Forecast simulaton showing heavy snow in eastern Colorado around noon local time Friday (National Weather Service)

Snow will move into eastern Colorado tonight and fall heavily at times before tapering off late Friday night. The combination of snow and sustained winds of 20-35 mph have prompted blizzard warnings just the east of Denver. For Denver itself, Boulder and Ft. Collins winter storm warnings are in effect.

The National Weather Service in Denver has cautioned: Travel conditions across northeast Colorado are expected to become very difficult, if not impossible, later tonight.

After socking Colorado, the storm will head east into the southern and central Plains, where it will begin to lose some of its punch. Neverthless, winter storm watches extend into northern Kansas and much of Nebraska covering the period from Friday night through Saturday night.

Some time late Saturday and Saturday night, precipitation will begin streaking into the Ohio Valley, possibly crossing the Appalachians and reaching the mid-Atlantic.

All week, computer models have simulated an area of high pressure over northeast Canada which, in some simulations, has crushed this storm system, keeping any precipitation south of the D.C./Baltimore region. But some models bring the precipitation shield farther north.

If the precipitation reaches the D.C. metro region, enough cold air may be in place for some light snow or a mix of light snow and rain as early as late Saturday afternoon and possibly continuing through Sunday morning. Temperatures during this period would just marginally support snow, if they do at all. Significant accumulations are not likely, but if everything comes together just right, light snow accumulations are possible.

National Weather Service assessment of the probability of 1” of snow between Saturday night and Sunday night

No precipitation: 45% chance

Mostly rain: 15% chance

Rain/snow mix, no accumulation: 15%

Mostly snow, a coating to a couple inches: 15%

More than a couple inches: 10%

We will have additional updates Friday and may issue a Snow Lover’s Crystal Ball (SLCB) for the D.C. area if needed. The SLCB is used when there is at least a 30% chance of 1” of snow in the metro region.