Portland, CO 81432 Weather

Key messages

- Precipitation chances return Friday with light rain at the lower elevations and flurries above 10,000 ft.

- Deeper moisture arrives Saturday night and will increase the chances for impactful precipitation for southwest CO Sunday and Monday.

- Flooding/flash flooding remains a concern, especially along vulnerable terrain or areas that have saturated soils from last week's rain.

Discussion

Issued at 1054 AM MDT Thu Oct 29 2026

TODAY:

A low pressure system continues to drop down the West Coast today. This will transition the parent flow to southwesterly, which will advect upper level moisture into the region. This will increase cloud cover over the coming days, but keeps the moisture confined to those upper levels. Therefore, a pleasant fall day is on tap today.

ISOLATED TO SCATTERED SHOWERS FRIDAY AND SATURDAY:

A wave rotating around the parent low will provide enough lift to kick off showers beginning Friday afternoon and lasting through Saturday. PWAT values are projected to be upwards of 200% of normal, although dry surface levels will take time to fully saturate. Precipitation totals through Saturday will be on the lighter side as a result, with predominantly rain showers, with some snow flurries possible above 10,000 ft. There is a possibility for a few stray thunderstorms, which would be capable of producing localized heavier rainfall across the region.

WETTER AND UNSETTLED BY SUNDAY AND MONDAY:

A stronger moisture push associated with an atmospheric river (AR) arrives by Sunday. This AR will begin taking a southern track through Baja California, propagating through the Desert Southwest. There continues to be disagreements between both the ECMWF and GFS models. The ECMWF insists on bringing the moisture plume further north, while the GFS confines the highest PWATs to the Four Corners region. Therefore, there are still some uncertainties when it comes to the extent of this moisture. Either way, this is an impressive amount of moisture that, when combined with enhanced lift ahead of an approaching low, will result in widespread precipitation. Models do still agree on an area of 1-2 inches of rainfall across southwest Colorado and southeast Utah Sunday into Monday. Chances for river flooding remains low at this point, as these totals will be spread over an almost 48 hour period. The bigger concern lies with flash flooding across areas with already saturated soils from last week's rainfall, particularly for areas of steep terrain, and over recent burn scars. See the Hydrology section below for additional information.

Additionally, a cold front pushes through from northwest to southeast Sunday night into Monday, with snow levels dropping to around 8,000 ft by Monday morning, and close to 7,000 ft by the evening as colder air pushes behind the front. Snow could be heavy at times. Mountain passes will likely see impacts, with some travel slowdowns for motorists Monday morning and into the afternoon. Precipitation will taper off Monday night, with colder and drier conditions anticipated Tuesday and beyond. Daytime highs on Monday and Tuesday will run close to 10 degrees below normal, with temperatures remaining in this range through much of next week.

Aviation

Issued at 537 PM MDT Thu Oct 29 2026

VFR conditions are expected through the TAF period with light, terrain-driven winds turning southwesterly Friday afternoon.

Hydrology

Issued at 1054 AM MDT Thu Oct 29 2026

Low pressure begins to dig southward from the PacNW on Friday, tapping into a fetch of Pacific moisture that will evolve into an atmospheric river streaming into the Desert Southwest this weekend. Showers and thunderstorms will develop Friday and Saturday, but totals will remain on the lower side. However, a few thunderstorms could produce impactful downpours on saturated soils left over from last weekend's historic rainfall.

Deeper moisture develops Saturday night into early Sunday. This is expected to produce heavier and more widespread rainfall across southeast UT and southwest CO Sunday and Monday, mostly below 10,000 ft. While rivers are forecast to remain below action stage, a growing concern lies in the potential for runoff around steep terrain in the region. This could produce rock, mud, and debris flows onto roadways, as well as flash flood prone burn scars, washes, slot canyons, and arroyos. Early estimates predict an area of 1 to 2 inches of new rainfall for portions of southeast UT and southwest CO.

This is a preliminary forecast that hinges on slight shifts in a strong moisture plume impacting the region. It also attempts to capture the most statistically likely outcome, despite stronger and weaker outlier predictions. Outdoor enthusiasts, motorists, and residents of recent flood impacted areas are encouraged to remain abreast of the developing forecast in the coming days.

Watches, warnings and advisories

CO: None. UT: None.