Wasatch Weather Weenies

In the wake of yesterday's epic storm, which produced a 2" at Alta-Collins, the biggest storm since Jan 7–8 and what qualifies for all intents and purposes as a deep-powder day , fog and low clouds have filled the lower elevations of the Great Salt Lake Basin and Cache Valley.  It was a cool scene this morning with fog behind downtown and in some cases fingering around the skyscrapers. GOES true-color satellite imagery for 1946 UTC (1246 MST) shows fog or low clouds covering the Great Salt Lake and surrounding playa, extending up through lowland areas and the Cache Valley to southeast Idaho.   Forecasting fog and low clouds sucks and I'm not good at it.  With the ridge building in, I wonder if it could linger for several days, possibly spreading in coverage, or if it might break up.  I also wonder if it could spread down into the Salt Lake Valley this afternoon as the lake breeze and up-valley flow advects it southward.  That's really a battle between the t...

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.

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...

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.

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 ...

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 trou...

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 sk...