textproduct: Grand Junction

KEY MESSAGES

- The Flood Watch continues for southeast Utah and southwest Colorado as an atmospheric river brings rain, rainshowers, and snowfall to the area.

- Several rivers across southwest Colorado are forecast to reach minor flooding stage.

- The San Juan River at Pagosa Springs is forecast to reach major flood stage which has prompted a Particularly Dangerous Situation Flood Warning for that area.

- Winter weather highlights have been issued for the San Juans and central Colorado mountains for accumulating snow Sunday morning through Monday evening.

DISCUSSION

Issued at 909 PM MDT Sat Oct 31 2026

CALM BEFORE THE STORM:

A weak shortwave moved across the area today with only a few showers and storms noted on radar. A few showers remain across the area at this hour but are trending downwards and this will continue. Good news for the trick or treaters this evening. Satellite is showing plenty of cloud cover to our southwest, poised to move into the area very shortly.

RAIN, SNOW, FLOODING POTENTIAL:

More widespread precipitation will begin falling between midnight and 3am thanks to a potent Atmospheric River (AR). This AR remains forecast to bring anomalous precip to our CWA for the next 24 to 36 hours. PWATs from the ensemble GFS and EC remain in the 250 - 350% range for this time of year, no change there. Widespread rain and rainshowers, possibly some embedded thunderstorms, will bring valley rainfall to near/at an inch for the central valleys, and 2 to 2.5 inches for the Four Corners valleys eastward, less up north. 1.5 to 2.5 is likely for the Book Cliffs/Tavaputs and central mountains while the San Juans may see 3 to 4 inches of liquid precip. The Flood Watch remains in effect for southeast Utah and southwest Colorado as already saturated soils, along with this rainfall, may result in flash flooding and debris flow issues, not to mention river flooding. Rivers are expected to respond quickly to this additional rainfall, especially in the Pagosa Springs area.

As far as snow is concerned, snow levels will remain above 10K feet, if not a bit higher, before dropping Sunday afternoon onwards. Amounts remain in the 12 to 18 inch range with locally higher amounts still possible so the Winter Storm Warning remains in effect. The Advisories also remain in effect for the central mountains, Grand Mesa, and Flat Tops where 5 to 10 inches are expected. As snow levels lower late Sunday night into Monday morning, some of this snow will reach pass level. Be prepared for sloppy driving conditions during the Monday morning commute along US-550, US-50, and along I-70 over Vail Pass.

NEXT WEEK:

Behind this system, conditions dry out for a few days as high amplitude ridging moves overhead. We'll see a slight warm up through the mid-week period, although highs remain 5-10 degrees below normal for early November. Looking further out, a quick moving clipper system has the potential to bring some light showers to the region mid-to-late next week, although model agreement is poor.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Issued at 1155 PM MDT Sat Oct 31 2026

A few light showers continue to push up into eastern Utah and southwestern Colorado with no impacts TAF sties, but deeper moisture will move in from the southwest overnight becoming widespread heavier showers across the higher terrain west of the Continental Divide with more scattered showers in the lower valleys by 12Z. Expect MVFR/IFR conditions at most TAF sites after 12Z with conditions below ILS breakpoints through the remainder of the TAF period. Stronger winds aloft will produce areas of Low-Level-Wind-Sheer (LLWS) through the morning before these winds start mixing down to the surface with south to southwest surface winds gusting 20 to 40 kts from late morning well into the evening hours (past 00Z).

HYDROLOGY

Issued at 1226 PM MDT Sat Oct 31 2026

Deeper moisture develops later tonight into early Sunday. This will produce widespread rainfall with stronger rain rates across southeast Utah and southwest Colorado Sunday and Monday, mostly below 10,000 feet. 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. Current guidance supports 1 to 3 inches of rainfall for far southeast Utah and portions of southwest Colorado, with locally higher amounts close to 4 inches possible. As a result, a Flood Watch remains in effect 5 AM Sunday through 11 AM Monday. Latest forecast guidance has a number of rivers in southwest Colorado climbing above minor flood stage, with the gage at Pagosa Springs now expected to hit Moderate to Major flood stage. As a result, targeted River Flood Warnings along the La Plata and San Juan rivers are in effect.

Of note, the River Flood Warning for Pagosa Springs is a Particularly Dangerous Situation due to the significant and possibly historic flooding along the San Juan River. Excessive runoff will also increase flooding risks. That region should prepare for a dangerous and impactful flood event.

Outdoor enthusiasts, motorists, and residents of areas recently impacted by flooding are encouraged to remain tuned to the forecast in the coming days.

GJT WATCHES/WARNINGS/ADVISORIES

CO...Winter Weather Advisory from noon Sunday to 6 PM MDT Monday for COZ009-010-012-013. Winter Storm Warning from 6 AM Sunday to noon MDT Monday for COZ018-019. Flood Watch from 5 AM MDT Sunday through Monday morning for COZ019-021>023. UT...Flood Watch from 5 AM MDT Sunday through Monday morning for UTZ022-028-029.