[ADEQ Forecasts] ADEQ Daily Air Quality Forecast For Wednesday, July 15, 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 Tuesday, July 14: Unusually Sensitive People should consider limiting prolonged or heavy exertion outdoors.  

Health message for Wednesday, July 15: Unusually Sensitive People should consider limiting prolonged or heavy exertion outdoors.  

Synopsis and Discussion
Not a whole lot of change is expected to with the weather pattern over Arizona the next couple of days.  Excessive heat will continue through the weekend with afternoon desert highs climbing well above 110 deg F.  Moisture continues to be absent as the position of the high pressure system remains to our southeast.  This puts Arizona under a dry, southwesterly flow.  Surface dewpoints could reach the upper 50s Wednesday morning, but there's just not a strong enough fetch of moisture from Mexico and the Gulf of California to produce those desert thunderstorms.

Ozone levels were fairly low on Monday.  Thanks to the dominating west-southwest winds, the invisible plume is not able set up very long over the forecast area.  It is spread out rather than pooling in an isolated location as is drifts to the east.  Though still very light, a slight change in the winds to a more southerly flow by Thursday and Friday with upper level winds turning back out of the northeast could hold ozone closer to downtown Phoenix.  While the highest concentrations are expected to be in the far east Valley on Wednesday (Apache Junction, Queen Valley, Mesa, Chandler), the central and north part of the Phoenix forecast area (North Phoenix, Central Phoenix, Glendale, Cave Creek) could be the recipient of the highest ozone levels on Thursday and Friday.

A large spike in PM-10 concentrations around 8-9pm on Monday caused three sites to reach the "Moderate". Higley was the highest, reaching 70 AQI, followed by South Phoenix and West 43rd at 53 and 52 AQI, respectively.  Because this was not a usual occurrence given the current weather pattern (likely due to small thunderstorm well south of the forecast area), concentrations should return the "Good" range by Wednesday.

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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