Forecast for the approaching upper-level low. Nice upslope rain even expected for the front-range Tue pm through Thu am

10/11/26 8:15pm: Hi, hope you are having a good Sunday! (Glad the Broncos won). It was another hot one, that is for sure!...85 for Denver (at the airport) and that marks the 10th day in a row in Oct with a high above 80 (ties the record longest streak)...but we do have some relief on the way and its looking better for precip in Den/Bou hopefully 🙂

A little check-in on the approaching storm system which is looking rather good. Models are now in better agreement and show a pretty favorable storm track for much of CO to get a good dose of precip from Tue pm through Thu pm (especially for parts of the mountains and northern front-range).

Models show a large upper-level low moving from near the 4-corners on Tue pm and up across CO Wed into Thu. Still some questions on overall track or if the low will stall out. And if we get a second shot of cold-air and precip on Thu night. The position and track of the low should produce a nice round of east to west upslope flow on the front-range from Tue pm through Thu pm.

With the models showing the low further south it appears that Den/Bou and the front-range will get a good shot of rain from 9pm Tue through 3am Thu (with biggest impacts on Wed), and rain showers possible before this on Tue. Models are showing 0.40"-1.00" of precip with highest amounts from Boulder north to Ft. Collins and in the northern foothills to the west.

As I mentioned, In the mountains: the snow-level likely drops from 12k on Tue to closer to 9500ft by Wed am with snow accumulation down to pass level on Wed into Thu am: likely 4-10" of snow for areas near the Cont. Divide mostly above 9500ft. Maybe some rock skiing on Thu am, who knows!

And overall heaviest rain/snow is still expected across southern CO: San Juans to Grand Mesa areas to Elks can expect 1-3" of liquid precip with 6-16"+ of snow mostly above 10k ft with heaviest amounts in the San Juans.

Should be some good rain/snow as well for most of the north-central mountains / I-70 mountains corridor with 0.50"-1.00" rain (maybe even some snow in Silverthorne/Dillon by either Wed am or Thu am).. But still a little bit of uncertainty as some models show too much east to west upslope flow and hence less precip in the heart of Grand and Summit Co. etc.

This storm is looking good. And although we will go back to some hot temps after this storm system for about 1-week again (typical with a strong El Nino / positive PNA, more on that later), it then gets active again with another strong storm forecast around Oct 22-23.

The El Nino / winter pattern typically does not get going until late Oct into early Nov. I still think we are in for an overall active pattern but it will be hot in-between storm systems.

First image shows the storm system at 12pm Wed via 500mb vorticity / wind from latest ECMWF model. Images 2 and 3 show forecast total liquid precip and snowfall from latest NWS Blend of Models, and image 4 and 5 show total liquid precip from latest GFS and ECMWF, take modeled rain/snow amounts with a grain of salt, but you get the picture, it will change some.