Slowvember

The State of the Snowpack - Utah

Before I get into the current weather and conditions going forward, I want to talk about the state of weather and snowpack affairs so far this November. To put it simply, this season has gotten off to a very slow start. November has been exceptionally dry and warm across northern Utah, and the snowpack in the Wasatch reflects that. Thus far, November 2025 is the warmest November on record in Salt Lake City, with an average (max_temp+min_temp/2) of 50.8 F. This is about 8 degrees above normal. Additionally, the area has only received about 1/3rd the total precip for the month. 

KSLC November Numbers

Month-to-Date Summary	Observed	Normal	Record Highest	Record Lowest
Avg Max Temperature	60.3	52.2	60.8 in 1965	37.0 in 2000
Avg Min Temperature	41.3	33.8	41.3 in 2025	21.0 in 1930
Avg Temperature	50.8	43.0	50.8 in 2025	30.0 in 2000
Total Precipitation	0.37	1.05	5.05 in 1875	0.00 in 1914
Total Snowfall	0.0	5.0	27.8 in 1886	0.0 in 2025

Average November temperatures (F) at KSLC 1875-2025. Red star represents 2025 November average temp through 11/24/2025. 

So how do the snowpack numbers look? Currently, snow water equivalent (SWE) numbers are sitting at abysmal near nonexistent depths at the higher elevation SNOTEL sites in the Wasatch and central mountains. Basin and site SWE percent of normal are anywhere from 0-40% of average (median).

NRCS snow water equivalent percent of normal at Utah SNOTEL sites and Basin wide 

The only locations that have come out on top this November are the southern Utah mountains, where the previous few storm cycles have favored those areas. But how does this early season snowpack rank in terms of the past few years?

Looking back on the late November SWE from 2021-2024 (WY's 2022-2025), the majority of the years have had an objectively slow start. The only year with above normal SWE in late November was 2022 (WY 2023). If we're trying to compare 2025 to other years, the current 2025 SWE over northern Utah is most comparable to 2021 (WY 2022). 

But is early season SWE a predictor of how the entire winter will unfold? 

Let's look at two popular Utah SNOTEL sites in the Wasatch - Brighton and Snowbird - over the years 2021-2025 to identify if the early season SWE numbers can act as a gauge for SWE over the course of the winter. In the figures below, the SWE for water years 2022-2026 - e.g. water year 2022 goes Oct. 2021 - Oct. 2022 - and November SWE for the years 2021-2025 are given for the Brighton and Snowbird SNOTEL sites. The highest SWE WY and November SWE are highlighted in red.

In terms of WY SWE and November SWE at Brighton and Snowbird 2021-2025, both WY and November SWE numbers are ranked the same 2023, 2024, 2025, and 2022 (greatest SWE to least). If we were to take meaning from this overly simplified analysis, the results allude that the higher the early season SWE the more likely it is to have a winter with a greater maximum SWE (more snow). 

November SWE vs. Water Year (WY) SWE at Snowbird SNOTEL 2015-2025. Red star represents 2025 numbers. Trend line and R squared value are shown. 

Taking this a step further and expanding the analysis to 2015-2025, I plotted the November SWE vs. the water year SWE at Snowbird (above). Obviously, this analysis is still only from a small sample size and there are many assumptions and variables left out of play, so lots of caveats here and not to be taken super seriously. Either way, the trend/relationship is moderately strong (R squared = 0.544). This is not exactly comforting if the above relationship holds true for the winter 2025-2026. Maybe 2025 will be a wildcard...?

Current and Future Conditions

At this time yesterday, the Salt Lake Valley was socked in with fog and low stratus complements of inversion conditions. This morning the skies have partially cleared over Salt Lake thanks to a slight weakening of the low-level inversion and some venting caused by increased NW winds near 750-700mb as seen in the Nov. 24th sounding below.

View of downtown SLC looking west on the morning of Nov. 23 (top left) and Nov. 24 (top right), with corresponding sounding from KSLC. Inversion depth and 700mb winds are noted on soundings

GOES-East 11/24/2025 Nighttime Microphysics: Bright yellow colors represent low clouds and fog

Nevertheless, some fog and low status remains across other northern Utah valley areas. Air quality also remains moderate for areas, with elevated PM2.5. Fortunately, some relief may be in store later today as a weak dry cold front slides across the state. 

Analyzed 300 mb heights, winds, and divergence 11/24/2025

A shortwave trough will progress across Idaho and Montana Monday, with the base of the trough grazing Utah. Although, most energy and moisture will remain north of the state, a weak cold front will slide south over Utah this afternoon through Tuesday morning. This will be a dry cold front, with the main impacts being a bit cooler temperatures and winds to help mix out inversion conditions and the associated fog and stratus. A transitory ridge builds over the state Tuesday through Thanksgiving, bringing warmer temperatures and a mix of clouds and sun the remainder of the week. Some light haze may reinstate itself under the ridge. 

ECMWF 12Z 11/24/2025 four-panel forecast 11/24-12/1/2025: (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

Looking forward to late this week/weekend, there are indications a few systems may track through northern Utah bringing periods of valley and mountain rain/snow. However, there are a wide range of model solutions for these storms, with some splitting the storm and others only having grazing impacts to Utah. I feel like this is only par for the course for how things have panned out this past month. Not holding my breath for this weekend but holding onto some hope. I can feel the frustration with skiers and snow lovers. People are itching to get out, but there is literally not even scraps. We need snow/rain...

How the Turn Tables have Turned

The low clouds and precipitation from yesterday evening have cleared, leaving a few high stratus and cirrostratus clouds interspersed with pockets of blue sky. Peaks higher than 7500' look to have gotten a fresh dusting of snow for the first time in a few weeks. 

View looking from Alta, UT down Little Cottonwood Canyon 11/17/2025

Officially, Alta and Snowbird - two ski resorts at the top of Little Cottonwood Canyon - have reported 3-4" of fresh snow. It's not much, but I guess it's something. The Salt Lake Valley eked out with 0.1-0.2" of precipitation in the form of rain, which is also not much. We're more than halfway through November with less than a fifth of normal total liquid for the month. One would hope this meager storm from yesterday - 11/16/2025 - was just the start of something more substantial but that doesn't quite seem to be the case anymore...

GOES East True Color imagery 11/17/2025

The system that brought excessive rainfall to central and southern California the first half of this past weekend then rain and snow to NV, AZ, and UT the second half has now exited the region and is spinning across the Continental Divide. Following behind that storm, a transient short-wave ridge is filling in across the Great Basin and Intermountain West, which can be noted in the above satellite imagery as the region of decreased cloud cover between Nevada and Utah. The ridge will bring some short term subsidence and largely dry conditions over the area on Monday until the next storm - currently along the central U.S. Pacific coast - moves inland on Tuesday. 

How the turn tables have turned

Just a few days ago deterministic and ensemble models alike were pointing at an active, cold, and wet period across the western CONUS and northern Utah. While the first half of that story remains largely true, the later half looks to have changed in a significant way. An unsettled pattern looks to continue across the West, but unfortunately most of the moisture and impacts look to miss northern Utah.

So what happened? In short, can blame it on splitting systems. 

Although storms will continue to roll off the Pacific into the western CONUS through the upcoming workweek, the pattern will continue to be characterized by splitting storms. The tracks and impacts of these storms will have similarities with the system that impacted California up through Utah this past weekend. Weak to moderate Atmospheric Rivers will continue to impact California through Arizona. Unfortunately, this means northern Utah will likely only experience periphery impacts from these storms. 

12Z 11/17/2025 Observed 300 mb heights, winds, and temp (C)

Looking at the 300 mb chart this morning - jet stream level - a fairly amplified trough exists just along the U.S. Pacific coast, with a strong upstream jet maxima. This jet streak will pinch off the trough, creating another closed/cut-off low and sending it on a southerly track through central and southern California. If you read my past post about cut-off lows, then you may be familiar with the difficulty in forecasting such storms. The split storm pattern seems to stay put through the week as a potential third Pacific system is forecasted to split and again move across the southern tier of the western CONUS late week into the weekend. California will continue to get walloped by these systems, adding more rainfall to already saturated ground. 

ECMWF 00Z 11/17/2025 four-panel forecast 11/17-11/24/2025: (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

All this said, what does this mean for Utah? These southern splitting storms are actually beneficial to southern Utah, bringing storms tracks and moisture in a more favorable direction for increased precipitation. The opposite can be said for northern Utah, which usually is not favored with these types of storms. So southern Utah will likely see the bulk of the impacts going through this week, while the Wasatch Front could get some fringe impacts but likely nothing substantial. 

ECMWF Ens 00Z 11/17/2025 5-day precipitation anomaly (in) 11/17-11/22/2025

Typically, northern Utah is favored by storms that track from the northwest. Simply put, the splitting nature of the storms as of recent and potentially through the next 5-7 days diverts energy and moisture away from northern Utah. 

Left: GFS Ens 00Z 11/17/2025 Total QPF; Right: ECMWF Ens 00Z 11/17/2025 Total QPF

The near and long term don't look all that great in terms of snow or liquid for the Wasatch, but that doesn't necessarily mean things can't change. In fact, considering the split nature of storms in the next week or so, I would heavily wager forecast models will be constantly changing and evolving. The ensemble GFS and ECMWF total precipitation for SLC is given below. Not very compelling but also revealing of how much spread there is in the model runs, meaning the models don't have a firm grasp on the situation.

In short, I am trying to remain neutral forecast mindset for the next little bit. Until this wonky pattern smooths out, very little can be trusted further out than 2-3 days. 

But why are all these systems splitting?

It's not uncommon for storms to split along the western U.S. coast. This is mainly due to dynamic interactions between upper-level winds and the terrain barriers along the western half of North America. Winds split, diverge, and converge as they encounter the coastal ranges and Rocky Mountains, altering the upper-level pattern coming off the Pacific. These atmospheric mechanics are analogous to when water in a stream encounters a rock, changing directions, accelerating, and creating turbulent flow on the upstream side. As to why this splitting has become so prevalent as of recent, I can't say for sure but I think it has to due with relative northern location and strength of the northern branch of the polar jet coming off the Pacific. 

Full on Fall

Another relatively warm and calm November morning. The clouds from yesterday rolled out of the state late last night, giving way to clear skies this morning. Today - 11/13/2025 - will see mostly sunny conditions with some intermittent high clouds throughout the day. Temps will once again be warm nearing near 70F for the Salt Lake Valley. 

KSLC observed temperature and precipitation compared to climate normals (credit: SLC NWS)

Warmvember has continued relatively unimpeded since the beginning of the month, with above normal temperatures every day in SLC except for one. The nice sunny and warm days have also meant Salt Lake City has been abnormally dry. Luckily, the record precipitation from October has closed in the gap needed to be close to on-track for the normal year-to-date total precipitation. SLC sits at 12.74" of total precip with normal being 13.36" year-to-date. 

Year-to-Date Summary	Observed	Normal	Record Highest	Record Lowest
Total Precipitation	12.74	13.36	22.46 in 1998	6.89 in 1931

Warm and largely dry weather will continue into the first half of the weekend, but significant pattern changes are forecasted starting the second half of this weekend into next week. Fall may actually start being fall, so get out while you can and enjoy the nice weather...

12Z 11/13/2025 observed 500mb heights and temps

A closed upper-level low/trough currently spins off the west coast of the CONUS. As this low digs south, it will become pinched off from the main polar jet/westerlies, which will direct it inland on a more southerly track across southern California come Friday through Saturday. An additional upper-level trough will slide in behind this low off the Pacific late Saturday, integrating it back into the main westerlies and lifting it SW to NE over Nevada, Arizona, and Utah. 

GOES-18 West 11/13/2025

What does this mean for Utah? 

Like mentioned previously, the warm and mostly dry weather will continue for much of the state through Saturday. As the storm approaches the Utah from the SW, a few spotty light showers are possible Friday afternoon across the Wasatch, but valley areas like SLC will likely stay dry. Winds will become a bit breezy out of the south Friday and Saturday afternoon across areas as the long-wave ridge currently over Utah progresses eastward and a southwesterly flow regime becomes dominant. 

ECMWF 00Z 11/13/2025 four-panel forecast 11/13-11/18/2025: (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

Moisture and energy will mainly filter into the state late Saturday into Sunday, with waves of valley rain and high mountain snow moving SW to NE as the low spins across the state. Northern Utah and the SLV will likely see showers Sunday morning through the afternoon. Not a ton of cold air is associated with this system, with 700 mb temps bottoming out near -3 to -4 C on Sunday across the Wasatch. Snow levels will gradually fall through the day Sunday bottoming out  near ~7500' by Sunday evening. 

ECMWF Ens 00Z 11/13/2025: Total precipitation (in) Alta, UT

There has been quite a bit of uncertainty with precipitation amounts related to this storm - due to the storms track and cut-off-ish nature - so any forecasted precip values should be taken with a grain of salt. However, current ensembles have the 50th percentile total liquid in the Cottonwoods (Alta, UT) through Sunday evening at around 0.5-0.6", which equates to about 4-6" of snow. I think the more interesting weather comes in the week ahead, but there is considerable uncertainty related to this. 

Sunday is only the prelude into a more extended period of unsettled weather going through next workweek. Warmvember will be coming to an abrupt end after Sunday, with below normal temperatures replacing the warm conditions Utah has been experiencing. The fine details of events are still uncertain, but in general a more intense and prolonged push of cold air and energy is forecasted to move in on Monday behind the Sunday storm. Additional systems are forecasted to impact Utah through the week as a progressive troughing pattern sets up across the western CONUS. However, there is still quite a bit of uncertainty and spread in the models on how these systems impact the region.  

ECMWF Ens 12Z 11/13/2025:7-day 500mb height (dam) anomaly 11/16-11/23/2025

Considering the much colder temps and more consistent bouts of moisture, the third week of November could be the first real snowpack building event of the season in the Wasatch. We'll see how much total liquid we get through this period, but 50th percentile ensembles are hinting at the best potential being between 2-3" of liquid in the Wasatch with 2-3ft of snow - upper end of that range for the upper Cottonwoods. 

ECMWF Ens 00Z 11/13/2025: Total QPF 50th percentile (in) 11/13-11/23/2025

 

50th Anniversay of the Edmund Fitzgerald

Today - Nov. 10th, 2025 - marks the 50th anniversary of the sinking of the Edmund Fitzgerald. The Edmund Fitzgerald was an iron ore cargo ship that got caught in a rapidly intensifying mid-latitude cyclone on Nov. 10, 1975,  causing the ship and all of it's 29 crew to sink and perish in Lake Superior. A ship wreck of that size - in a body of water that was not the ocean - was a shock to the nation, and the exact mechanisms for the ships demise are still a mystery to this day. Even a hit folk rock song by Gordon Lightfoot called the "Wreck of the Edmund Fitzgerald" was written in 1976 to encapsulate the unprecedented tragedy. 

The anomalous and mysterious condition's of the Fitzgerald's final voyage holds a large part in the culture, lore, and mystery of the Great Lakes as well as a significant place in meteorological history. In fact, the sinking of the Fitzgerald is so heavily embedded in weather history the majority of college atmospheric science or meteorology programs across the country teach about this event in one course or another.

Edmund Fitzgerald's final voyage (credit: Hultquist, et al. 2006)

There have been many retrospective analyses of the severe storm that sunk the Edmund Fitzgerald. Case studies like those done by Hultquist, et al. "Reexamination of the 9–10 November 1975 “Edmund Fitzgerald Storm Using Today’s Technology" published in the Bulletin of the American Meteorological Society provide excellent recaps of the conditions that led to the storm and how we can better simulate these conditions using todays numerical weather prediction. This reexamination, along with other reanalyzes of the storm, have served to improve the science of forecasting mid-latitude cyclones as well as forecasting the rapid intensification of such storms. 

So what made the storm system that sunk the Fitzgerald so strong and so surprising?

Edmund Fitzgerald Reanalysis

The storm that sunk the Fitzgerald originated as a somewhat casual surface low that was located across the southern Great Plains on the morning of Nov. 9. The surface low was associated with an approaching negatively tilted short-wave trough - trough axis tilted SE to NW, indicating strong baroclinicity and warm/cold-air advection - as well as an upper level jet maxima located over the central plains. The Edmund Fitzgerald storm evolution is shown by the NCEP reanalysis fields of 500 mb heights, 1000-500 mb thicknesses, and surface pressure from the morning of Nov. 9 through the evening of Nov. 10, 1975. 

NCEP reanalysis 500 mb heights (color shading), 1000-500 mb thickness (dashed lines), and surface pressure (black lines)

This synoptic environment provided large scale lift via jet maxima divergence and strong surface forcing via frontogenesis that aided in the rapid strengthening of the storm. Over a 12-hr period from the morning to evening of Nov. 9th, the short-wave trough, jet maxima, and surface low lifted to the NE out of the southern plains and over Iowa, intensifying from a central surface pressure of 1000 mb to 993 mb. The storm was still not considered a significant threat at this point, and the Edmund Fitzgerald left port from Superior, WI (west end of Superior) on the evening of Nov. 9th and began it's last voyage eastward to Whitefish Bay (west end of Superior). 

Location of the Fitzgerald (along with other ships) and the center of the surface low Nov. 9-10th, 1975 (credit)

The track of the surface low and Edmund Fitzgerald from the night of Nov. 9th through the evening of Nov. 10th is shown above. Over the course of the night of Nov. 9th to the morning of Nov. 10th, the storm progressed over Lake Superior. The storm intensified further as strong coupled upper-level jet maxima dynamics, frontogenesis, and lake-atmosphere interactions aligned to create optimal conditions for a severe mid-latitude cyclone. The surface pressure of the storm dropped another 11 mb to 982mb by the morning of Nov. 10th and centered over the south-central shore of Lake Superior.

Modeled wind field Nov. 9-10, 1975 (credit: NWS Marquette, MI)

By this point, the rapid pressure decreases and the collision of warm and cold airmasses over the lake made for  exceptionally strong storm that retained it's strength as it moved over central Lake Superior. Coincidently, as the surface low moved northward over the center of Lake Superior on the afternoon of Nov. 10th the Edmund Fitzgerald moved into the same waters. From the afternoon to evening of Nov. 10th, the storm reached peak intensity with significantly strong winds (> 50 mph) and extreme wave heights (> 10 meters or ~30 ft) in the exact location of the Edmund Fitzgerald (near Whitefish Bay). 

Modeled wave height (meters) Nov. 9-10th, 1975 (credit: NWS Marquette, MI)

The cyclonic nature (counter-clockwise rotation) of the wind field and the large fetch - extended distance the winds traveled over the lake surface - created swirling-bathtub like wave conditions that focused directly over the location of the ship. The timing and location of the storm track and ship corresponded in a very unfortunate manner, leading to extreme storm conditions that ultimately led to the Fitzgerald's sinking on the evening of Nov. 10th, 1975. 

To this day, there is still speculation as to the exact mechanism that caused the Fitzgerald to sink. The wreck of the Edmund Fitzgerald remains a stark reminder of the power of mother nature and unpredictability of the weather.

Not much

High cirrus shielding the morning sun

Another warm one out there this morning across the Salt Lake Valley, with some mildly breezy winds out of the south. A blanket of high thin cirrus clouds cover the sky, which usually can be indicative of a potential change in the weather. The high clouds and the relatively breezy conditions overnight likely aided in keeping things warmer than they would have been if winds were calm and skies were clear. Most areas in the SLV bottomed out in the upper 40s/low 50s which is 10-15 degrees above the normal low for this time of year. I have enjoyed the warm start to November thus far. Mild and dry weather with mostly clear skies and fall colors in the valley can't be beat.  In my opinion, these are the best sort of conditions to do outdoor activities in the valley and foothills. 

Unfortunately, the high cirrus across northern Utah this morning are indeed a sign of change. A broad long-wave trough is currently making landfall off  the Pacific into the interior of the PNW. The trough is associated with a mid-intensity AR, bringing heavy rain and mountain snow to the northern Sierras up through British Colombia. Some of this moisture and energy is forecasted to progress over the Intermountain West and into northern Utah come late Wednesday night into early Thursday morning. However, not expecting much as this weak system clips Utah overnight. 

GOES-West 11/5/2025 water vapor imagery

A cold front along with some showers will move into northern Utah come the second half of Wednesday night. The Wasatch Front valley areas could see a few light rain showers the during this time up until the morning commute, mainly focused towards the ID/UT border where better dynamics and moisture will reside. Areas south towards the SLV and Utah County will miss out on the 'bulk' of the moisture. All models are fairly consistent that total liquid amounts will be light, with the 50th percentile ensemble ECMWF and GFS forecasting 0.1-0.2" for the far northern Utah valleys and mountains. Otherwise, I would be impressed if areas like the SLV get enough precip to even fully wet the ground. 

ECMWF Ensemble 00Z 11/5/2025 : Total precipitation (in) at Alta, UT

The higher elevations across the Wasatch could see some light snow >6500-7000' for the Bear River mountains and >7000-7500' for the central Wasatch. Total snowfall amounts will range from dustings+ in the central Wasatch to 1-2" for the higher peaks in the Bear River mountains. So meager pickings in terms of winter weather...

Forecasted surface temp (F) at KSLC 11/5-11/12/2025

Thursday will be 10-15 degrees cooler than the unseasonably warm temps today (Wednesday), but will actually be near normal for this time of year. Dry air and a short-wave ridge will bring a mix of clouds and sun to Utah Thursday morning into the afternoon. A trailing short-wave trough and attendant moisture will move into the northern tier of the State come late Thursday into Friday, but impacts will be minimal to nil. Likely just bringing some cloud cover and keeping temps similar to Thursday. Beyond this workweek, things look to gradually warm back up over the weekend into early next week as a fairly amplified ridge sets over Utah. 

Long-range

Typically, this time of year when attempting to gauge what the longer range weather has in store we like to look at the forecasted trends of certain climate oscillations or teleconnections. The most common climate oscillation or teleconnection that people are familiar with is ENSO (El Nino Southern Oscillation). However, as much as the news and skiers alike love to talk about El Nino/La Nina and what that means for Utah's winters, the ENSO impact/signal for northern Utah is weak or even can be considered indeterminant. If you were to really try and parse out any ENSO trends across northern Utah, there is a weak positive snowfall anomaly signal during La Nina years for the Wasatch. But even this isn't that meaningful and shouldn't be read into. On average, there's about a 50/50 chance that the Wasatch will have a wetter/drier winter during both El Nino or La Nina. 

CPC Dec, Jan, Feb La Nina Average Snow Anomalies (in) and frequency of occurrence

For the reasons above, ENSO is not the best teleconnection to analyze when attempting to conduct seasonal or even monthly long-range forecasts for northern Utah. Other oscillations such as the Pacific North American (PNA) oscillation are much more influential and impactful for Utah weather due to the synoptic pattern they describe and relatively shorter timescale of influence. The PNA describes the large scale upper-level pattern across the eastern Pacific/western North America. When the PNA has a negative signal that represents troughing across western North America and vis versa for a positive PNA signal. Troughing across western North America indicates a pattern that is conducive for bringing storm tracks down from the Gulf of Alaska/western Canada into Utah. Therefore, a negative PNA can indicate an active storm pattern across the western CONUS. 

ECMWF 12Z 11/5/2025 forecasted PNA signal

Models have trended fairly consistently that deeper troughing and a more significant pattern change is possible come mid to late next workweek. Forecasted trends reveal the PNA is likely to go negative come mid to late month. What this means? Without trying to rub the forecasting crystal ball too hard, the long range and forecasted PNA alludes to a more extended period of active weather across the Western CONUS mid to late November... But don't want to wish cast so that is still heavily tbd...

ECMWF Ensemble 12Z 11/5/2025: 7-day precipitation anomaly (11/13-11/20/2025)

Warmvember

Deja vu... Looking out across the Salt Lake Valley this morning, and it looks fairly similar to yesterday. There is a upper-level vorticity lobe and shortwave trough progressing across Utah, but with no significant coincident moisture northern Utah is only seeing a few high cirrus clouds associated with this "disturbance". 

High clouds northern Utah 11/3/2025 (credit EB)

Surface temps aren't even being impacted by the cooler upper-level air at the center of the trough due to the presence of a low to mid-level thermal ridge undercutting the upper-level shortwave trough. The vorticity lobe (cyclonic spin) can clearly be identified in the satellite water vapor imagery. 

GOES East water vapor 11/3/2025 with analyzed 500 mb gph, winds, and vorticity overlaid

Besides this benign upper-level feature, it is unseasonably warm, clear, and calm this morning in SLC. Times like this are when a persistence forecast - forecasting the same weather for tomorrow as what is occurring today - would work very well. All of us in Utah can thank the longwave upper-level ridge that has been planted overhead for the past 4-5 days for the great mid-fall weather. 

11/3/2025 12Z 500 mb gph, temp, and observed winds

Because there isn't much weather going on, let me give a brief overview of why we associate ridges and high pressure with nice weather. Ridges are typically associated with nice weather due to the upper-level dynamics associated with them. Under a ridge, air often converges or piles up due to force imbalances on air parcels traveling in the upper-levels of the atmosphere. The principles of conservation of mass or more specifically the continuity equation in the atmosphere dictate that the change of mass within a given volume of air is equal to the net mass flow into or out of that volume. Therefore, as air converges (added to the closed volume) mass or air needs to be removed to balance. This leads to the net effect of a sinking motion below where air converges (subsidence), and sinking air dries and warms due to adiabatic processes (thermodynamic process where no heat is transferred into or out of a system). 

Air rises/sinks at the adiabatic lapse rate (~ 10 C/km) (credit Brit Seifert)

Simply put, as the air sinks it encounters an environment with higher pressure and the air parcel compresses. This is due to the relationship where pressure decreases logarithmically with height above the surface and vis versa as you decrease height above the surface. As the air sinks and is compressed, it's temperature increases due to the temperature, pressure, and density relationship described by the ideal gas law P = qRT or T = P/qR (P = pressure, T = temp, q = density of dry air, and R = dry air constant), which reveals that as pressure increases temperature of the sinking air parcel will increase. 

Given that an air parcel's moisture remains the same, a sinking air parcel warms but it's dew point remains the same. The difference between the air parcel's temperature and dew point increases (dew point depression) as the air sinks towards the surface, which aids in creating cloudless skies. 

11/3/2025 12Z KSLC sounding: dew pt. (green) and temperature (red)

This morning's sounding from KSLC showcases this concept in real life. If you look at the green (dew pt) and red (temp) lines in the sounding figure above, a large spread or difference between the two lines is apparent below about 400 mb down to the surface, indicating the drying effect of subsiding/sinking air. Just for reference, the proximity of the green and red lines near 400 mb to about 250 mb indicates the high cirrus cloud layer. Subsidence this time of year can also create warmer layers overtop cooler air pooled in valley areas, which can create inversion conditions conducive for poor air quality.

ECMWF 00Z 11/3/2025 four-panel forecast for 11/3-11/10/2025: (Top left to bottom right) MSLP/precip and 1000-500 mb thickness;700 mb gph, RH, temp, and winds; 300 mb gph and winds; 500 mb gph, vorticity, and winds

A few pieces of energy look to graze Utah come mid to late workweek, which will break down the ridge currently overhead and allow for some cooler temperatures (but not cold) and possibly even a bit of precipitation for northern portions of Utah. However, it's likely that most areas - particularly the Wasatch Front valleys - will largely just see increased cloud cover but some light precip isn't out of the question. Peering further ahead, ridging is forecasted to build back for this upcoming weekend into the beginning of next workweek, so more mild November weather is possible. 

11/3/2025 00Z GFS Ensemble Total precipitation at KSLC: Green line is ensemble average; Blue line is control run

Many are probably wondering, when will Utah get some actual winter weather again? Model ensembles have all be hinting at a pattern shift come mid-month (~ 11/14 ish) and potentially sometime towards the later half of the month as well. Definitely too far out in forecasting fantasy land to talk about possible impacts during these periods, but it is likely some sort activity will occur. For now, every skier and snow lover should do some breathing exercises and be patient...