[ADEQ Forecasts] Daily Air Quality Forecast for Wednesday, October 7, 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 October 6: Unusually sensitive people should consider reducing prolonged or heavy exertion outdoors. 

Health message for Wednesday October 7: Unusually sensitive people should consider reducing prolonged or heavy exertion outdoors. 

Synopsis and Discussion
The same trough of low pressure that brought the region windy conditions this past weekend will finally push through Arizona Wednesday.  Stronger winds, clouds and moisture will be confined to eastern Arizona Wednesday.  As with most frontal systems including this one, drier air will fill in behind the system.  This will allow overnight temperatures to drop well into the 60s here in the Phoenix forecast area (possibly the upper 50s in the outer lying areas) while desert highs struggle to reach the mid 80s.  A weak ridge moves over head Friday and Saturday, warming the Valley temps to near 90°F.  Winds won't be much of an issue the next several days, but morning inversions combined with accumulating work-week pollution could result in increased PM-10 concentrations.
  
It's still a bit early for fireplace activity but never too early to discuss the effects it will have of the Valley's air quality.  As morning temperatures begin to drop and inversions get stronger with almost no wind, any pollution put into the Valley's air will become trapped near the surface.  This includes fireplace smoke. Sometimes these inversions are so steep and strong that they don't break at all. This usually occurs in November and December but can happen much earlier.  Under such conditions, PM-2.5 concentrations can begin to approach unhealthy levels.  This is why it is extremely important to limit fireplace activity as much as possible in the Phoenix forecast area unless absolutely necessary.  Education now can go a long way towards much cleaner Valley air this winter.

Check back tomorrow for the latest weather and air quality info.  Until then, have a good day!  


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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