textproduct: Grand Junction

KEY MESSAGES

- Several creeks, streams, and rivers have already reached flood stage due to persistent rainfall, and modeled responses suggest several others will do the same overnight.

- Impacts from high water levels and flooding may be seen throughout Friday.

- A few stronger storms capable of localized heavy rainfall, small hail, and gusty outflow winds may develop around the San Juan Mountains Friday afternoon.

- Active weather is expected to persist this weekend.

DISCUSSION

Issued at 1005 PM MDT Thu Oct 22 2026

FLOODING CONCERNS REMAIN. A FEW STRONG STORMS POSSIBLE:

We're past the peak in moisture, hence why rainfall has diminished across the region to a degree. Regardless, showers will continue for some areas throughout the night, and as daytime heating picks up tomorrow, look for additional showers and a few discrete thunderstorms to develop, particularly around the San Juan mountains. Excessive cloud cover today diminished the threat of stronger storms, but as the forecast stands, clouds should break up more during the afternoon tomorrow. This should provide a slightly better environment for small hail and strong outflow gusts to develop. This threat does not overshadow the ongoing hydrologic concerns. Even as we begin to exit this widespread stratiform-type rain pattern, creeks, streams, and rivers will continue to respond to the plethora of rain which has fallen, keeping the concerns for river flooding in place through Friday. Additionally, where thunderstorms do develop, localized heavy rainfall could prompt flash flooding, even in less flashy areas given the saturated nature of soils.

THE WEEKEND + NEXT WEEK:

Deterministic models are in agreement with a deepening closed low descending into the Desert Southwest this weekend. This locks in moist southwesterly flow across our CWA. This moisture is more your standard sub-tropical flow and less like what we are currently enduring. This leaves PWAT's more around 200% of normal, which, although less than we've seen recently, is still plenty to promote a continuation of active weather. Given this system's arrival coming so quickly, the saturated atmosphere will likely lean towards denser morning cloud cover. This would diminish the potential for localized heavy rainfall, but most of the Four Corners and surrounding areas have already seen such a significant amount of precipitation this month that it may not take much, even from stratiform rain, to spark additional flooding and flash flooding problems. We'll forego speculating on additional details for the time being as some of our forecast may be dictated by how Friday plays out. Stay up to date over the next 24 hours for additional information on this weekend's active weather.

As we move towards next week, models are also in fairly good agreement that dry zonal flow will begin to propagate the region by Monday. Because of this, we will be seeing cooler than normal temperatures, with the potential for overnight lows to drop below freezing for a couple hours at a time. Keep in mind, this is still relatively far out, so confidence remains low on this matter.

AVIATION /00Z TAFS THROUGH 00Z SATURDAY/

Issued at 555 PM MDT Thu Oct 22 2026

Widespread rain showers continue across most of the region with scattered embedded thunderstorms across the southern areas. Low ceilings and visibilities are common in heavier precipitation. Expect MVFR to IFR conditions associated with showers mostly south of I-70 below ILS breakpoints for most TAF sites through about 12Z. Look for generally light winds overnight becoming gusty after 10Z and lasting through the remainder of the TAF period.

HYDROLOGY

Issued at 1005 PM MDT Thu Oct 22 2026

Hydrologic concerns remain elevated through Friday due to the influx of highly anomalous tropical moisture across the Four Corners area into the Central Rockies. Potential hazards include localized flash flooding from thunderstorms producing heavy rainfall rates and river flooding due to a prolonged period of widespread moderate to heavy rainfall. Several river gauges across southwest Colorado and southeast Utah overperformed the forecast today. As we continue to adapt to these shifts in the forecast, we are increasingly concerned with additional rises in water level rises. Some areas are already experiencing notable flooding issues, and over the next 24 hours several other locations should anticipate similar concerns to arise.

There is a moderate risk of excessive rainfall leading to flooding across portions of the San Juans, extending west towards southeast Utah where precipitation totals of 2 to 4 inches will be possible. The bulk of this precipitation will fall through early Friday morning. Higher precipitation totals over portions of the southern San Juans of 4 to 5 inches are definitely possible. An additional concern is of rain on snow leading to additional runoff making it into the waterways. Snow levels are forecast above 12-13 kft throughout the day Thursday, which will likely result in melting of some of the existing early-season snow pack. The combined runoff from rain and rain- on-snow will result in a rapid rise in many of our creeks, streams and rivers.

Modeled responses suggest several rivers reaching bankfull or higher at river forecast points across southwest Colorado and southeast Utah. The San Juan River near Pagosa Springs continues to be of the greatest concern as it has already reached the major flooding threshold as of this evening. Water level is expected to continue rising throughout the night with a forecasted crest of nearly 15 ft and streamflows over 9000 cfs. Additionally, other creeks and tributaries within the Four Corners are remains susceptible. As another note, we've begun to see evidence that the Dolores river will exceed the moderate flooding threshold as it nears the confluence with the Colorado River. All river responses are heavily dependent on where the heaviest precipitation falls, so please monitor the conditions as the event continues to unfold. Remember, even after rainfall has ended, creeks, streams, and rivers will likely continue to rise before water levels alleviate.

GJT WATCHES/WARNINGS/ADVISORIES

CO...Flood Watch through Friday evening for COZ017>023. UT...Flood Watch through Friday evening for UTZ022-027>029.