A moderate risk of excessive rainfall was identified for portions of southern Utah and southwest Colorado on October 20, 2026. The National Weather Service reported that a deep mid to upper level low tracking through the West is expected to bring significant moisture to the region.
The moderate risk was expanded westward into south central and southeastern Utah. While instability in this northern flank is expected to be comparatively lower, portions of southern Utah already received heavy rainfall on October 19, leaving hydrologic sensitivity elevated. A prolonged duration of scattered showers and thunderstorms was forecasted for the area. While hourly rates might be capped around 0.5 inches per hour, the combination of destabilization and brief cell training could support localized rain rates of 1 inch per hour over sensitive terrain, such as slot canyons and washes, leading to scattered to numerous instances of flash flooding.
In the San Juan Mountains, the heaviest rainfall accumulations were expected from this event. Model consensus supported accumulations of 3 to 4 inches, with localized totals potentially exceeding 5 inches. This magnitude of rainfall generally equates to a 10 to 50 year recurrence interval for 24-hour totals. Although the lack of higher convective rates keeps the event below high risk levels, officials noted it is expected to be a high impact hydrologic event for the region.
The weather system is expected to continue moving eastward. By October 24, a slight risk of excessive rainfall was forecasted for the Sacramento Mountains through the El Paso metro. By October 25, a slight risk was projected for eastern New Mexico into southeastern Colorado, with hourly rainfall locally exceeding 1 inch appearing likely. The threat is expected to begin winding down by October 27 as the primary ascent shifts northward.
The moisture being transported into the region includes near to record precipitable water values for the time of year. In the San Juan Mountains, some snowmelt is expected to enhance runoff and the flood threat, though temperatures at higher elevations should remain in the 30s and 40s, potentially allowing existing snowpack to absorb some of the rain.
