textproduct: Grand Junction

KEY MESSAGES

- Record warmth highlights the forecast through midweek.

- Rain and snow return to the forecast Wednesday PM and beyond. Warm temperatures will keep snow levels high and snow ratios low.

SHORT TERM /THROUGH MONDAY NIGHT/

Issued at 227 PM MST Sun Dec 21 2025

A ridge of high pressure has begun to build in over the Intermountain West and will continue to do so through the forecast period. Locally, we will be on the southwesterly flow side of the ridge which will promote warming temperatures and an influx of drier air. As a result, record warmth is the focus of the short term forecast. Tomorrow's record high temperature at KGJT is 54 (set in 2010) and our forecast currently calls for a high of 61. Much of the Interior West will be in the same boat, so expect many records around the region with high temperatures projected to be 20-25 degrees above normal for the valleys and 15-20 degrees above normal in the mountains.

LONG TERM /TUESDAY THROUGH SUNDAY/

Issued at 227 PM MST Sun Dec 21 2025

Tuesday is still looking dry with record warm temperatures due to an expansive ridge over the central US. While that is occurring a deep trough will be setting up off the West Coast. That system will be associated with atmospheric river that initially goes north and west of us. The deep trough off the coast will be stationary during this period, so the AR continues for several days eventually moving into southern California and the Baja. There is decent model agreement that this AR moisture arrives in our forecast area on Wednesday. At this point the trough becomes a closed low off the coast of northern California, which keeps us in the moist southwest flow through at least Saturday. In those fews days models are hinting at the potential for one or a few pieces of energy breaking away from from the main low and tracking overhead. Those waves could result in mainly orographic precipitation becoming more widespread at times. The models show PWAT values approaching 300 percent of normal on Thursday, which is impressive. Although this will be a sub-tropical air mass so snow levels will be around 9-10 kft with relatively low snow ratios upon arrival. Therefore expecting rain for most of the valleys at first. The models begin to diverge on Friday and Saturday with how or if the low pressure finally makes landfall and how it evolves moving inland. The two main scenarios is the low weakens and passes over our region as an open wave. The other is that the low becomes cut off and drifts southward off the coast of southern California. This will play a role in how cold the temperatures can get, which in turn dictates how low the snow levels get Friday into the weekend. Both of those scenarios do not favor a massive snow storm for the valleys. Of course the models could change. Although as of now the ensembles are not showing a deep low pressure over us, so confidence is slowly increasing. Stay tuned for more details about how the second stage of this storm is shaping up.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/

Issued at 448 PM MST Sun Dec 21 2025

SCT to BKN clouds remain as strong winds aloft result in mountain wave activity downstream of ridges. Some of these winds are mixing down to the surface, especially across the north but these winds should subside by sunset with LLWS developing at mountain TAF sites as winds decouple. Lighter winds are expected for Monday with passing mid to high clouds from time to time. Cannot rule out periodic wind gusts to 25 mph Monday afternoon. VFR conditions should prevail for the next 24 hours.

GJT WATCHES/WARNINGS/ADVISORIES

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