[ADEQ Forecasts] ADEQ AIR QUALITY FORECAST FOR SATURDAY, SEPTEMBER 13, 2008

[forecasts@lists.azdeq.gov]

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

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

Health message for Friday, September 12:  Unusually Sensitive People
should consider limiting prolonged exertion outdoors.
 
Health message for Saturday, September 13:  Unusually Sensitive People
should consider limiting prolonged exertion outdoors.
 
Synopsis and Discussion
   High pressure will return to the forecast area this weekend, pushing
the upper-level trough of low pressure to the east.  The means that we
will see afternoon desert temperatures rebound to about 104 by Sunday
and Monday with moisture significantly decreasing across the region.
The average high temperature in Phoenix for this time of year is only
97, so this will be slightly above normal.  Towards the end of next
week, we could see moisture return as another tropical system may form
off the coast of western Mexico and move north into the Gulf of
California.  We'll keep our eyes on that.  With a little over two weeks
left in the official Arizona Monsoon Season, we'll take all the rain we
can get.
   Ozone season is beginning to wind down as well, with the season
ending here in Phoenix on September 30.  We could experience a few more
days of mid "Moderate" concentrations with high pressure driving the
local weather.  However, with the sun angle getting lower in the sky and
duration of intense overhead sunshine decreasing, it's getting more
difficult for ozone to form/accumulate and hold together over the
forecast area long enough to produce those unhealthy levels.  As troughs
of low pressure and associated cold fronts drop further and further
south, it won't be long before we start seeing Particulates replace
ozone as the pollutant of concern.  There won't be any health issues to
worry about this weekend as far as either of those pollutants go.  Check
back on Sunday for a look at the coming work-week.  Until then, have a
great weekend!  -J.Paul


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