The national radar on Thursday morning shows the precipitation to our west and over western Colorado.

Closers to home, the radar over western Colorado early on Thursday morning shows a line of showers near the Utah border, and also a few scattered showers over the southern mountains (south of where “Montrose” is marked on the map) and also just west of Aspen.

Snow-stake cameras and automated weather stations showed that these showers on early Thursday morning brought a coating to an inch of snow to Aspen Mountain, Aspen Highlands, Snowmass, and Crested Butte in the central mountains, and also to Telluride, Silverton, and Purgatory in the southern mountains.

The caveat to this overnight snow is that the temperature is very, very warm, with a freezing level close to 11,000 feet. Snow can fall below the freezing level, especially during the most intense showers, so some flakes likely fell down to 10,000 feet, and I saw snow on the webcam at the town of Silverton at 9,400 feet, so that must have been a very strong cell.

For most of Thursday morning and midday, expect scattered showers especially over the southern and far western mountains. Otherwise, the temperature will be warm with a gusty wind from the south and partly cloudy skies.

On Thursday afternoon and evening, a line of intense showers will move across Colorado. Expect a burst of snow for 1-2 hours with 1-3 inch per hour snowfall rates, then we’ll see lighter snow showers through Thursday night and into Friday morning.

This graphic from the CAIC high-resolution 4km WRF model is for Winter Park and nicely shows the nature of Thursday night’s snow. We could see 1-2 hours of snowfall rates near or above 1 inch per hour, then we’ll see lighter snow through the night, ending on Friday morning. The times given in this graphic are local time in Colorado ("Mar-16 00" = Thursday night at midnight).

This graphic makes Thursday night's snow look straightforward, but it will be anything but. The reality is that the initial round of intense snow on Thursday night will be similar to summertime afternoon thunderstorms where the strongest cells are randomly placed. This means that, early on Thursday evening as the intense precipitation moves through, some mountains could get 3-6 inches in 1-2 inches, and nearby mountains could just get a dusting to an inch.

The snowfall map below, made by the same CAIC high-resolution 4km WRF model as I show just above, tells a good story for snowfall from Thursday afternoon through Friday midday.

That map above looks awesome with many mountains receiving 6+ inches.

But, below is the same map but made 6 hours more recently (early Thursday morning). This newer forecast shows lower snow amounts for many mountains.

I do not think that this drop in the snow forecast is a trend. Rather, it reflects the randomness of how some of the snow will fall early on Thursday evening.

Let’s look at maps that try to capture and illustrate the randomness.

Below is the University of Utah ensemble forecast, showing data for the American GFS and Canadian models. This forecast for Berthoud Pass shows about 1-11 inches on Thursday night, with an average of 6 inches. This average of 6 inches is in line with the bar chart for Winter Park above (Winter Park is very close to Berthoud Pass, so these forecasts are comparable).

Below is the forecast for Cameron Pass (far north-east mountains), with an average of about 8 inches. Most models show a good chance for these higher totals around Cameron Pass, so watch for that.

And below is the forecast for Red Mountain Pass, between Telluride and Silverton in the southern mountains. The average snow forecast on Thursday and Thursday night is for 13 inches. That might be a touch on the optimistic side, but it’s reasonable if the squall line on Thursday afternoon hits this area with vigor.

The bottom line is that all mountains will see a period of intense snow on Thursday afternoon and early evening.

This intense snow could shut down highways due to low visibility and rapid icing as the initial snow melts on a warm road surface and then quickly freezes.

Snow should then continue on Thursday evening and overnight.

Snow totals by Friday mid-morning should average 4-8 inches with the majority (but not all) of this snow falling after lifts close on Thursday and before they open on Friday.

Snow quality on Friday morning will be right-side up. This means that the first snow on Thursday afternoon will be dense and thick due to warm temperatures and strong winds, then the snow on Thursday night will be fluffier due to colder temperatures. Fluffier snow on top of denser snow is what we want.

Get out on Friday morning and enjoy, and don't forget that we will see surprises on the high and low side of the forecast range due to the randomness of the showers on Thursday afternoon/evening!

We should then see dry weather form Friday late morning through late Saturday night.

The next round of snow will fall on Sunday and Sunday night.

This round should behave similarly to what we’re seeing on Thursday night with an initial squall line of intense snow on Sunday morning followed by lighter but consistent snow through Sunday evening or Monday morning.

You can see on the three graphics above that the thick blue line (the average of all the models) notches upwards by about 8-12 inches on Sunday and Sunday night, so it’s likely that most mountains will enjoy powder on Sunday afternoon and also on Monday morning.

Speaking of Monday morning, as the Sunday storm moves east of Colorado, most models are trending toward slowing and strengthening this storm, with a track that’s slightly further south. If this happens, it would be similar to a few past events that I've tracked over the previous years which resulted in a “surprise” deep and fluffy powder day on the morning after the storm (in this case, Monday morning). This will not happen at all mountains, and I think we'll have a better shot in the northern mountains. In any case, I’ll keep you posted, and keep your eye on Monday morning.

This is already a long forecast, so I’ll be brief about the long range.

We could see another weak wave of snow bring light accumulations later on Monday through Tuesday.

Then next Tuesday night through Wednesday night should be dry.

After that, expect another storm or series of storms starting around Thursday (March 22) with chances for snow likely continuing through the following weekend of March 24-25.

Thanks for reading!

JOEL GRATZ

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Geography Key

Northern Mountains
Steamboat, Granby, Beaver Creek, Vail, Ski Cooper, Copper, Breckenridge, Keystone, Loveland, Abasin, Winter Park, Berthoud Pass, Eldora, Rocky Mountain National Park, Cameron Pass

Along the Divide
Loveland, Arapahoe Basin, Winter Park, Berthoud Pass

East of the Divide
Eldora, Echo, Rocky Mountain National Park, Cameron Pass

Central Mountains
Aspen, Sunlight, Monarch, Crested Butte, Irwin, Powderhorn

Southern Mountains
Telluride, Silverton – north side of the southern mountains | Purgatory, Wolf Creek – south side of the southern mountains