A two part storm sytem for the weekend. Turning much cooler Sun into Mon

10/03/25 8:40am: Happy Friday! Enjoy the hot weather for one day lol. Near record highs for Den/Bou and the front-range today (mid-80s) ahead of a cool down with some rain (and snow above 10k ft). Forecast remain on track for the approaching storm system with a few changes for Sun into Mon.

The storm system is coming in two parts: first part: 9pm Fri through 9pm Sat, favoring western / southern CO.

Second part from 6pm Sun to 12pm Mon, favoring the northern Front Range mountains, foothills and maybe the urban corridor (Den/Bou).

First it will be turning quite windy over western CO this afternoon: southwest wind-gusts of 20-40 mph ahead of the short-wave.

Rain showers move into southwest CO / San Juans after 6pm this evening. With rain/snow ongoing over western and southern CO tonight into tomorrow morning (favoring areas west and south of Vail Pass initially). Some snow mostly above 11k ft in parts of the San Juans and Elks into tomorrow morning: 1-4" in a few spots (favoring upper San Juans).

Then the main cold front (and short-wave) will move across the north-central mountains tomorrow morning into the afternoon. For areas near Routt, Eagle, Summit, Grand, ClearCreek, western Boulder/Larimer counties etc: rounds of rain showers (and snow above 10k ft) from about 3am-7pm Sat. Some minor snow accumulation near the Cont. Divide above 10k ft (near Tenmile Range, Loveland, Berthoud Pass, IPW, etc): Trace-3" in spots.

It will also be very windy in spots on Sat as the cold-front sweeps across the mountains: westerly wind-gusts of 20-50 mph, strongest south of I-70.

For Den/Bou/Ft.Collins and the northern front-range maybe a few showers from Ft. Collins to the WY border on Sat am, otherwise just more cloudy and breezy for Denver initially Sat. Then a chance for some thunderstorms and rain showers from 2pm-7pm as the cold-front and short-wave move through. Likely not much actual rain (too much downslope flow).

The interesting part of the storm system for the Front Range comes in on Sun afternoon into Mon. Models shows a stronger back-door cold-front moving into the front-range on Sun (much cooler with highs in the 60s for Den/Bou). Then some upslope flow and some rain and snow for the front-range from about 6pm Sun through 4am Mon with some colder rain for Den/Bou and snow above 9500ft for parts of the upper foothills and Front Range mountains...

The Front Range mountains and foothills above 9500ft could get 2-5" of new snow from Sun night into Mon morning, favoring areas near Cameron Pass, RMNP and IPW.

Also some rain/snow showers expected over part of the north-central mountains on Mon during the day. Cool and unsettled in the mountains on Mon.

Then it clears out by Mon evening. So a pretty active weekend, with light amounts initially but then maybe some better rains/snow for parts of north-central / northeast CO on Sun night into Mon.

First image loop shows forecast radar over the next 60 hours (6am this morning through 6pm Sun) from latest NAM-3km model. Second image shows forecast total snowfall from now through 6am Mon from latest RFFS model (a new HRRR-like model). Image 3 and 4 compare forecast total liquid precip from now through 6am Mon from RFFS and ECMWF, take liquid and snow amounts with grain of salt.