[ADEQ Forecasts] ADEQ Issues Ozone Health Watch For Thursday, April 23, 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, April 22: Unusually sensitive people should consider reducing prolonged or heavy outdoor exertion outdoors. 

Health message for Thursday, April 23: Unusually sensitive people should consider reducing prolonged or heavy outdoor exertion outdoors. 
 
Synopsis and Discussion

AN OZONE HEALTH WATCH HAS BEEN ISSUED FOR THURSDAY APRIL 23
Tuesday's local ozone levels dropped off considerably from those of Monday.  The metro area High Pollution Advisory Action Day/Trip Reduction Plans that were in effect likely played a role in the noticeable drop in some monitored ozone precursor emissions, but does not explain such a large decrease in ozone production - an event that is still being analyzed.  At any rate, a shift in the weather pattern and wind direction may bring a rapid return of high ozone readings today and Thursday.  A weak upper level low and trough over southern California - responsible for the cloudiness currently overhead - will slowly move east over AZ the next 24 hours or so.  In doing so, winds upstream in the 5-10K' foot layer have already shifted out of the west and will become more northwesterly with time.  This directional component will be capable of transporting additional ozone and its precursors from California over the local forecast area.  Afternoon surface winds will become southwesterly, so north and east Valley locations will be most prone to having high ozone levels. This transport effect is advertised to peak during the overnight hours, so an Ozone Health Watch has been issued for Thursday.

If you have any questions or comments regarding this forecast please contact:
The Arizona Department of Environmental Quality
Office of Communications
1110 W Washington St, Phoenix, AZ 85007
(602) 771-4583 
communications@azdeq.gov


 

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