[ADEQ Forecasts] ADEQ Daily Air Quality Forecast for Wednesday, August 20, 2009

[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 Wednesday, August 19: Unusually sensitive people
should consider reducing prolonged or heavy exertion outdoors.
 
Health message for Thursday, August 20: Unusually sensitive people
should consider reducing prolonged or heavy exertion outdoors. 

Synopsis and Discussion
A trend toward increasing summer monsoon moisture and thunderstorm
activity for AZ in general and the local forecast area in particular is
underway.  This is due to the incipient re-establishment of a summer
monsoon circulation pattern with rather strong easterly flow aloft, and
the subsequent tapping of much more humid air currently located to the
east and southeast of the state.  The occasional presence of upper level
disturbances over Mexico may focus monsoon storms and their outflow over
southern AZ thru the weekend.  In fact, outflow boundaries may generate
blowing dust on the Valley outskirts as early as Thursday evening.
Forecast models are indicating that winds aloft over the Valley will
become easterly as low as the 10K' level by Thursday afternoon and by
Saturday afternoon may reach 15-25 mph in the 10-18K' layer.  This shift
to a non-laminar flow may be sufficient to retard westerly surface winds
to a degree that excess accumulation of ozone occurs.  At this point the
mention of the potential for an Ozone Health Watch issuance for Friday
seems warranted for locations east of the Valley center.

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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