Tuesday, December 29, 2009

Slickrock Country Talk

I'll be giving a presentation at the Bend REI store on February 23 about the Slickrock country of southeastern Utah. The program, which starts at 6:00 p.m., will be a visual tour of Arches and Canyonlands National Parks, and feature the cultural and natural history wonders of the area. I'll be signing copies of my latest book, as well as having some of the others on hand. Hope to see you there!

Living in the Soup - A Central Oregon Inversion

We are living in a soup, more like a cloudy broth brought on by an inversion. The inversion layer has trapped a layer of cold air and fog beneath a ceiling of clouds. Pretty cool as a weather-related event, but you can tell that people are ready for a new pattern.

According to the weatherman from the National Weather Service in Pendleton, a stable, high pressure atmosphere is holding over our area. The inversion is like a pot lid, holding in stagnant air boiling in the pot. During an inversion, the Cascade Mountains block any warm air flow off of the Pacific Ocean from moving the clouds out of the area. Because it is winter and cold here, now cold air flows down from the mountains, creating cold temperatures in the lowlands. The nighttime lows have been in the upper teens and low 20s.

With the cold temperatures and the sun farther to the south, the daytime warming trend is not strong enough to warm up the ground. If it could, the ground would radiate the heat back up into the air to break up the inversion. At the same time, the cold temperatures near the ground are around the same level as the dew point - the temperature at which dew starts to form. That means that the moisture in the cold air condenses and forms fog, freezing fog or very fine snow. You can see this coating on the trees and shrubs in town; they appear to have been sprayed with a mist.

Moving the inversion layer out will take a stronger storm front or upper atmosphere disturbance, which is in the forecast. Although this type of weather is pretty cool to observe, it does pose health problems as the stagnant air holds wood smoke, pollution and other contaminants in for us to breathe.

Locals know that to get out of the gunk, they have to drive to higher elevations like along Century Drive towards the Mt. Bachelor Ski Area. At a certain point, they pass out of the cloud layer and into the sunshine. And for some, into a much better mood.