[ADEQ Forecasts] ADEQ Daily Air Quality Forecast for Saturday, September 05, 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 Friday, September 4: Unusually sensitive people might want to consider limiting prolonged or heavy exertion outdoors.

Health message for Saturday, September 5: Unusually sensitive people might want to consider limiting prolonged or heavy exertion outdoors.


Synopsis and Discussion

Hurricane Jimena will not make its way up the Gulf of California and into southwestern Arizona.  Instead, it will continue to lose strength as it spins out over Baja.  In fact, it has already been downgraded to a Tropical Depression with sustained winds around 30 mph.  Some of Jimena's moisture bands have drifted north into Arizona as evident by those thunderstorms Thursday night.  They were fairly isolated with rain totals ranging from 0.04 to 0.25 inches.  Many locations only experienced blowing dust.  

Storm outflow winds sent PM-10 concentrations soaring around 8pm with a 1-hr maximum concentration at the West 43rd monitor well above 2,500 micrograms per cubic meter.  That 1-hour concentration was enough to cause a 24-hr hour exceedance even though the other 23 hours only averaged 67.9 µg/m3.  Ozone reached the "Moderate" category at the Queen Valley site, but was "Good" at all the rest of the local monitors.

Additional moisture will move north into Arizona this weekend, increasing the chances for showers and thunderstorms in the deserts.  As of now, it looks like Friday afternoon into Saturday morning will be the best shot for measurable rain in the forecast area.  There will be about a 30% chance of rain on Sunday and Monday.  Cloud-cover much of the day Saturday should significantly limit ozone production.  A little more sunshine on Sunday could allow ozone to reach the lower "Moderate" range once again.  Particulate levels will depend on whether there is more rain or wind.  If we experience thunderstorm outflow winds with little to no rain, we can expect to see PM-10 concentrations well in the "Moderate" range on Saturday and Sunday.  

Check back on Sunday for a look at your Labor Day weather forecast and resulting air quality.  Until then, have great weekend!

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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