Major winter storm to dump up to a foot of snow in Denver in Saturday

Water vapor satellite image as of 3:15 pm MST Friday

A powerful storm system is currently moving into Colorado from the southwest as of Friday afternoon, bringing heavy snow to the San Juan mountains.  The storm will track toward the east overnight Friday, with easterly winds developing early Saturday morning, bringing heavy snow to Denver and the Front Range through Saturday evening.  Skies clear out on Sunday, with sunshine returning to the whole state.  

Front Range and Eastern Plains

Cloud cover has kept temperatures cooler than forecast on Friday, with temperatures holding in the low to mid 40's in the Denver metro area.  Scattered rain and snow showers will be possible late tonight in the metro area as moisture moves into the region ahead of the main system, with an outside chance of thunder occurring with these initial showers.  Temperatures fall to around freezing in the Denver area during the early morning hours with the main precipitation event beginning just before daybreak as all-snow behind northeasterly (upslope) winds.  Moderate to heavy snow will fall throughout the day Saturday along the urban corridor from Ft. Collins to Denver to the Palmer Divide.  

Heavy snowfall will make for difficult driving conditions throughout the day, especially as temperatures slowly fall into the 20's throughout the day and moderate winds lead to blowing snow.  Denver, Boulder, and Ft. Collins should expect a general 8-12" with locally higher amounts possible.  The snow will fall at even heavier rates at higher elevations in the foothills and along the Palmer Divide, due to orographic effects (increase in elevation generates more moisture).  Expect 12-20" of snow to fall in the foothills all the way up to the Continental Divide.

The Divide will act as a sharp barrier, with significantly less snow falling west of the Continental Divide (easterly winds are not favorable for areas west of the Divide).  For skiers, Loveland and Berthoud Pass will still see good snowfall since they are located right on the Divide, but Eldora may see the highest snowfall totals of all ski areas in the Front Range, due to its location east of the Divide.  The Indian Peaks, Rocky Mountain National Park, and Cameron Pass east, should all see good snowfall totals as well.  

On the northeastern plains, Blizzard Warnings are in effect for 10+ inches of snow along with 40 mph + wind gusts, including the towns of Castle Rock, Limon, Greeley, Ft. Morgan, and Sterling.  South of the Palmer Divide, the Colorado Springs area will see little snowfall due to an unfavorable wind direction.  Northern and northeasterly winds produce a downslope effect off of the Palmer Divide into the city of Colorado Springs.  Downsloping winds by nature dry out the air, producing a "rain shadow" effect downwind of a higher elevation feature.  There will be enough moisture and storm energy to produce snow showers over Colorado Springs, but accumulations will be very light compared to Denver.  Heavier snow is expected in the foothills and mountains west of Colorado Springs, though, including Pikes Peak.

Snowfall concludes in the Front Range Saturday evening, with low temperatures falling into the teens in Denver metro area on Saturday night.  Sunday brings quickly clearing skies and temperatures rising into the upper 30's as a ridge of high pressure moves in.

Southern/Western Mountains

Heavy snow is already falling in the San Juan Range and will continue into Saturday, with southwesterly winds favoring areas such as Wolf Creek, Silverton, and Purgatory (Durango).  As the system moves through, winds will fluctuate from southerly to westerly, and heavy snow will also be possible for the Grand Mesa and the Elk Range from Aspen to Crested Butte, though confidence is much lower for these areas compared to the San Juans.  Wolf Creek will likely see the greatest snowfall totals, with up to a couple of feet possible.  Monarch is also going to see heavy snow from this storm as winds switch to easterly on Saturday morning, as the Monarch Pass area does well with upslope winds.  The eastern Sawatch Range in general should see good snow totals (highest in the south toward Monarch), with upslope winds possibly bringing good snow to the Independence Pass area as well.  The southern storm track and easterly winds are going to favor the Sangre de Christo Range with heavy snowfall as well.  Snow will slowly taper off in the Southern mountains during the day Saturday, with clear skies returning on Sunday.

Northern/Central Mountains

Unfavorable wind directions associated with the storm system (southwest and easterly) will lead to significantly lower snowfall areas from Steamboat to Vail to Summit County.  Under southwesterly winds, the San Juan, Elk, and Sawatch Ranges block most of the moisture from reaching the northern and central mountains, while under easterly winds, moisture is blocked by the Continental Divide from reaching areas west of the Front Range.  As a result, these areas are going to stay mostly dry, despite what models and many weather forecasts are predicting.  It is possible that some heavy snow bands could develop in this region on the backside of the storm system, probably later on Saturday, but confidence of this occurring is low.  The western slopes of the Continental Divide, including areas like A-Basin and Winter Park, are very borderline as far as receiving heavy upslope snow from easterly winds.  Since both are located near the Divide (but on the western side), it is possible that moisture could spill over and produce big snow totals for these areas, but confidence of this happening is low.  Just like the rest of the state, skies will clear out on Sunday with temperatures quickly warming up.

Medium to Long Range

A ridge of high pressure moves into Colorado following the storm system on Sunday and is going to be the dominant weather feature over the next week into the following weekend.  Temperatures are expected to warm up quickly starting on Sunday and Monday, though fresh snow cover should initially have a moderating effect on high temperatures on the Plains.  Sunshine will present throughout the week, with progressively warmer temperatures affecting the state.  In Denver, highs in the 60's will be a good bet by midweek, while spring skiing conditions are going to be the rule in the mountains.  The warm and dry weather will persist through at least next Saturday.