[ADEQ Forecasts] ADEQ AIR QUALITY FORECAST FOR SATURDAY, JUNE 28, 2008

[forecasts@lists.azdeq.gov]

http://www.azdeq.gov/ensemble.pdf

For transportation alternatives:
http://www.valleymetro.org 

Health message for Friday, June 27:  Unusually Sensitive People should consider limiting prolonged exertion outdoors.
 
Health message for Saturday, June 28:  Unusually Sensitive People should consider limiting prolonged exertion outdoors.
 
Synopsis and Discussion
It was a very interesting day air quality-wise in the Valley of the Sun on Thursday.  Ozone levels jumped much higher than anticipated, and it was assisted in part by a wild fire in the southwest part of the Valley that put out a large amount of smoke in the afternoon hours.  This fire (the Ethan fire) made a little run and has now burned somewhere in the neighborhood of 1,200-1,500 acres in the Salt River bed.  Towering columns of thick, smoke rose and moved to the northeast across downtown Phoenix at about 3:00PM and continued towards the far northeast part of the Valley through the evening hours.  Studies have shown that Carbon Monoxide from smoke can cause a significant increase in Ozone levels.  The North Phoenix and Rio Verde Ozone monitors had readings in the low 90s (ppb) in the early afternoon before dropping off again.  How about Particulate levels?  Most PM-10 monitors realized an increase in concentrations around 6-7PM, as the mixing heights began to collapse.  PM-2.5 concentrations jumped at West Phoenix around 2PM and again around 6-7PM.  Estrella Mountain's PM-2.5 monitor had the highest concentrations of the day as it is the closest monitor to the fire.  Fortunately, none of the monitors recorded concentrations that posed health concerns.  Experts expect the fire to mostly burn out by Friday afternoon if everything goes according to plan.  If this occurs, Ozone generation won't have any additional help this weekend.  With westerly winds, however, we are expecting a slight increase in levels, primarily back to the mid-to-upper "Moderate" range in the east part of the Valley.  Particulates will remain in the low-to-mid part of the category through the weekend as well.  High pressure is still struggling to reach its destination of the Four Corners area and thus we will not see a huge influx of moisture this weekend.  This means that the chances for ground-soaking, air-clearing rains here in the Phoenix forecast area through Sunday remain very slim.  Check back on Sunday for next week's weather and air quality outlook.  Have a great weekend!  -J.Paul

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