LCC is back, at least temporarily. The recovery from the storms over the past week in upper Little Cottonwood Canyon has been remarkable.  The skiing yesterday for a non-powder day was really great, with great groomers you could carve the hell out of and an open and well covered (or as covered as it ever gets) High-T providing access once again to "real skiing."  

Although deep powder is the pinnacle of skiing, I always pinch myself on sunny groomer days like yesterday because I didn't know weather and snow like that were even possible when I was a kid in upstate New York. 

Looking down Mambo and remember my roots

Sadly the forecasts are dismal.  I don't know if I've ever seen the Utah Snow Ensemble completely flatlined for a 10-day period, but it is.  

Actually there may be a couple of members in there that produce a skiff of snow here or there as I see a couple of whiskers poking up just a bit in the middle panels, but for all intents and purposes it's over for at least the next week.  The good news is that it's January and between the low sun angle and cool forecast wet-bulb temperatures, Mother Nature won't be spoiling the snow on upper-elevation aspects on the north half of the compass.  The skiing should hold up about as well as it can without a refresh.  

And, given the conditions this year and my plans to be in Austria in a few weeks, I'm looking for a front-side all-mountain ski for groomers and off-piste skiing when it isn't deep.  Although I'm a reasonably proficient technical skier, given my advancing age, I appreciate a ski that doesn't require huge energy input.  If you have suggestions, add to the comments.