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.