[ADEQ Forecasts] ADEQ Daily Air Quality Forecast - Saturday, September 10, 2011

Fri Sep 9 12:33:29 MST 2011

Health message for Friday, September 9: Unusually Sensitive People
should consider limiting prolonged exertion outdoors.

Health message for Saturday, September 10: Unusually Sensitive People
should consider limiting prolonged exertion outdoors.

Synopsis and Discussion
Showers and thunderstorms will increase later Friday afternoon and
evening with peak intensity between 6 and 11 pm.  Another round is
possible Saturday afternoon and evening.  These storm are driven by an
area of low pressure dropping south near the AZ/CA/NV border.  With this
feature in play, storms are more likely to be sustained in through the
overnight hours without the help of the sun's surface heating.  Modeled
soundings indicate the possibility of some cells producing hail and
damaging straight-line winds.  With cooler weather expected Saturday and
Sunday, many people are planning outdoor activities.  It's important to
stay tuned to the local weather reports as storms can build rapidly.
Conditions will improve Sunday through early next week, though the
Valley will still have about a 20% chance for isolated storms each of
those days.

The clouds from the forecasted storms and the resulting winds from the
up/down drafts will help to keep ozone production down.  Highest
concentrations across the Valley may be held to the GOOD range of the
Air Quality Index (AQI) on Saturday and no higher than the lower
MODERATE on Sunday.  Dust is always a concern when thunderstorms are in
the forecast.  It's fairly unusual to see a classic dust storm (Haboob)
coming from the west-northwest, but there could be some isolated pockets
of dust kicked up around the Valley, especially since some agriculture
fields have recently been plowed.  Rain should help reduce the
likelihood of blowing dust.  Thus, we are forecasting PM10 and PM2.5
levels to be in the GOOD range Saturday and Sunday. 

Check back on Sunday for the latest.  Until then, have a great weekend!

For more information, please visit our Web page:

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

More information about the Forecasts mailing list