The Tuesday Update:
First, lets start with the NWS and the winter storm watch for areas west of I-25 and running from Berthoud down to the Palmer Divide (only western Denver, for example).
...WINTER STORM WATCH IN EFFECT FROM WEDNESDAY EVENING THROUGH
THURSDAY AFTERNOON...
* WHAT...Heavy snow possible. Total snow accumulations between 4 and 10 inches, with heavier totals possible across the higher
elevations.
* WHERE...The Southern Front Range Foothills, Boulder and the western suburbs of Denver, and Castle Rock.
* WHEN...From Wednesday evening through Thursday afternoon.
* IMPACTS...Roads will likely become slick and hazardous. Travel could be difficult during the Thursday morning commute.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Roads will be slick resulting in slow and hazardous travel. Allow extra time to reach your destination.
Chain and traction laws will possibly be enacted for the mountains. If travelling to the mountains, be prepared for winter driving
conditions.
______________________________________________________________________
Temperatures with this system will be marginal, but expected moisture is higher than we saw five days ago.
Precipitation will start in the late morning in the mountains and around 3 p.m. Wednesday. Precipitation chances drop after noon on Thursday (Figure 1 update). Figure 2 update shows how little snow will fall east of I-25, but by the time one gets to Boulder, you are up to a few inches.
I'm expecting Fort Collins to Loveland to get 0-2 inches. Berthoud to Broomfield getting 1-4 inches. Lyons to Boulder to Golden 2-5 inches. Estes Park 3-6 inches. The Denver International Airport is in the 1-4 inches range. With rain at the start of the storm and warm ground, the best amounts will build up on cool/grassy surfaces. (I'm calling for less accumulation than the NWS.)
As for rainfall, we see about 1/5th inch in Ft. Collins increasing to 3/4th inch of water above Boulder (this model OVERDOES liquid precipitation).
