Warmvember

De javu... 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...