[ADEQ Forecasts] ADEQ AIR QUALITY FORECAST FOR SATURDAY, JUNE 12, 2010

[forecasts@lists.azdeq.gov]

 For more information, please visit our Web page:
http://www.azdeq.gov/ensemble.pdf

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

Health message for Friday, June 11: Unusually sensitive people should
consider limiting prolonged or heavy exertion outdoors. 

Health message for Saturday, June 12: Unusually sensitive people should
consider limiting prolonged or heavy exertion outdoors. 

Synopsis and Discussion
Starting today, a large, late-season trough of low pressure will impact
Arizona's weather this weekend. Clouds have already begun to stream in
from the southwest ahead of the system. Afternoon winds will increase
Friday. Peak gusts could top 20 mph at times on Saturday. As the system
continues east, it will weaken and pressure gradients will relax. This
will allow winds to become much lighter by Monday. No rain is expected
for the deserts, but a few spotty showers and thunderstorms are possible
in the mountainous areas of northern Arizona on Saturday and Sunday.
With plenty of dry fuel across the landscape, the threat of
lightning-sparked fires is high this weekend.  Desert temperatures will
also drop well below normal, with highs in the lower 90s on Saturday and
Sunday. High pressure returns next week, warming temperatures into the
triple digits once again.  
If it weren't for the clouds today, it's likely that the Valley would
see ozone concentrations approach the health standard Friday afternoon.
With the approach of the trough of low pressure, a classic transport
scenario has set up.  Both Yuma (150 southwest of Phoenix) and Alamo
Lake (100 miles northwest of Phoenix) registered mid to upper "Moderate"
ozone concentrations on Thursday. The clouds save us today, and the
winds will disperse the precursors on Saturday, keeping ozone in the
"Good" range this weekend. PM10 levels will likely climb into the low to
mid "Moderate" category on Saturday due to gusty winds and no rain.
They'll drop off on Sunday as the winds relax.
Check back on Sunday for the latest.  Until then, have a great weekend!


If you have any questions or comments regarding this forecast please
contact:

Arizona Department of Environmental Quality
Office of Communications
1110 W. Washington St., Phoenix, AZ 85007
(602) 771-2215
ms15@azdeq.gov


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