Wednesday morning’s radar animation shows the approaching storm currently over Idaho and Montana.

The high-resolution models have been in reasonable agreement the past two days, so I am comfortable showing the forecast below, which is from Wednesday 6 pm through Friday at 6 am.

On Wednesday night, the band of intense snow hangs around Steamboat, and then on Thursday morning this band slowly moves to the east through the rest of the northern mountains and over to Denver. By Thursday afternoon and Thursday night, the steadiest and most intense snow will be long gone, and the northern and central mountains will be left with a few snow showers.

Today’s high-resolution CAIC-WRF 2km model shows total snowfall still in the 4-8 inch range for the northern mountains.

However, yesterday’s high-resolution CAIC-WRF 2km forecast (below) was for somewhat greater amounts and for the storm to push a little farther south.

So the trend in the forecast from this model (and a few others) is to weaken the storm just a bit and for the storm to track a bit farther north. These little wiggles in the forecast are normal, even when the storm is within 24 hours, so I’m not at all panicked.

Also, the main driver of snowfall from this storm will be the jet stream creating a few narrow yet intense bands of snow. Whichever northern mountains happen to be hit by these bands will see the most snow, and with snowfall rates of 1-2 inch per hour in these bands, the difference between a storm total of 4 inches versus 8 inches will generally be due to getting lucky and sitting under one of these bands for an extra few hours.

Our snowfall map available on OpenSnow shows the distinct pattern of this storm favoring the northern mountains. Also, the map below often errs a bit on the high side because it sums snowfall ranges from each day and each night and rounds up if there is a decimal.

Once the snow ends on Thursday evening, we’ll see very cold temperatures on Friday morning (around 0F on the upper mountains at 11,000 feet) and Friday’s temperatures will be cold with highs in the upper teens to low 20s.

The weather on Friday, Saturday, and Sunday will be dry, and temperatures will warm back into the 40s in the mountains on Sunday and into early next week.

The colder-than-average temperatures on Thursday, Friday, and through the weekend will be great news for snowmaking crews and I expect a lot of snow to be made over the next five-ish days.

The next chance for a storm will be in about 10 days, between Friday, October 18 to Tuesday, October 22.

Right now, our potential system on Oct 18–22 is known as Super Typhoon Hagibis, which is spinning in the Pacific Ocean and heading toward southern Japan.

Hagibis will turn to the north, and then east, join another storm over the Northern Pacific Ocean, and eventually will make its way into North America, and it could bring rain and snow to the western United States around Oct 18-22 (see the blue colors over Colorado on the map below).

For now, let’s sit back, enjoy the incoming storm, and I’ll post again on Thursday morning with a mid-storm update, and again on Friday morning with a storm recap.

Thanks for reading!

JOEL GRATZ

Upcoming talks

These talks usually range from 30-45 minutes and allow me to show a little of the science behind snow forecasting, have some fun, and answer lots of questions. I’ll post details about each talk soon.

Boulder: Oct 24 @ Neptune Mountaineering

Golden: Oct 30 @ Powder7

Frisco: Nov 8 @ Highside Brewery

Nederland: Nov 12 @ Salto Coffee / Tin Shed Sports

Denver: Nov 14 @ Denver Athletic Club

Evergreen: Nov 21 @ Boone Mountain Sports

Basalt: Dec 12 @ Bristlecone Mountain Sports

If you have a venue in a town not listed above and would like for me to give a presentation this fall, send me an email ([email protected]).

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