textproduct: Grand Junction

KEY MESSAGES

- Our next weather system moves in tonight with peak impacts expected tomorrow afternoon. Mountain snow and strong winds combine for slippery to hazardous travel over mountain passes. - 3 to 6 inches of new snow is forecast for the high country above 9000 feet with locally higher amounts over the Park Range. - A colder air mass arrives Thursday with additional snowfall and more winter-like temperatures.

SHORT TERM /THROUGH TUESDAY/

Issued at 155 PM MST Sun Jan 4 2026

The forecast remains on track for an upper level jet and its attendant shortwave trough to move across northeast Utah and northwest Colorado tonight through tomorrow night. With unseasonably warm temperatures in place, impactful accumulation will remain isolated to 9,000 feet and above with a rain/snow mix possible between 7,000-9,000 feet. Convective enhancement is expected north of I-70 tomorrow afternoon which could lead to locally higher snow amounts, but in general we are expected 4-8" over the Park Range and 3-6" for the rest of the northern and central mountains. Mountain winds up to 40-50 mph will accompany the falling snow reducing visibility at times.

As a result, a Winter Weather Advisory has been issued for the Elkhead Mountains and Park Range Monday morning through Monday night where the highest wind and snow probabilities are anticipated. However, slippery stretches are anticipated over most mountain passes as this system moves through. Snowfall winds down Monday night into Tuesday with minor mountain accumulations possible in the wake of this system.

Dense fog may continue to plague the lower valleys over the next couple of nights, but stronger surface winds and increased mixing will chip away at the likelihood of widespread dense fog with each passing day.

LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/

Issued at 155 PM MST Sun Jan 4 2026

Some bad news with regards to snowfall and that being snowfall amounts have dropped considerably from forecast amounts 24 hours ago. So much for that confidence. While the evolution of the system and timing has remained fairly consistent, available moisture has dropped resulting in less snowfall. The synoptic features look the same with a closed low over the Baja Peninsula opening up as it moves across the US/Mexico border while a long wave trough and surface cold front approach from the northwest. Some light precip will fire out ahead of the trough as a weak shortwave ahead of the main trough pushes through. This minor wave will bring some light precip to the northern valleys and mountains early Thursday morning and through the day Thursday. Coverage increases Thursday afternoon and continues through midmorning Friday once the front and trough push through. The Park Range is favored for the heaviest snowfall while the Flat Tops, Grand Mesa and central mountains will see amounts from 2 to 6 inches. This all needs to be taken with a grain of salt considering the changes that occurred from just a few model runs. Looking ahead to the weekend, models are indicating a rex block setting up across the desert southwest keeping dry weather in place through the remainder of the forecast period.

As far as temperatures are concerned, highs will run several degrees above seasonal values, dropping to near normal by Thursday. Once the cold front pushes through, high temps will drop to at or just below normal before a slow warmup is expected during the weekend.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/

Issued at 442 PM MST Sun Jan 4 2026

Another push of moisture and passing wave will increase shower activity across the region overnight. The forecast challenge is will this moisture and mixing from the system keep dense fog from forming or will persistence win out. Went with the later scenario attm but will be monitoring observations and webcams closely for fog over eastern Utah and portions of western Colorado. Otherwise expect falling ceilings overnight as this mositure moves in...initially leading to widespread terrain obscuration then ILS to MVFR/IFR conditions at many TAF sites as precipitation and lower clouds become more likely. Stronger winds aloft will also lead to localized LLWS and areas of mountain wave turbulence through tomorrow afternoon.

GJT WATCHES/WARNINGS/ADVISORIES

CO...Winter Weather Advisory from 5 AM Monday to 5 AM MST Tuesday for COZ004. UT...None.