textproduct: Grand Junction

KEY MESSAGES

- Winter Weather Advisories remain in effect for the northern mountains where 3 to 7 inches of new snow above 9000 feet are expected, along with gusty winds.

- Gusty winds of 45 to 50 mph will be possible for portions of the northern valleys where Wind Advisories have been issued.

- Periods of light mountain rain/snow are possible north of Interstate 70 this weekend.

SHORT TERM /THROUGH THURSDAY/

Issued at 308 AM MST Wed Dec 17 2025

Clouds will be on the increase through the day as moisture from an atmospheric river starts to move into the area. There is little change to the going forecast as a strong jet stream takes aim at the forecast area while supporting a surface cold front. This jet will be impressive reaching close to 160 kts at 250mb as it moves overhead later tonight. As the cold front moves through, some deeper mixing will allow these stronger winds to reach the surface. Ensembles are in good agreement that some gusts of 45 to 50 mph will move into eastern portions of the northern valleys and the Steamboat Springs area so issued a wind advisory to account for these gusts later this afternoon and overnight. The highest elevations of the central and northern mountains will likely see gusts of 50 to 60 mph...an occasional gust to 70 mph can't be ruled out.

Along with the gusty winds, snowfall amounts of 3 to 7 inches above 9,000 feet will accompany cold frontal passage so the Winter Weather Advisories remain in effect. Snowfall rates will be maximized as the front moves through and with stronger surface winds expected, travelling will be difficult at times as visibilities drop quickly in snow squalls. Some convection may also accompany frontal passage, despite any strong CAPE or midlevel instability, thanks to the strength of the cold front and upper level support.

By Thursday morning, snow will have ended though some lingering snowshowers may persist over the Park Range. The cold front will make it as far south as the San Juans so look for cooler highs Thursday and not much change for the southern valleys.

LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/

Issued at 308 AM MST Wed Dec 17 2025

Northwesterly flow will allow for orographic lift in the northern mountains through the end of the workweek. Increased atmospheric moisture will advect through the area Thursday afternoon through early Friday. Orographic lift is expected to produce light precipitation in the northern terrain from this moisture push. Forcing will be pretty limited until the weekend, so not much is anticipated in terms of accumulating snow. The highest peaks of the Park Range might see an inch or two by Thursday night.

Relatively drier air will briefly move in during the day Friday, but anomalous atmospheric moisture returns Friday night. Northwesterly flow is expected to persist, supporting orographic lift. Energy from passing disturbances in the mean flow may also provide additional forcing. As such, greater snow accumulations in the northern mountains are anticipated over the weekend when compared to Thursday. However, the ECMWF Ens and GFS Ens disagree on moisture, as the latter suggests a decrease Saturday afternoon before increasing again Sunday morning. The ECMWF favors continuous well above normal moisture values through the weekend with no major decrease.

Above normal temperatures will persist through the long term period. Beginning Friday, highs are expected to be more than 15 degrees above normal. This means most areas, with the exceptions of the highest mountain peaks, will reach above freezing temperatures during the day. So, snow levels could remain above 8000 feet for much of the weekend.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1042 AM MST Wed Dec 17 2025

Winds aloft are increasing with lower ceilings as a fast moving storm system comes in from the northwest. Expect widespread wind shear though mountain TAF sites with surface winds gusting 30 to 40 kts at times. Lower ceilings and vis are possible for KASE, KEGE, KRIL and KHDN as showers move between 21Z and 03Z ahead of a surface cold front with conditions below ILS breakpoints as these showers move through. Conditions improve after 06Z with clearing skies and winds decreasing.

GJT WATCHES/WARNINGS/ADVISORIES

CO...Wind Advisory from 2 PM this afternoon to 5 AM MST Thursday for COZ002-005. Winter Weather Advisory until 11 PM MST this evening for COZ004. UT...None.