[ADEQ Forecasts] ADEQ Extends Ozone Health Watch through Fri., May 1

[forecasts@lists.azdeq.gov]

http://www.azdeq.gov/ensemble.pdf

For transportation alternatives:
http://www.valleymetro.org

Health message for Thursday, April 30: Unusually sensitive people should
consider reducing prolonged or heavy outdoor exertion outdoors. 

Health message for Friday, May 01: Unusually sensitive people should
consider reducing prolonged or heavy outdoor exertion outdoors. 
 
Synopsis and Discussion
TODAY'S OZONE HEALTH WATCH HAS BEEN EXTENDED THRU FRIDAY MAY 01
The highest local ozone levels of the season thus far occurred on
Wednesday with eight monitoring sites above the 70-AQI level and three
sites reporting 80+AQI readings.  Most of the highest concentrations
occurred over downtown and nearby suburbs - in part due to a mostly
light afternoon wind regime.  This morning's ozone concentrations have
rebounded quickly at city center sites following overnight scavenging
that reduced hourly levels below 10 parts per billion at eight sites as
of 6:00 a.m. As of 10:00 a.m. hourly readings at most Valley sites were
in the 50-60ppb range and most were running ahead of those of 24 hours
ago.  Similar trends were observed at upstream monitors located in
Riverside and Imperial counties of CA.  Increasing and thickening high
clouds ahead of an approaching weather disturbance will occur on Friday,
with mostly cloudy skies forecast by the afternoon.  However, winds in
the 5-10K' layer will remain capable of additional ozone and precursor
transport from southern California, and despite the cloud cover,
afternoon temperatures will remain in the lower 90's.  Also, stronger
westerly surface winds will mean that communities located in the
northern and eastern Valley will have the highest risk for elevated
ozone levels. As a result, today's Ozone Health Watch has been extended
thru Friday.   -Reith   

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