Some forecast deails for the approaching storm. Flash Flood Watch for southwest CO 9pm Thu through 9pm Sat.

10/09/25 8am: Alright, here are some forecast details for the approaching storm system: a surge of deep tropical moisture (remnants of hurricane Priscilla) coming up from the southwest with heavy rain for southern and western CO. Forecast remains on track.

Biggest impact expected over southern CO / San Juans (including areas from Moab to Cortez to Durango, western San Juans: Telluride, Silverton, and towards Pagosa Springs and Wolf Creek). Those areas are under a Flash Flood Watch from 6pm tonight through 6pm Sat. Parts of southwest CO could pick up 2-3" of rain by Sat pm.

As mentioned earlier the snow-level will generally remain above 13k ft through Sat afternoon and then lower to 10k ft by Sun am with a little bit of snow in spots.

Already some rain showers and moisture moving into southwest CO now.

For today some isolated to scattered weak thunderstorms and rain showers expected over much of the central mountains from 2pm-8pm, best coverage expected over southwest CO (west and south of Vail Pass), won't be much today.

Heavier rain moves into the San Juans overnight, really getting going after 12am Fri, with rounds of heavy rain down there through the day on Fri and Sat.

First batch of moderate to heavy rain will move across much of the mountains on Fri between 6am-9pm, again favoring areas south and west of Aspen...

But even the north-central mountains (Eagle, Summit, Grand, ClearCreek counties, etc) will get rain showers tomorrow during the day, best chances 11am-8pm but it won't be as heavy as further south and west.

Den/Bou and the front-range will also have a chance for some weak storms / high-based rain showers from 2pm-9pm Fri, likely not much measurable precip for most areas.

Then the heaviest rain overall for the San Juans and central CO will be from about 11pm Fri through 11pm Sat, heaviest during the day Sat: heads up Sat will not be a good day to be in the San Juans or much of the mountains for that matter.

North-central mountains (Summit, Grand, etc) will also have rounds for rain on Sat, mostly from 10am-10pm again, with heaviest rain expected west and south of Vail Pass (but all the central mountains will get some). So some rounds of rain for the north-central mountains just not nearly as heavy as southwest CO, but generally 0.25" to 0.75" of rain total by Sun am.

Den/Bou will have another chance for some weak thunderstorms and rain showers on Sat 12pm-9pm, hit or miss. But again may not be that much actual rain (overall models don't show that much accumulated precip for Den/Bou proper with this southwest flow setup: too much downslope), maybe 0.10" to 0.25" in spots total between Fri and Sat.

The bulk of heavy rain starts to clear out of southern CO by late Sat night Sun morning....

But a trailing short-wave and cold-front will move across north-central CO early Sun am (3am-12pm). It doesn't look like a strong wav but with the colder air it will change some of the rain over to snow in the mountains lowering the snow-level to 10k ft by Sun am...

So some minor snow accum for parts of the north-central and south-central mountains from say 9pm Sat through 12pm Sun: 1-4" in spots favoring the Elk Range, central Sawatch and towards the Tenmile Range.

Storm system clears out on Sun afternoon.

First image shows the Flash Flood Watch (9pm Thu through 9pm Sat). Second image shows forecast radar over the next 48hrs (6am this morning to 6am Sat, doesn't show the entire event) from latest HRRR. Image 3 shows forecast total liquid precip from now through 6am Mon from latest ECMWF model (it has been rock-solid consistent for this storm). Fourth image shows forecast total snowfall (10:1 ratio) from now through 6am Mon, take with a grain of salt as the snow forecast is uncertain.