[ADEQ Forecasts] ADEQ Extends the Current Ozone Health Watch for the Phoenix Metro Area through Thursday, May 10, 2012

[forecasts@lists.azdeq.gov]

Health message for Wednesday May 09: U Unusually sensitive people should consider reducing prolonged or heavy exertion outdoors.

Health message for Thursday May 10: U Unusually sensitive people should consider reducing prolonged or heavy exertion outdoors. 

Synopsis and Discussion
*THE CURRENT OZONE HEALTH WATCH HAS NOW BEEN EXTENDED THRU THURSDAY MAY 10*
OZONE:  Ozone concentrations on Tuesday within the ADEQ forecast domain reached Heath Watch criteria (90-100AQI) at a half-dozen monitoring sites with near-exceedances at Cave Creek and North Phoenix.  On the plus side as of noon today ozone levels were running behind those of 24 hours ago and thunderstorms and their cloud debris were approaching the forecast area from the east.  On the negative side a strong and warm ridge aloft is forecast to begin building overhead from the west on Thursday.  A rapid increase in afternoon high temperatures and a relatively light wind regime - combined with decreasing debris clouds by the afternoon - is likely to mean a return to near-to-unhealthy ozone levels.  In addition, winds in the 5-10K' layer above and to the west of the metro area are forecast to become capable of transporting additional ozone and/or its precursors from the west as early as noon Thursday.  For these reasons the existing Ozone Health Watch has been extended thru Thursday with a High Pollution Advisory possible for Friday.      

PARTICLES:  Strong and gusty thunderstorm outflow winds and areas of dense blowing dust - mainly over the east and southeast Valley - are possible late this afternoon and evening.  As a result, some residual dust may occur on Thursday with some slightly elevated PM-10 (coarse particle) concentrations.  Going forward no strong winds and blowing dust are expected in the Phoenix metro area and PM-10 levels should be in the good range of the Air Quality Index. 


For more information, please visit our Web page:
www.azdeq.gov/environ/air/ozone/ensemble.pdf 

For transportation alternatives:
www.valleymetro.org 


If you have any questions or comments regarding this forecast please contact:

Mark Shaffer, Communications Director
Arizona Department of Environmental Quality
Office of Communications
1110 W. Washington St., Phoenix, AZ 85007
(602) 771-2215
ms15@azdeq.gov