[ADEQ Forecasts] ADEQ Issues an Ozone Health Watch for the Phoenix Metro Area for Wednesday, August 5, 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 05: Unusually sensitive people should consider reducing prolonged or heavy exertion outdoors. 

Health message for Thursday, August 06: Unusually sensitive people should consider reducing prolonged or heavy exertion outdoors. 


Synopsis and Discussion

*AN OZONE HEALTH WATCH IS IN EFFECT FOR THE REMAINDER OF TODAY*

The latest air quality forecast was thrown for a loop with the unexpected arrival of a thunderstorm outflow boundary and dense blowing dust late last night, as well as unhealthy ozone levels over the far eastern Valley (Queen Valley) yesterday afternoon.  Not only did the Higley PM-10 (coarse particle) monitoring site record an hourly concentration of 531.9ug/m3 at 11:00 p.m., but six other sites recorded hourly levels between 316.6 and 521.5ug/m3 at midnight.  Since the latter readings will be used to calculate the 24-hour values for today, and since there is a decent chance for another blowing dust event this evening, the AQI forecast value for PM-10 has been increased substantially.  Latest surface observations, AMDAR soundings, and VAD profiler data indicate that Valley winds at noon from the surface to near 8K' were light and variable and from 8K to 11K' were east to southeasterly.  This admittedly temporary environment will nonetheless allow additional ozone accumulation to occur, and enhance local ozone levels that were already running ahead of Tuesday's 10:00 a.m. readings.  Since east Valley locations may again experience high ozone concentrations, an Ozone Health has been issued for the rest of today.   An unusually strong and far south (for August) upper level trough is advertised to bring gusty winds and much drier air to the metro area by Friday.  Thus, ozone levels are expected to decrease but PM-10 levels may increase if winds hit critical speed & durations thresholds.

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) 771-2215
ms15@azdeq.gov


 
 

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