textproduct: Grand Junction

KEY MESSAGES

- Widespread rain continues through early Friday.

- Flooding/Flash Flooding is likely across portions of southwest Colorado and southeast Utah.

- Modeled responses suggest several rivers reaching bankfull or higher at river forecast points across southwest Colorado and southeast Utah.

- Strong to severe thunderstorms will be possible today, favoring the Four Corners area. That threat begins to gradually diminish overnight.

DISCUSSION

Issued at 103 PM MDT Thu Oct 22 2026

TODAY + FRIDAY:

Southwesterly flow continues to dominate the region, which is working to continuously advect subtropical moisture into western Colorado and eastern Utah this afternoon. Certain locations in southwest Colorado and southeast Utah are already overperforming the forecast, which means the risk of flash flooding/flooding is ongoing in some areas, if not likely to occur. Please continue to stay weather aware in the coming hours. Additionally, there is a threat for embedded thunderstorms within these rain showers, particularly in the Four Corners area this afternoon. Some storms are capable of producing small hail, gusty winds, and additional heavy rainfall. As we approach sunset, the threat for convective activity gradually diminishes and showers appear to shift to more stratiform in nature. Precipitation chances will continue into the overnight hours before scattering out by Friday afternoon. Shower and thunderstorm chances don't stay away for long as Friday night into Saturday morning will see additional shower and storm activity, particularly south of the I-70 corridor. This is mainly due to residual moisture from the previous system in combination with a new low pressure system forecast to track over the region this weekend.

THE WEEKEND + NEXT WEEK:

Models stay in fairly good agreement through the weekend that unsettled weather will remain in the forecast. The timing and specific track of the next low pressure system is still uncertain, therefore there are still unknowns. All in all, precipitation chances remain in the forecast this weekend.

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 far out, so confidence remains low on this matter.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 1134 AM MDT Thu Oct 22 2026

Widespread rain showers are ongoing today, with the possibility of embedded thunderstorms near the Four Corners area. Low ceilings and visibilities will be common under the stronger precipitation. Conditions will fluctuate between VFR and down to IFR through the day, with the worst conditions expected south of the I-70 corridor. ILS breakpoints will likely be met for most TAF sites thanks to those lowered ceiling and visibilities. Generally light winds are expected, though gusty outflows in and around showers and storms cannot be ruled out. Flight conditions slowly improve after 10-12Z Friday, if not before.

HYDROLOGY

Issued at 103 PM MDT Thu Oct 22 2026

Hydrologic concerns remain elevated through Friday due to the influx of highly anomalous tropical moisture across the 4 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.

Portions of southwest Colorado and southeast Utah continue to overperform the forecast, therefore flooding is ongoing in some locations, if not likely to occur in the coming hours.

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 highest confidence in minor flooding and related impacts will be along the San Juan River, Piedra, Animas, La Plata Rivers and above Vallecito Reservoir. The most recent river forecasts for the San Juan River near Pagosa Springs are depicting the river to reach the major flooding threshold, with a forecasted crest of 13.82 ft and streamflows just over 7650 cfs. Additionally, other creeks and tributaries within the Four Corners region remain susceptible. All river responses are heavily dependent on where the heaviest precipitation falls, so please continue to monitor the forecast as the week unfolds.

GJT WATCHES/WARNINGS/ADVISORIES

CO...Flood Watch through Friday morning for COZ019-021>023. UT...Flood Watch through Friday morning for UTZ022-027>029.