Summary

The last week (Aug 12-18) has been warm and dry, and the current week (Aug 19-25) looks like more of the same, with a few afternoon showers thrown in as well. The only big weather story will be a strong cold front, which should drop temperatures near and east of the continental divide starting around Wednesday, August 28th. The air might be cold enough that the areas near and above treeline could see a few flakes. Read to the end of the post to see a quick discussion about the outlook for the upcoming season.

Short Term Forecast

First up, let’s look at the temperatures across the western United States from August 12-18. The below-average readings were in Idaho, Montana, Wyoming, and the Dakotas, while areas along the west coast, the southwest, and Colorado were generally warmer than average.

For precipitation, the previous seven days were about as dry as could be over areas near and west of the continental divide. The stormiest areas were over the far northern Rockies and east into the plains, which makes sense as the active storm track stayed to the north and east of Colorado.

Comfortable temperatures and little moisture results in picture-perfect scenes in our mountains. Below is a cam from near the summit of Copper Mountain, looking north toward the Gore mountain range. Glorious!

Something to think about during this time of year is the increased risk for wildfire.

During late August and early September, wind speeds often increase as the jet stream begins to shift south into the northern United States. And fast winds can allow fires to quickly get out of control.

Please keep this in mind if you’ve camping over the next few weeks and have the desire to light a campfire. Please map sure the fire is completely smothered before you leave the area. A strong wind can pick up a lump of small hot coal and things can escalate quickly. Let’s get through this year with no major fires!

Here is the current wildfire risk across the United States.

Extended Forecast

The main story through the rest of August will be a cold front that should drop temperatures by 10-20 degrees across eastern Colorado on Wednesday, August 28. The cold front will arrive from the northwest.

While the best chance for snow through the end of August will be in western Canada…

…models do show some hints of snow potential along the higher elevations of the continental divide from Colorado northward to Wyoming, Montana, and Canada as that cold front moves through.

If the cold front arrives as expected on or around Wednesday, August 28, and if there are some showers associated with the storm that will push in the cold front, it’s possible that some of our higher mountains near and east of the divide could get a fresh coating of snow. This is NOT going to be a bit snowstorm unless something in the forecast drastically changes. But it’s always fun to feel the first real cold front of the season.

El Nino and Snowfall in Colorado

Frequent reader, commenter, and weather nerd Jeff Lyslo sent me the chart below, which compares snowfall in the town of Breckenridge (not on the mountain) with El Nino and La Nina.

To the left on the graphic is a stronger La Nina (colder than average water temperatures in the central Pacific Ocean) and to the right on the graphic is a stronger El Nino (warmer than average water temperatures in the central Pacific Ocean).

The key point is that during a stronger La Nina or stronger El Nino, history shows us that snowfall often is close to average. However, during a neutral year, with no significant La Nina or El Nino, snowfall variability is the highest.

For the upcoming 2019-2020 season, most forecasters agree that we’ll see neutral conditions, so no strong La Nina or El Nino. Based on this graph, a neutral year has the widest variability in snowfall, anything from well below average to well above average. So that’s what to expect this year…pretty much anything between a terrible year and an amazing year.

Look for future posts during the middle of each week. Even though we’re pretty far from ski season, we still have things to talk about, including the week-ahead forecast, the longer-range outlook for any colder air heading our way, and any new nuggets of data that might give us a glimpse into the forecast for the season ahead (remember that I do NOT find much value in 6+ month predictions).

Thanks for reading!

JOEL GRATZ

Announcements

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