[ADEQ Forecasts] ADEQ Issues an Ozone Health Watch for the Phoenix Metro Area for Saturday and Sunday, July 16 and 17, 2011

Fri Jul 15 13:00:24 MST 2011

Health message for Friday, July 15: Unusually sensitive people should
consider limiting prolonged exertion outdoors.

Health message for Saturday, July 16: Unusually sensitive people should
consider limiting prolonged exertion outdoors.

Synopsis and Discussion:
Thursday was another GOOD day air quality-wise, but that will be short
lived.  Particulates were up at the West 43rd Avenue monitor this
morning, likely pushing the day's concentration into the lower MODERATE
category.  Ozone levels are sharply increasing across the forecast area
this morning as well.  
This is a turning point NOAA's Ozone Forecast Model.  So far this
season, the model has been shaky at best.  Sometimes it hits the
forecasts closely, sometimes it fails miserably.  The forecast tomorrow
calls for a doubling of ozone concentrations from today's levels
resulting in exceedances stretching along the I-10 corridor from Phoenix
to Tucson.  Does this make sense?  A slight southeasterly flow will
return tomorrow as high pressure backs into the region from the east.
Several models have suggested this for the last week.  But the bigger
question: Is this enough to cause ozone levels to exceed?  I don't
believe so.  Concentrations may approach the standard, but I don't see
an exceedance that quickly.  We're issuing an Ozone Health Watch for
Saturday and Sunday.
Possible thunderstorms may help disperse ozone and precursors Sunday and
Monday.  Possible blowing dust from thunderstorm outflow could push PM10
levels well into the MODERATE range Sunday and Monday.  Recent rains
should help minimize overall impacts.

We'll have more for you on Sunday.  Until then, have a great weekend!

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For transportation alternatives:

If you have any questions or comments regarding this forecast please

Arizona Department of Environmental Quality
Office of Communications
1110 W. Washington St., Phoenix, AZ 85007
(602) 771-2215

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