05/17/26 10am: Its going to be a wild weather ride over the next 3 days! So much to cover, but this morning, focusing on my snowfall / rainfall map through Tue am. Potent storm still on track, devil is in the details.

Looks like a good event for the northern front-range favoring areas from Denver north to Ft. Colilns.

But still some questions for areas south of Palmer Divide to Springs in terms of significant precip and also how much rain/snow for parts of Summit and Eagle counties (models differ greatly there, due to the upslope windflow).

I'll let the map mostly speak for its self.

For today, a round of scattered to numerous thunderstorms for both the north-central mountains and front-range (Den/Bou) between 11am-6pm initially, best chances for Den/Bou and the foothills will be 1pm-5pm, some heavy rain in spots, small hail and strong wind.

Strong to severe thunderstorms can be expected over the northeast plains (east of a Greeley to DIA line) from 2pm-6pm today, with some larger hail in spots and maybe even an isolated tornado (eastern plains near the KS border will be favored for strongest storms).

Edit: storms are already forming over parts of Den/Bou this morning with a cell near Superior already!

Then the main event for Den/Bou/Ft.Collins in terms of cold upslope with rain and snow will be from 11pm Sun through 12am Tue, heaviest Mon morning through afternoon. Generally 0.75" to 2.25" of rain, favoring areas closer to Ft. Collins and Larimer county.

Still looks like Den/Bou/Ft.Collins and lower elevations will have all snow flying between about 9am-9pm tomorrow, but given this is during the day, likely little to no accumulation, maybe a Trace-2" on grassy surfaces, favoring western suburbs above 5500ft (from Boulder to west of Ft. Collins).

Northern Foothills (Ned to Allenspark to Estes Park) can expect 5-10" of new snow

Southern foothills (areas closer to Idaho Springs, Floyd Hill, Evergreen, Conifer, etc): 4-8" of new snow.

In the mountains, most of the snow initially from late tonight into tomorrow am will favor the Front Range mountains along/east of the Cont. Divide.

For the north-central mountains further west, not great wind-flow initially through Mon night (east to west upslope flow), better wind-flow and colder air works its way into all the mountains Mon evening into Tue.

For the Front Range mountains near Loveland, Jones, Berthoud passes, G/T, IPW, RMNP, Cameron Pass, etc a good 5-12"+ of new snow favoring areas closer to RMNP and Cameron Pass.

All of the Front Range mountains and form Summit county east is under a Winter Weather Advisory from 12am Mon to 12am Tue

For the rest of the mountains further west, higher terrain near Summit, and Eagle counties, likely 2-6" for the ski areas, favoring areas further east.

Also 4-8"+ for higher terrain near/north of Steamboat ski area and Flat Tops, mostly above 9k ft.

Parts of the Elks to San Juans will also get 3-8" of new snow.

The main event will likely end Tue morning. But models show more on/off rounds of rain/snow for all of northern CO (mountains and front-range) on Tue afternoon into Wed and again Wed afternoon into Thu....looks wet and unsettled through Wed evening.

A note about temperatures. For Den/Bou and lower elevations, temps will likely get down to about 32-34 degs either tomorrow or more likely Mon night into Tue am, so some precautions will be necessary to protect sensitive plants and exposed water (but shouldn't be a hard freeze).

That's all for now, I'll have more updates on today's thunderstorms later.

First image is my total snowfall and rainfall map through 6am Tue. Image 2 shows forecast total liquid precip from now through 6am Tue from latest ECMWF model (which has been very consistent lately from run to run). Images 3 shows forecast total liquid precip through 6am Tue from latest HRRR model (big differences for parts of southern CO). Image 4 is equivalent for total snowfall through 6am Tue from HRRR, take with grain of salt (ECMWF has more along parts of the southern front-range).

In the comments I'll attach and image showing the Winter Weather Advisory for the mountains. And a look at forecast radar for this afternoon.