Summary:

Completely busted forecast...snow fell last night and more will fall today with 3-6 inches total accumulation for most areas. There will be a break Friday night, then more snow showers for the northern 2/3rds of Colorado on Saturday with snow lasting through Sunday for the northern 1/3rd of Colorado. Total weekend accumuations will be 3-6+ inches for most areas, with more further north. The next storm will bring a quick shot of snow on Tuesday or Tuesday night, then the next-next storm might bring snow back into the forecast for Sunday 12/29.

Details:

Last night and this morning was very surprising as moderate to heavy snow fell for many areas. It didn't snow hard all night, and it's not snowing hard everywhere this morning, but there are heavier bands that produced a quick couple of inches in a few hours.

What happened?

Well, I got this one wrong. We'll start there:-)

Last night and this morning we are getting squeezed by moisture to the south and moisture to the north. This squeeze play means we have a lot of moisture in the air but not a lot of storm energy to lift the air. The lack of storm energy was why I discounted our chances for meaningful snow last night and early this morning. However, moisture is like a puddle of gasoline, and it just takes a little spark to make it go "boom" and turn into snow. Even though we have weak storm energy over Colorado right now, it's enough to act as the spark and ignite the moisture into snow.

A lot of moisture is streaming into Colorado from the south and some from the north. This is helping to ignite the heavy snow showers we saw last night and this morning. Source: Twisterdata.com

Looking at the big picture, it's funny how I was excited for this storm about 7-10 days ago, then lost hope in the last few days, and then it turns out that we get decent accumulations. Maybe reverse psychology works on the atmosphere?

For the rest of Friday, expect on and off snow showers. It could snow hard for 1-2 hours with a quick couple of inches, then not snow at all for a while. The best accumulations might be around Wolf Creek, though there are currently (930am) heavy snow bands over Vail and Powderhorn as well.

Friday night: A few lighter snow showers, but this will be a break in the storm.

Saturday: Snow showers return to the entire state with general accumulations around 2-4 inches.

Saturday night through Sunday night: Snow showers persist along and north of I-70 with another 2-4 or 3-6 inches. Less snow will fall around Aspen and likely no snow south of Aspen.

Monday & Monday night: Dry.

Tuesday & Tuesday night: Next chance for a few inches for the northern half of Colorado.

Wednesday through Saturday: Likely dry.

Sunday 12/29: The next chance for some type of storm ... it doesn't look big, but it's too far away to know the details.

JOEL GRATZ