textproduct: Grand Junction

KEY MESSAGES

- A winter weather system arrives tonight with more widespread accumulations and stronger winds at the high elevations. Winter Storm Warnings and Winter Weather Advisories are in effect for portions of the Colorado mountains this evening through Saturday evening.

- Unsettled weather continues through the coming work week in the northern Colorado mountains with mostly periods of light snow showers.

- A general warming trend is expected, but the snow covered mountains valleys will see cold inversions set up overnight lasting through the days.

SHORT TERM /THROUGH SATURDAY NIGHT/

Issued at 258 PM MST Fri Dec 5 2025

Radar imagery and traffic cameras have shown snow falling throughout the day, primarily in the northern and central Colorado mountains. Over the next few hours a lull in snowfall is expected, but late this evening rates should begin to increase again, first in the northern mountains, as anomalous atmospheric moisture advects into the area from the northwest. This plume of moisture looks to carry PWAT values around 200% of normal, and will quickly move across the region through Saturday. Both the forcing from the synoptic pattern, and orographic lift, will support accumulating snow across our terrain. The northern mountains are expected to get the most snowfall from this event, as favorable orographics occur with the prevailing northwesterly flow in place. The Park Range in particular could see one or two feet of snow, perhaps even more at the highest elevations. Snow totals generally came up a bit for most mountain areas in the latest forecast package, so a Winter Weather Advisory was issued for the northwest San Juan Mountains above 9000 feet from 11 PM this evening through 11 PM Saturday. The other Advisories and Winter Storm Warnings issued remain in place.

The synoptic setup will allow for upper level support from narrow waves of energy embedded in the flow, and some additional support from diffluence and the positioning of the jet aloft. The timing of the increased moisture and upper level support will result in the greatest snowfall rates occurring late tonight through Saturday morning. However, snow is expected to continue through Saturday evening. In addition to the falling snow, strong wind gusts exceeding 30 to 40 mph in some areas of higher terrain may create blowing snow conditions tonight through tomorrow afternoon. As such, hazardous travel conditions are possible, and travel may be very difficult to impossible at times during this winter weather event.

LONG TERM /SUNDAY THROUGH FRIDAY/

Issued at 258 PM MST Fri Dec 5 2025

The bulk of the heaviest snow should be done by sunrise on Sunday but a moist dendritic layer over the northern and central divide mountains through early afternoon will keep showers going. Warm air advection kicks in through the afternoon as the jet shifts onto the Plains and this stabilized the column and most showers should be ending by sunset. Next week a ridge builds over the West Coast, which will steer the jet stream to our north. Also, the ridge will cause temperatures rise to 10 degrees above normal by mid week. The northern mountains could get clipped by moisture advecting through the ridge, which may result in snow showers. As of now those amounts are minor. Valleys in deeper snow could experience strong inversions despite the warm advection. That means temperatures could end up cooler than the going forecast.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 435 PM MST Fri Dec 5 2025

Low clouds linger across much of eastern Utah and western Colorado, with many locations experiencing ceilings below breakpoints. This will continue through the next 24 hours, as the next storm moves in. Higher elevation sites and terminals along and north of I-70 have the highest chances of seeing snow beginning after 03z this evening, and lingering through 18z tomorrow afternoon. Winds will be strong and northwesterly, with gusts up to 25 knots possible for higher elevation terminals. LLWS will be an issue for most terminals tonight. VFR to MVFR conditions will prevail, with drops to IFR/LIFR likely, especially for KASE, KTEX, and KHDN. Conditions will begin to gradually improve after 18z tomorrow.

GJT WATCHES/WARNINGS/ADVISORIES

CO...Winter Weather Advisory until 5 PM MST this afternoon for COZ004. Winter Storm Warning until 11 PM MST Saturday for COZ004-013. Winter Weather Advisory until 11 PM MST Saturday for COZ005. Winter Weather Advisory from 11 PM this evening to 11 PM MST Saturday for COZ008-009-018. Winter Storm Warning from 11 PM this evening to 11 PM MST Saturday for COZ010-012. UT...None.