textproduct: Grand Junction

KEY MESSAGES

- Above normal temperatures persist through the period.

- Valley rain and mountain snow return tomorrow and Friday, with potentially difficult holiday travel expected over the mountain passes.

- After a dry weekend, unsettled weather could return by early next week.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 116 AM MST Wed Dec 31 2025

High pressure is expected to crest over eastern Utah and western Colorado today, bringing mostly clear skies and generally quiet conditions through this evening. Temperatures will run 10-15 degrees above late December normals as warm air advection continues. All this means that today will be a lovely, if unseasonable, send-off to 2025.

Clouds will be on the increase this afternoon and evening, however, as Pacific moisture is advected into the region on southwesterly flow aloft. Rain and high elevation snow showers will gradually overspread the region from southwest to northeast tonight, becoming widespread by daybreak tomorrow. The amount of moisture with this system is impressive, with ensemble guidance indicating PWATs running 250-300% of normal tomorrow. There are a few problems with this set-up, however. One is the very dry antecedent conditions we've seen the last several days. It's going to take some time for the atmosphere to moisten to the point that precipitation can reach the ground. Another is a lack of upper level dynamic support. Some very modest jet support is in place tomorrow, but orographics will be doing quite a lot of the heavy lifting to wring out this moisture into precipitation. Yet another problem is that this system isn't really all that cold. Temperatures are expected to remain 10-15 degrees above normal, with high snow levels keeping accumulating snow to above 8-9K feet. Totals of 4-8 inches will be possible above this level, meaning some potentially difficult holiday travel across the mountain passes on New Year's Day. No highlights have been issued yet, but stay tuned.

LONG TERM /FRIDAY THROUGH TUESDAY/

Issued at 116 AM MST Wed Dec 31 2025

On Friday there is the potential for an open wave trough to track over our area. For now the models consensus is over the southern half, which is further north than previous runs. Model trends are towards a more defined wave. If that occurs it could provide some extra forcing for precipitation and result in an increase in coverage and rates. There has been a modest increase in the QPF, which could be contributed to the high-res models and or the presence of the shortwave. The coldest air associated with this system is around -3C at 700 mb, which is a relatively warm air mass. Therefore snow levels appear to remain around 8 kft through most of this event, so that means impacts will likely be limited to travel over mountain passes for the most part.

That wave exits the region later in the day leaving orographic snow showers in the mountains. A ridge quickly builds over the region Friday night bringing in dry air that will shut down any lingering showers. Southwest winds persist over the weekend, with minimal moisture transport. Unseasonably warm temperatures will also stick around through the weekend, with highs hovering around 15 degrees above normal. Attention then turns to the potential for several low pressure systems making landfall along the West Coast starting this weekend. One of these could reach our area early next week.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1024 AM MST Wed Dec 31 2025

VFR conditions will continue throughout the day, with increasing cloud cover from the southwest. Overnight, moisture transport increases and showers will spread northeast across the Western Slope early Thursday morning. Expect TAF conditions to drop below ILS thresholds from west/southwest and eastward from about 12Z Thursday through 18Z. Aviation conditions will continue to deteriorate as weather crosses the region. Precipitation will be a rain/snow mix at most terminals and switch to rain by mid- morning. Mountain TAFs are more likely to observe wet, heavy snow throughout the morning.

GJT WATCHES/WARNINGS/ADVISORIES

CO...None. UT...None.