Almost Normal

Last of the weekend storm passing over northern Utah this morning. Cold valley rain in SLC, with some graupel and rain/snow mix along the benches under heavier showers. Heaviest precipitation will be focused through the next hour or so as moisture, forcing, and instability are maximized with the frontal passage. The KSLC sounding this morning reveals relatively steep low to upper-level lapse rates (>6.5 C/km) and a hint of CAPE (~160 J/kg). Storm activity will start to decrease after mid to late morning as the trough axis passes over and drier air filters into the region. In the meantime, the cooling of the mid to upper-levels has allowed some modest instability and the formation of some convective showers. 

These convective showers are dropping heavier rates and heavy snowfall has been observed in the mountains, with rate s1"+ in the the last 1-2 hours and near whiteout conditions in certain areas. The heavier rates have dropped snow levels as low as 5000-5500' in some locations. Road conditions in the Cottonwoods are snow covered down to the lower canyon in LCC and down to mid canyon in BCC. Conditions also deteriorate the further up canyon you travel. 

LCC mouth 5419' @ 0930 1/5/2026

LCC  6440' @ 0930 1/5/2026

LCC Alta 8700' @ 0930 1/5/2026

Storm snow totals over the last 24-hrs have been about 8-14" at the ski resorts across the Wasatch. Additional accumulations have fallen since these observations and a few more inches are possible through the afternoon, so all said and done storm totals could be near 20" for the favored resorts. 

Snowfall will become more intermittent and showery after mid morning, but residual moisture and some daytime heating will likely bring the potential for scattered snow showers going into this afternoon in the mountains. The northern valleys will likely dry out with a mix of clouds and sun by this afternoon, but can't rule out a spotty shower. 

And in related news, most upper elevation (>8000-8500') mountain SNOTELS in the central and northern Wasatch are now reporting near average SWE. We could even be above average SWE and above 2025 levels by the end of this workweek. That's not to say we have average snow depth at these locations. Storms have been warm and snow densities have been high, so while we have the liquid in the snowpack we don't necessarily have the depth. But we're not too far off and could get there. I wasn't so sure we could ever claw our way back to normal this season. The snowpack across mid to lower elevations (5500-8000') is still in poor shape or nearly nonexistent. Still work to be done there.   

Snowbird SNOTEL SWE (in)

Brighton SNOTEL SWE (in)

A brief intermission between storm activity is expected late Monday through early Wednesday (1/5-1/7/2026). Active conditions return late Wednesday through Friday as a colder system dives down from the NW, bringing snow across the state. This storm will be colder than this previous disturbance, and will offer the opportunity for valley snow late Wednesday into Thursday. 

Left: ECMWF 12Z 500 mb heights and vorticity ; Right: GFS 12Z 1/5/2026 500 mb heights and vorticity 

There is a bit of uncertainty in the exact storm track and trough location, with the GFS and ECMWF models differing slightly. While there are only slight discrepancies between model forecasts as of now, small variations in the storm positioning can influence storm impacts. Specifically, snow totals in the valleys and Wasatch will be dependent on how the trough approaches and passes over the state. The deeper the trough digs, the more NW the trough progresses, and the more consolidated the trough remains (rather than shearing apart) over the state the greater the potential for heavier impacts. So some uncertainty remains...

After this mid to late week storm, things quite down for what looks to be a more extended period. Ridging and the potential for inversion conditions are on the table going into this weekend and at least early next workweek. Hopefully, things pick back up again come the second half of January...

New Year, New Pattern?

Nothing like a cold rain, low clouds, and dreary conditions to remind you of an East Coast winter. The northern Utah valleys are socked in with light rain and some mixed precipitation this morning.  Temperatures are in the mid to upper 30s for most locations. Temperatures up in the Wasatch aren't that much cooler, ranging from right near freezing to the upper 20s. The rain/snow line is currently around 6500-7000'. Mountain and canyon road conditions are largely good, with mainly wet roads and some sloppy slush up near the ski resort elevations.

Salt Lake Valley to Park City surface conditions @ 0915 MDT 1/2/2026

UDOT Cardiff Fork ~7380' camera @ 0915 MDT 1/2/2026

Currently, we are seeing the last of a disturbance as it move eastward out of the state. Winds are out of the W-NW, which has aided in some cold air advection overnight into this morning and brought snow levels and snow density down. The ski resorts received about 12" of fresh snow across the board through the storm event for the Cottonwoods with a bit less for the remainder of the Wasatch resorts.

GOES-19 East Longwave Infrared imagery 1/2/2026 with surface observations and 500 mb heights and winds overlaid

Wasatch ski resort snow accumulations (in) 1/2/2026

Showers will largely taper off by mid to late morning in the valleys, with some lingering light snow showers potentially continuing in the mountains above 6500-7000' through the early afternoon. Probably not much more in the way of new snow accumulations. Drier and warmer air intrudes into the area later today as winds shift more W-SW. This will likely bring snow levels up some for any remaining snow showers. Nonetheless, any remanent moisture should move out of the region by this afternoon.

Conditions dry out and warm some late Friday through early Saturday as a transient ridge and flow shifts SW over the state. However, this dry interlude does not last long as the next storm on tap moves in off the Pacific and over the western U.S. by late Saturday. This setup could potentially keep conditions active for Utah second half of this weekend through mid to late next workweek. 

ECMWF 00Z 1/2/2026 four-panel forecast 1/2-1/6/2026: (Top left to bottom right) MSLP/precip and 1000-500 mb thickness; 300 mb gph and winds; ; 500 mb gph, vorticity, and winds; 700 mb gph, RH, temp, and winds

A broad upper-level trough with embedded waves of energy and moisture will center itself across the western U.S. Saturday through Monday, bringing an upper-level jet and moisture tap directed over Utah. Beginning late Saturday into early Sunday morning, a weak wave - out ahead of the main trough - will graze northern Utah. A few valley rain and mountain snow showers above 7000-7500' are possible during this period, but the main focus for precipitation and accumulating mountain snow looks to be Sunday into Monday as cooler air, additional moisture, and the best jet dynamics move into the state. 

The Sunday into Monday storm event will be tied to a landfalling atmospheric river (AR), but will differ from the past AR events we have had so far this season. Could the pattern finally be shifting? Mid-level temperatures will be a bit cooler than previous AR's, with snow levels near 7000' to start late Sunday before dropping down around 6000-6500' by Monday. The cooler temperatures will help more efficient snow production in the mountains rather than bringing mountain rain/snow that has been characteristic of many storms over the past 4-6 weeks. 

ECMWF 12Z 1/2/2026 72 hr Total Precipitation Accumulation (in)

ECMWF 12Z 1/2/2026 72 hr Total Snow Accumulation (10:1 ratio) (in)

Locations favored in SW flow, like Brighton or Deer Valley, could do well with this storm. Confidence in exact accumulations on the lower end, but as of now total liquid for the Sunday through Monday storms ranges from 1-2+" in the upper Cottonwoods to PC ridgeline. Areas further north towards Snowbasin and Powder Mountain could also see amounts in a similar range. The liquid totals could translate into total snow accumulations in the range of 12-24+", however, snow totals will be heavily dependent on location and the exact timing of colder temps as this will impact snow density. 

Alta, UT total snow accumulation plume 1/2-1/9/2026 (credit: UoU Atmo Sciences)

The late weekend into early next week storm could be one of the bigger if not the biggest mountain snow producer of the season thus far. But I guess that's not really saying a lot. There is the prospect of a colder and active pattern continuing into the mid to late upcoming work week. A more typical wintertime Utah storm has been trending fairly consistently across models for the this Wednesday into Thursday timeframe. 

ECMWF 12Z (left) and GFS 12Z (right) 1/2/2026 500 mb anomalies on 1/8/2026

Both GFS and ECMWF runs have noted negative 500 mb height anomalies across the Great Basin/Utah region during this period (1/7-1/8/2026), indicating troughing and potential storm activity. There are also signs that this mid-week storm looks to come out of the NW with more a more characteristic colder polar airmass and moisture source. The Wasatch shares the love the most with storms out of the NW, so hopefully this forecast stays true... 

Alta, UT UoU GFS Ensemble Total Snow (in) 1/1-1/11/2026 (credit: UoU Atmo Sciences)

For fun, let's goggle at the the 240 hr (10 day) UoU GFS Ensemble total snow accumulation for Alta, UT 1/1-1/11/2026. The ensemble 50th percentile puts a total of 50" at Alta from now through the end of next week (1/9/2026), which is nice to hope for. Even nicer, albeit less likely, is the 90th to 100th percentile totals of 65-96", respectively. Will these numbers be reality? Most likely not, but it is fun every once in awhile to wish-cast and hope for the higher end... 

Boiling a Frog

Finally, some weather that actually feels like winter. Temperatures have been the coldest of the season thus far along the Wasatch Front yesterday and this morning. Valley temps bottomed out in the upper teens and low 20s across northern Utah, and will only warm into the low to mid 30s by this afternoon. It's nice to see a semi-fresh coat of white plastered on the mountains on a nice bluebird day.  

Top of Alta, UT looking west 12/29/2025

GOES-18 West 12/29/2026

Resorts reported storm totals of around 10-17" from the last storm cycle (probably inflated some). However, as exciting and welcoming the new snow is, the snowpack in the Wasatch still remains in very poor shape for this time of year. The fresh snow from the last storm does a good job of whitewashing and concealing the rough conditions underneath. Wind, warm temperatures, and rain up to 10,000' over the previous 10-14 days has really done a number on what was already a subpar snowpack. 

While this season technically has been drier than normal, there have been many years that have been even drier but have had higher SWE and a deeper snow pack by this time of the season. If we look at total precipitation that has fallen to date at Snowbird SNOTEL, observed precipitation is only slightly below normal amounts (86% of median - green line). Snowbird observed 13.1" this season and 12.9" total precipitation up to 12/29 in the 2025 WY. Although the total precipitation amounts are nearly equal, the SWE this season is 6.9" compared to 8.5" last year on this date. The 2025 WY had over 1.5" of more SWE than this year but had gotten less precipitation. These sort of yearly comparisons are even more pronounced at mid to low elevation sites. 

So what is going on this year?

Snowbird SNOTEL - Total precipitation accumulation (in) 2026 vs. 2025 WY

Snowbird SNOTEL - Snow water equivalent (in) 2026 vs. 2025 WY

Why is it then that there is less snow this year than previous years (like 2025) that have had the same or less precipitation? 

It comes down to the very warm and abnormal conditions. A slow but steady warming has never really given the snowpack a chance to build efficiently. Additionally, frequent ablation or melting events caused by warm temperatures and rain have plagued the snow pack this season. The pattern that has been characteristic of much of the western U.S. has not allowed much cold air to infiltrate across the region. A semi-persistent or at least stubborn ridge centered off U.S. Pacific coast has continuously diverted storms on a more northerly track and allowed warmer air to reside further north. The 500 mb composite anomaly from the 12/1-12/27/2025 period reveals positive anomalies (green/warm colors) across the western U.S. associated with the persistent ridging.  

500 gph composite anomalies 12/1-12/27/2025

Surface temperature anomalies (F) 12/1-12/29/2025

We've had storms but it's been liquid not frozen

There have been storms, but they have been associated with subtropical airmasses and moisture not polar or artic, which is what is needed for decent snow events. Therefore, the rain/snow line has been near 10,000' at times for the past few storm cycles, causing precipitation to fall as liquid rather than frozen for much of the Wasatch. Not only do you get a rain soaked snowpack but all of that liquid that could have been building the snowpack is also lost. It's a bit frustrating. 

Mid to lower elevation snow has been nearly non-existent up until this last storm. A good proportion of precipitation has fallen as liquid at these locations or has had snow that has melted out. This is an extremely and historically warm fall into winter for Utah. It will likely be the warmest on record. While other seasons have had low snowpacks, they have had them because of exceedingly dry conditions. That is the difference between this season and others. This year has be marginally drier than normal, but it is the warmth which has killed our snow in the Wasatch not the mediocre drought. 

Maybe January or February could turn the sad snow situation around? I hold out hope but my expectations are heavily hedged...

We Got Some

After what has been a bizarrely warm December, a blanket of white has finally arrived across the Salt Lake Valley and the mountains this morning. I guess Santa has come a little late, but better late than never. 

Temperatures are in the low 30s around the valley as light to moderate snow falls. Some rain may mix in at times. Coverage and intensity will decrease through the morning. However, snow showers will likely continue in the Wasatch at times - largely in the Cottonwoods - through the day. 

A second push of moisture, energy, and colder air will arrive later this afternoon as a trailing storm slides over northern Utah. During this period, mid-level winds with shift more northwesterly which should enable orographics to be enhanced in the mountains through the evening. Valley areas could see some additional snow showers as well.

I don’t think this storm event will deliver blockbuster numbers, but it could also deliver some sneaky amounts. All said and done the Wasatch resorts could see another 4-10”. Maybe skiff in the SLV.

This storm almost feels abnormal with how warm it’s been, and unfortunately things look to dry out and warm some going into the work week. Next storm on tap looks to be just after the new year.

Sounds Like A Broken Record

Warm, breezy winds out of the south, and high status clouds on deck... The PNW continues to get hammered with atmospheric rivers (AR's), with another decaying AR on tap for northern Utah today through the first half of this weekend (12/19-12/20). This feels like a broken record. Decaying AR's seem to be the new normal this season, and they unfortunately don't elicit the same weather excitement as full scale AR's. 

Sometimes, these "partial" AR's end up being more of a nuisance rather than anything satisfying. You get almost none of the benefits of an AR - large precipitation totals - and instead get all the disbenefits, including warm temperatures and high winds. In addition, because there is never a strong push of cold air, snow levels remain high, snow water ratios remain low, and snow pack in some areas has the opportunity to melt out. It's all a bit frustrating. 

ECMWF 00Z 12/19/2025 four-panel forecast 12/19-12/22/2025: (Top left to bottom right) MSLP/precip and 1000-500 mb thickness; 300 mb gph and winds; ; 500 mb gph, vorticity, and winds; 700 mb gph, RH, temp, and winds

The best opportunity for precipitation across the Wasatch Front looks to arrive Friday night through Saturday morning as the best dynamics and moisture arrives. Some scattered shower activity, mainly focused over the mountains, is possible through Saturday afternoon as conditions become more favorable for terrain driven upslope. Cottonwoods could get a little extra during that time. 

Total Snow (10:1 in) 12/19-12/20/2025 Left: ECMWF 12Z 12/19/2025; Right: GFS 12Z 12/19/2025

Snow and liquid accumulations don't look particularly impressive, with quite a bit of uncertainty and a relatively wide range in lower and higher end totals. For the Cottonwoods, there is the potential for anywhere between 4-10" of snow (~0.5 - 1" liquid) through the storm event (Friday-Saturday afternoon). Note, that most all of the snow accumulations will be above 7500-8000' and the snow that falls in the higher elevations will be wetter and dense. 

GFS 12Z 12/19/2025 Derived Alta, UT Snow Accumulation (in) 12/19-12/26/2025 (credit: UoU Atmo Sciences)

ECMWF ENS 00Z 12/19/2025 Total Snow (10:1 in)

The bombardment of AR's along the PNW and California coast looks to continue through the late weekend into the holiday week. This will provide an opportunity for a few additional shots of moisture to graze Utah Sunday through Tuesday of next week. However, once again, these will be 'warm' storms, with high snow levels and strong gusty winds at higher elevations. There are hints that this pattern will change somewhat going into Christmas Eve and Christmas and offer Utah a more robust storm, but too far out in forecasting fairy tale land to say for certain. In the meantime, we will have to make do...

  

Some Records

A bit calmer and cooler today than 24 hours ago. The storm that rolled through yesterday morning through the afternoon was punchy and quick, but still managed to throw out some significant and noteworthy weather numbers. Strong wind gusts 70+ mph were recorded at many sites across northern Utah as the main energy/front passed over early afternoon. Top of Snowbasin reported a gust of 94 mph and a gust of 77 mph was observed at the Alta Guard House. 

The high winds aided in vigorous mixing and possibly some down slope warming off the mountains, which produced record high temperatures at many locations across the Wasatch Front for the date. 

If we look at soundings from KSLC from the morning and afternoon of 12/17, we can identify the valley was inverted in the morning, with cooler air pooled near the valley surface and warmer air overlying. The late afternoon sounding reveals the temperature inversion and cooler air in the valley had been eroded away in the afternoon by the strong winds. Note the afternoon KSLC sounding was observed well after the record high temps (67 F ~12:50 PM), but the sounding still exhibits how the temperature profile evolved with the storm.

So how did the winds create abnormally warm temps? The winds mixed warmer air from above the valley surface down to the ground. As the air was forced towards the surface, it compressed and warmed at the adiabatic lapse rate (9.8C/km). For example, when the 10C air at 800 mb (~1 km AGL) was mixed down to the valley floor it had the potential to warm to 20C (68F). This is how we observed record temperatures during the early afternoon hours from the storm yesterday. 

Unfortunately, no records or even significant numbers related to snowfall were observed. Only a few inches of wet snow/graupel were reported at Alta. All said and done, Alta observed a total snowfall of 3" with a total liquid of 1.06" over the course of the storm. This probably did not all fall as frozen precipitation as temps were warm enough for rain early on 12/17. Either way, I would say the snow that fell is dense or mostly graupel/rimed snow..

Something

Breezy and relatively warm in the Salt Lake Valley this morning. Temperatures actually bottomed out near midnight last night before clouds moved over and winds kicked up out of the south. A low of 36 F was recorded at KSLC just after 12AM 12/17/2025 before winds increased and temperatures rose by about 12 degrees by 6AM. 

Observations from KSLC 12/16-12/17/2025 Top: Temperature, RH, and dew pt; Bottom: wind speed, gust, and direction

Typically, nights are coldest when skies are clear and winds are calm. The lack of winds and clouds allows the most efficient conditions for nighttime radiative cooling, where the Earth's surface loses heat by emitting  thermal infrared energy (longwave radiation) upward into space. This allows the surface to cool faster than the air directly above it, creating a nocturnal temperature inversion. 

Nighttime temps with calm winds and clear skies (Credit: NWS)

On nights when there is sufficient wind, the warmer air from above the surface and cooler air near the surface are mixed, which has the net affect of warming the air near the surface. This process is similar to a fan in a room mixing warmer air near the ceiling down to the ground. Clouds act as another layer to inhibit nighttime cooling due to the fact that clouds radiate infrared energy towards the surface.

Nighttime surfaces temps with breezy winds and clear skies (Credit: NWS)

Today 12/17/2025

A decaying atmospheric river currently impacting northern Utah, bringing strong winds and precipitation through the afternoon hours. The main upper-level low associated with this storm is centered across the northern and Canadian Rockies as evidenced in the mid-level water vapor imagery below. 

GOES-18 West 12/17/2025

A strong jet maximum and coincident tight surface pressure gradient has already brought strong southerly to westerly winds this afternoon, with gusts 60-70+ mph observed, particularly across the West Desert. Winds were strong enough to create a brief window of blowing dust that swept across the SL Valley prior to the arrival of a band of moderate to heavy rainfall. 

Blowing dust moving across downtown SLC 12/17/2025. Camera image is looking west across downtown. 

Mosaic radar loop 1830-2150Z

The heaviest and most consistent showers have already come to an end in the SL Valley, but will continue over course of the afternoon in the mountains. A few sloppy inches of snow are possible above 8000', with less possible at the tail end of the storm between 7000-8000' as cooler air moves in and snow levels drop. Not much...

Another possible system this weekend. But once again, it looks to be a 'warm' storm and any substantial precipitation amounts may be hit or miss across northern Utah.