Active weather this week into the weekend with two storm systems on tap

01/21/25 8:30pm: Hi, we have some weather to talk about with an active pattern in store through the weekend with two storm systems on tap. And of course very strong wind this evening...window rattling on the west-side of Den/Bou right now. Getting gusts to 50-60mph at my house and just saw there was a gust of 80mph in west Arvada near Hwy 93 and 76 mph near Rollinsville (tons of blowing snow in spots).

Anyway, models show a northwest oriented short-wave, really two waves that will bring snow to the north-central mountains tomorrow into Thu and wind for the front-range / plains.

Then models show a complicated storm system for the weekend with the jet-stream sagging across CO on Fri into Sat (bringing in another shot of cold air) with a big upper-level low dropping well to the west of CO (but streaming in some moisture and lift), so forecast details for the weekend are highly uncertain but does look like more snow coming to both the central mountains and front-range mostly Sat into Sun.

Here is a look at very general timing and amounts

For the north-central mountains including Routt, Pitkin, Eagle, Summit, Grand, ClearCreek, western Boulder/Larimer counties (and the local ski areas / I-70 mountain corridor)

• 5am Wed to 2pm Thu (two waves, break Wed night): 1-5" favoring areas near the Cont. Divide / Front Range mountains

• 5pm Fri to 11pm Sun (multiple waves): additional 3-9" seems likely with highest amounts over northern CO (Flat Tops, Park Range, Medicine Bow Range will be favored, up 12"+ in spots)

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For Den/Bou/Ft.Collins and the northern front-range, including foothills and Palmer Divide

• A chance for snow primarily from 2am Sat to 8am Sun, heaviest Sat night. Much colder on Sat again with high in the low 20s. Generally 1-4" of new snow. Best chances for heavier snow will be from Boulder north across Ft. Collins (up to 6" in spots up there)

High uncertainty in regards to the weekend storm for southern CO including the San Juans from Silverton to Wolf Creek...all going to depend on where the upper-level low tracks, if it can creep closer like latest GFS is showing then San Juans could get 6-12"+ of new snow. If it ends up staying further west (with zonal flow over CO) like ECMWF is showing then likely little snow down there (1-4"). Most of the snow would be from 8pm Sat to 8pm Sun

First image loop below shows the evolution of the forecast pattern via 500mb winds/vorticity from now through 11am Mon from latest ECMWF model (static image valid 5am Sat). Image 2 shows forecast total snowfall from now through 5pm Thu from latest HRRR (first storm system). Images 3 and 4 compare forecast total snowfall from now through 11am Mon from latest ECMWF and GFS models (both storms combined), take modeled snowfall amounts with big grain of salt but shows some possibilities.