[ADEQ Forecasts] ADEQ Daily Air Quality Forecast - Wednesday, September 14, 2011

Tue Sep 13 11:11:35 MST 2011

Health message for Tuesday September 13:  Unusually sensitive people
should consider reducing prolonged or heavy exertion outdoors.

Health message for Wednesday September 14:  Unusually sensitive people
should consider reducing prolonged or heavy exertion outdoors. 

Synopsis and Discussion
OZONE:  Just like on Monday, a moist and unstable air mass will likely
yield lots of afternoon cloud cover today along with a strong potential
for thunderstorm outflow winds.  These factors should again help to keep
local ozone production and accumulation well below average with highest
Air Quality Index values forecast to remain in the good range.  On
Wednesday and especially Thursday there are indications that weather
conditions will be highly conducive to a rapid increase in ozone
concentrations.  Daytime cloud cover will be on the decrease as drier
air moves overhead and afternoon surface winds are projected to be
mostly <15 mph on Wednesday and mostly light on Thursday.  Also,
additional outflow boundaries from the northeast or east could
dramatically alter the local ozone chemistry due to an influx of
additional precursors.   
PARTICLES:  On Monday evening another wind (up to 41mph) and blowing
dust (visibilities as low as one mile) event occurred that produced
unhealthy levels of PM-10.  The highest hourly concentration was
2,881.1ug/m3 at the Durango monitoring site at 8:00 p.m.  The
interaction of an upper level low moving east in the mid-latitude storm
track and ample summer monsoon moisture already in place will yield an
increased chance for significant thunderstorm activity in the Phoenix
metro area today along with an increased risk for unhealthy levels of
PM-10 due to areas of dense blowing dust generated by outflow
boundaries.  With the onset of a drying trend less activity is expected
on Wednesday and none is forecast for Thursday.  

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

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