Sawatch Range in Eagle County helping to create line between good, moderate air quality | AspenTimes.com
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Sawatch Range in Eagle County helping to create line between good, moderate air quality

Areas south of Eagle, Pitkin and Lake counties are in the green

The AirNow.gov view of air quality in Colorado as seen on Monday. Green indicates good air quality while yellow is moderate and orange is low.
Screengrab

The AirNow.gov smoke map shows a line through the center of Colorado, with areas in the northwest part of the state experiencing moderate air quality while southern communities enjoy clear skies.

Part of that dividing line runs through Eagle County and neighboring Lake County as the Sawatch Mountain Range is helping to trap haze and smoke from the Morgan Creek fire in Routt County, as well as faraway fires burning in Canada and the northwestern United States. The Elk Mountains in Pitkin and Gunnison counties are also helping keep air quality in the green — AirNow.gov’s indicator of good air quality — in southern Colorado, while areas to the north are yellow, or moderate.

The Bureau of Land Management issued a smoke statement for northwest Colorado on Monday, saying that afternoons could be better for air quality in the coming days.



“Smoke should lift from valleys and drainages late morning to early afternoon with warming from sunny skies,” the statement reads. ”In addition, fire activity in Wyoming, Oregon, Idaho, Montana, California and British Columbia will be visible in the upper atmosphere throughout the day. A plume of smoke may be visible from firing operations on the Morgan Creek Fire near the 400 road north of Clark. This plume will move primarily to the west this afternoon.“

High moisture contributing

Meteorologist Kris Sanders with the National Weather Service in Grand Junction said the moisture in the air is unusually high for this time of year, which doesn’t help visibility.




The postcard blue skies of the West occur as a result of the region’s aridity, but with the dew point reaching high levels for western Colorado in recent days, the outline view of the horizon isn’t going to be as crisp, Sanders said.

“For example, in Grand Junction, a 60 dew point is some of the highest that we get,” Sanders said on Monday. “And it’s hit 60 almost every morning (in recent days).”

In the higher-elevation areas east of Grand Junction, those numbers are slightly lower, on average, but are still registering quite high for this time of year.

“As you start to get into Gypsum, Eagle and parts of Vail, you’re looking at lower 50s, upper 40s,” Sanders said.

The National Weather Service office in Grand Junction is one of only 60-or-so offices in the country that launch weather balloons twice per day.

“Within the balloon is a little instrument that measures pressure and things like that,” Sanders said.

The Grand Junction office also measures precipitable water, a by-the-inch look at the depth of water in a column of the atmosphere, and Sanders said the precipitable water numbers have been coming in high in western Colorado recently.

“We’re over 1 inch, and the daily mean here in Grand Junction is about .8,” Sanders said. “We’re getting pushed close to the daily maxes.”

A view of the Gore Range in Vail in early July. Hazy conditions have been off and on for weeks as winds push smoke from the megafires in the Northwest around to neighboring regions.
Vail Daily file photo

Afternoons better

But with high water content in the air, an air-quality flush is more likely to occur in the form of rain.

Afternoons in Eagle County, following rainy conditions, is when skies have been the clearest in recent days.

Sanders said by the end of the week, western Colorado could be seeing even more active monsoonal conditions.

“We’re gonna get that continual push of moisture that we typically see in the really good monsoon years,” Sanders said.

That will be the result of a stronger high pressure system moving over the central U.S. later this week, Sanders said.

Holy Cross barrier

In recent days, a weak high pressure system to the north has allowed smoke to settle in valleys and stop alongside mountains, “like a natural dam,” Sanders said.

The Sawatch Range and the Elk Mountains have created barriers in central Colorado, keeping skies clear in the south, Sanders said.

The Sawatch Range contains Mount of the Holy Cross — Eagle County’s highest peak at 14,011 feet — as well as Mount Elbert and Mount Massive, the two highest peaks in Colorado.

“With any kind of flow coming from the north or northwest into central Colorado, all that air is going to get banked up on the western side of those peaks and in those valleys,” Sanders said. “So until we get a big, strong system that really cranks up the winds throughout the entire atmosphere, a lot of that just kind of settles or dams up. The air is moving like fluid; it behaves by the same principles.”

The haze that has resulted from the smoke and high moisture in the air should break by the end of the week, Sanders said.

“With the high pressure centered over Wyoming and northern Colorado, there has been a clockwise flow that has been bringing some of that wildfire smoke from the Pacific Northwest and California all the way around to the Central Plains and then back westward towards Colorado,” Sanders said.

Later this week, “We’re expecting the high pressure to move more over the Central Plains, which puts us at more of a southeasterly or southerly flow for our region,” Sanders said. “So that will help steer the wildfire smoke well into Canada and the northern U.S.”


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