[ADEQ Forecasts] ADEQ Extends Ozone Health Watch Through Wednesday, July 01, 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


Synopsis and Discussion

*AN OZONE HEALTH WATCH REMAINS IN EFFECT FOR TUESDAY, JUNE 30, 2009, AND HAS BEEN EXTENDED THROUGH WEDNESDAY, JULY 1, 2009*

We're looking to the east and southeast today for potential thunderstorms that could make it into the Valley.  This mornings Phoenix weather balloon sounding indicates an increase in atmospheric energy which could help produce a few moderate to severe storms across the mountains and/or deserts.  Monday evening saw some storms make their way into the northwest part of the Valley with Lake Pleasant and Sun City seeing most of the action.  Outflow winds from these cells put a plug on the ozone bottle, keeping ozone and precursors from escaping to the east while limiting the typical overnight scavenging effect.  The result: ozone concentrations starting out 10-15 parts per billion higher on Tuesday at various sites.  High pressure near the Four Corners region will keep local ozone here in the Valley much of the day leading to concentrations approaching the health standard at many Valley spots on Tuesday.  Thus, an Ozone Health Watch remains in effect for Tuesday.  If it occurs, rain this evening would be beneficial in scrubbing the atmosphere of all the pollutants.  It would give us at least a day or two to recover from the elevated ozone levels.  If not, then we could be looking at even high concentrations on Wednesday.

Models indicate that the high pressure system may once again be squeezed south by early next week.  This would shut off the moisture valve for a bit while shifting the wind flow pattern out of the southwest, which is less favorable for high ozone local ozone concentrations.  
We'll keep an eye on that as well as tonight's potential event.  Check back tomorrow for more.  Until then, have a good day!

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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