textproduct: Grand Junction

KEY MESSAGES

- Moderate to heavy snow rates and strong winds have materialized over the Colorado High Country creating hazardous travel conditons. Winter Storm Warnings and Winter Weather Advisories are in effect through this evening and into Sunday morning. - 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 SUNDAY NIGHT/

Issued at 132 PM MST Sat Dec 6 2025

The plume of moisture bringing precipitation to the area now will drop to our south this evening. Weak cold advection in northwest flow will keep orographic snow showers going in the northern mountains and perhaps some of the central mountains. Increasing snow to liquid ratios could turn this minor QPF into several inches for the higher terrain especially the Park Range. Most valleys shut off this evening. Winds decrease tonight but remain breezy along the peaks and ridges, which may contribute to blowing snow after the snow ends. Clouds clear out across the south so sheltered valleys with new snow may get pretty chilly. Most locations are dry tomorrow as northwest flow continues. However another weak plume of moisture reaches the northern mountains so snow showers could develop later in the day. High temperatures tomorrow do not change much as the cold air arriving tonight struggles to drop south.

LONG TERM /MONDAY THROUGH FRIDAY/

Issued at 132 PM MST Sat Dec 6 2025

The beginning of the long term period is characterized by generally quiet weather for all but the northern Colorado mountains, which are expected to receive somewhat continuous snowfall while persisting northwesterly flow supports orographic lift. Atmospheric moisture amounts through the day Monday are expected to be pretty close to average for this time of the year, so any snowfall during this time period should be light.

An atmospheric river looks to move through the Rocky Mountain region beginning Monday night, and is expected to move into our CWA from the north overnight Monday into Tuesday. Despite to abundance of moisture from the atmospheric river, synoptic forcing will be limited due to a broad region of high pressure over the Pacific which will keep ridging in place over much of the West. It also appears there will not be good jet support during the timing of the moisture advection, but disturbances within the mean flow should be able to provide a bit of support for snowfall rates to increase at times. The high pressure to our west keeps our region under northwesterly flow, which will continue to support orographic lift in the northern mountains. Thus, the northern mountains look to be favored for receiving the most snowfall from this event.

However, there is still a lot of uncertainty regarding the details. The GFS Ens seems to be suggesting a stronger atmospheric river than the ECMWF Ens is, so the GFS Ens is favoring much higher snow totals. There is also significant disagreement between ensemble members, more so among members of the ECMWF Ens than the GFS Ens. Another potential concern will be temperatures during this event, as temperatures are expected to be well above normal through the long term, potentially leading to daytime highs near or above freezing in some of the higher terrain. Once there is better agreement between models on the strength of this atmospheric river, and temperatures, there will be greater confidence regarding snow totals.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1044 AM MST Sat Dec 6 2025

Snow showers will continue along the high terrain, ending from south to north late this afternoon through the evening. Chances of snow at KTEX, KGUC, and KRIL drop before 00Z, but increased chances persist at KASE, KEGE, and KHDN through the evening hours. MVFR to LIFR conditions, and drops below ILS breakpoints, are possible at these sites as the winter weather brings lower ceilings and visibility. Gusty winds and wind shear aloft will may impact some sites as well. Conditions should improve tonight, but terrain obscuration could prevail through the overnight hours.

GJT WATCHES/WARNINGS/ADVISORIES

CO...Winter Storm Warning until 5 AM MST Sunday for COZ004. Winter Weather Advisory until 11 PM MST this evening for COZ005-008-009-018. Winter Storm Warning until 11 PM MST this evening for COZ010- 012-013. UT...None.