How gusty winds helped Arizona's Pocket Fire grow to 15,376 acres
Tevian Whitehurst- The Pocket Fire rapidly expanded to over 15,300 acres northward over the last few days due to critical fire weather conditions.
- The strongest winds have passed, but gusts up to 35 mph will persist and smoke will continue covering towns to the northeast, like Flagstaff.
- High ozone pollution air quality alerts were issued for Monday and Tuesday, but smoky conditions may persist through the week due to a similar atmospheric setup of dry conditions, gusty winds.
The Pocket Fire north of Sedona grew explosively over the final weekend of June and an increasing amount of smoke in the air is blowing into nearby cities and towns, lowering air quality and dropping ash.
A low-pressure trough over the weekend brought gusty winds up to 60 mph and extremely dry air to middle and lower parts of the atmosphere, dropping relative humidity values to the single digits, or at most, 20%. This triggered critical fire risk and red flag warnings in the high country (along with the rest of the state) and ultimately were what helped push the rapid expansion of the Pocket Fire from 1,100 acres on Friday, June 26, to 15,376 acres by Tuesday morning, June 30.
Air quality alerts, specifically high ozone pollution advisories from the fire, were issued along the western Mogollon Rim for Monday, June 29, and Tuesday, June 30.
Air quality was at its worst in Flagstaff over the weekend when the winds were at their strongest. Air Quality Index levels were “unhealthy” to “very unhealthy” (the second and third highest ratings) for nearly 12 hours on Sunday, June 28. These index values ranged from 154 to 291.
As winds shifted Sunday night, the smoke, and danger levels, shifted to Kachina Village, south of Flagstaff. This led to similar AQI levels overnight, and a brief deterioration to fully “hazardous” air quality during the morning commute on Monday, June 29.
“Hazardous” is the highest intensity rating on the AQI scale, over 300, where everyone is recommended to avoid outdoor activity.
Smoke forecast offers help for residents
While the strongest winds have passed, the overall setup remains the same: Dry air from the southwest will blow 15 to 20 mph and gust up to 35 mph moving northeast. This will keep fire risk near-critical to critical for much of the week. The orientation of winds puts those north and northeast of the flames at the highest risk.
The Arizona Department of Environmental Quality activated the Pocket Fire Wildfire Smoke Forecast, with a fire overview, smoke synopsis, forecasts for nearby locations and multiple links and contact points for more information. The most helpful piece of information may be the smoke map, released daily to show what towns are in the direct path of that rising smoke.
The city of Flagstaff shared on Facebook how to build a DIY air filter using a box fan, air filter and tape and bungee cords due to the lowered air quality. They suggested this in addition to remaining inside, or wearing an N95 mask if going outdoors in the smoky and ashy conditions.
The Coconino National Forest has been diligent about posting updates on its Facebook page.
A weather pattern shift doesn’t come until the weekend when high pressure will begin to build back into the southwest from our east. This will bring weaker winds through Independence Day weekend and into next week.
A very slow influx of moisture could come next week, creating a slight chance for mountain showers, but no deep monsoonal moisture is in the forecast. If nothing else, more tranquil conditions could be an opportunity to get ahead of the fire’s development.
Meteorologist Tevian Whitehurst covers extreme weather and climate for The Republic and azcentral.com. Follow him at @TevianWX on Instagram and Facebook (Meteorologist Tevian Whitehurst).