textproduct: Grand Junction

KEY MESSAGES

- Showers and thunderstorms are expected over the high terrain Wednesday afternoon. A few stronger thunderstorms are possible and some isolated storms may occasionally track into valleys.

- Isolated, terrain-driven showers and thunderstorms continue through Saturday.

- High temperatures will be 5 to 15 degrees above normal for this time of the year.

- A stronger storm system may pass through early next week, bringing chances for widespread precipitation and cooler temperatures.

DISCUSSION

Issued at 955 PM MDT Tue Oct 6 2026

ISOLATED SHOWERS AND THUNDERSTORMS THROUGH THE WEEK:

Storms Tuesday over-performed compared to what was seen in hi- res model guidance the past couple days. Though storms were in fact isolated as anticipated, they also proved capable of dropping small hail, producing bouts of heavy rainfall, and even developing in valley locations. Satellite imagery and radar reveal one culprit for this being a MCV which has persisted over the western San Juans, supporting more favorable dynamics for stronger thunderstorms. This paired with a few strong outflows to result in activity beyond what was expected.

Interestingly, one of the only models to detect this MCV, the GFS, is also hinting at a similar feature developing tomorrow afternoon (though it is not as pronounced). Meanwhile, other models are not detecting this feature, also consistent with trends leading up to Tuesday. We don't want to put all of our eggs in one basket, but considering the GFS reasonably modeled today's overall pattern, we cannot discount similar weather tomorrow. This primarily means two things: storms may be capable of producing strong winds, small hail, and localized heavy rainfall again; and some valleys (primarily along and south of I-70) may see measurable precipitation Wednesday in addition to the high terrain. NBM probabilities of measurable precipitation in these valleys Wednesday is around 10-20%, but given the situation, it may be safest to treat that as the low- end scenario. As such, we have boosted PoP's over the southern half of the region by about 10% Wednesday. It is vital to note that while we are messaging the potential for some more potent weather Wednesday, this is only expected to occur should a MCV redevelop Wednesday afternoon. Should the pattern follow most other models' guidance (i.e. no MCV), look for storms to be weaker and much more confined to the high terrain.

Otherwise, Thursday and Friday look to be on track for mostly terrain-driven showers with minimal impacts. High temperatures continue to sit 5 to 15 degrees above normal as well.

POTENTIAL FOR WIDESPREAD RAINFALL RAMPS UP THROUGH THE WEEKEND:

The PacNW trough which we have been keeping an eye on seems to be on the slightly faster track, meaning we should see precipitation potential begin to ramp up beginning Saturday. Regardless, moisture and support won't be favorable for widespread storms until Sunday and beyond. Both the GFS Ens and ECMWF Ens are in agreement with PWAT's reaching their peak (225-250% of normal) around midnight to 6 AM local time Sunday and persisting at least through Monday. We remain too far out in time to speculate just how long the pool of moisture will sit over us, but prepare for multiple days of rainy weather region- wide. As it stands, the wettest period appears on track to be throughout the morning and afternoon of Monday, but this is still a low-confidence detail of this system and the forecast still has time to shift. The finer details of the storm may not come into view until hi-res model guidance becomes available in a few days, but we are confident that early next week will see a return of more widespread active weather.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 1155 PM MDT Tue Oct 6 2026

A weak disturbance in western CO, producing some showers and thunderstorms will dissipate early this morning. Scattered mid and upper level clouds will slowly diminish as well. Ceilings should remain above breakpoints through this period. Some showers are expected to develop on the mountains again Wednesday afternoon. Left PROB30 verbiage in the KASE, KGUC, and KTEX TAFs to cover the possibility with some uncertainty in breadth of coverage. Gusty winds and brief ceilings could impact terminals around the showers. VFR conditions return again Wednesday evening to close out this period.

GJT WATCHES/WARNINGS/ADVISORIES

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