The Slide Fire burning in Oak Creek Canyon - and now on the outskirts of Flagstaff - is being fueled by dry conditions and strong winds. Many communities near the blaze are experiencing extremely smoky conditions and ash fallout. Arizona Public Radio's Gillian Ferris spoke with meteorologist Lee Born about the fire's effect on air quality.
GF: Lee, what were the weather conditions yesterday that we now know really helped fuel this fire?
LB: Well, Gillian, yesterday was a Red Flag Warning day issued by the National Weather Service. And, a Red Flag Warning means critical fire weather conditions. And what comes together is warm conditions, very dry outside with the relative humidity usually in the single digits. And also, we have tinder-dry fuels in the forest with the very dry winter and spring we had. And, when we get together with very strong winds and low relative humidities, if a wildfire breaks out, there is explosive growth with the fire. And that's what we saw yesterday and again today on this fire with the wind still blowing. It's not a Red Flag Warning day - we're just under that threshold. But still quite windy out there and challenging for the firefighters.
GF: At KNAU - we're still many miles away from the fire - but even here it is very ominous, the plume of smoke, the ash that's falling. What is the air quality like? We've had a lot of callers today concerned about air quality and health.
LB: Well, the air quality is not good. Obviously, the plume's right on top of us. We're even seeing ash fallout here in Flagstaff. And when you have a plume on top of you, you have particulate matter in the atmosphere which means you have some soot, and ash - it's all components of this smoke plume. And certain populations can be sensitive to this - you can have some trouble breathing, or possibly some eye irritation. And if that's the case, you want to avoid being outside, or if it gets worse, you would maybe want to see a health care person.
GF: The plume is quite dramatic and seems to be shifting back and forth. What can we expect? Where is it going? I know we can't really predict Mother Nature...
LB: The plume is quite dramatic. In fact, it's so huge you can see it from space on visible satellite imagery. The plume moves around and the winds have been out of the southwest with the fire right off to our southwest. The plume is directed right up Oak Creek Canyon, right into Flagstaff. But we do have a shift in the weather coming up over the next couple of days. The spring low pressure system that's been approaching us the last few days, bringing the southwest winds, will now set up right on top of Arizona and slowly beginning tomorrow through Saturday. And what that's going to mean is that we're going to see a lot less wind and chances for some light rain showers beginning late Thursday through Saturday is what the forecast is calling for. And, some thunderstorms, even. So it's kind of tricky with the plume now because the winds are going to kind of lighten up, so the plume's not really moving around much. The winds are going to start shifting to the south and east a little bit vs. the south and west. So, we could see this thing sort of wobble around Flagstaff. And in the vicinity of these showers and thunderstorms, we're going to get some erratic winds. The best thing we can see happen over the next several days is some nice rainfall. Rainfall obviously washes some of the smoke out of the atmosphere and it would really help on the fire scene, as well.